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RE: (ET) Batteries and lighting
stay with the flooded lead acid batteries. the agm's are very fussy about
being over charged. there's many on this list that can explain this way
better than I.
at the Seattle EV mtg this last tues Dave Cloud brought about 6 or 8
batteries and did a draw down test with each. he had various types,
including several optimas (an agm type), a Genesis (hawker?), and a
regular old flooded lead acid car starting battery. the surprise was this
last battery which actually had more capacity than the the optimas in fact
more than any others but the genesis. I'm sorry I didn't take some
pictures but I can send the results in another note compiled by Bruce
Sherry.
Dave
> 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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