System Updgrade

Phxsunuser

12 KC130 wired in series of 3, with an Outback 80 Charge Controller
4 Solar World SW175 wired in series of 2, Outback 60 Charge Controller
Inverter - Zantrax SW4024
Battery Bank - 12 Trojan L16RE-B - wired in series and paralleled for 24v system

Recently we experienced the failure of 2 batteries after 4 years in service. Wondering if I took 4 batteries out of the original bank, could I add a separate bank of 8 batteries? Could I possibly use the generator transfer switch and the low voltage disconnect (both features included in the Zantrax SW2024) to charge one bank while using the other? The idea is that if there was a problem with one battery bank I would be able to isolate and make repairs without being out of power.

If this is not possible, I am currently looking at the 2v Rolls Surette, what would be the correct amp hour for the aforemention system and/or what required system changes would be necessary? Finally, does Northern Arizona Wind & Sun carry the equipment?

inetdog

Re: System Updgrade

Phxsunuser wrote: »

Wondering if I took 4 batteries out of the original bank, could I add a separate bank of 8 batteries? Could I possibly use the generator transfer switch and the low voltage disconnect (both features included in the Zantrax SW2024) to charge one bank while using the other?

I doubt that the generator transfer switch is rated to switch DC at the currents involved with your battery bank. DC switching under load is a lot harder on a switch than interrupting AC.
You could use it to run a contactor with DC rated contacts though.

Cariboocoot

Re: System Updgrade

It is entirely possible to have parallel battery banks separated by a battery switch so that you can use one or the other or both.

You can't use an inverter-charger to charge one battery bank and "run the inverter" from the other because it will be in charge mode, not invert.

You could dedicate array to individual battery strings so that it could be isolated from use while charging from solar.

How practical any of this is would be debatable. It should not occur often enough that manually re-wiring wouldn't be a viable solution.

Your Solarworld array (700 Watts) ought to be capable of about 22 Amps. Your Kyocera array (1560 Watts) ought to be capable of about 50 Amps. Meanwhile your three parallel battery strings would be 900+ Amp hours (L16's are usually 320 or more Amp hours). Therefor you've never really had enough panel to charge them properly by Trojan's recommendations.

If I were you I'd drop down to two parallel strings of the best eight L16's you've got. That should be 640 Amp hours @ 24 Volts, enough to provide 7 kW hours of power. The 70 Amp charge potential should be fine with that much battery.

You can get 2V cells in that 600-700 Amp hour range: http://www.solar-electric.com/2voltbatteries.html

Rather an expensive choice.

Cariboocoot

Re: System Updgrade

Battery bank switch: http://www.solar-electric.com/basw1300amp.html

vtmaps

Re: System Updgrade

Phxsunuser wrote: »

Battery Bank - 12 Trojan L16RE-B - wired in series and paralleled for 24v system
Recently we experienced the failure of 2 batteries after 4 years in service.

First of all you should know that three parallel strings of batteries is workable, but hardly optimal. It requires regular monitoring to be certain that current is being shared equally by all three strings. read: http://forum.solar-electric.com/showthread.php?14674

Phxsunuser wrote: »

Wondering if I took 4 batteries out of the original bank, could I add a separate bank of 8 batteries? Could I possibly use the generator transfer switch and the low voltage disconnect (both features included in the Zantrax SW2024) to charge one bank while using the other? The idea is that if there was a problem with one battery bank I would be able to isolate and make repairs without being out of power.

Yes you can add a separate bank, but you cannot switch them with your transfer switches as you described. You will need some heavy duty battery switches. Also, the Xantrex cannot invert from one bank while charging another. It is possible (but very complicated) to invert from one bank while charging the other via solar.

Phxsunuser wrote: »

If this is not possible, I am currently looking at the 2v Rolls Surette, what would be the correct amp hour for the aforemention system and/or what required system changes would be necessary? Finally, does Northern Arizona Wind & Sun carry the equipment?

You currently have a 1110 ah battery bank at 24 volts. It would be a much better design to have a single string of 2 or 4 volt cells.

These are some possibilities:
http://www.solar-electric.com/suba2vo12am.html
http://www.solar-electric.com/repoba2vo10a.html
http://www.solar-electric.com/tr1am4vodecy.html

--vtMaps

Photowhit

Re: System Updgrade

Less batteries rather than more, or rather less battery bank capacity. I understood Trojan expecting 7+ years of service out of those batteries, so at some point your system is a failure. Trojan asks for a 10-13% charge rate. If you have 350 390 0r 415 amp hour batteries, you need to run your genny often.

Going by 'Coot's estimates of your array's charging capacity you should have a max of 720 amp hour battery bank. Did you test the specific gravity of the batteries when you started having problems? Did you do an equalizing charge to try to recover the failing cells. Was the failure catastrophic as in having a cell short?

Definitely fix the system before you condemn additional batteries to an early death.