Power Inverter for Fridge in Sprinter

Johnp3337

Rookie Expediter
So I'm breaking in a 2013 Sprinter 2500Ext. Want to install a fridge on a power inverter. Already have a roof AC that runs off a gen. With the sprinter battery under the seat I have ideas on getting power to an inverter but curious on what size inverter , do i set up a 2nd battery? Don't want to ruin the alternator. What ideas and what do you have for a set up that is install friendly and alternator friendly. I bought a very small black and decker fridge 1.7 cubic foot. Please advise.
 

TonyD

Active Expediter
Hey John we run a 2010 sprinter with same style fridge. I have two golf cart batteries with isolator for charging. Generator for roof ac. Batteries run fridge tv laptop tablets phones some led lights etc. No problems.
 

bill98

Seasoned Expediter
go with ENGEL frig /freezer mine been on for 5 years its 12 run I run 3 house batteries and starter battery on my 2007 sprinter with a Shure power isolator between them alt is stock 180 amps realey charges above 60 amps on my xantrex meter use the book manage 12 volts can get it at most camper supplies places
 

Turtle

Administrator
Staff member
Retired Expediter
A 1500 Watt inverter will run everything you want to run.

But the first thing you need to know is the amp hour requirements, in order to properly size the battery (or batteries). The battery needs to be sized so that the amp draws between fully recharging the battery doesn't discharge the battery down to below 50% Depth of Discharge. If you fail to properly size the battery, and undersize it, or fail to fully charge it when charging, or let it discharge down to the point where lights dim and inverters scream, the classic "no problems" of today turns into the classic "these batteries are a piece of crap" 18-24 months later.

Batteries don't die, their owners kill them.

That fridge is listed as 130 Watts, 1.6 amps. In reality it's less than that, more like .9 amps as the Watts will vary from 80-120 most of the time. But that .9 amps is at 120 volts. At 12 volts (120 volts divided by 12 volts = 10) it's 10 x.9 amp = 9.0 (+ 10% for inverter loss) = 9.9 amps per hour on the average. Depending on ambient temps and other factors it will run as low as 5 amps and as high as 16 amps, but about 10 amps overall.

Over the course of 10 hours, assuming nothing else whatsoever is connected to the batteries, that's 100 amp hours removed from the battery. To keep the Depth of Discharge to no more than 50%, you need at least a 200 aH battery bank. If you routinely run the battery down below 50%, the lifespan of the battery will be greatly reduced (a year or two rather than 6 or 7 years, for an AGM or true deep cycle battery, like golf cart batteries). Marine deep cycle batteries are not the batteries for running a fridge. You can do it, but they won't last much more than 18 months.
 

xiggi

Veteran Expediter
Owner/Operator
You could also save on battery drain by running the fridge off the Gen when its running. Most likely have the reserve to do so.

Sent from my Fisher Price ABC-123.
 
Last edited:

mjmsprt40

Veteran Expediter
Owner/Operator
I'm sitting here thinking of generators, inverters, secondary batteries---- and a switch-panel that looks like it came out of a B-17. Which it probably did.

So, how do you keep your electricals down to a wild party in there???
 

TonyD

Active Expediter
Sometimes it feels that way. Lol. We have a power strip off the inverter and a box from generator. All the light loads run off inverter including fridge unless we choose to just switch plugs.
 

purgoose10

Veteran Expediter
Turtle had a photo of his layout and it was done right. Looks good too. It's in the C/Van set up guide somewhere.
 

mjmsprt40

Veteran Expediter
Owner/Operator
Earlier in this thread, there is some mention of running the inverter from the main starting battery. Whatever you do, don't do this. It's tempting, but if you do, you'll kill the starting battery way before its time. It was never designed for that type of load, and even if you somehow manage to never take the battery down below starting minimums you'll wreak havoc on what was meant to be only a temporary-load battery.

The starting battery is designed to do two things: Provide a high amount of current for a short (like, in ten-second bursts) time, and then having got the engine started it provides ballast/capacitance for your charging system which takes over running the electrical load once the engine is running. The alternator does all the heavy lifting in your van's main electrical system.

You NEED to set up a good set of golf-cart batteries to run the "house loads" like your inverter. Golf cart batteries are designed for all-day power drains, your starting battery isn't. It also has the advantage that even if you do drain the golf cart batteries down, you can still start the engine from the starting battery and eventually pull everything back together. You're not risking having to tell dispatch that you can't do a run because your refrigerator killed your battery and now your van won't start.
 

Turtle

Administrator
Staff member
Retired Expediter
For the record, you need deep cycle batteries, not necessarily golf cart batteries. It's just that golf cart batteries happen to be deep cycle batteries that are relatively cheap and readily available. They may or may not be the size you need.

If I used golf cart batteries in my van instead of the four aerial lift batteries I'm using, I would need at least ten, maybe twelve of the 6-volt golf cart batteries. My battery bank consists of two pair (four) of the aerial lift batteries and has a capacity of 610 amp hours (so I have 305 aH capacity down to 50% DoD).
 

Johnp3337

Rookie Expediter
Thanks for all the responses. Been running hard and haven't been able to repost to you all. I bought a deep cell and 1500 watt inverter and a trickle charger. Runs great and its not tied to my alternator. When we stop to sleep or wait for a load we run the fridge off the gen and plug in the charger for the battery.
 

Murraycroexp

Veteran Expediter
John, are you still happy with this setup? How big is your trickle charger? 2 amp? More?
I'm about to get a 1500 watt inverter. Bought a coffee maker this weekend and didn't even think about its power requirements. LOL!!
Hopefully 1500 watts is enough. But my next step is going to be to add a battery. I'm probably going to tie it to my charging system but am curious how yours panned out.
 

Moot

Veteran Expediter
Owner/Operator
I bought a deep cell and 1500 watt inverter and a trickle charger. Runs great and its not tied to my alternator. When we stop to sleep or wait for a load we run the fridge off the gen and plug in the charger for the battery.
If you are charging your deep cycle using your generator and a trickle charger why not buy and use a charger designed for charging deep cycle batteries and extend the life of the deep cycle?

Turtle?
 
Last edited:

Turtle

Administrator
Staff member
Retired Expediter
A trickle charger won't charge a battery, it'll only keep it topped off and counter the self-discharge when a battery is stored or unused for a period of time.
 

Murraycroexp

Veteran Expediter
10-4.
I'm really thinking I should tie it to the alternator. Just one less thing to carry. I really need to put some thought to this as I'm lost. I don't want to overdo it and waste money and payload capacity, but I prefer not to kill batteries and alternators prematurely.
 

Murraycroexp

Veteran Expediter
Ok, cool. That's a great $300-$400 solution to battery charging.
I'll add that to the info bank and see how much money I have to play with when the time comes.

I'm sure all this information is on here somewhere, but I just have not even begun to start looking for it. But I'd like to design my power bank system and not overdo it, wasting money, yet still design it with enough power.

What I have currently.
'06 Express 4.8. I think it's a 140-150 amp alternator.
Hyundai 2000 watt gen. 2200 max.
Cobra 400 watt PI. 800 watt max. Wired to crank batt.

What I leave plugged in to PI.
Laptop. Charging & using.
Jetpack. Charging & using.
iKicker. When listening to music and podcasts.

I need to replace my power inverter since it won't run my new coffee pot, a Mr Coffee for K-cups. I'm hoping 1500 watts is enough.

I also have a new heated mattress pad that I PLAN on using my generator for but I read that it only pulls 60-90 watts on high. Hope that's right. But seems like I could use it in a small inverter an a house battery. Maybe????

I do not yet have a house battery. I don't run the above listed "appliances" with my engine not running.
 
Top