Cooling your batteries?

System

Sorry, still dont know how to use a forum.

System2

Re: Cooling your batteries?

Not sure how much extra life you'd get, but my thought is, if you go to that trouble, why not drop the temp lower - - to just above freezing - - something like an average of 33* to make it worthwhile?
That's where my batteries temps hang all winter, and with the loads etc that I have, the only noticeable difference was the higher charge voltage the controller dictated to compensate for the temps. I was pleasantly surprised at how well they worked, and was aware that their life would be longer due to that lower temp.
OH, Just got hit by another thought: Ventilation! That could be a serious problem and something to look into.
Wayne

niel

Re: Cooling your batteries?

i don't know that the kind of effort you plan on putting into cooling the batteries like that will be worth it. keep them out of the sun and use a temperature compensating controller with a battery temperature sensor on the batteries. controlling the charge voltage at said temperatures will go far in keeping the life of the batteries good. btw the humidity normally won't hurt a battery. also allowing some space between the batteries (1 inch or more) could help by allowing the heat generated in the batteries through charging/discharging to go into the air. fans won't work to cool below ambient as you are pushing hot air to begin with. if that wall the batteries are near gets lots of sunshine, it could be a good idea to add some insulation in that wall to help prevent the infiltration of that heat to the batteries.

System2

Re: Cooling your batteries?

I think waynes got the right idea. bring em down close to freezing and keep the sol cero nice and cold! shark

System2

Re: Cooling your batteries?

By the way, what is the best ambient temp. for the battery bank?
Or: Are they (the batteries) confortable in an ambient temp. of about 95 farenheit?

BB.

Re: Cooling your batteries?

From what I have read--the "ideal" temparature for a lead acid battery is 77F.

At 95F (average), the activation energy theory (10C or 18F rise is 1/2 life. 10C/18F fall 2x life) would say that, the battery would last about 1/2 as many years as one running at 77F.

Helicoil,

What if you made a pit/hollow mound for your battery "bin" in the earth (perhaps with some foam insulation for the top--if needed--with ventilation)... If you go down a couple feet, what is your soil temperature? In deep caves in the desert--they average around 55F year round.

I have heard that ~12" the soil temperature is not affected much by daily temperature swings (average daily temperature) and ~12' down, is the average yearly temperature...

-Bill

System2

Re: Cooling your batteries?

I love the idea of burying the batteries. I have two problems, dirt is 30-35 feet away and the ground is very rocky and hard to dig down. I think I will try the chest freezer with a temp controller set at 60-70 degrees. I only need to run it in the summer when its too hot to be there. Thanks

BB.

Re: Cooling your batteries?

How about the night time temperatures? Create a ventilation system that you can open at night and circulate cool air through the battery bank. If you get salt air/fog from the ocean--might be a bad idea (I grew up on the coast of California--salt air never played well with sheet metal or electrical circuits).

Keeping the batteries in a freezer--besides the cost in power of running a freezer to keep the batteries cool, you might only be able to dissipate a 100+ watts or so--or the freezer will heat up even though the compressor is running...

Plus you have the issue of hydrogen gas and the possibility of thermal run-a-way in an insulated freezer (battery over heats during charging, discharging, thermostat fails on or off, compressor fails, problems with condensation/ice on the walls, etc.)...

Decades ago, I made a couple of environmental chambers for testing disk drives (fans, small heater, limit switches, emergency temperature shutdown switch). Worked well for what it was--but not something I would recommend for long term unattended operation.

I would recommend that you stay away from the freezer and active cooling just on safety grounds--let alone the issues of costs.

-Bill

westbranch

Re: Cooling your batteries?

Bill, using a 'root cellar' is a capital idea. I am going to keep it in mind out at our cabin, there are a couple of suitable spots...;)
thanks
Eric