RE: (ET) PV powered ET more questions

["Markus Lorch" <mlorch vt edu>]

Chris,

if he'd get three independent chargers then this is not a problem.
I hooked up my three Soneil chargers last night after riding around 
and doing some trimming work in the evening. The two 12V 100ah 
batteries I  have were at about 70% and (each attached to one charger)
are full this morning floating at 13.8V. The two larger 6V are hooked 
up to my third 12V charger. These batteries were at about 80% and
the 12V charger was still working on them this morning (13.6V) but
should be done soon. 

So for the charging with solar, if Robert would use three 12V 
charge controllers and also have the solar panels in parallel to
generate roughly 14V, then he could let them all connected. The
smaller batteries would just finish charging earlier as the large
ones but due to the different charge controllers they would not
overcharge. What I learned the last days was that having a
controller per battery is the best solution for the batteries
(even if they are the same size). 
The only issue I see with three 12V charge controllers is that
the power diverted by one charge controller when the battery reaches
full may not be available for charging the other batteries. (I 
think you made that point in an earlier mail)

I do agree that if you can use a 36V DC-AC inverter then thats
the better solution for generating AC power and balancing the 
load. Especially if you don't use much other 12V accessories
like lift and lights. 

Markus

> -----Original Message-----
> From: Chris Zach [mailto:czach computer org] 
> Sent: Donnerstag, 29. April 2004 22:25
> To: Markus Lorch
> Cc: 'robert winfield'; Elec-trak cosmos phy tufts edu
> Subject: Re: (ET) PV powered ET more questions
> 
> 
> Um no.
> 
> If the higher capacity batteries are in series with the low capacity 
> ones and you run the charger, what will happen? Either you 
> will boil and 
> overcharge the lower ones to charge up the higher ones, or you will 
> never fully charge the higher capacity batteries.
> 
> The "right" solution is a 36 volt inverter. If you're only 
> going to use 
> a little bit of power, then a 24 volt (better) or a 12 volt 
> could *do*. 
> However two of your batteries will be out of sync on charging, and 
> you'll still wind up overcharging some batteries on the pack to get 
> everything back in sync.
> 
> Get a Trace DR3624. You'll have 3,600 watts of power, and it 
> will pull 
> the pack down evenly. With that you should be able to run anything. 
> Chainsaw, etc.
> 
> Chris
> 
> 
> Markus Lorch wrote:
> 
> >>This is so I can use Solar PV to charge my batteries,
> >>carry a small inverter on the ET to run a small
> >>commercial inverter for string trimmers and electric
> >>chain saws (Price Club/CostoCo had a nice deal on
> >>1.75kw Xantrex inverters)
> >>(and run the fridge, a radio and a couple of lights in
> >>a pinch.) (There are a LOT of trees hanging over a LOT
> >>of electric lines anywhere I drive, many more than
> >>10-15 degrees past vertical)
> > 
> > 
> > The previous owner of my E20 has put two larger (higher capacity)
> > batteries in my elec-trak. These drive the 12V components. I also
> > have a 300W inverter hooked up (cheap $20) to which I connect my
> > small electric trimmer. It worked fine all afternoon yesterday. 
> > 
> > Maybe you can also have two batteries be larger? 
> > 
> > see my other post on chargers.
> > 
> > Markus
> > 
> > 
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>