battery maintenance

[Mauri Meere]

Hi
My battery terminals are corroded and need cleaning. What is the safest way/sequence to disconnect and reconnect batteries for cleaning? Do I need to cover the PV panels etc, etc.

Also how many Hanwha Solar Q.PEAK-G4.1 310 Watt, 60-cell mono PV modules can safely be connected to Solar EF 2215BN MPPT controller. Is it better to match pv array voltage to battery bank voltage or have a higher array voltage?

Thanks, Mauri

[Rob Beckers]

Hi Mauri,

For battery banks, keep in mind that the Voltage cannot hurt you. At most that is around 60 Volt (for a 48V battery bank) and most people can barely feel that. It's not enough to hurt you. What can do damage is the current: Batteries can deliver thousands of Amps, enough to melt tools or turn wire (briefly) into a light bulb if you short-circuit a battery. In short, no problem to touch any of the terminals, just don't cause a short!

With that in mind, the safest aproach is to disconnect the wire from the negative terminal of the bank, then, if you want to be very careful, the positive as well. Just keep in mind that you can still cause a short between the battery terminals, so work carefully with metal tools! What I do is tape all but one end of the wrench with electrical tape, so I can't accidentally short it with the tool.

The 2215BN has a maximum input Voltage of 150V DC. That is three of those 60-cell Hanwha panels in series. For a 12V battery bank the advise is to keep it at 2 panels in series max, for 24 or 48V three is fine. Generally it's better to have a higher array Voltage.

You don't have to disconnect the array from the charge controller to do battery maintenance (the manufacturer recommends it, but personally I've never managed to do damage to a charge controller by leaving it connected). If you have an easy way to disconnect, a breaker etc., then of course it's better to disconnect before disconnecting the battery.

Best of luck!

-RoB-

[Mauri Meere]

Thanks for that.

Right now in my 24volt system, I have 4 Kyocera 3amp 12volt 50watt modules(in series

for 48volt) is there a way to increase the array size by adding a couple of Hanwha 310watt

60cell modules or do I have to abandon the Kyocera's (which are still in good shape).

Thanks

[Rob Beckers]

Mauri, you double-posted the same question in another thread...

What you didn't mention in the other post is that your battery bank is 24V. Putting those panels in series would require an MPPT charge controller to convert the Voltage down to 24V, if you put that into a PWM type controller you'll loose 50% of the output power off the bat. For a simple PWM controller you would be much better off putting two panels in series, and connecting the two strings you get that way in parallel (about 8A into the batteries).

-RoB-