"Unique" battery cooler

[gnappi]

My setup is obviously not for boating but I have two (soon to be three) 80 Ah batteries being charged by over 450 watts of solar cells running my outdoor lighting, and water feature pumps.

Since my batteries are in direct sunlight shaded only by a dense bush in a pot, I'm building a dual system (charge and cooling) in a white pretty well insulated marine cooler for my 2/3/4 batteries with an electronic water cooled AC unit (using TECs) and a third/fourth deep cycle battery for the AC unit being built inside the cooler.

I'm using an existing water feature pump to circulate water to the two TEC radiators. It will be interesting juggling the temperature and voltage issues to see what it turns out like. More to come as the innards get connected with parts on order.

 

[CedarRiverScooter]

Great idea. Can you let us know how much this costs? I have been thinking about a solar panel too.

 

[gnappi]

Solar panels (~18 volt rated for 12v systems go up to around 200 watts max) are about a dollar per watt (less if you shop right) the larger you go in wattage, the less expensive. Smaller 100 watt panels can go as high as $1.50 per watt.

If you go for over 200 watt panels for higher voltage systems, the prices can go even lower for the panels, but the controllers are more pricey.

For a 12v system figure $25-$35 or for an inexpensive PWM controller unless you go over 200 watts and a 24 volt (and up) system then you're talking an MPPT controller and prices can go VERY high on them, and the TEC array is ~$65, temperature controller $25-$35, plus all the doodad connectivity stuff like water pump for the radiators and wiring / connectors.

I started with a single 100 watt panel but on a cloudy day, the charge controller went into low voltage battery protect mode overnight. Adding a second panel at 125 watts gave me usable battery power after 2 cloudy days. I'm adding another 325 watts this week which depending on how cloudy it gets may give me 4-6 days of usable power. Plus I'm adding another 200 watt panel and 35Ah battery to power the electronic air conditioner.

I have much of it here already so it's more a matter of assembly time than anything else.

 

[LDUBS]

I learn something new every day. How critical is it to keep a battery cool? Or maybe a better question is when does this become a requirement?

Thanks.

 

[gnappi]

I'm torn on this issue. Experts say anything above 85 on a battery that gets cycled often is bad for it but car batteries last a LONG time in a pretty hot environment.

That said since mine are in the sun full time and being charged and discharged often, I'm taking the safe cooler route.

 

[LDUBS]

Thanks Gnappi. Maybe the auto batteries are less exposed because they don't cycle down so much, but this from an admittedly non-expert. Anyway, interesting approach.

 

[gnappi]

Thanks Gnappi. Maybe the auto batteries are less exposed because they don't cycle down so much, but this from an admittedly non-expert. Anyway, interesting approach.

Yeah, initially I thought so too, but we had some 50 12 volt lead acid batteries in our corporate UPS which basically NEVER cycled down below 95% before they were topped off by the UPS charger. We had a few batteries (which were in 75-80 degree ambient) go bad after a few years and some sales man talked our execs into buying a VERY expensive air conditioning system citing the 85 degree premature failure rate.

Oh well, it wasn't my money

 

[gnappi]

I got most all of the parts in and can start assembly, temperature and current analysis this weekend. We'll see!