Todd chargers... again [RE-wrenches]

[Bob-O Schultze]

<x-flowed>>Hey everyone,
>
>Two questions for the list here:
>
>I don't want to whip a dead horse, but went to look at a job today 
>and they had 2, 75 amp Todd chargers in series feeding a 1250 AH 
>bank of Trojan T 105's. The inverter is a trace mod sine wave with 
>charger (SB option), so this makes little sense as when chargers are 
>added like this in parallel, it seems the more of them you add, the 
>less you get out of each one. The small voltage boosting 
>transformers in series with the generator are much more effective at 
>increasing charging output from mod sine wave inverters and the 
>price is less also. The question I have is: does series-ing 2, 75 
>amp switching chargers like these Todd's work? It seems to me that 
>Richard said he had tried this and had marginal results.

Yes, it works. I had a system in Alaska working that way for years 
until one of the Todds died. They aren't particularly robust. I agree 
that using them in combination with the Trace SB reduces the 
effectiveness of BOTH chargers, but as the 2024 or 2524 (I'm just 
assuming the system has one of these) the MAX output of the SB is 
50A.. Parallellling the Todds was probably an attempt to get close to 
a C-10 rate into those batteries. It work work if the batts were 
pretty low but fall off pretty rapidly once the voltage got much over 
26-27V

>
>Here's a new one I've never seen before... the system above has 16 
>identical Kyocera J51 panels... as they are 12 volts each they need 
>to be in series to get 24 volts out. Generally I connect a bunch of 
>individually series 24 volt strings into parallel to feed the 
>load... this installer paralleled 2 sets of 8, 12 volt panels 
>together and then series these to get 24 volts... probably the same 
>result, but I know there is some reason this is not done when 
>combining batteries for higher voltage, and I wonder if the same 
>reasoning holds for PV combinations as well.  Anyone got any info on 
>this wiring style, or pro's or con's for each variation?

There are two main problems with that setup. One is shading. Any 
shading to one side of the string will GREATLY reduce the output of 
the whole array. The other is voltage loss. Why run your 
interconnects a 12V when you can run them a 24?
Good Luck, Bob-O

>
>Thanks,
>
>TC
>--
>Todd Cory
>KE6SXS
>toddcory at jps.net
>Bald Mountain Solar
>P.O. Box 689
>Mt. Shasta, Ca. 96067
>(530) 926-1079
>  - - - - - - - To send a message to the list use: To view an 
>archive of previous messages go to: Hosted by Home Power magazine: 
>for info contact: 
>______________________________________________________________________ 
>__ Start an Email List For Free at Topica. 
>http://www.topica.com/register

Bob-O Schultze, Electron Connection
PO Box 203, Hornbrook, CA 96044
800.945.7587 fax 530-475-3401
www.electronconnection.com
- - - - - - -
To send a message to the list use: <RE-wrenches at topica.com>

To view an archive of previous messages go to: <http://www.topica.com/lists/RE-wrenches/

To unsubscribe send an email message to: <RE-wrenches-unsubscribe at topica.com>

Hosted by Home Power magazine: <http://www.homepower.com>

for info contact: <michael.welch at homepower.com>
_________________________________________________________
Enlighten your in-box.         http://www.topica.com/t/15
</x-flowed>