Batt/Inverter

[TMD]

TMD
I have a question about suppling power for electrical equipment in my "B" unit.

currently I have a two batterie system in a 2004 sprinter van powering a 1000 watt inverter, this supplies power for a tv,frig and microwave. (This is not a dealer installed system). when the vehicle is off the avg run time before restarting the vehicle is 4 to 5 hrs.
my question is how can I get more batt time, do i need more or different batt, any help would be appreciated

 

[redytrk]

A third battery will prob give you about 6 to 7 hours. It should be deep cycle, and gel type if located inside the van.

Two batteries should be isolated away from your main starting battery.

If you dont want to isolate I would recomend a battery alarm,by Volt Minder. It can be set to go off when a pre-determined low voltage has been reached.
http://www.voltminder.com/
Hope this helps.

 

[TMD]

TMD
thanks for the input, so it looks like the 4hrs im getting now is normal for two batt, would it help to put 6volt batt in series? I have been told that would make a difference, but I have no idea and I dont want to just keep throughing money into it if its not going to help.

 

[davekc]

I would get two deep cycle marine batteries. They will last all night if they are the decent ones.

Sounds like you are using a standard grade battery. If using deep cycle batteries, and only getting four hours, either they are old or bad cell, or the following.
bad ground
bad lead to something it powers
weak or no ground (check ground on inverter)
issue with charging. This needs a volt meter to measure in and output of the system.

Hope that helps

Davekc

 

[Loose_Cannon47]

DO NOT PUT A 6 VOLT BATTERY IN SERIES. You will be applying 18+ volts to your inverter, for which it probably was not designed. Make sure you are using deep cycle batteries. A standard automotive (not deep cycle) battery will not live very long under deep discharge cycles. Go for the highest amphour rating battery that you can fit in the available space. Message me if you need some more ideas.

Loose

 

[mvbn1]

Hey! Just a quick question:

Let's say your using two marine, deep cycle batteries and a 1500watt inverter. Could you plug a trickle charger into the inverter, and then attach the trickle charger to the batteries? If so, wouldn't that give you extended power time? If you can't do it, why?

Just something to stir the grey matter.

 

[anadarkos1]

The ONLY way that would is if the charger charged at a higher rate then the loss incured. It's like perpeptual motion.

 

[greg334]

OK here is some advice.

First is make sure you know what your load of all the devices you have on the inverter, how many WATTS the fridge, microwave and TV use separately and put them on paper. If you have only amp ratings, multiply that by 120 and it will give you watts. Don’t multiply that by 115 or 110, trust me go for the higher number.

With the Fridge and microwave there is a startup wattage that sometimes needs as much as 30% more wattage to start the device, so always figure 30 to 40% headspace on your inverter.

Second is your battery supply, I would highly recommend Optima batteries. I have had a lot of experience with all kinds of batteries but I have yet found a better dependable battery. They are not cheap, mine cost $150 each on sale but worth it; no acid, can mount at any angle, etc…which battery would I recommend from the Optima line? The yellow top battery. It is made for high current and deep cycles. How many? Two would be good, but you may get away with one, it all depends on your average load.

Third I would isolate the entire inverter/battery system from the Sprinters electrical system either through a high current solenoid or though an RV isolation system. The latter is made for systems like this and you don’t have to worry about forgetting to “charge’ your battery system.

Most Important

I would recommend being careful with the wiring of the batteries/inverter and MAKE SURE you fuse the source (battery) end of the supply. I mean use the proper gage of wire for the size of the inverter plus 500 watts and make sure that you use some sort of wire loom and securely mount the wiring so not to cause a short and a fire. I personally use screw-in anchors from the computer industry opposed to nail anchors. Fusing the source simple is an additional precaution to prevent a fire. If you have a short in the wiring by the inverter and you have 10 feet of wire, at 900 amps per battery (900 times 12 is 10800 watts of heat), you will have one hall of a fire and no Sprinter without much warning.

Redytrk posted about voltminder, which I have only seen once. I thing it is a good idea that you have one. I know that some inverters really don’t like to be run under 11.5 volts so try not to discharge your batteries completely.