On 9/5/19 11:03 AM, Lee Hart via EV wrote:
Again, that works as long as nothing goes wrong. But I can see checking
all 11 voltages will get tedious, and he'll stop doing it. Then you're
back in the same situation, where something can fail dramatically.
"Preaching to the choir". I don't think a charger per cell is a very
good idea. Were I to do it, I would have the little monitors that allow
quick and easy voltage observation.
I have been using massively parallel ~4ah salvage hoverboard batteries
in my 36v golf cart for several years with good results. A box of 8 HB
batteries will run the cart ok. I am running four boxes right now.
Range with 4-5 boxes is 15-20 miles. Being parallel, it is VERY easy
to add or remove boxes. Everything is connected with SB50 splitter
cables.
What are *you* doing to know they are working correctly? If the packs
are directly in parallel, is there a fuse somewhere (inside the pack?)
so if one develops a shorted cell, all the others won't dump *all* their
power into the short?
I've placed my faith in cheap chinese BMSs. :-) Actually, when I got
the batch of HB batteries, I got the same neighbor to do some testing.
He had rigged a capacity testing setup. The capacities of the test
samples all looked good. Low voltage cutoff seemed good. They did fail
to protect against overcharging; I had hoped to use a lead charger, now
I just take care not to charge to 42v.
I was doing some V2H testing with the GC last night and over estimated
the capacity. I was reducing my PowerWall demand by 230 watts through a
36v powered grid tie micro inverter and saw things shutdown about 2am.
The GC batteries were the expected 20v and charged back readily.
Crossing my fingers, I have not seen any short failures. I don't know
whether the BMS has taken care of it but the failures I've seen are
batteries at zero voltage that will not accept charge.
My neighbor got written up by the electric coop magazine last year:
http://austinfarm.us/homegrown/downloads/BLUEBONNET-MAG-DEC-2018_The-Electrified-Life.pdf
BTW, QuickCharge can configure their 36v lead chargers to not go 42v.
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