Battery for -40 deg.

[Jester]

What rechargeable battery chemistries are suitable/not suitable for operation at -40 deg.?

Lead acid must be as they are used in automotive, I'm not sure about the other types?

 

[chuckey]

NiCads will work down to -50 degs C.
Frank

 

[KlausST]

Hi,

Maybe goldcaps are an alternative.

Klaus

 

[treez]

I never heard anything that was ok down to -40degC, if it is used, its probably some secret military. NiCad is traditionally the tough one, so maybe that, I don't know.

 

[schmitt trigger]

Indeed lead/acid will work at such low temps, but with a significant capacity reduction.

 

[Jester]

Indeed lead/acid will work at such low temps, but with a significant capacity reduction.

Yes, with a significant reduction in capacity. The other interesting thing is that even though some lead-acid batteries are rated to -40°C for storage or discharge, usually the minimum specified temperature for charging is -20°C. Then I think about vehicles in locations such as Alaska or northern Canada that definitely see temperatures dip to -40°C and are charged in these conditions. I suppose there is enough heat from the engine trapped under the hood (while it's running and hence charging) to keep the battery above -20°C, but not immediately after starting the vehicle.

 

[bigdogguru]

Then I think about vehicles in locations such as Alaska or northern Canada that definitely see temperatures dip to -40°C and are charged in these conditions. I suppose there is enough heat from the engine trapped under the hood (while it's running and hence charging) to keep the battery above -20°C, but not immediately after starting the vehicle.

An engine block and hence the engine compartment tend to cool down relatively quickly, after all they are normally designed to dissipate heat, not retain it.

Alaskans and residents of similar climates often make use of battery blankets/heaters along with oil pan or block heaters. In the winter months, the typically ritual is to venture out first thing in the morning, with an extension cord and plug in your vehicle so that it has risen to a sufficient temperature to start when it's time to head to work.

Alaskan Apartment Complex Parking Lot



BigDog

 

[andre_teprom]

An additional care on this case at which the battery will work near to the limit of its specifications, an option that also could be considered is to oversize the capacity and add a self heating system to ensure a minimal condition to operate properly. Of course, a thermal insulation design would be required to increase the energy saving.

A classic example of that is the space vehicles in the 70's that employed a similar approach.

 

[Jester]

NiCads will work down to -50 degs C.
Frank

First hand experience or can you provide a link to NiCad rated this low?

Thanks