Re: Marathon batteries

[John Wayland <dat1200@europa.com>]

Hello to All,

>From Neon:

>I'm hoping someone knows something about these batteries, Marathon BB600
>NiCad cells. All I really know is they are 1.2 volts and 34 amp hours, and
>I'm told are sintered plate NiCads....They come as single cells, each about 3 inches
>by 1.5 inches by around 9 inches tall....Any information about these batteries
would 
>be helpfull.

    Paul, I have a pair of  Marathon aircraft starting  NiCads batteries, that are
of the sintered plate type and are 25.2v, 26 ahr each. These batteries that I
acquired as brand new back in  '85 or so, are made up of cells nearly identical to
the cells you are describing, only they are slightly less powerful in their ahr
rating than the ones you've found.

>I was wondering how they might take to 400 to 600 amp draws (naturally not
>for long). 

   400 to 600 amp discharges is child's play for these incredibly stout batteries.
My 26 ahr ones are rated for 2000 amps at 18 seconds! Sintered plate type NiCads
have horrible energy density (unlike the pocket plate types used in EVs), even less
energy density than lead acid batteries, but their power density is the stuff
legends are made of! It would be close to impossible to hurt these batteries with
extreme discharge currents.

>The ones I'm looking at are used surplus batteries, but have been stored with a
>wire between each terminal. 

     Yes, this is the proper way to store such batteries. If you get some of these,
do not try to add water to them until you have first charged them up to full
voltage. When peering down throught the filler cap hole or when looking through
their translucent sides, sintered plate NiCads will look almost dry when they are
discharged, but the water will magically reappear once they are charged up. Use
caution when playing around with these babies....they are short circuit current
rated in excess of 4000 amps!
     If you remind me, when you come to Portland for the Woodburn drags, I can bring
a Marathon shop manual for these batteries that has everything you'd ever want to
know about their care and feeding. 
     Hmmmm....all this talk makes me want to go out to the Wayland backyard EV shop,
pull out the pristine condition blue Marathon Nicad pair, dust them off, charge 'em
up, slap both into that minibike frame I have, mount up my XP-type 24v Avanced DC
series wound motor, and hit it with 50 volts of NiCad power and see she'll do in the
1/4 mile!

See Ya........John