Wiring 4x12 volt panels in series for 48 volts, how many diodes

[chuckinnc]

I bought 4 - 12 volt panels to help trickle charge my 48 volt golf cart. Each panel came with a diode, Im going to hook the panels in series to give 48 volts
total, I think only one diode will be needed, is this correct?

[Sunking]

Correct.

[R Schoeb]

Golf Cart Solar

I have decided to charge my 36 volt golf cart (6 6 volt batteries) using 3 12 volt panels charging each 2 batteries. I have connected each panel to two batteries charging each bank of 2. I'm using 12 volt solar controllers on each panel to keep from overcharging. I have temporarily hooked this up and hooked a meter to monitor the voltage and it did increase the voltage by .5 volts in about one hour. Does anyone see any problem with this setup?

Someone ask me if I can still use the cart battery charger with the solar panels hooked up. I don't see any problem since the solar controllers have diodes to keep reverse current from destroying the solar panels. I have extra diodes that I can put in line with the solar panels just in case.

I know this in reply but didn't see original message post. Sorry, this is my first post.

[Sunking]

I have decided to charge my 36 volt golf cart (6 6 volt batteries) using 3 12 volt panels charging each 2 batteries.

Very very poor idea. Basically means all you rbatteries will be at different State of Charge levels. Double trouble without a charge controller.

[R Schoeb]

Separate charge controllers

Very very poor idea. Basically means all you rbatteries will be at different State of Charge levels. Double trouble without a charge controller.

Using separate charge controllers for each bank of 2 batteries. Before I started I checked the 3 banks (2 6volt batteries) and they were uneven. That was using a 36 volt charger. Water level is okay. I figured the controllers would bring each bank up to the same level. What am I missing?

[SunEagle]

Using separate charge controllers for each bank of 2 batteries. Before I started I checked the 3 banks (2 6volt batteries) and they were uneven. That was using a 36 volt charger. Water level is okay. I figured the controllers would bring each bank up to the same level. What am I missing?

If you charged each pair of batteries with separate charge controllers and solar panels at the same time you would have to be very lucky to get them all charged up to the same level. Each set of batteries would be at a different charge level.

Once you reconnected them back to a single 36volt system the voltage of the highest pair of batteries would drop to somewhere above the lowest pair. This may work for a period of time but I feel would shorten the life of the batteries and reduce the number of cycles.

It would be better to have a single bank of batteries at 36 volts being charged with a properly sized solar CC and panel wattage or a good factory 36volt battery charger. If you were not getting an even charge using your 35v charger then there is an issue with that charger, battery wiring or you already have a couple of batteries starting to fail and have a higher resistance compared to the other batteries which will result in an uneven charge.

What is the Imp of those 100 watt panels, type of 12volt charge controller and the Ah rating of those 6v batteries you are using? Chances are each panel provides maybe 6 amps of charging and I doubt those batteries are only rated 60Ah each. If they have a higher than 70Ah rating I do not believe you can properly charge a pair with just one 100 watt panel.