24v bank supplying 12v power to inverter

[taxer]

Checkthisout

what you are describing is a hybrid of my long term goals as mentioned above.

Its been a while since I played with electrical solutions and Im trying to get the brain muscle memory back.

I have done many electrical setups mostly standard in many forms, but I have not explored charging banks and discharge banks etc in terms of type of equipment used and its application.

on the side,

i remember setting up 2 equalizers in series in that pinto wagon to make it louder.
souping up the power wheels to double or triple power for the kids - fastest gator that would keep up with the real ones..
and ordinary house wiring for additions basements etc..

but limited battery solutions with the the 2 dimensions..


mobile power you can drive to a remote location - worksite/cabin/or a solar array..

but 36v is not anywhere near standard, switches. uneven charging, lots of fun.

[taxer]

Trying not to get too ahead of myself, but ideally I would like to use the equipment to keep the 36v carts charged too.

again do I hook up directly to 24v of the 36v bank? or run the 12v charger from the current bank?(obviously less efficient, but charging is more even..)


in the great plan of things, I see a huge value / advantage to be able to charge my power and drive it to a remote location on the property and use it through a cart or carry it along side it in a trailer.
ideally, a 36v cart as a power backup or mobile power unit would be in my sights


sizing and options for mppt charging and inverter input has to be planned for the long term in this case.

or just run the noisy generator.

.

[taxer]

No I hear you, I have the extra equipment and I'm just trying to make use of it.

I have a few electric golf carts and I know how out of balance batteries can become with 12v accessories attached to them.

The batteries are good but have had a previous life.

I appreciate being able to experiment on paper in this forum...
safer and less costly.

I still have some ideas and arrays kicking around and i can build on this better.

i realize a solar array is only as good as its weakest link.


so any long term solution should be pure sine.

I will be using them on my other projects., but wow, took the fun out of solar by making it much more $$$$.


Back to the drawings, still has to be a better solution to use this leftover useable? equipment.


thanks for the feedback.

[checkthisout]

So here together is not considered parallel..

so 2 separate panels/cc/batt banks/ but sharing 12v from each sharing an inverter...is another scenario... assuming wiring a 12v from a separate system/array (separate panels/inverter/battery bank)



2 array.jpg2 array.jpg

That would work but all you are doing is spending money and time to create headaches for yourself. You are back to the same scenario where you are drawing two different loads from batteries connected in series and one battery will become out of balance.

I can't emphasize enough, that especially in solar, you cannot have batteries in series in a differential draw. This causes problems even in 24V equipment where someone has put an AM single speaker 12V radio for listening to the game. That small amp draw from the radio throws the batteries out of balance and the remaining battery ends up getting boiled over or has a cell that gets nuked early.

Buy a 24 inverter and be done with it.

Here is a cheapie unit rated at 2500 watts but probably has 1250 in the real world for $245.00 https://www.ebay.com/itm/20303730690...Cclp%3A2334524

[Mike90250]

It could work, but only until one inverter has a different load than the other inverter. Then the batteries become unbalanced and one is either undercharged, or the other is overcharged.

I know you are trying to economize and use the gear at hand, but while the latest scheme sort of works, it won't work with mod sine inverters and can only work with transformer isolated pure sine inverters. There are issues with the inverters AC grounding interfering with the battery grounding, Again - the easiest way is to get a 24V pure sine inverter.
Why pure sine :

fans, Pure sine required for the motor
lights , mod sine works for incandescent, otherwise pure sine for electronic bulbs
electronics, Some work with mod sine, some don't.
pellet stove the feed motor requires pure sine

Feeding mod sine into a motor causes it to consume about 20% more power that gets dissipated as 20% more waste heat. Few consumer motors have that much margin and the motors die sooner.

[taxer]

got cut off...

so if two separate systems sending 12v to a shared inverter is not considered parallel, this should work...

[taxer]

No, use a single 24v inverter, that solves both the wiring problem and the problem of drawing unequal currents from the batteries. As you have found, you can’t have batteries wired both in series and in parallel at the same time.

So here together is not considered parallel..

so 2 separate panels/cc/batt banks/ but sharing 12v from each sharing an inverter...is another scenario... assuming wiring a 12v from a separate system/array (separate panels/inverter/battery bank)



2 array.jpg2 array.jpg

[taxer]

yes 24v inverter is the easy answer, but i have a few 12v 's already.,,,

so,the

4 inverters or just 1 24v bank and 2 inverters to each separate 12v

would work without defying principles of the wiring arrays, but excessive costs and possible uneven discharging?


I'm asking because there are other possible panel/cc/battery/inverter array combinations that may work with the equipment I already have.

I already have my mppts and inverters penciled in for my garage and cottage project. blueprints.

I'm not so much into efficiency for the bunkie, but to make use of my extra equipment in a safe manner.

[sdold]

So putting the 2 12v batteries in parallel to the inverter causes the short?

I'm guessing only way around it is to have 4 inverters or just 1 24v bank and 2 inverters to each separate 12v...

No, use a single 24v inverter, that solves both the wiring problem and the problem of drawing unequal currents from the batteries. As you have found, you can’t have batteries wired both in series and in parallel at the same time.

[taxer]

So putting the 2 12v batteries in parallel to the inverter causes the short?

I'm guessing only way around it is to have 4 inverters or just 1 24v bank and 2 inverters to each separate 12v...

[sdold]

That doesn’t work, you’re connecting points that have 12V between them together, causing short circuits.

[taxer]

array.jpgarray.jpg

Has anyone ever tried this array?
Pulling one 12v from each 24v charging bank to power a 12v inverter A
Take the remaining 12v from each 24v charging bank and route it to a second B inverter.

[taxer]

Yes, sort of Russian roulette...

and the cost of switches/relays...

Maintenance and attention to switch the battery banks would be tedious.

[checkthisout]

Taxer, you can easily do what you want to do if you don't want to charge the batteries and use the inverter at the same time, or you only want capacity of one of the batteries at a time.

The problem is that you're going to end up with kind of a rube goldberg setup. It's simply a matter of matter of installing a couple heavy duty battery relays that allow you change your setup to 24V for charging and 12V when the inverter is on.

When your inverter is on, you can use the power it's producing to switch a few relays that changes your battery bank to 12V. This will act as an interlock so that you never accidentally apply 24V to your inverter.

The problem with this is that your lack of knowledge (not making fun of you) in regards to basic electrical could create problems. Once you make the necessary cables, install the relays and such, you will find that your money would have been better spent on a new inverter. I would sell some of your 6V batteries to raise cash do that instead of ending up with a band-aid system that only you know how to operate and could create a fire hazard if one of the relays goes bad or you have had a few too many cold ones and forget something.

[Mike90250]

This can be accomplished with a large bank of switches: ( I'd suggest Blue Seas marine battery switches, rugged & reliable)

1) Switch off PV arrays

2) disconnect charge controllers from batteries

3) disconnect * some * of the series batteries to get 12V vs 24V

4) parallel connect switches to parallel the 12V blocks of batteries

5) connect inverter

mis-perform one step and you will severely damage something, either shorting out batteries, frying your 12v inverter with 24v or
suddenly finding out one of the 6v batteries is only 4v because of a shorted cell, and when paralleled with a batch of 12V blocks,
you get all the good blocks discharging into the block with a dud cell.

You will spend more on the many quality switches, than you would on a decent 24V inverter