HELP! I'm in Africa and trying to survive with what I have.

tajalazy

Ok, I'm looking for some help here. I've attached a picture of my set up (basically a wiring diagram). 

Short version;

The entire setup is less than seven months old.

(6) 12v Rolls Surrette batteries 210AH wired for my main inverter 24v Magnum 2600w modified sine inverter. It works the whole house, except the ceiling and wall fans. Well, I need the fans to work because it's friggin Africa and hot. So, I added a 12v AIMS 1000w pure sine inverter that will not burn the fan motors. Also, the house is wired with a 12v lighting system that runs 12v LEDs throughout the house so that you can walk around at night (I can technically disconnect this because the main inverter works all lights in the house, but it's nice when you don't want all of the bright lights on). I have two Iota 27v 40amp chargers (labeled A&B) that are hooked into grid power that charges all the batteries (when grid power is on).

This attached sketch shows how it is all hooked up....

Here is the problem. When looking at the diagram, batteries 2, 3, & 6 discharge down to 7-9volts. While the other three stay at around 11-12v after a long time of no charging power. All charge above 13volts on full charge. What am I doing wrong? Is this a cluster or what? Are my three batteries ruined? Please help. Cant afford another $1500 in batteries especially if they go bad in six months again because of the way I have it set up?

Thanks for taking the time.

Estragon

I think the main problem is mixing 24v and 12v loads and charging sources. There is no good way to do this without more gear, and even then it wouldn't be ideal.

Your best bet may be to rewire for 12v only, charge each battery individually, and parallel as many as are still good for 12v. Some may be beyond saving, but you could try extended charging on the weak ones to see if they can be salvaged. Just watch their temperature during extended charging so they don',t get too hot, and add distilled water if needed (assuming flooded batteries).

Run the 12v inverter for essential loads only during outages. Trying to handle all loads normally powered by grid can be prohibitively expensive.

Running 6 batteries in parallel is difficult to keep balanced at best, with a mixed voltage like this it will be pretty much impossible, and will almost certainly result in early death for the entire bank as some get overcharged and others get undercharged.

When the time comes to replace the batteries, get big enough batteries to avoid multiple batteries/strings in parallel. Instead of 6 x 12v batteries in parallel, for example, get 6 x 2v batteries and wire in series for 12v.

mcgivor

You cannot center tap a 24V system, it will draw the tapped batteries down and the 24V charger will be unable to charge the depleted ones. Choose a single voltage, say 24V since you have the chargers and use a buck DC-DC converter for 12V loads, or split the system into 12V and 24V, you'll need a 12V charger. But first charge 2 batteries in series for as long as it takes to bring them back to capacity or individually if possible using a 12V charger, automotive charger if available, to at least get something into them before series charging at 24V with the Iota, you don't want a depleted battery in series with another of higher voltage. You may get lucky, good luck.

mike95490

Yep.  its a mess.   You can't mix 12V  & 24v on one bank.

tajalazy

Thanks everyone. I think I have a possibility to buy a 12v Iota charger. I suppose I will take two batteries off the 24v system and make a separate 12v system out of the two batteries. Keeping 4 batteries on the 24v system. 

I thought I was trying to do too much with it all, but needed your confirmation. I was trying to rob Peter to pay Paul.

Thanks again!

mcgivor

tajalazy said:

Thanks everyone. I think I have a possibility to buy a 12v Iota charger. I suppose I will take two batteries off the 24v system and make a separate 12v system out of the two batteries. Keeping 4 batteries on the 24v system. 

I thought I was trying to do too much with it all, but needed your confirmation. I was trying to rob Peter to pay Paul.

Thanks again!

That's the route I would go, keeps it simple.