Dedicated Battery to power cooler, solar re-charged

[obiwancanoli]

I recently acquired a powered mobile cooler/freezer which I plan to house in one of the storage bays in my Class A. In this configuration, it can be powered by an accessible AC plug, and will sit on a slide-out tray for ease of access. The cooler measures 33 L x 20 H x 19 Deep.

It can also be powered via DC, and would be an easy fit for the back of my SUV, where I have a DC lighter-type plug for access. DC rated consumption is average of 1.43 Ah/h, and includes 3-stage battery protection system, preventing deep draw, and dead battery.

I'd like to install a separate battery, to power the cooler when vehicle is not running, and set it up so that this battery may be recharged via a portable solar panel (120W). The battery would be encased in a plastic case designed for such purpose, but I'm unsure how to put something like this together. Doesn't seem difficult, just need to know the right components to do so... I'm considering AGM, but open to Lithium for all the reasons one would want it, including fast recharging.

Cooler manufacturer offers a LI 40Ah batter for $850, but for that, I can pick up a 100Ah and hopefully secure the components to achieve my objective...

Anyone done something like this? Sure would appreciate the many voices of experience here... thanks!

[mr_andyj]

Mount the battery close to the fridge. Run the fridge to the battery to get power. Super easy.
For charging use a solar charge controller connected to your new solar panel.
Also, connect it to the vehicle alternator for when you drive. Use a solenoid switch so it is electrically connected to the alternator/starting battery when the motor is running and when ignition is off the switch turns off. Hint, you can use the radio ignition power feed to tell the solenoid switch when the vehicle is on/off.

For charging off of shoreline you can put a switch to connect it to the coach batteries that are being charged, or you can add a new charger just for your fridge battery, and when it is powered from shoreline it will charge.

[wa8yxm]

Setting up a solar system is very straight forward

Solar panel----Solar Controller----Battery----Load (See note)

The load may also be connected to the controller depending on the max current draw.. The configuration above is in my "Living room" running a radio.
It is the one the battery maker suggested

I would recommend a LiFePo4 battery for reasons including the one you stated.

Advantage of connecting load to controller: Low voltage protection
Advantage of LiFePo4.. You might not need low voltage protection

Disadvantage of solar: If battery is not big enough cooler may cease to cool due to low voltage. This happens with LiFePo-4 very late in the discharge cycle (like below 10%)

[CA_Traveler]

You usage is not obvious: a few hours, 24/7, etc. The SUV plug can power the refer but not battery charging. You'll need larger SUV wiring and/or a DC-DC converter and both have losses. Plus some newer vehicles don't fully charge the vehicle battery - rather reduced charging to help with the EPA mileage. In addition the alternator and vehicle battery are close which is part of the charging design. A remote battery - thinking in the back - ie the starting battery is charged while the remote battery not so much.

Consider a DC-DC converter that can be set for Li or AGM or whatever battery type and alternator load.

[obiwancanoli]

Thanks

[BarneyS]

I have a feeling you will have better response with your question if this were in the Tech Issues forum. I will move it there. Good luck with your project.
Barney

[obiwancanoli]

OK, it seems I'm not being clear in describing my need here. Let's try it this way...

Assume the MH is not in the picture... just me, my SUV, and the portable/mobile fridge/freezer. I have a lighter-type plug in the cargo section which the portable will plug into, and it will run the cooler no problem while the engine is running. When the engine is NOT running, I could power the cooler via the plug, and the cooler has a battery protection system which shuts down the power draw when the battery gets to minimum SOC. In this case, the portable will keep things cool or frozen, losing about 1 degree per hour.

My goal here is to set up a separate battery from which the cooler can be powered, and, to recharge the battery, I would employ a portable solar panel(s) with sufficient capacity to recharge the battery everything's attached to. If it's relatively easy to do so, perhaps a system which ties this independent battery to the alternator so that when the car is running, it will also charge the independent battery might also be worth considering...

That help?

[mr_andyj]

First, what refrigerator do you have? powered mobile cooler/freezer is pretty vauge.

Don't run it off AC power unless you are plugged into shoreline/generator. Using an inverter to run it is less efficient than straight off DC.

I agree, if you will be away from shoreline power rarely then just run this off of the house batteries (or add to house batteries).

If you want a new battery system then it is no different from your current battery system. Charging source - batteries - outlet.

I would really consider a roof solar rather than the portable.

Mount the battery close to the fridge. Run the fridge to the battery to get power. Super easy.
For charging use a solar charge controller connected to your new solar panel.
Also, connect it to the vehicle alternator for when you drive. Use a solenoid switch so it is electrically connected to the alternator/starting battery when the motor is running and when ignition is off the switch turns off. Hint, you can use the radio ignition power feed to tell the solenoid switch when the vehicle is on/off.

For charging off of shoreline you can put a switch to connect it to the coach batteries that are being charged, or you can add a new charger just for your fridge battery, and when it is powered from shoreline it will charge.

[BarneyS]

Here is a video, link posted before, of a guy who built his own.
Home built Li battery

Here is where you can purchase the components (except for the cells) for a 12v system.
12v system

and for a 24v system.
24v system
Barney

[2oldman]

Ivylog wrote:
. Today you can build a 100AH Lithium battery for $200.

where?

[Ivylog]

Not sure why you don’t use your current house batteries in the MH???
“Fast recharging” not going to happen with 120W of solar… is not enough most of the time. Today you can build a 100AH Lithium battery for $200.

[2oldman]

40ah 12v Li battery at Walmart, $369

[obiwancanoli]

Agreed on the variables, and considered that... using house batteries would otherwise be workable, but in cases where vehicle isn't situated for easy access, I'd need a pretty long connection to reach those batteries, an inconvenience I'm hoping to avoid... installing a separate battery, say, in close proximity to the cooler using it, would require no more than the connection that comes with the portable solar panel. Further, when the vehicle is being used and driven, the connecting & disconnecting of said house battery connection would be unnecessary. Greater portability and access to sunlight of the panel is also a potential advantage

[CA_Traveler]

Why not use your house battery vs 3rd battery bank? The cooler uses a average of 34Ah per day. So 40+Ah or more for non average days. I'd definitely use a larger Li battery to cover overcast days and a flooded 100Ah battery should be limited to 50% SOC, hence a bigger flooded battery is needed.

I use 66% efficient for solar for 5 hours. So 240W/12V*.6*5 = 66Ah charge per day. I'd want more. And of course solar charging is rather weather dependent.

Lots of variables.