Battery Charging Station in Remote Place

nthamizh

We are planning to put a battery charging station at a remote place. The batteries that are going to be charged are 30 X 100 Ah 12V Lead Acid Batteries. What would be the best design

- (Solar PV + Charge Controller) combo for each 100Ah 12V batteries, for example - 1 (Solar PV + 12V Charge controller) for each battery OR

- (Solar PV + Charge Controller) combo for multiple 100Ah 12V batteries, for example - 4 Batteries in Series with 48V Charge Controller

Which of the above is the best way of charging or if there is any different configurations from the above for effective charging.

Please let me know.

- Arasan

BB.

I am guessing that this is a remote charging station for folks living in the area (run some lights, radio, cell phone chargers, etc.)?

So--These would be individual batteries brought to a central charging station... No "sets" of batteries. Each battery with its own history/state of charge, etc.

Ideally, each battery should have its own battery charger. Charge at 14.5 volts or so (exact voltage depends on type of battery--GEL, AGM, Flooded Cell, Sealed, etc.). Do you know/have control of exactly what type of batteries will be brought in? GEL Batteries are going to be the most problematical... They have to be charged at a controlled current (30 AH battery would be ~1.5 amps) until full. If you charge with too high of current and/or too long, the batteries will develop gas pockets in the GEL and ruin the batteries (most likely, there are variations in GEL batteries, you should find the charging specifications for the batteries you will be charging).

And AGM/GEL/Sealed batteries--If they are not matched strings/matched in level of discharging--You cannot charging a string of 4x of them in series... The battery that gets charged full first will start to gas--Which will overheat the battery, cause it to vent, and/or develop gas pockets--if GEL.

Placing batteries in parallel for charging (if my guesses are correct) is your only safe and reliable option if you cannot have one charging port per battery. And you would need to group them:

Maximum (typical) charging voltages:
14.2 volts -- GEL
14.4 volts -- AGM
14.5 to 14.8 volts -- Flooded Cell (you would need to check electrolyte levels--add distilled/filtered rain water as needed)

And, you would need to check the condition of each battery... If you have a near dead battery in parallel with batteries that are reasonably full charged, the near dead battery will draw all the current from the other batteries until it too become more charged--Then the rest of the batteries will begin to share charging current.

On occasion, you can have a battery with a shorted cell--That can draw current from the other batteries and discharge them instead of charging them--And the battery with the shorted cell will probably overheat/do bad things (if left on long enough).

So, now you are left with having to monitor each battery with a DC Current Clamp meter to ensure that it is getting its fair share of current (not too much, not too little)... This is the problem with paralleling batteries for charging--And especially with paralleling batteries of mixed age/state of charge/quality.

You can do some things to midigate some of the issues... You can put a blocking diode in the + wire to each battery--That way, one battery cannot discharge the other batteries. You could put a resistor with a cheap millivolt meter on each resistor--The voltage across the resistor will tell you how much current each battery is taking (higher voltage battery is charging or possibly a shorted cell--As battery becomes full, the charging current/voltage drop falls).

However---The ideal method would be to setup a 1.5 Amp charger for each battery brought in for charging. There are chips that can do this easily--And if done in some quantity, it would not be too expensive to have a custom circuit board designed to your requirements and built (of course, there is probably not a lot of extra money floating around in the first place--So that may not be a practical answer).

For example, this is way to expensive (I would guess) for your needs--But something along these lines:

http://www.powerstream.com/DCC.htm

There are lots of companies that make DC to DC Converters like this: For example (I know nothing about the product or the website) is a $6.10 USD power supply. You supply 24 volts, and it supplies an adjustable dc output @ 2 amps--With an integrated volt meter:

http://www.aliexpress.com/item/LM259...900707610.html

Attachment not found.

You make a 24 volt solar power system, and then attach these modules (one per 12 volt battery) to charge...

Anyway, some thoughts on the question.

-Bill