Uses for an Old Car Battery

[Marc Boucher]

My battery's seen a few too many extreme discharges and I'm about to replace it before winter hits.  

Was curious who had ever hung onto their old car battery for a backup power source around the house.

For example, both my cable modem and router run from 12V DC.  

Given that the old battery is good enough to start the car, it should more than serve for a backup in the event of a power failure.

An alternative would be an inverter, but I think that the work involved in taking a battery, converting it to AC 120V, only to have the modem and router's adapters convert it back to 12V DC, would be inefficient.

I know new car batteries are closer to 12.6V, however, this battery is old enough such that its reading closer to 12.2V, which I doubt will fry anything requiring 12V.  Of more concern is the type of charger attached to the battery, and its potential for affecting electronics.

In terms of safety of the battery acid, I've got an enclosed plastic container that should handle battery acid should it ever leak.

Has anyone used their old car battery around the house for backup purposes?  If so, what kind of charger did you use, and or what was your setup?

I guess I should add some Audi content: Bosch replacement battery available for $180, size 41.  Then there's the Energizer battery, who's equivalent size has about 100Amps more Cranking Amps and 100Amps more CCA than the Bosch, at a cost of $70 less.  Energizer is manufactured by Johnson Controls.  Any valid reason for not going with the Energizer over the Bosch?


Thanks
MC