Frozen Batteries

[angelorange]

Anyone know the effects of extreme cold on aircraft Nicad or Lead Acid batterys both on ground and in flight? For flight senario assuming the Generators are still working what would the indications be on electrical instruments?

Thanks

[411A]

Forget about 'cold' problems in flight with large jet aeroplanes.
In the Lockheed TriStar for example, the ships battery is located in the mid-electronics service center, and it gets hot enough in there during flight to do your Sunday roast medium rare...:}

[angelorange]

On turbo prop king air it's in the wing root and has vent under wing.

[mitzy69]

on the classic B747, the APU battery was aft of the rear pressure baulkhead and was not in the warm pressurised zone, and had a heater mat underneath it to keep it warm, if too cold after a long flight and cold soaked a cold APU and a cold battery would make the starting of APU fail on taxi in
If batteries frozen should imagine they would not produce any amps output, and the case might split.

[Short_Circuit]

Does not exactly answer your question but full of FACT.

COLD WEATHER OPERATION

Temperature is a vital factor in the operation and life of a storage battery. Chemical
reactions take place more rapidly with heat than with cold. For this reason, a battery will
give much better performance in temperate or tropical climates than in cold climates.
On the other hand, the battery will deteriorate faster in warm climates. In some cases, a
lower specific gravity electrolyte is specified for warm climate operation in order to add
to the life of the battery because chemical reactions are more rapid in warmer climates.
In cold climates, the state of charge in a storage battery should be kept at a maximum.
A fully charged battery will not freeze even under the most severe weather conditions,
but a discharged battery will freeze very easily. When adding water to a battery in
extremely cold weather, the battery must be charged at once. If this is not done, the
water will not mix with the acid and will freeze.
The following table gives the freezing points of electrolyte for various states of charge.
These are the approximate points at which ice crystals start to form. The electrolyte
does not freeze solid until a lower temperature is reached. Solid freezing of electrolyte
in a discharged battery will damage the plates and may rupture the container.
Specific Gravity / Freezing Point
SG Deg C (minus)
1.300 - 70
1.275 - 62
1.250 - 52
1.225 - 37
1.200 - 26
1.175 - 20

[Blacksheep]

Yes mitzy69, but the classic 747 APU Battery not only had a heater mat to keep it warm in the extreme cold of high altitude flight, it also had a cooling blower to stop it getting too hot on the ground in tropical conditions. Probably one of the most pampered batteries ever.

We used to store the dry cell emergency lighting nicad cells in the freezer to preserve their charge. The extreme cold inerted them to the extent there was no internal discharge. I don't know why we bothered, a deep frozen cell straight out of stores was pretty useless for issue, as it wouldn't light a TocH lamp for several hours after leaving the freezer.

[mustafagander]

On the Metro 23 (AKA San Antonio Sewer Pipe) the ships batteries are in little dog boxes in the wing root area. On overnights in freezing OATs the ships batts are barely able to start an engine. If they're in need of service (NiCad) you often do not get a successful start. It needs careful management of the capacity available - minimal lights, fuel pump for the 1st engine on to build up line pressure, then off and wind the prop a few revolutions by hand to free up the gearbox oil.

[angelorange]

Thanks for the infomative replies!