RE: (ET) charger info

["Hazen, Dwight L" <hazen indiana edu>]

My rule is, if you use an battery operated device then you recharge it when
you are done. It would be hard to over charge the batteries with the 
charger
inside the tractor. I have an E-meter on my E14 (now more like a E20 with a
motor replacement). So I have a good feel for the charger. If the cells are
out-gassing a lot and the battery is warm to hot  then you are over
charging. You have to leave it on for a long time with good  batteries to
get to this point. If your batteries are of low capacity or have a shorted
cell then they will out-gas and become warm in a short amount of time. 

I use an automotive regulated charger with cut off, set in the high charge
mode to do my equalizing charge about once every six weeks or so. With an 
10
amp charger it takes six to eight hours to get the 220 amp hr. batteries up
to about 15 volts. This is done after the E-meter says the batteries are
full using the internal charger. I have to do this three time as the 
charger
is for 12 volts. 

Use a volt meter and hydrometer if you are not sure. but after awhile you
can tell just by the sound of the bubbling if they are at full charge or
not. Remember ambient temperature will affect all of this. What works in 
the
summer will not work the same in the winter. 


  Dwight 


Dwight L. Hazen, Indiana University, UITS 
Bloomington, In. 47408-7378 812-855-5367 hazen indiana edu
http://php.ucs.indiana.edu/~hazen/ Ham Radio wb9tlh arrl net


> -----Original Message-----
> From: David Roden (Akron, Ohio, USA) [SMTP:roden ald net]
> Sent: Monday, September 13, 1999 1:05 PM
> To:   Anthony Bailey; Elec-Trak List
> Subject:      Re: (ET) charger info
> 
> > Say I use my tractor 
> > for 30 minutes or so, to move something, mow a small patch, etc... 
> > How would I know where to set the charger at to recharge my 
> > batteries, rather than just guessing at the amount of discharge and 
> > setting it at "A-I"?
> 
> 30 minutes is actually a significant amount of use time.  If you were 
> just moving it out of the garage, around the driveway, and back in, that 
> would be pretty inconsequential.
> 
> The rule of thumb I've heard for lead batteries is to charge them if you 
> have withdrawn 5% or more of capacity (measured as amp-hours at the 20-
> hour rate).  If the battery will be unused for some time (say 24 hours 
> or 
> more) this becomes more critical.  The reason is that, with time, the 
> lead sulfate formed during discharge becomes less able to take part in 
> the chemical reaction during charge; thus capacity is lost.
> 
> How do you know how many amp-hours you've used?  Some folks have added 
> amp-hour or watt-hour meters to their ETs.  One such animal is made by 
> Cruising Equipment and is called the E-meter.  It is a bit tricky to 
> install; if you add one, follow the wiring diagrams ~exactly~ or you 
> will 
> destroy it.  They cost around $200.
> 
> The problem in this case is that the ET's crude charger control (a 
> timer) 
> may make the risk of overcharging the batteries greater than the risk of 
> sulfation from leaving them sit.  But for 30 minutes of mowing, I'd say 
> running the charger for an hour or so shouldn't hurt and might help.
> 
> BTW, for those whose chargers fail, here's a quick and dirty fix.  Junk 
> the charger and buy three $40 automatic car battery chargers at the 
> hardware store.  Reconnect your lift so it's at either 12 or 24 volts 
> (so 
> you can pair evenly discharged batteries).  Connect the chargers to 
> pairs 
> of 6v batteries.  If you have small enough chargers, they may even fit 
> in 
> the front of the tractor where the old charger was, and can be connected 
> permanently to the batteries (I recommend a 15 amp fuse in each charger 
> connection).
> 
> Now you have better (though still not optimal) charge regulation, and 
> the 
> chargers can put more into the batteries which run the lift (which are 
> always lower than the rest of the pack) without overcharging the ones 
> that don't.  I still recommend unplugging the chargers after 18-24 
> hours, 
> however.  I use this method with a shutoff timer.
> 
> By the way, most capacity loss attributed to memory effect in nicads is 
> caused by depressed voltage.  Repeated overcharge can cause the nominal 
> voltage to drop.  Even though the same amount of energy is available 
> from 
> the battery, the voltage drops below the electronic device's minimum 
> voltage threshold sooner.  The cure is a complete discharge to zero 
> volts 
> followed by a full equalizing charge.
> 
> As for lead batteries, I have only heard of one case of alleged memory 
> effect.  It involved Hawker Genesis batteries ~only~.  It manifested  
> itself as a premature rapid loss of capacity.  I haven't been able to 
> learn more about this problem yet, so I may be premature in calling it 
> "memory effect."
> 
> Hope this helps.
> 
> 
> David Roden - Akron, Ohio, USA
> 1991 Solectria Force 144vac
> 1979 General Engines ElectroPed 24vdc
> 1974 Honda Civic 96vdc
> 1970 GE Elec-trak 36 vdc