NiMH AA battery - application question

[metroplex]

I was looking for a battery backup unit for my alarm system and their "official" add-on pack was overpriced and used a crappy SLAB (Sealed Lead Acid Battery) rated at a meager 700 mAh at 12VDC.

I was thinking of using a pack of 10 AA NiMH batteries (roughly 2000 mAh) instead... however the operating environment is in a car - and temperatures can reach -5F up to 100F ambient (internal temperatures may be a lot higher).

Do you think a set of Duracell or Rayovac NiMH AA batteries would be useful in this environment? The charger would just be the +12VDC system of the car... which ranges from 12.48V DC up to 14.8V DC

However, keep in mind that when its cold, the NiMH batteries might not even be close to 12VDC. I'm sure the alarm system would still be operational with the capacity of the NiMH at 10VDC...

Any advice would be appreciated.

 

[0roo0roo]

i can't help u, ask dan from dansdata.com he generally answers questions like that.

 

[Thegonagle]

You'll want to make sure you're protected from overcharging. Lead-acid batteries handle overcharging very well compared to NiMH. Whether you want to try will depend how the backup battery is wired.

If the alarm system back up just charges straight from the vehicle electrical system with no current limiting, don't even try NiMHs. You might want to consider a 12V motorcycle or lawn tractor battery secured under the floor of your trunk instead. That would probably be similar in price to a bunch of NiMHs.

 

[metroplex]

How are SLABs in terms of longevity and durability? Can they handle say, 5000 charges? (not fully discharged) just connected directly to the 12V DC system w/o any charging protection, etc?

 

[metroplex]

ttt