Parallel charge controllers

Lauren8363 · Mar 18, 2023

The use of the FLA batteries is just temporar. The plan is to upgrade to Li batteries ASAP, but for now I want to utilize what I have.

I am confused by some of those calculations, so I may have described what I hav incorrectly. Please tell me if I am calculating this wrong:

My batteries are 6 Volt GC2 batteries with 210 WH
2 in series = 12 volts and 210 WH
3 in parallel = 12 volts and 630 WH
50% draw down = 315 WH Max available

I have not yet calculated the output of the panels because the unit is not currently in my possession. I want to know exactly what panel I currently have so I can match it with the additional panels and if necessary change out the existing panel for a different one…

I’m still learning, so be patient with my questions please. ?

chrisski · Mar 18, 2023

Lauren8363 said:
The use of the FLA batteries is just temporar. The plan is to upgrade to Li batteries ASAP, but for now I want to utilize what I have.

I am confused by some of those calculations, so I may have described what I hav incorrectly. Please tell me if I am calculating this wrong:

My batteries are 6 Volt GC2 batteries with 210 WH
2 in series = 12 volts and 210 WH
3 in parallel = 12 volts and 630 WH
50% draw down = 315 WH Max available

I have not yet calculated the output of the panels because the unit is not currently in my possession. I want to know exactly what panel I currently have so I can match it with the additional panels and if necessary change out the existing panel for a different one…

I’m still learning, so be patient with my questions please. ?

GC2 batteries tend to be around 200 amp hours, or 1200 watt hours each (6 volts x 200 amp hours=1200 watt hours). With two GC2 batteries, that will get you 2400 watt hours.

I think yours are a little bigger and might have 1320 watt hours (6 volts X 210 amp hours = 660 watt hours, and two of those equals 1320 watt hours.)

SamDeleted · Mar 19, 2023

Lauren8363 said:
2 in series = 12 volts and 210 WH
3 in parallel = 12 volts and 630 WH

I think you might be confusing watts and amps. I think that 210WH rating is actually 210 amp/h

Amp X volts = watts

One battery:
6volts X 210amps = 1260watts

So 2 in series makes 12v:
12v X 210ah = 2520w

2 in parallel doubles the amps:
6v X 420ah = 2520w

It doesn't matter which way round you do it , you always keep the watts

Edit: thinking about it, if they are quite small they could be 210wh, that mean they are 35amp batteries @6v

Lauren8363 · Mar 19, 2023

chrisski said:
SamG340 said:

I think you might be confusing watts and amps. I think that 210WH rating is actually 210 amp/h

Amp X volts = watts

One battery:
6volts X 210amps = 1260watts

So 2 in series makes 12v:
12v X 210ah = 2520w

2 in parallel doubles the amps:
6v X 420ah = 2520w

It doesn't matter which way round you do it , you always keep the watts

Edit: thinking about it, if they are quite small they could be 210wh, that mean they are 35amp batteries @6v

Click to expand...

You are correct, I was interchanging Watt/Hr for Amp/Hr.

chrisski said:
The one thing I see with putting more panels on a lead acid battery is the potential to exceed a max charge rate. A 100 amp hour pack should be limited to 10%, 10 amps, or battery specs. A 175 watt panel can reach that and if the SCC can limit charge, adding more panels is fine.

Since I’ve dumped the lead acid batteries and upgraded to lithium, life is mostly easier. Today I fix the torque and cabling on my lithium batteries since I have a cable not sitting flat.

The individual lithium cells have a very low torque value. Hard to tell, but the lug was not flat on the tiny terminal. That caused some out of tolerance voltages on that cell when it was nearly charged. That 24 volt pack got charged and discharged at 1000 watts.
View attachment 140162 View attachment 140163

Can I inquire as to your choice of 24 volt over 12 volt?

Additionally, how did you learn about the “out of tolerance voltages”, Something I would not even thought about. D*MN electronics! They do so much for us but without accuracy things happen. Something on my list to watch for going forward. Thanks, I will take all advise like this I can get.

Lauren8363 · Mar 19, 2023

chrisski said:
GC2 batteries tend to be around 200 amp hours, or 1200 watt hours each (6 volts x 200 amp hours=1200 watt hours). With two GC2 batteries, that will get you 2400 watt hours.

I think yours are a little bigger and might have 1320 watt hours (6 volts X 210 amp hours = 660 watt hours, and two of those equals 1320 watt hours.)

Yes, the batteries I currently have are 210 AH each. In my previous post I had incorrectly said the batteries were 210 Watt Hr but meant Amp Hr.

Lauren8363 · Mar 19, 2023

MisterSandals said:
210Wh / 6V = 35Ah
Using 2 in series brings the pair to 12V but still 35Ah
3 of these in parallel bring this to 105Ah at 12V

Sorry, I mis stated Watt Hr when I meant to say Amp Hr

chrisski · Mar 19, 2023

Lauren8363 said:
Can I inquire as to your choice of 24 volt over 12 volt?

I run 2000 watts off the battery for hours at a time. That is a much for a 12 volt system.

Lauren8363 said:
, the batteries I currently have are 210 AH each.

In that case, I would guess you’d need at least 400 watts of power. If you have any data based off a shunt and charging that would be good. If not a solar calculator like in my signature block would give you a good idea on how much you need based off power consumption.

Two golf cart batteries are enough to go Boondocking for two to five days with sun, provided you don’t use an inverter to run very much, and you do not let the propane heater fan blower motor run too much either. More panels will get you more comfortable and more batteries more so.

Really need a shunt to monitor.

Parallel charge controllers

Lauren8363

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chrisski

Solar Boondocker

SamDeleted

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Lauren8363

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Lauren8363

New Member

Lauren8363

New Member

chrisski

Solar Boondocker

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