[SEL] SEL Digest, Vol 79, Issue 9

[Jerry Evans]

At 06:00 PM 10/10/2010, you wrote:
>Date: Sun, 10 Oct 2010 09:48:52 -0400
>From: "Elden" <edurand at mchsi.com>
>Subject: Re: [SEL] 32 volt question
><snip>
>Jerry:
>
>In my (not so) humble opinion, it would be best to get four
>identical 8-volt lead-acid batteries and charge them to about 37
>volts with the genset.  8-volt batteries are available (at least
>in the U.S.) at farm supply stores and the larger auto parts
>stores.  8-volt batteries are used to replace 6-volt batteries in
>some slow-cranking cars, trucks and tractors.
>
>Next best would be three identical 12-volt lead-acid batteries
>and charge them to 41.4 volts.  This would be a little high for
>"32 volt" lamps and would shorten their life a bit.
>
>Originally, the 32-volt sets were used with sixteen individual
>lead-acid cells and they were actually charged to about 37 volts.
>
>Some of the 32-volt sets used "Edison" nickel-iron batteries.  It
>took about 26 cells (1.2 volts per cell) to form the bank.
>
>Charging time depends on the state of discharge of the batteries,
>the voltage and current available and how "soft" the generators
>are.  Most times, don't expect peak charging current except when
>the batteries are almost fully discharged.  The current will
>taper-off as the batteries reach full charge.
>
>If you can actually maintain current to full charge voltage,
>divide the amp-hour capacity of the batteries by the charging
>current and add about 50% to get the charging time.
>
>Simple, eh?
>
>Take care - Elden


Hi Elden and Curt,
         I appreciate your answers - thank you.

         As I answered on the "other" list, it is not my intention to "end 
up" with 32 volts (which I omitted to mention in my original post) - I'm 
going to use 12 volts and was just wondering if I could use one of my 32 
volt genny's to charge the 3 batteries at the same time. It was just an 
idea (some would say "brain fart" :-) ) but I realise that it was 
unrealistic and I will connect them in parallel and just use a 12 volts 
machine to charge them. (I've got a few 12 volt charging sets - Iron Horse 
- Briggs and A.N.Other). Of course there is also the trusty old battery 
charger plugged into the mains supply.

         Regarding  8 volt batteries. I have never seen an 8 volt battery 
in South Africa - they may have been available many years ago but 
definitely not for the last 35 years or more. We could find 6 volt 
batteries relatively easily up to about 25 years ago but the supply 
eventually dwindled to the stage that the only way to get them these days 
is by special import. There was a manufacturer in Durban not too many years 
ago who still made small batches but I believe they also no longer do so. 
The market is just too small. Our vintage car and FATG's battle with this 
problem and, although not original, it is common to see conversions to 12 volt.

         The only glass batteries I've seen (even as a kid) were on farm 
scrapheaps :-)

         In my teenage years, I remember my Dad "scrounging" old batteries 
from battery suppliers. He would then isolate any dead cells and bridge the 
good cells until he ended up with 32 volts. Quite easy in those days when 
the thick lead bars connecting each cell were exposed on top of the battery 
but a different story today with sealed batteries.

         Thanks guys and keep well,

Keep the revs up (or down)
Jerry Evans
Near Johannesburg in Sunny South Africa.
Etched Brass Engine Plates made to order:
<www.oldengine.org/members/evans/plates/index.htm>