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Low-Temp Chart for Rechargeable Batteries


wolf

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Low-Temp Chart for Rechargeable Batteries

Temp Fahrenheit 5°F 14°F 32°F 73°F 140°F

Temp Centigrade -15°C -10°C 0°C 23°C 60°C

Capacity Delivered Lithium-Ion rechargable 70% 90% 100% 95%

Capacity Delivered Lead Acid 65% 85%

This means if the ambient temperature is 14°F, the lithium Ion battery still delivers 70% of its capacity.  If it’s rated for 7 hours use, then 70% of 7 hours is 4.9 hours. 

Always charge at room temperature.  Blow hot air at ‘em.

The manufacturer warns of explosions. The manufacturer recommends to charge under supervision only. Why not put the Battery on something that will not catch fire while charging: the bathtub, a tile floor, sand outside, cat litter, a metal coffee can, etc.  Keep from carpets and curtains!

If you charge at low temperatures, you will ruin the lithium ion battery immediately. Charging Lead Acid cold will not hurt but is completely inefficient.

It takes HOURS for cold cells to get to room temperature.  Their core warms up slowly.  Use a hot-air heater (or hair dryer) and blow HOT AIR directly on the batteries to heat the core of the battery quickly.  140°F should be OK.

Li-Ion:  You may be able to expect better than 70% performance at 14°F if you discharge the battery very slowly.  At normal rate:  C/4, expect 70%.  At high rates like C/2, you may get 98% capacity, as the battery would warm up internally.  Maybe!

Alternative battery for cold:  Primary Lithium.  These cells, packaged by Stuart Cody – http://automatedmedia.com -- keep 50% capacity to -40°C.  They deliver twice the power for their weight.  Use them once and discard them.

Lead Acid Batteries and Cold:  You know they crank a car at –15°F in North Dakota.  They deliver 65% capacity below 32°F.  The lead acid sealed dry batteries should behave the same as wet ones.

Hint:  Keep batteries in coolers made for food for insulation and put hand warmers in with them.  On an expedition, just keep ‘em in your underwear.

P.S.  You know, LCDs that don’t work in the cold. Ask for instructions how to ship all this stuff.

wolf

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