Re: (ET) Leaves and BB600 maintenance

[Chris Zach <cz alembic crystel com>]

I typically water once a year. 90 cells will usually drink about half a 
gallon of distilled water. The Elec-trak charger only goes to about 42.5 
volts and these should be charged to 45 or so, so it's a bit low. I do 
sometimes put them on a CC charger at 2a@45v to get them peaked.

They mostly stay in balance but sometimes a battery will slide out. I'm 
monitoring two of them now to see if they are low, I might try charging 
just them at 1.5v and see how many amps they take.

They do self discharge somewhat, normally if sitting more than a week or 
two I have to charge them for an hour before getting going. They like 
being deep discharged, that is part of the protocol.

Three strings in parallel can lead to some discharge issues, I really 
should put a contactor on each string so they don't discharge into each 
other, but I'm too lame to do this.

Overall they are nice. They have less capacity than lead, but they do 
seem to be lasting forever.

On 11/9/2019 3:48 PM, David Tiefenbrunn wrote:
> Hi Chris,
>
> Since you are running these batteries, I am curious - how often do you 
> have to add water to them?
> How do they do as far as sitting - loose charge / self discharge?
>
> Dave
>
>
> On 11/9/2019 1:47 PM, Chris Zach wrote:
> > Been doing leaves all day. When the tractor really slows down I 
> > noticed that turning off the deck and blower got me some more power to 
> > the main motor. So something is wrong with the battery pack.
> >
> > Drove it till it was pretty much dead, then parked, put the blower and 
> > the deck on and started checking voltages on the BB600 cells. Most 
> > were at 1.0v (pretty low) however one cell in pack 1 was down to .4 
> > volts under load, 2 in pack 2 were down to .4 and .6 volts, and one in 
> > the third pack was reading a solid 0.0v. Not good. So I turned off the 
> > blower+deck and checked voltages again. Aside from the dead cell in 
> > pack 3, rest of cells came up to 1.1 or so volts.
> >
> > Time to pull the bad cell. Put the rest of the pack on charge, checked 
> > the cell and it was at 2.00 volts to 3 volts. Bad. Pulled it out, took 
> > it to the shed, and on a lark hooked it up to a 1.5 volts power supply.
> >
> > Sure enough it was pulling 2a no problem. Interesting. I then 
> > remembered one of the bolts was a bit loose, and the interconnects 
> > were pretty filthy. So I cleaned it up, cleaned up the bolt threads on 
> > the wire wheel, sprayed electronics cleaner into the bolt holes on the 
> > battery with a straw, cleaned up the nickel plated interconnects, and 
> > put it back in the battery. Now it reads a happy 1.4v under charge and 
> > after a drive was reading 1.0 under load at the end with the rest of 
> > them.
> >
> > You can't kill these damn batteries. Well unless you overcharge them 
> > terribly with a bad E15 charger and a cap that takes the pack voltage 
> > to 45v.
> >
> > I then checked the other cells that were low: Pulled two of them, 
> > cleaned them up, cleaned the contacts, put them back in. Now they are 
> > reading better. I think I'll pull the last one that's reading low and 
> > clean it up as well.
> >
> > So BB600's are nice, and do live for awhile, but the interconnects are 
> > a true pain: Tighten the stainless steel bolts too tight and they will 
> > break off. Not tight enough and the interconnects lose contact. But 
> > they do seem to last....
> >
> > C
> >
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