Re: Batteries

[dmp@tmedbsd.mcg.edu]

> From:          "Brian K. Michalk" <michalk@awpi.com>

> which causes the battery to lose efficiency.  The less current
> you demand, the better the performance.

Yup. Since how many amp-hours depends on how fast you draw it out, 
most rechargable batteries are rated at a 20 hour rate. So with a 10 
amp hour battery supplying 1/2 an amp will last 20 hours, one amp for 
0.9 hours, or 0.36 amps for 30 hours.

> amps.  The reason why they are not rated in AH is because they
> are designed to be drained by 1% to 10% of their total

For cranking, you want lots of plates to supply lots of current. To 
keep weight down, they have to be thinner, reducing total capacity.

> cause failure of the thin lead plates.  I'm not a chemist,
> but I imagine that the deposition of lead from lead sulfate
> is not uniform, eventually eating holes in the thin plates.

More like the active part just crumbles off and settles in the bottom 
of the batery. That's why lead acid batteries are life limited. Even 
sitting, they're slowly decaying. Long life batteries just have more 
active materials to crumble away.

---
David Parrish