5 battery's how to keep at 12 volt

Have 3 100 watt panels and 5 deep cell battery's.

I have them wires up like a line + to - and it at 12 volts.

Just have it so it powers my server.

But after time it was messing up the battery's. Looks like over charging them. I had to put more distilled water in them it would like bold it out.

So now just have it on 1 battery and it's working real good with that one. But I like it to use all the 5 battery's got it out in the garage and a thick wire going back to my bedroom were the server is.

So I guess it could not see that the battery's were all 12 volt and keep changing them with 5 as one.

Is there a way to wire them up right for 12 volts or do I have to buy some sync unit or something?

Thank you.

-Raymond Day

You need a charge controller.
A "12V" PV panel will deliver about 21V open circuit, 17V at maximum power point.
Some PV panels sold as battery maintainers barely reach 14V or so (typical charging voltage of a battery.)

You can get a cheap PWM (pulse width modulation) controller.
For higher power systems we usually use MPPT (maximum power point tracking) controllers which down-convert from 50V or so to 12V, while increasing current.


MPPT:


MPPT and PWM:


You can find much cheaper PWM controllers on eBay.

This is a link to the solar charger controller I have. I got it because it can have a display going back to my room from the garage.

I guess the only way to hook up a lot of battery's is to up the voltage all the battery's added up. So then is then a step down to 12 volts not sure.

-Raymond Day

All batteries in parallel for 12V should be good, so long as they are similar age and condition.

That charge controller should be good. But it may not work well with a single "12V" PV panel or all PV panels in parallel due to low voltage into the charge controller. Three "12V" PV panels in series would be about 51 Vmp, 66 Voc, so good for it.

"MPPT Max Input 100V"

"Warm tips：
Step: Connect the system in the order of 1.battery-->2. load-->3.PV array, and disconnect the system in the reverse order 3. 2. 1.

• NEVER connect the soalr panel array to the controller Without/Before a Battery.
• Battery must be connected FIRST !!!
• DO NOT connect any inverter/ wind/Alternator or Charger into the charge controller!
• If the remote temperature sensor is not connected to the controller,, the default setting for battery charging or discharging temperature is 25 °C without temperature compensation."

Here is some photos I just got of the 5 deep cell battery's got in the garage. I got the center small battery hook up with the left bigger battery they seem to work good together.

They were all working for maybe a year or more. Then started to leek water out the tops. So I guess it seen it as 14 or so volts but the other battery's were over that voltage. Because it can't know.

So a "PWM" could wire 4 battery's for 48 volts and it would step it down to 12 volts. It could still change them all then? I guess would need a 40 amp one because that is what my solar controller is.

Any links to one that would work? That don't cost like over $100.

-Raymond Day

PWM won't drop voltage from 48 to 12. PWM is only used to charge 12V battery from "12V" PV panel, by periodically connecting and disconnecting. It is MPPT that will drop high panel voltage to low battery voltage - it works like a transformer for DC.

If you have that Epever MPPT charge controller, that should do what you need. It is better than PWM.

If batteries starting leaking out the tops after a period of use, probably have some bad cells and others are getting over-charged.
If the tops are removable, you can wear goggles & old clothes, use a hygrometer to test specific gravity of cells, add distilled water as needed.
But they may or may not be recoverable.
Mixing batteries of good and bad condition will pull down voltage of the good ones and cause them to sulphate.
Best to service and charge each battery individually, the let them rest for a day and check to see which settle to a good voltage and which end up low due to a bad cell. Then only use the good ones.

Servicing batteries (if they are FLA wet cell) can include equalizing charge. Find instructions and use a charger or charge controller with appropriate settings for equalization.

RaymondDay said:

Here is some photos I just got of the 5 deep cell battery's got in the garage. I got the center small battery hook up with the left bigger battery they seem to work good together.

They were all working for maybe a year or more. Then started to leek water out the tops. So I guess it seen it as 14 or so volts but the other battery's were over that voltage. Because it can't know.

So a "PWM" could wire 4 battery's for 48 volts and it would step it down to 12 volts. It could still change them all then? I guess would need a 40 amp one because that is what my solar controller is.

Any links to one that would work? That don't cost like over $100.

-Raymond Day

View attachment 39227View attachment 39229View attachment 39230View attachment 39227

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That's a lot of weight on that flimsy looking shelf.
Looks hazardous and lead acid over your Epever is not a good idea.
Batteries on the ground would be safer.

Forbisher said:

That's a lot of weight on that flimsy looking shelf.
Looks hazardous and lead acid over your Epever is not a good idea.
Batteries on the ground would be safer.

Click to expand...

Can't you see the 2 chain's got helping to hold it. It's been up there maybe 5 years now. Has not fell.

-Raymond Day

Some of us look for ways to make things fail, not ways to make them work.



The concern would be how close to ultimate strength that wire shelf is being used.
If I loaded it with an additional battery on top of the end one and it didn't collapse, then I might have confidence using it as shown.
(Better to perform with equivalent weights not containing battery acid.)
"Proof testing"

if it was me, i would get rid of the small battery, and then hook up in this fashion to let the cells discharge more even and charge more even. Found this on web. Then make sure your voltage is not over a floating charge, if they are not drawn down you don't need 14.5 volts or higher charge rate.

The photo just looks the same on the left and right. The wires are all connected still to - and + the same way. What does the length of the wires matter?

RaymondDay said:

The photo just looks the same on the left and right. The wires are all connected still to - and + the same way. What does the length of the wires matter?

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"Photo"? Do you mean the diagrams RoadRunner posted?

Difference is that when high current is drawn, with diagram on left there is additional voltage drop through the daisy chain wires causing slight difference in voltage at each battery, so slight difference in current drawn from each. Because cables are connected to one end for positive and other end for negative, it is pretty good. Just not perfectly balanced. With just two batteries it would be perfectly balanced, but more in parallel and there is slight imbalance. You can figure that out by assuming some wire resistance and identical current from each battery, calculate voltages; the voltages won't agree.

If positive and negative were both connected at same end, imbalance would be much greater.

Diagram on right with four short wires of identical length and two longer wires of identical length is perfectly balanced so identical current will be drawn from each battery.

Guaranteed balance problem.

1) The batts need to be the same. Remove that dinky one.
2) Charge each battery up *individually*, and then put them back in parallel.
3) Dirty install - clean up your terminals and tighten connectors.
4) Follow best practice wiring - ie, don't use a "ladder" type connection where you charge and discharge only off one battery at the end of the string.

Now try again. Otherwise you'll be chasing your tail forever.

I found out it needs a battery management system. That's because it can see one battery at 12 volts and other batteries overcharge because it seizes all his 12 volts but the other batteries can be over at 12 volts and mess them up.

RaymondDay said:

I found out it needs a battery management system. That's because it can see one battery at 12 volts and other batteries overcharge because it seizes all his 12 volts but the other batteries can be over at 12 volts and mess them up.

Click to expand...

You shouldn't need a bms for lead acid batteries connected in parallel.

A bms is used with lithium batteries to maintain balance within the battery of individual cells and as a protection against over charging/discharging. You can't connect to individual cells on your batteries like with lithium packs.

There are also balancers/bms to maintain balance of multiple 12v batteries connected in series, but that's not relevant to your setup either as you are connected in parallel.

Substrate gave you an excellent plan for getting your setup working properly, I'd also suggest checking your charge settings on the controller to make sure they aren't set too high causing the overcharging issues.

see this

Have you cleaned up your terminals with at least a wire brush? Last we looked, it was REALLY bad.

I also notice that you are using the aux-terminal extensions, usually used for hooking up low-current devices like fish-finders etc. Don't do that. Use the main terminals for your dc-interconnects.

Sure, it's convenient to use the aux terminals with jumpers, but many a battery install (especially a hastily constructed marine application) has failed because of this. Use the REAL terminals for the main interconnects.

If you are serious, you'll put some time into doing it right. Otherwise it's just a never-ending lashup.