I need some help with a battery chemistry choice. My project requires that my battery be in an enclosed box that will be out doors during the summer months of areas like S. Florida and Arizona. I will try to shade the battery box from direct sun light, but I'm sure the temps will still reach several degrees over 100F. It needs to be 12V, approximately 9Ah capacity and it must have a low self-discharge rate. Lead-acid will probably operate OK, but its self discharge rate is too high; we want to go at least several months between recharges. Lithium Ion or LiFe looks good as far as self discharge, but I'm concerned about the temperature. Can anyone suggest a battery chemistry that would be best? Rechargeable is preferred, but disposable is OK if the cost is relatively low.

 

I need some help with a battery chemistry choice. My project requires that my battery be in an enclosed box that will be out doors during the summer months of areas like S. Florida and Arizona. I will try to shade the battery box from direct sun light, but I'm sure the temps will still reach several degrees over 100F. It needs to be 12V, approximately 9Ah capacity and it must have a low self-discharge rate. Lead-acid will probably operate OK, but its self discharge rate is too high; we want to go at least several months between recharges. Lithium Ion or LiFe looks good as far as self discharge, but I'm concerned about the temperature. Can anyone suggest a battery chemistry that would be best? Rechargeable is preferred, but disposable is OK if the cost is relatively low.

Make shade for the lead acid battery with a small solar panel. That should take care of your self discharge rate.

See AGM battery. 80% of charge capacity after 6 months and 140 degreeF operating range.
http://www.tnrbattery.com/power-sonic-ps-1282s-f1-battery-12-volt-9-amp-hour/

 

Take a look at the old fashion lantern battery. Not rechargeable but...

 

I need some help with a battery chemistry choice. My project requires that my battery be in an enclosed box that will be out doors during the summer months of areas like S. Florida and Arizona. I will try to shade the battery box from direct sun light, but I'm sure the temps will still reach several degrees over 100F. It needs to be 12V, approximately 9Ah capacity and it must have a low self-discharge rate. Lead-acid will probably operate OK, but its self discharge rate is too high; we want to go at least several months between recharges. Lithium Ion or LiFe looks good as far as self discharge, but I'm concerned about the temperature. Can anyone suggest a battery chemistry that would be best? Rechargeable is preferred, but disposable is OK if the cost is relatively low.

Batteries REALLY do not like temps above about 80F. They function best between about 60 - 80F. That's why auto designers put the little heat covers on batteries under the hood.

 

Tadiran has batteries rated to 125deg C op temps.. (TLH series) and many other "high performance" batteries.

 

Tadiran has batteries rated to 125deg C op temps.. (TLH series) and many other "high performance" batteries.

Those are great batteries but best used for back-up or low load applications (5 mA and less). Which raises a question for the OP if he ever returns. What type of load (duration and interval) do you expect to supply? Constant low power or high power for short bursts each day, ...

The Tadiran batteries can handle high temperatures but don't put them anywhere that physical damage could cause them to open up. They are filled with lithium metal and thionyl chloride (SO2Cl2), nasty stuff.