KenA via EV wrote:
...I think my use pattern may be the real culprit here.
My commute is now 15 miles of mostly highway travel - typically at 55mph.
It's not uncommon for me to be pulling 200+ amps for extended periods of
time. From what I'm hearing, FLA in any configuration may not be a good
option for this mission.
The capacity of batteries drops at high currents. This is called the
"Peukert effect". Lead-acids are affected by this more than other types.
For example, a T-105 flooded golf cart battery delivers about:
5 amps for 20 hours = 200 amphours
35 amps for 5 hours = 175 amphours
75 amps for 105 minutes = 130 amphours
180 amps for 30 minutes = 90 amphours
Thus at high currents, you get much less range than you might expect.
This also means that you are more deeply discharging your batteries on
each drive, which is bad for their life.
AGMs are better than floodeds; but you pay more for them initially, and
their cycle life is shorter. Thus your cost per mile is much higher.
The solution to this problem is to somehow get your discharge time over
an hour or so, so Peukert doesn't take such a big bite out of capacity:
- Drive slower.
- Reduce the current.
- Have enough lead-acids so your discharge time is longer.
- Use some other type of battery.
--
I do not waste my life in friction when it could be turned into
momentum. -- Frances Willard
--
Lee Hart's EV projects are at http://www.sunrise-ev.com/LeesEVs.htm
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