Simple circuit system question. 5

[jmgardner]

Hi guys,
I am a Civil Engineer, and have a simple charging question I was hoping to get some help on.

I have a few sites where I am having power issues at, here is the layout:

Solar panel -> charge controller (one input, two outputs) -> each output runs to a 12V battery which powers a piece of equipment(resistor).

Occasionally, one or the other pieces of equipment experience a power failure.

I was wondering if I was to connect the batteries in series rather then parallel, if this would give me a better chance of not occurring a power failure.

Both of the layouts are depicted on the image attached.

Please let me know what you think and thank you for your time.

J. Myles Gardner

 

[MikeHalloran]

Please direct us to more information about the charge controller.



Mike Halloran
Pembroke Pines, FL, USA

 

[VEBill]

Ref. image:

Short answer: probably not. The two batteries in series would be nominally 24 volts (12 + 12). The information you've provided hints that it's a 12-volt system (as is quite common).

 

[IRstuff]

When do they experience power failures? If the draw is larger than the charging capacity, then you drain the battery. There's nothing magical about that. What is the power output of the charger and what are the power draws on each battery, and what's the solar availability?

TTFN
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[jmgardner]

Thank you guys for the quick answers, I will go out to the field and gather some more information regarding the charge controller (i.e. output and ???). Outside of that information, what would you guys recommend for increasing the reliability of this system? Buy bigger batteries/solar panel?

 

[IRstuff]

Your bottleneck is the charger, since that's what's ultimately providing the energy; the batteries are merely buffering the supply from the demand. That said, your batteries will be what allows you to run when there's no sun, so you need to determine how many days of no sun you what to tolerate.

TTFN
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[MikeHalloran]

We need a manufacturer's name and model for the charge controller in order to look up its limitations and to see if its output can be made amenable to the scheme you propose.



Mike Halloran
Pembroke Pines, FL, USA

 

[jmgardner]

I was not able to see the name on the charger, but was able to read the following:

Solar input: 6.5 A

Battery charge: 10A (Not sure on that, might have been 10V)

The third spot is actually for load.

 

[Sparweb]

That's not a lot of info to go by. The ambiguous 10 amp or 10 volt measurement is crucial! You could have been staring at the answer and didn't bother to pay attention.
For each component, PV panel, charge controller, battery and load, there is probably a datasheet or intallation manual of some sort. Usually downloadable from the manufacturer's website. For free. Troubleshooting always starts with knowing how the equipment works.
You should take a multi-meter out into the field with you, and determine the status of the battery, even try disconnecting the solar panel to see if it's delivering a reasonable current with respect to the dataplate on the back and the amount of sun shining on it. If the panel passes, but the battery doesn't, then test the controller because it's responisible for maintaining the battery charge. If there's no manufacturer name on the top then you're probably dealing with cheap consumer stuff from china.


STF

 

[waross]

The few charge controllers that I have used limited the voltage to the battery to about 14 Volts to prevent over charging. You need about 27 volts or 28 Volts to charge two 12 Volt batteries in series. You may need more solar panels, you may need more batteries (in parallel) or you may need both more batteries and more solar panels.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[OperaHouse]

Typically with a controller with that number of terminals, two are for the battery and two are for the load which will cut off at low voltage. Hence the 10A rating. What you have provided so far may be a slick presentation for the local garden club but it doesn't cut it here. Just about everything you have provided is false information.

 

[IRstuff]

Nonetheless, the issue is not whether you have 12V or 24V; if your charger is inadequately specified, then it's irrelevant how your batteries are configured.

TTFN
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[OperaHouse]

A surprising number of small controllers will auto select the voltage based on what it sees for a battery. Of course the input panels must be configured for the right battery voltage. Drawing separate loads off each battery is NEVER a good idea. It will eventually lead to a charging imbalance. At this point it is impossible to determine the actual problem. My experience with solar is there os often not enough battery or panel to cover all situations regardless of what the charts tell you.

 

[LionelHutz]

It won't work. The controller will likely just blow up being connected that way. The loads also have to be exactly to connect in series and I doubt they are.

Put the 2 batteries in parallel and connect the load to the controller where it's supposed to connect. Of course, this could also just blow up the controller since you can't provide any useful data to determine if this can work. But hey, it seems you're just messing around with this stuff wihout really knowing what it does, right?

Saying one of the 2 loads has a power failure seems to imply that the other battery is still charged enough to work. Putting both batteries in parallel would mean both have to be discharged before you experience a power failure. But then, one load could be more demanding and just kills it's battery quicker.

If re-wiring the batteries doesn't keep the system powered long enough, then you need more storage or more charging, or possibly both.

You should pay an electrical engineer to review these sites if you actually need them to work to some specification.

 

[jmgardner]

Thanks for the help everyone, Over the weekend we tested the batteries to see if they were fully charged (If they were then SP+Controler were fine) which they were. Therefore we simply have too much of a draw and the system is undersized. I will go ahead and consult an EE for further guidance.

To answer both Operas and Lionel questions, Yes, I do not know much about electrical, that is why I sought help in the first place.