Battery pad

[Stonewall]

Re: Battery pad

only WEAK battery can freeze . a charged one or one in good cond will not freeze instead of putting one more fire hazard to your car , get a good battery

Also a good point but even a new battery will loose capacity when it is this cold. I put the largest Interstate battery in my car and so far it has been great. Bert and Jacks can get them for a bit over $200 (last year pricing). Pricey yes but an awesome warranty and good quality battery. I will look up the part number for those who want it later tonight.

[MusicalGenius]

Re: Battery pad

I opted for a Red Top two years ago, love that battery.

[longsock]

Re: Battery pad

I opted for a Red Top two years ago, love that battery.

x2

[J-hop]

Re: Battery pad

only WEAK battery can freeze

true, according to wiki lead acid batteries at full charge contain a concentration of 33.5% sulphuric acid, which would have a freezing point of somewhere between -48 and -56 degrees C. However decrease the concentration by 2% (down to 31.5%) and you are looking at a freezing point of somewhere between -37.6 and -43.4 celcius.


Now wiki states the natural discharge rate of a battery to be somewhere between 3 and 20% per month (i know huge range). So it is possible even with the natural discharge rate you could decrease the electrolyte concentration enough to freeze the battery if left for a while.


Note I am not sure what the relationship between electrolyte concentration and level of charge is so someone would have to look that up to get a relationship between the discharge and electrolyte concentration. So as you can see even a small change in the concentration will cause the freezing point of the battery to rise quickly, i haven't plotted the data available from the site below but I think it is an exponential relationship.

http://www.resistoflex.com/sulfuric_graphs.htm