24v bank supplying 12v power to inverter

Now of course unless the charging complication by the charge controller has an ....

When running 12v accessories (horn, lights, etc..) off of a 36v golf cart they are connected to any 12v combination of 6v batteries. ideally not all to the same 12v bank.

was trying to download a simple diagram picture but wouldn't do it, any document restrictions?

Because when you wire 2 12V batteries in parallel they become a 12V system not a 24V system. You can put 24V to them but while they might charge they also may cook. Usually a 12V battery can except maybe 15V but 24V may be too high. So you can try it but don't expect the batteries to last very long

If you mean wire the batteries in series (24V) for charging and then disconnecting them and wiring then in parallel (12V) to run the inverter, sure, you could do that. When we say you can't, what we really mean is that you can't do it without re-wiring each time you go from one to the other.

You could do that, but the draw off each of the 12 volt batteries has the [potential to be vary uneven and kill one battery prematurely.

This would work for a science experiment by connecting the batteries in series, then putting a separate set of wires off each battery as 12 volts, and running this sun parallel, but not sure how it would hold up day after day, week after week, month after month, year after year.

Any reason you would want to try this?

It’s a horrible idea to power your RVs 12 volt system by tapping into one of two batteries in series of a 24 volt system because of uneven charging, but I never read tapping into each battery and running these in parallel. To me, I will not be the first on the block to try this, especially with how much money a 2000 watt inverter, wiring, and four golf cart batteries cost. Not worth the science experiment to me.

Yes, each 12V battery in a 2 battery 24V system will show 12 volts even when connected in series.

If the batteries are connected in parallel and you go head and install a jumper between the pos/negative it's not hard to see what will happen.

Please film the results and post link on here.

Ok, thanks for your input, at least the comments that are not smart ass ones.

I'm trying to think outside the box, to power a bunkie with limited equipment without blowing up the place.

I would have 2 banks of 24v (6vx4 x2)
And 2 cheap inverters.
min 5 x 230w (30v) panels
2 × 50amp cheap pwm charge controllers allowing solar panel power streams of 650w for 12v and 1200w for 24v.

I am attempting to use only 1 charge controller(cc)

Again, another scenario...

2 x 24v banks with 5 panels 5x230w = 1150w
With cc charging 24v.

tap into one 12v from each string to one inverter and the remaining 2 on another inverter.

Ideally it would discharge them more evenly if they were tied to the same inverter, but I would be doing much the same as the original scenario.

Of course I will ask if anyone has tried it.


Idea by sdold of charging and then disconnecting might work ok with the 2 banks

So one charging and the other discharging

Lots of switches and constant attention to battery charge/discharge though..

Also anyone who can forward me to a site that has basic wiring rules in this area or experiments with various scenarios would be appreciated.

I have mppt cc's but I'm looking to use these pwm cc's for a temporary cheap alternative for now.

I’m not sure what a “30V” panel is, is there a label that gives the specs for Vmp (max power voltage) and Voc (max open-circuit voltage)?

What’s the make and model of the charge controllers?

Solar panel is osm off grid max power
30.65v vmp
7.69 amp imp
37.46 voc
235w
cc's are cheap no name 50 amp pwm.

I don't think your 30 Vmp panels will adequately charge a 24V battery, typically a "12V" panel Vmp is about 18V and a "24V" panel is about 36V Vmp. These sound like re-purposed 60-cell grid tie panels.

I'm not trying to talk you into re-designing your system, but in case you're interested, the options seem to be:

1. Use all five panels in parallel and wire the batteries as a 2s4p 12V system and use an MPPT or PWM CC. With PWM you wouldn't get anywhere near full power from the panels. The four parallel battery strings would likely shorten their life significantly. Having more than two parallel panels requires a fuse for each panel.

2. Use all five panels in series with an MPPT charge controller. 5 x 37.46 Voc = 187V so the CC max voltage input must be 200V or more. Batteries wired same as above, or as 24V if you don’t mind buying a new inverter. No panel fuses since you only have one string.

3. Add or subtract one panel so you can have two or three in series, and put two of those strings in parallel (2s2p or 3s2p) feeding an MPPT CC. No panel fuses needed since there are only two parallel strings. Your batteries can then be 12V in four parallel strings (bad) with the inverter you have or 24V in two parallel strings (not as bad) with a new inverter. That’s probably what I’d do.

50 amp pwm

Max pv voltage is 50v

Max Pv input power:
650w 12v / 1200w 24v

If you can't find a manual telling you the input Voltage range for your PWM, then download any and take a look.

My PWM is 18-24 volts for a 12 volt battery, and 36 to 48 volts for a 24 volt system. Your panel fits neither 12 volt or 24 volt battery charging criteria.

With PWM, about the only option is to add panels in parallel with those voltages, so amperage and voltage loss can become a factor in those systems. Again though, panel voltages fall outside all PWM specs I've read. I have not read all PWM specs, only about 10 or so. Maybe your PWM is different.

If you must use those panels, appears to me you need to buy a MPPT controller. With those panels, Five can only be put in parallel, but 4 can be put 2S2P or 1S4P; Six can be put 3S2P, 2S3P, or 6P. More options with non-prime numbers of panels,.

What are you trying to avoid doing? Spending money on a 24V Inverter?

Yes, and sounds like I have to use one of my mppt cc's too. Was hoping to set it up on the cheap for a bunkie...