Re: (ET) BB600 status and some failures.

["David Roden" <etpost drmm net>]

On 5 Mar 2017 at 15:49, Christopher Zach wrote:

> So 30 cells now need to go to the recycler. 

Ouch.  Sorry to hear of the carnage.  :-(

Something similar happened to a gentleman around here.  Several years 
back, 
he somehow got his hands on an extremely rare set of golf-car size NiCd 5-
cell monoblocks (Saft STM5-180s). 

He was awfully keen to get them running his conversion road EV, and didn't 
take time to get a proper charger for them.  One night he put them on his 
"bad boy" (unregulated / non-isolated / totally manual) charger, then went 
in the house and forgot about them.  He came back to pretty much the same 
scene you have there.  

Lead golf car batteries as specified by GE for our ETs are remarkably 
forgiving of abuse.  Most other battery chemistries aren't.  The higher 
the 
specific energy and specific power of batteries, the more potential they 
have for disaster -- which may involve more than the batteries themselves.

Such batteries as lithium ion, NiMH, and even NiCd need fairly 
sophisticated 
redundant and fail-safe automated systems to prevent overcharging and, in 
many cases, overdischarging.  Otherwise you get disasters like your 
meltdown 
and the hoverboard fires of a couple years ago.

I hope you don't have trouble disposing of your wrecked batteries safely. 
My 
understanding is that you usually have to pay to unload NiCds, or at least 
pay to ship them to a collection point.

Cadmium is nasty stuff and some battery recyclers don't want to deal with 
it.  The ones that do often work only on industrial scale and don't accept 
small quantities, though 30 cells might be enough.  

> Moral: Don't try to charge the BB600's over 42-43 volts.

Saft has specific instructions for charging their batteries, but they've 
never had a "one size fits all" method.  

The one I'm familiar with is for their EV monoblocks, which I'm not so 
sure 
they even offer any more.  The older ones have or had a straightforward 
algorithm, but regrettably the GE charger is too dumb for even that.  It 
requires a constant current charger and a count up / count down / shut off 
timer.

Your easiest safest route would be to buy a good quality charger designed 
to 
charge NiCd batteries.  I think Delta-Q makes one.

If you can be absolutely sure that your GE charger never again exceeds 43v 
you could probably still use that.  Most of the Saft specs I've seen seen 
to 
hover around 1.40v to 1.43v per cell as a float voltage.  Charging at that 
rate (42v - 42.9v for 30 cells) would take a fairly long time to fill an 
empty battery, but it  should be safe for long term charging as long as 
you 
check and top up water regularly.

The GE charger is a ferroresonant design, and that stabilizes its output 
voltage to some extent.  Is I stable enough?  I don't know. 

Come to that, didn't we have this same NiCd charging conversation some 
years 
ago?


David Roden - Akron, Ohio, USA

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