Re: Batteries (time sensitive)

[Tim Vanderhoek <vanderh@ecf.utoronto.ca>]

On Sat, Feb 26, 2000 at 02:44:25PM -0500, Joyce Poon wrote:
> 
> Upon more reflection, a more plausible explanation of the short circuited
> batteries might actually be the fact that they were hooked up in parallel.

Mm, this is particularly likely to happen if you hook together a set
of new batteries in parallel with a set of used batteries...
(!! sound familiar? !!)

To avoid the problem, one could simply connect a couple diodes in the
correct places.  You should still make sure you're using equally
(dis)charged pairs of batteries, but at least you're guaranteed not to
short them.

In fact, I'm going to __strongly__ urge you not to ever try putting
batteries in parallel again without diodes to protect them.

[Whether this is what happened or not is a different question --- if
 this is what happened, why didn't two battery packs overheat --- the
 one that was undervoltage and acted as the short circuit and the one
 that was overvoltage and powered the short circuit? ... but this is
 beside the point ... just don't try it again w/o diodes!]


> torque to work?  (Nevermind, our robot probably needs more torque than a
> screwdriver due to the mass.)

Uh....  Your assertion is quite incorrect.  :-)


> I know I was shot down before with this idea: how about lantern batteries?
> Do they provide more amps?

I don't remember you suggesting it before, but if you say it was shot
down, you're probably right --- you keep better track of what gets
show down than the rest of us...  :)

I do think lantern batteries are a poor idea.  If you're going to move
into that size/weight range, just go all the way and buy a decent lead-acid
battery.  The advantages to the AAs are that they're throw-away and
cheap to replace if they do get shorted.


-- 
Signature withheld by request of author.