mark hanson via EV wrote:
Hi Dave etc,
I haven't tested the Ah rating, doesn't matter whether 14ah-probably or the
advertised 36ah (just have a few led lights for night when sitting) since
I'm more concerned about starting frequently when skiers are in the water
(which it does fine). I just can't find any reviews on longevity or if it
does suddenly without warning (which I assume LiFePO4 small batteries do).
Just no reviews/longevity data yet. Until I see actual data on how/when it
dies, I'll keep a spare battery onboard (although with predictable heavier
40lb lead I didn't).
Hi Mark,
To paraphrase an old gamblers' joke, if you don't know who the product
tester is, then YOU are the product tester. I think the Chinese leave
the adventures of product testing up to their customers.
Since this battery uses small cells for high current engine starting, my
guess is that it will fail due to excessive internal resistance.
The amphour capacity of a starting battery is relatively unimportant, so
loss of capacity with age is probably not an issue. It will still start
with 1% of its original capacity as long as the engine starts in a
second or two. 100 amps for 1 second is only 0.028 amphours.
But a low internal resistance is a vital requirement. The battery will
fail when it becomes unable to supply sufficient current. The extra
internal resistance could come from one or more cells that get damaged
from too deep a discharge or excessive charging. The likelihood of this
depends on how good their internal BMS is. This situation would probably
lead to a gradual failure.
Or, it might fail because the internal interconnects aren't good enough
to last, and one pops open at some point. For instance, they might have
just used a few tiny spot welds for the inter-cell jumpers. That could
cause an "instant" failure someday.
For fun... instead of a backup lead-acid battery, what about a bank of
supercapacitors? They would be as big as a battery, but much lighter and
probably won't fail any time soon. They could be kept charged for
emergencies, maybe even by a small PV panel. I saw a golf cart with a PV
panel on its roof to charge a bank of supercapacitors, which were then
used for starting the ICE.
--
"Verschlimmbessern" (German, verb) - To make something worse by
trying to improve it. (English translation: "Microsoft"?)
--
Lee Hart, 814 8th Ave N, Sartell MN 56377, www.sunrise-ev.com
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