Solar Panel-Battery won't fully charge

The "built-in" regulator supplied with the solar panels are not very good and perhaps you should consider upgrading it to a smart solar regulator which is better placed at the battery end of the circuit.

But why is the main battery being flattened? You shouldn't be running any heavy loads off it. That is what auxiliary batteries are designed for.

You should first get the main battery load tested. It may be faulty and either not reaching a full charge, or not maintaining the charge due to a faulty cell.

Hi Jimmy,
Sounds like it is your solar regulator. As Sandman has indicated
If you are still getting 20 volts or there abouts at the panel before the reg, then it seems the panels are OK. So that points to the reg.

I would get a new reg rather than direct connect.

Cheers, Bruce.

Jimmy,

There is something wrong with your setup. If the panels are delivering any charge, you shouldn't see such a high voltage at the panels. Also, the regulator shouldn't cut out at such a low voltage.

I'd go ahead as you propose and charge the battery directly from the panel, as I think you have a crook controller. (You'll need to disconnect the controller so it doesn't interfere.)

It will be necessary to manually monitor your battery voltage so as to disconnect the panel when that voltage gets up over about 14V. This will take quite a few hours and the battery should be able to start the engine well before it rises that far. (Assuming the battery itself is ok, and nothing is drawing charge while you are charging.)

Cheers

John

When you flatten a cranking battery they take a fair bit of power to charge them. They also will not take a lot of current until the charge level rises significantly. The only time I have monitored the charging of a deeply discharged battery I was surprised how much it took to get a charge back into it.

I was using a bench power supply capable of 10 A at OP voltages between 9 & 16 V. In the beginning I had to set the PSU at 16 V to get any sort of current into the battery. At that point the battery would only accept 1.5 A. When the charge level rose slowly until the battery would accept 10 A. I then had to keep reducing the applied voltage to keep the output current at 10 A or below.

When you commence to charge a flat battery like that the solar regulator will not be doing any regulating at all, it will be running flat out (or trying to do so.) Initially the battery terminal voltage will rise to somewhere around 12 V fairly quickly. It will then mark time with a very slow rise in voltage until you start to get some capacity back into the battery . With only 12 V at the terminals you will be only getting a small trickle of current into your battery (see my experience above where it took 16 V to get any significant current into the battery.)

Quote - "It cuts out when the battery reaches around 12v." Did the charger actually cut out or did you not wait around long enough (a few days) to see if the current would keep rising?

Jimmy88
Charge your cranking battery from the mains, for 2 days solid or 2 times overnight if necessary.

If the battery then comes back after you disconnect for 1 hr , with 12.4 volts or lower, then it's probably stuffed.

Pls let us know what you found if you get it sorted.

Look what I did

http://www.exploroz.com/Forum/Topic/89551/Solar_Panels_and_controller.aspx?ky=bucky+&sn=&p=%2fForum%2fDefault.aspx%3fs%3d1%26ky%3dbucky%2b%26pn%3d1

Cheers
Bucky