RE: (ET) Batteries and lighting

["MakingLightning" <MakingLightning comcast net>]

I was considering using these batteries called AGM, absorbent glass mat. A
model UPS12-475 (Dynasty division of CD Technologies). I could series
parallel 6 of them to get 36v at 268ah (20hr rate)
I have used a standard 36v charger with timer in the past, can you still 
use
that charger with these kinds of batteries?

Yes, I would like long run times. Most likely not even using a mowing deck
or blower, this will be mainly for transportation of me.

Yea, the landing lamps are way over kill, but so will everything about this
little project.

Maybe I could just put a power resistor in series with a lamp? It would
waste a little power, but would keep the battery load even and make the 
lamp
last longer. Would you calculate like this, 600w at 28v is 21 amps. If 21
amps goes across the additional voltage of 8v you get 0.38 ohms at 168w?
Am I correct on this?

The lights will be on gimbals so that they can be angled as I wish. So I
don't have to blind people. This way they will double as headlights and
searchlights. One will be a landing lamp with the big powerful narrow beam,
the other will be a taxi flood.

Kevin

-----Original Message-----
From: elec-trak-bounces cosmos phy tufts edu
[mailto:elec-trak-bounces cosmos phy tufts edu] On Behalf Of David Roden
Sent: Friday, March 11, 2005 2:43 PM
To: Elec-trak cosmos phy tufts edu
Subject: RE: (ET) Batteries and lighting

TWO aircraft landing lights?  That's some pretty serious light, especially 
if driven at 36+ volts.  If you mow or plow late at night, I'd hate to be 
your neighbor!  <grin>  But at that voltage I suspect they won't last long 
anyway.  (I seem to recall that ACLs are not cheap to replace.)

I recommend against tapping the pack at 24 or 30 volts for these lights.  
The taps for the regular lights and lift already unbalance the battery 
pack 
enough.  The kind of current your ACLs will require will make matters much 
worse.  If you do go this route, junk the original GE charger and provide 
separate charging for the batteries that power the lights.  They will wear 
out a little sooner, but at least you won't be grossly overcharging the 
other batteries in the pack while trying to bring the light batteries up 
to 
charge.

I'm sure you have your reasons, but this much light seems like serious 
overkill to me.  But of course I know nothing about your situation, so 
ignore me.  <grin>

As for batteries, unless you have a huge lot or very long driveway to 
plow, 
running an ET is not usually very tough on them.  I consider Exides to be 
the least durable golf car battery available (some will disagree with me 
and

that's OK), but in most cases they still last a fair lifetime in an ET.  

Again unless you need very long running times T-145s are overkill.  T-105 
type should be plenty and will be more reasonably priced.  Trojans are 
probably fine, though some have reported that they are not as well made as 
they used to be.  I have had good results and decent life from US Battery 
brand in my road EVs, and they usually are cheaper than Trojans.  

For some time I've been using 8G24 12 volt gel batteries from East Penn in 
my ET - 6 of them in series-parallel for 36 volts.  They have the same 
footprint as a golf car battery, but are shorter.  They give me a good bit 
less capacity than golf car batteries, but they weigh less and have as 
much 
energy as I need for my size of lot.  Being VRR type (valve regulated 
recombinant) they never need watering or maintenance, save periodic 
checking

of terminal tightness.  They've been going fine for 3-4 years now.  I 
charge

them with three automatic 12 volt chargers, since the original GE charger 
is

WAY too violent for gel batteries.  

Hope this helps.  Good luck with your project!


David Roden - Akron, Ohio, USA

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