Please help! why is my system not charging?!!!

[martinho]

hello! Newb here.
We live in a van with a small 12v pv system which has just stopped working....
I have been trying to figure out what the problem is but I'm totally stumped.

basically the panel is not charging the battery. the system was working perfectly until a few days ago when the battery got a bit over juiced....but the battery still reads 11volts when disconnected, so i dont think it is kaput..
currently the panel is producing about 19volts at the point of entering the regulator. but the output from the regulator to the batteries is only around 4 volts. the regulator seems to be on, but not charging.

i have taken the whole system apart, tested each component and put it back together again... no change.

So is it that the battery is too low? or that the regulator has broken... or something else?

thank you in advance for help or advice

[Sunking]

This will be easy to figure out so relax OK

Sounds like you tested the panel, at least you see voltage (19 volts) which indicates the panel is probable OK.

What sounds fishy is the output of controller and battery voltage. They should be the same. Not possible to have 11 volts on the battery, and 4 volts on the output of the controller unless you have an OPEN CIRCUIT like a fuse that has blown, or a bad connection.

Use your meters Ohm Meter function and test continuity of the wiring. On the positive output terminal of the controller put one lead of your meter, and the other end on the battery positive term post. You should read a dead 0 Ohm short. Repeat for the Negative circuit.

If the battery is bad what you should observe is a low voltage of like you said 11 volts when disconnected or at night with no sun shinning with no charge. When under charge should go up even if the battery is bad. Up to 14 or more volts very quickly if the battery is bad.

But something is fishy because the output of the controller and battery should be roughly the same voltage. If not find the open circuit with your Ohm Meter. Once you got that issue solved we can proceed if necessary.

[PNjunction]

currently the panel is producing about 19volts at the point of entering the regulator. but the output from the regulator to the batteries is only around 4 volts. the regulator seems to be on, but not charging.

i have taken the whole system apart, tested each component and put it back together again... no change.

In this case I'm assuming by regulator you mean solar-charge-controller, and not your vehicle regulator.

If so, one of the classic mistakes is trying to measure the output of the solar charge controller with no battery attached. They don't work without the battery, and you'll get skewed to no results that way. I suspect that the battery is toast from an underpowered system.

One other 'gotcha you can encounter in the field, especially when taking it all apart for testing, is attaching the panel to the controller first, and then attaching the controller to the battery last. For many controllers, that is the wrong sequence, and the charge controller may ignore the panel output trying to protect what it *thinks* is a bad battery with very low voltage! In your sequence of events, the battery is just missing completely, which the controller thinks is a highly discharged 0-volt battery and will refuse to charge for safety reasons. See what I mean?

So attach battery first, then attach the panel. See if this brings things back to life, although you may just simply have a dead battery. Need more info on your panel size, controller, and battery ....

[inetdog]

It can be even worse than that. The CC may rely on the presence of battery voltage to complete the startup of its microprocessor. If you connect it to the panel first, it cannot boot successfully even if you later attach it to the battery while the panel is still connected.

[PNjunction]

I've seen that!

Also bad are some that might only get their brain together enough to bulk charge to the float voltage setting and no higher. This can cause problems for those that were expecting absorb voltages from it but the safety kicked in first when the battery was attached last.

[inetdog]

One of the other possible bad outcomes is the multi-voltage charger which decides that the bank is 12V instead of your 24V and is unable to charge it, or worse decides that your 12V bank is a 24V bank and cooks the heck out of it.