Just wondering if anyone has had the problems we're having. We own a 2007 Sterling Acterra with a 96" Bentz sleeper, Rigmaster APU, and a 1000 watt inverter. Early on, we noticed with the gen running and microwaving something for 5-7 minutes, the generator would actually shut down, and if we didn't crank the truck immediately, would kill the battery. So now if we are microwaving something that long we crank the truck. The Auto-on feature now kicks on every 30-45 minutes when sitting with the engine off. Also recently, the QC actually shuts itself off when the auto-start engages. I had the truck batteries tested, the mech said they were slightly weak and charged them the whole time we were having a pm done and this helped for a day or two, then things returned to status quo. I figure if I bought top of the line high cranking power batteries, this would stop for awhile but the problem would return. Am suspicious of the 1000 watt inverter, is this much too small for a 96" sleeper with 1750 watt microwave and refrigerator/freezer? My guess would be a 2000 or 3000 watt inverter and new batteries might solve this, but I don't really want to spend another 500-1000 bucks on this if I can avoid it. Not sure if we have a sleeper, truck, generator or inverter issue. What do y'all think?
Electrical issues
- Thread starter Caldonna
- Start date
I can't imagine Bentz putting that small an inverter in the unit but I think that's your problem. I have the same sleeper and APU and my inverter is 2250 watts continuous.
Leo Bricker, 73's K5LDB
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Owner, Panther trucks 5508, 5509, 5641
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Leo Bricker, 73's K5LDB
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Owner, Panther trucks 5508, 5509, 5641
EO Forum Moderator
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Support the entire Constitution, not just the parts you like.
Read this thread and follow the links that are further down in some of the replies. It may provide some clues. And yes, a 1,000 watt inverter seems small. You might also have your alternator checked. It may be working well enough to keep your dash board warning lights turned off, but not well enough to fully charge your batteries.
http://www.expeditersonline.com/dcforum/DCForumID16/1857.html#5
http://www.expeditersonline.com/dcforum/DCForumID16/1857.html#5
riverrat2000
Seasoned Expediter
also check all of you grounding connections
jaminjim
Veteran Expediter
A 1k inverter is very small. But I don't see how a small inverter would drain the battries more than a larger one.
The truck sounds like it should still be under waranty (sp). Take it to the dealer you bought it from and tell them your problem and have them fix it for free. Sounds like it was bought from John in Knoxville. Call him and tell him about your issues, that way they can have some ideas to fix it when you get there.
The truck sounds like it should still be under waranty (sp). Take it to the dealer you bought it from and tell them your problem and have them fix it for free. Sounds like it was bought from John in Knoxville. Call him and tell him about your issues, that way they can have some ideas to fix it when you get there.
Just a couple of observations. Your inverter is likely over 1000watts. I would recheck. A 1750 watt microwave would trip its breaker or toast a fuse.
Our class 8 Sterling has the same inverter output as Leo's. Actually, we have the same identical truck.
My guess is as mentioned, a bad ground or connection, or a bad battery(s).
How did they test your battery? A simple battery test is no good. You have to actually have a load test done on it.
Our Sterling batteries went by the wayside after 6 months. We went to a much better grade than the standard manufactures battery.
Warranty on a Freightliner/Sterling battery is pretty much worthless as well. Buy some real batteries if everything else checks out.
Davekc
owner
23 years
PantherII
EO moderator
Our class 8 Sterling has the same inverter output as Leo's. Actually, we have the same identical truck.
My guess is as mentioned, a bad ground or connection, or a bad battery(s).
How did they test your battery? A simple battery test is no good. You have to actually have a load test done on it.
Our Sterling batteries went by the wayside after 6 months. We went to a much better grade than the standard manufactures battery.
Warranty on a Freightliner/Sterling battery is pretty much worthless as well. Buy some real batteries if everything else checks out.
Davekc
owner
23 years
PantherII
EO moderator
Thanks for all the info. The microwave and inverter were stock items. Will have load test done on batteries next time we're home. I was guessing we would have to replace, but since the truck is less than 1 year old, I was hoping otherwise. Went back and re-read the manual for the inverter, guess its continuing education! Thanks again for all the posts.
Tennesseahawk
Veteran Expediter
I agree about the load test. Just charging them does nada when you have one bad battery dragging down the rest. You might also consider a couple of spare batteries hooked up (some say) just to the starter.
As for your inverter, I suggest 2500 or more. You can get some good deals on ebay for brand new models. I got a 3000 watt for $165, new in box. Just make sure you read it to make sure you're getting new, not refurbished.
-True independence can only be gained if you're trully independant.
As for your inverter, I suggest 2500 or more. You can get some good deals on ebay for brand new models. I got a 3000 watt for $165, new in box. Just make sure you read it to make sure you're getting new, not refurbished.
-True independence can only be gained if you're trully independant.
riverrat2000
Seasoned Expediter
if yo want to spend the money the gel cell batteries are the way to go somewhere around $300.00 bucks a pop, you can find them at a lot of the thermoking dealers
What ever you buy, make sure it has at least a three to five year warranty or better. The ones Freightliner/Sterling sell are junk. Plus they only have a year warranty. For less money you can get a 3 year commercial battery at Autozone for $90.00 dollars.
Davekc
owner
23 years
PantherII
EO moderator
Davekc
owner
23 years
PantherII
EO moderator
I'd recommend separating out the starting batteries from the house bank batteries. Use the starting batteries to start the thing, use the house bank to run everything else. I'd go with Dave on the Autozone batteries for the truck. That or some higher end Deka commercial batteries. And then I'd get AGM batteries for the house bank, like Concord Lifeline or Discover-Energy batteries in the golf cart or L-16 footprint (6-volt batteries). The L-16 footprint is also known as floor scrubber batteries and are used in floor scrubbers (duh) and in some high lifters (aerial lift), electric vehicles, boats, RV's, lots of applications. Biggest physical difference between golf cart and L-16's is the L-16's are significantly taller (taller lead plates).
Someone mentioned gel batteries, which can be a good choice, but there are both ups and downs to them. The upside is they can withstand deeper discharges (more than 50% Depth of Discharge) more often. The downside is they are by far the most picky when it comes to charging requirements, and if you overcharge them even slightly just once, or charge them at even half a volt too high, they're toast. With gel batteries both the voltage and the amps must be strictly controlled during charging.
AGM's require strict charging, but only insofar as the voltage (between 14.2-14.4 volts). They will accept as many amps as you can feed them, which means they will recharge much faster.
As with most everything else, but especially with batteries, you get what you pay for. The more you spend, however, the more critical it becomes to treat them properly. That means using a battery monitor to ensure they never are discharged more than 50% (which means getting twice as many batteries as your amp requirements between chargings) and it means using a 3-stage charging system, either from the charger via a generator or from a 3-stage charging regulator from the alternator.
L-16 batteries are $325 each, and you need two of them to make 12 volts. Two or four of these represents a substantial investment, but if you treat them properly they will last you 5-8 years.
The magical thing about the golf cart, and especially the L-16 footprint, is the lead plates are not only thicker, but are much taller than regular batteries, which means you'll not only get more amp hours packed into the battery, but you'll actually get a disproportionately longer reserve time in minutes compared to other batteries of equal amp hour ratings.
Concord doesn't make an L-16 battery, but they make one that's really, really close, the GPL-6CT, 300 amp hours, 93 pounds each. Again, you'll need two to make a single 12-volt battery, which would give you 12 volts, 300 amp hours, 186 pounds. But at a 25 amp sustained draw, you'll get 690 minutes of reserve time. At an 8 amp sustained draw, you'll get 2205 minutes. Best price I know of on the 6CT is $315.97.
http://www.thesolar.biz/LIFELINE Batteries for Marine and RV.htm
Discover energy makes a true L-16, the EVL16A-A, and is 390 amp hours, 123 pounds each. That's 246 pounds for a pair. But, at a 25 amp sustained draw, you'll get 915 minutes, and at 8 amps you'll get a serious 2977 minutes. (remember, all these "minute" figures would need to be cut in half to prevent you from discharging more than 50%). Best price on the EVL16A-A is $319.97.
http://www.thesolar.biz/Discover_batteries.htm
(they only list the MSRP of $580.15 on this page, but they really do cost only $319.97).
(Concord) http://www.lifelinebatteries.com/rv.php
(Discover Energy) http://tinyurl.com/ys7fq4
Slow and steady, even in expediting, wins the race - Aesop
Someone mentioned gel batteries, which can be a good choice, but there are both ups and downs to them. The upside is they can withstand deeper discharges (more than 50% Depth of Discharge) more often. The downside is they are by far the most picky when it comes to charging requirements, and if you overcharge them even slightly just once, or charge them at even half a volt too high, they're toast. With gel batteries both the voltage and the amps must be strictly controlled during charging.
AGM's require strict charging, but only insofar as the voltage (between 14.2-14.4 volts). They will accept as many amps as you can feed them, which means they will recharge much faster.
As with most everything else, but especially with batteries, you get what you pay for. The more you spend, however, the more critical it becomes to treat them properly. That means using a battery monitor to ensure they never are discharged more than 50% (which means getting twice as many batteries as your amp requirements between chargings) and it means using a 3-stage charging system, either from the charger via a generator or from a 3-stage charging regulator from the alternator.
L-16 batteries are $325 each, and you need two of them to make 12 volts. Two or four of these represents a substantial investment, but if you treat them properly they will last you 5-8 years.
The magical thing about the golf cart, and especially the L-16 footprint, is the lead plates are not only thicker, but are much taller than regular batteries, which means you'll not only get more amp hours packed into the battery, but you'll actually get a disproportionately longer reserve time in minutes compared to other batteries of equal amp hour ratings.
Concord doesn't make an L-16 battery, but they make one that's really, really close, the GPL-6CT, 300 amp hours, 93 pounds each. Again, you'll need two to make a single 12-volt battery, which would give you 12 volts, 300 amp hours, 186 pounds. But at a 25 amp sustained draw, you'll get 690 minutes of reserve time. At an 8 amp sustained draw, you'll get 2205 minutes. Best price I know of on the 6CT is $315.97.
http://www.thesolar.biz/LIFELINE Batteries for Marine and RV.htm
Discover energy makes a true L-16, the EVL16A-A, and is 390 amp hours, 123 pounds each. That's 246 pounds for a pair. But, at a 25 amp sustained draw, you'll get 915 minutes, and at 8 amps you'll get a serious 2977 minutes. (remember, all these "minute" figures would need to be cut in half to prevent you from discharging more than 50%). Best price on the EVL16A-A is $319.97.
http://www.thesolar.biz/Discover_batteries.htm
(they only list the MSRP of $580.15 on this page, but they really do cost only $319.97).
(Concord) http://www.lifelinebatteries.com/rv.php
(Discover Energy) http://tinyurl.com/ys7fq4
Slow and steady, even in expediting, wins the race - Aesop
Holy Guacamole! I read the post that Phil linked earlier regarding batteries and between that and this last post Turtle, I deem you Jedi Master of all things battery! Wow! Thanks to you and all contributers for the great education! Shop is searching for an electrical drain on the batteries, will make a decision soon. Got to get back out on the road.
We went the way of Turtle's explanation. We are running three truck batteries on one side, and golf cart batteries on the other with a solenoid between them for charging. It actually is working quite well.
Davekc
owner
23 years
PantherII
EO moderator
Davekc
owner
23 years
PantherII
EO moderator
And I've only scratched the surface. Things can get much more complicated, actually. Like, Greg brought up a question in that other thread that I neglected to address, which is why would they put a 30-60 amp alternator on an APU.
Basically, it's because most starter batteries require a charging current of no more than 30 amps, because more than that, and the acid begins to boil. Trying to force 100, 200 amps into a battery that can only take 30 is about the same as getting a high pressure washer stream in the face from about 6 inches away - it's gonna get messy.
Starter batteries (car, truck, commercial, these are generally flooded lead acid, or flooded maintenance free, which is also known as sealed lead acid, or SLA) have relatively high internal resistance, so when current (amps) are fed into them (or drawn out at a high sustained rate) they heat up. Most of these batteries can be charged with a maximum of 20% to 30% of the amp hour capacity of the battery. A 100 amp hour starting battery can be charged at a rate of about 25-30 amps, give or take. More than that and they'll just sit there and cook in their own juices, literally.
That's why APU's come with either a 30-60 amp alternator, or they come plugged into a battery charger that outputs 30 amps. With most everything other than gel and AGM batteries, the slower you can trickle the amps back in the better.
To over-simplify things, there are two kinds of batteries, starting and deep cycle. There are, of course, many more types, but for us, we deal primarily with these two types of batteries.
Starting batteries are designed to punch out a buttload of amps in one whack to start the engine, those cranking and cold-cranking amps. A big diesel engine requires a lot of cranking amps, which is why trucks generally have multiple batteries, because the cranking amps add up with each battery. Starter batteries punch out a lot of cranking amps, but only for a few seconds, and over those few seconds very few actual amp hours are drained from the battery. So, a charger that puts 30 amps at a time back in isn't a problem. They'll be back to fully charged in no time at all.
The thinner lead plates of starting batteries are not designed for deep discharges. They do not last very long under a sustained heavy amp draw, and do not recover very well when deeply discharged. Most truck batteries, however, have somewhat thicker plates so they do exhibit some deep cycle properties, like they can be used in limited deep cycle operations, like small inverter loads with relatively low amp draws.
These types of thicker plated batteries are pretty much the same as marine deep cycle batteries, which, technically, doesn't even exist. There's no such thing as a "marine" battery insofar as a type, construction or chemistry that makes it any different than any other starting battery with thicker plates. It's marketing, pure and simple. A marine battery is a starting battery that will not fold under a sustained draw, like with a trolling motor, for example. Hook your car battery up to a trolling motor and you won't get very far out of the marina.
By the same token, a marine starting battery, or a truck battery (Group 31 is the most popular size for both) can handle some deep cycle loads, as well as have enough juice to start a motor (if you have enough of them wired together for a diesel). But you can't expect a marine or truck battery to be up to the task of a genuine deep cycle battery.
Marine and truck batteries are more accurately referred to as hybrid batteries, in that they are designed for starting, but they have the extra lead and thicker plates to allow them to deal with sustained low amp draws without draining dry within a couple of hours. So, when someone says they have marine batteries, whether they know it or not, they have a hybrid battery, a starting battery on steroids.
Deep cycle batteries have much thicker plates and can sustain heavy amp draws for longer periods of time. Deep cycle batteries can be gel, AGM, maintenance free, and traditional flooded lead acid that you have to add distilled water to periodically after it boils off during charging. For our purposes, the only deep cycle batteries worth considering are the gels and the AGMs, unless you have relative modest amp hour requirements (between full recharges).
If your requirements are small, then regular "marine", truck, commercial, el cheapo "deep cycle" hybrid batteries are fine. The Wal Mart Everstart Maxx marine batteries have an 18-month full replacement warranty, so if you murder your batteries and have to replace them every year, it's a free replacement.
By modest, I mean something along the lines of a total of 50 amp hours drawn between full recharges. Know what your amp hour requirements are. Everything depends on it.
The thicker plates and design of AGM and gels give them very low internal resistance, which means they don't heat up nearly as much when being recharged. Most AGMs in particular, can be fed as many amps as your cable thickness will allow, provided you have a constant voltage. The lower the internal resistance, the more efficient the batteries are, which means you can get more amp hours out of them, less energy is lost in resistance heat loss.
Gel batteries are an excellent choice for deep cycle operations. They don't handle very high draws very well (20 minutes to microwave a lasagna, a circular saw, electric heater), but they do handle deeper discharges better than AGMs and other battery types. You can discharge a gel to as much as 90% DoD (Depth of Discharge) a few times and the batteries won't be any worse for wear. But the most important thing about gels is that they must, absolutely, be charged under the strictest of conditions. Voltage and amps is critical. If your alternator's voltage regulator is off by just a half a volt too much for some reason, just one time, the gels will be cooked and they won't hold a charge for diddly (or anyone else) for very long. Gels that lasted for 18 hours to 50% DoD yesterday will only last an hour or so today, and tomorrow it gets worse.
AGM batteries are nearly as picky, only they won't die horrible death if you screw up once or twice like gels will. (Although rarely necessary, you can even "equalize" AGM batteries, something that will make a gel battery just melt right in front of your eyes) That can be an important factor if you are going to trust $300 a pop ($600 for a pair of 6-volt) batteries to a truck or APU's regulator. If your APU comes with a high quality charger which charges the batteries, instead of charging directly off the alternator, then you can trust that a little (a lot) more. But still, all the benefits of gels are in AGM, plus other benefits, like being able to mount AGM batteries in any orientation except upside down. Can't do that with gels. AGM's can take a good rattling, like in Detroit or Chicago. Gels like it smooth, like on a boat.
But, both gels and AGMs will not outgas hydrogen gas under normal, and even most abnormal conditions. They are safe to place under your bunk and inside a non-vented space.
Now, if you're like Dave and you separate out your starter battery bank from your house bank via a continuous duty solenoid (or better would be a true isolator, Schotkey isolator, or a voltage sensing battery combiner), then all that really matters is that both the house and starter batteries be as close as possible in battery type. You don't want a starter bank that requires one charging voltage and the house bank to require a radically different voltage, because the regulator will only output one voltage for both. And then the house bank needs a lot of amps put back into it, but the starting battery is already fully charged, the solenoid combines the batteries so that the starting battery bank is subjected to the same charging voltage and currents that the house bank requires.
If the batteries in both banks are relative the same type, it's not a major problem, particularly if you have regular run-o-the-mill truck starting and golf cart batteries, as they are cheap and easy to replace every year or two.
And of course, if you have your batteries completely separated, with the starting batteries used for starting and the truck's alternator handling those, and an APU handling the deep cycle batteries, then each will get the proper voltage, as long as the APU's voltage and current can be properly adjusted, as with a battery charger that can be programmed for the deep cycle batteries. (wow, what a sentence).
The real problems come into play when you have a Sprinter, or something like it, as the Bosch alternator and regulator think that 13.5 volts should be plenty for anybody. And it is enough for the starter battery in the Sprinter. But it's nowhere near enough for even the el cheapo Wal Mart Everstart Maxx maintenance free marine deep cycle batteries that aren't really deep cycle but I'll call them that, anyway, much less for a 14.2-14.4 volt AGM battery bank. At 13.3, 13.5, 13.8 volts, putting 200-250 amp hours back into three of the Everstart Maxx batteries can take days to fully recharge, and that's with nothing drawing amps while it's being recharged.
For the Sprinter and other vans, trucks, cars, trains and catamarans with a low-ish regulator output, you need to turn the internal voltage regular of the alternator into an external voltage regulator, and you need to do it with one that can be programmed for the specific type of battery in the house bank. Balmar makes one, the Max Charge ($300), that is a three-stage charger/regulator that can be set to charge AGM batteries. In effect, you take the van's alternator and rig it up to charge the house bank's AGM's with a regulated charge (14.2-14.4 volts), connecting the house bank directly to the new external regulator, taking the starter battery out of the equation.
But then, how do you charge the starter battery, since it needs far fewer volts and amps, and for less time? Balmar makes the Duo Charge regulator ($250), which is essentially a solenoid voltage sensing battery combiner, that is hooked to both the house bank and the external regulator, and it takes the field output from the regulator and the re-regulates it for the starter battery. The house bank is separated from the starter battery when not being charged, and the two banks are combined when charging, but they each receive the proper charging parameters. One alternator, two regulators, both regulators are programmable for the proper charging, including temperature sense voltage compensation at the alternator (don't want the alternator to get too hot and burn up) and the batteries (hot batteries require less volts, cold batteries require more volts).
The Balmar stuff, they make regulators and alternators, and are almost exclusively for marine applications. They do boats. But what we do out on the road is nearly identical to that of a boat. More like a sailboat, but really any boat that doesn't pull into the marina and plug into shore power very often.
Incidentally, the Duo Charge, which regulates the starter battery, has a maximum output of 30 amps.
So you see it can get very complicated. It's less complicated if your amp hour requirements are low and/or you have an APU. The higher your amp hour requirements, the more likely it is you need higher end batteries. But with higher end batteries comes regulated charging complications, and closer battery monitoring. In any case, I cannot recommend a battery monitor too strongly, unless you are running with cheap batteries that you don't mind replacing an a regular basis (which is certainly the case for many people). Without a battery monitor (like the Xantrex Battery Monitor) you simply cannot determine the state of charge of your batteries (except, of course, with traditional wet cell batteries where you can actually measure the specific gravity of the cells).
A voltmeter to measure the voltage, contrary to popular belief, does not work. It's a rough ballpark, at best, and that assumes the battery has been at rest with no loads whatsoever for at least one hour.
To get an indication of the battery's state of charge, you can do either of the following:
A- Disconnect everything from the battery, wait an hour, hunt down the voltmeter, take a reading that's plus/minus anywhere between 5% and 20%
or
B- Look at the battery monitor
You choose. :+
I'll stop now, even though I could keep on going, and going, and going...
Slow and steady, even in expediting, wins the race - Aesop
Basically, it's because most starter batteries require a charging current of no more than 30 amps, because more than that, and the acid begins to boil. Trying to force 100, 200 amps into a battery that can only take 30 is about the same as getting a high pressure washer stream in the face from about 6 inches away - it's gonna get messy.
Starter batteries (car, truck, commercial, these are generally flooded lead acid, or flooded maintenance free, which is also known as sealed lead acid, or SLA) have relatively high internal resistance, so when current (amps) are fed into them (or drawn out at a high sustained rate) they heat up. Most of these batteries can be charged with a maximum of 20% to 30% of the amp hour capacity of the battery. A 100 amp hour starting battery can be charged at a rate of about 25-30 amps, give or take. More than that and they'll just sit there and cook in their own juices, literally.
That's why APU's come with either a 30-60 amp alternator, or they come plugged into a battery charger that outputs 30 amps. With most everything other than gel and AGM batteries, the slower you can trickle the amps back in the better.
To over-simplify things, there are two kinds of batteries, starting and deep cycle. There are, of course, many more types, but for us, we deal primarily with these two types of batteries.
Starting batteries are designed to punch out a buttload of amps in one whack to start the engine, those cranking and cold-cranking amps. A big diesel engine requires a lot of cranking amps, which is why trucks generally have multiple batteries, because the cranking amps add up with each battery. Starter batteries punch out a lot of cranking amps, but only for a few seconds, and over those few seconds very few actual amp hours are drained from the battery. So, a charger that puts 30 amps at a time back in isn't a problem. They'll be back to fully charged in no time at all.
The thinner lead plates of starting batteries are not designed for deep discharges. They do not last very long under a sustained heavy amp draw, and do not recover very well when deeply discharged. Most truck batteries, however, have somewhat thicker plates so they do exhibit some deep cycle properties, like they can be used in limited deep cycle operations, like small inverter loads with relatively low amp draws.
These types of thicker plated batteries are pretty much the same as marine deep cycle batteries, which, technically, doesn't even exist. There's no such thing as a "marine" battery insofar as a type, construction or chemistry that makes it any different than any other starting battery with thicker plates. It's marketing, pure and simple. A marine battery is a starting battery that will not fold under a sustained draw, like with a trolling motor, for example. Hook your car battery up to a trolling motor and you won't get very far out of the marina.
By the same token, a marine starting battery, or a truck battery (Group 31 is the most popular size for both) can handle some deep cycle loads, as well as have enough juice to start a motor (if you have enough of them wired together for a diesel). But you can't expect a marine or truck battery to be up to the task of a genuine deep cycle battery.
Marine and truck batteries are more accurately referred to as hybrid batteries, in that they are designed for starting, but they have the extra lead and thicker plates to allow them to deal with sustained low amp draws without draining dry within a couple of hours. So, when someone says they have marine batteries, whether they know it or not, they have a hybrid battery, a starting battery on steroids.
Deep cycle batteries have much thicker plates and can sustain heavy amp draws for longer periods of time. Deep cycle batteries can be gel, AGM, maintenance free, and traditional flooded lead acid that you have to add distilled water to periodically after it boils off during charging. For our purposes, the only deep cycle batteries worth considering are the gels and the AGMs, unless you have relative modest amp hour requirements (between full recharges).
If your requirements are small, then regular "marine", truck, commercial, el cheapo "deep cycle" hybrid batteries are fine. The Wal Mart Everstart Maxx marine batteries have an 18-month full replacement warranty, so if you murder your batteries and have to replace them every year, it's a free replacement.
By modest, I mean something along the lines of a total of 50 amp hours drawn between full recharges. Know what your amp hour requirements are. Everything depends on it.
The thicker plates and design of AGM and gels give them very low internal resistance, which means they don't heat up nearly as much when being recharged. Most AGMs in particular, can be fed as many amps as your cable thickness will allow, provided you have a constant voltage. The lower the internal resistance, the more efficient the batteries are, which means you can get more amp hours out of them, less energy is lost in resistance heat loss.
Gel batteries are an excellent choice for deep cycle operations. They don't handle very high draws very well (20 minutes to microwave a lasagna, a circular saw, electric heater), but they do handle deeper discharges better than AGMs and other battery types. You can discharge a gel to as much as 90% DoD (Depth of Discharge) a few times and the batteries won't be any worse for wear. But the most important thing about gels is that they must, absolutely, be charged under the strictest of conditions. Voltage and amps is critical. If your alternator's voltage regulator is off by just a half a volt too much for some reason, just one time, the gels will be cooked and they won't hold a charge for diddly (or anyone else) for very long. Gels that lasted for 18 hours to 50% DoD yesterday will only last an hour or so today, and tomorrow it gets worse.
AGM batteries are nearly as picky, only they won't die horrible death if you screw up once or twice like gels will. (Although rarely necessary, you can even "equalize" AGM batteries, something that will make a gel battery just melt right in front of your eyes) That can be an important factor if you are going to trust $300 a pop ($600 for a pair of 6-volt) batteries to a truck or APU's regulator. If your APU comes with a high quality charger which charges the batteries, instead of charging directly off the alternator, then you can trust that a little (a lot) more. But still, all the benefits of gels are in AGM, plus other benefits, like being able to mount AGM batteries in any orientation except upside down. Can't do that with gels. AGM's can take a good rattling, like in Detroit or Chicago. Gels like it smooth, like on a boat.
But, both gels and AGMs will not outgas hydrogen gas under normal, and even most abnormal conditions. They are safe to place under your bunk and inside a non-vented space.
Now, if you're like Dave and you separate out your starter battery bank from your house bank via a continuous duty solenoid (or better would be a true isolator, Schotkey isolator, or a voltage sensing battery combiner), then all that really matters is that both the house and starter batteries be as close as possible in battery type. You don't want a starter bank that requires one charging voltage and the house bank to require a radically different voltage, because the regulator will only output one voltage for both. And then the house bank needs a lot of amps put back into it, but the starting battery is already fully charged, the solenoid combines the batteries so that the starting battery bank is subjected to the same charging voltage and currents that the house bank requires.
If the batteries in both banks are relative the same type, it's not a major problem, particularly if you have regular run-o-the-mill truck starting and golf cart batteries, as they are cheap and easy to replace every year or two.
And of course, if you have your batteries completely separated, with the starting batteries used for starting and the truck's alternator handling those, and an APU handling the deep cycle batteries, then each will get the proper voltage, as long as the APU's voltage and current can be properly adjusted, as with a battery charger that can be programmed for the deep cycle batteries. (wow, what a sentence).
The real problems come into play when you have a Sprinter, or something like it, as the Bosch alternator and regulator think that 13.5 volts should be plenty for anybody. And it is enough for the starter battery in the Sprinter. But it's nowhere near enough for even the el cheapo Wal Mart Everstart Maxx maintenance free marine deep cycle batteries that aren't really deep cycle but I'll call them that, anyway, much less for a 14.2-14.4 volt AGM battery bank. At 13.3, 13.5, 13.8 volts, putting 200-250 amp hours back into three of the Everstart Maxx batteries can take days to fully recharge, and that's with nothing drawing amps while it's being recharged.
For the Sprinter and other vans, trucks, cars, trains and catamarans with a low-ish regulator output, you need to turn the internal voltage regular of the alternator into an external voltage regulator, and you need to do it with one that can be programmed for the specific type of battery in the house bank. Balmar makes one, the Max Charge ($300), that is a three-stage charger/regulator that can be set to charge AGM batteries. In effect, you take the van's alternator and rig it up to charge the house bank's AGM's with a regulated charge (14.2-14.4 volts), connecting the house bank directly to the new external regulator, taking the starter battery out of the equation.
But then, how do you charge the starter battery, since it needs far fewer volts and amps, and for less time? Balmar makes the Duo Charge regulator ($250), which is essentially a solenoid voltage sensing battery combiner, that is hooked to both the house bank and the external regulator, and it takes the field output from the regulator and the re-regulates it for the starter battery. The house bank is separated from the starter battery when not being charged, and the two banks are combined when charging, but they each receive the proper charging parameters. One alternator, two regulators, both regulators are programmable for the proper charging, including temperature sense voltage compensation at the alternator (don't want the alternator to get too hot and burn up) and the batteries (hot batteries require less volts, cold batteries require more volts).
The Balmar stuff, they make regulators and alternators, and are almost exclusively for marine applications. They do boats. But what we do out on the road is nearly identical to that of a boat. More like a sailboat, but really any boat that doesn't pull into the marina and plug into shore power very often.
Incidentally, the Duo Charge, which regulates the starter battery, has a maximum output of 30 amps.
So you see it can get very complicated. It's less complicated if your amp hour requirements are low and/or you have an APU. The higher your amp hour requirements, the more likely it is you need higher end batteries. But with higher end batteries comes regulated charging complications, and closer battery monitoring. In any case, I cannot recommend a battery monitor too strongly, unless you are running with cheap batteries that you don't mind replacing an a regular basis (which is certainly the case for many people). Without a battery monitor (like the Xantrex Battery Monitor) you simply cannot determine the state of charge of your batteries (except, of course, with traditional wet cell batteries where you can actually measure the specific gravity of the cells).
A voltmeter to measure the voltage, contrary to popular belief, does not work. It's a rough ballpark, at best, and that assumes the battery has been at rest with no loads whatsoever for at least one hour.
To get an indication of the battery's state of charge, you can do either of the following:
A- Disconnect everything from the battery, wait an hour, hunt down the voltmeter, take a reading that's plus/minus anywhere between 5% and 20%
or
B- Look at the battery monitor
You choose. :+
I'll stop now, even though I could keep on going, and going, and going...
Slow and steady, even in expediting, wins the race - Aesop
greg334
Veteran Expediter
Turtle,
I pointed out that there is some sort of cheapness with the APU's on the market and they are deficient in the charging of batteries. I fail to see where a 30 to 60 amp alternator is sufficient when the sale of the APU is predicated on the idea that it can be used to charged batteries at the same time you can use cab accessories, i.e. microwave - 30 amps falls too short and 60 barely gets the job done in a limited time. We are not talking about a 500 amp starting cycle where it only lasts 30 seconds and the recovery starts but rather a 2 to 5 minute 100 to 125 amp draw on the batteries.
I would say that the APU designers have taken steps to design a system that uses some technology, like low voltage sensing but there is a lack of real battery charging control in what I have seen on the market.
There is no reason that the alternator on an APU should be less then 120 amps, with the proper regulation and controls, the battery bank can have a proper charge at the length of time needed. This would actually mean that is would run for the duration of a proper charge.
I pointed out that there is some sort of cheapness with the APU's on the market and they are deficient in the charging of batteries. I fail to see where a 30 to 60 amp alternator is sufficient when the sale of the APU is predicated on the idea that it can be used to charged batteries at the same time you can use cab accessories, i.e. microwave - 30 amps falls too short and 60 barely gets the job done in a limited time. We are not talking about a 500 amp starting cycle where it only lasts 30 seconds and the recovery starts but rather a 2 to 5 minute 100 to 125 amp draw on the batteries.
I would say that the APU designers have taken steps to design a system that uses some technology, like low voltage sensing but there is a lack of real battery charging control in what I have seen on the market.
There is no reason that the alternator on an APU should be less then 120 amps, with the proper regulation and controls, the battery bank can have a proper charge at the length of time needed. This would actually mean that is would run for the duration of a proper charge.