I have a battery problem... According to my solar charge controller

[Kelpie]

A few years ago I installed a 50w solar panel and a cheap eBay charge controller with remote monitor. This is hooked up to my two 110Ah leisure batteries. The controller and monitor are the same as in this listing:
https://www.ebay.co.uk/itm/200W-DUA...210236?hash=item239cd749fc:g:YvsAAOSwHgdatAA-

I recently noticed that a red light had come on on the controller, and on the monitor one battery was flashing and showing no voltage information.
The battery in question is showing a slightly low voltage (about 12.5v) compared to the healthy one which is at about 12.8v. It still powers up cabin lights and my plotter, which is quite voltage sensitive.
Is there a chance that my cheap solar setup might have damaged the battery? The batteries are about five years old and have seen very little use, I expected to get a few more years out of them.

 

[jiris]

The 50 W panel is capable of delivering about 2.5 A in a full sunshine - that is just about a trickle charging for 220 Ah battery bank. Taking in account this current would be delivered only for a fraction of day, it is unlikely the panel would be capable of cooking your batteries even without any regulator.
Not sure what type of batteries you are using, but unless they are quality AGM, the 5 years lifespan is quite reasonable and you should consider anything over that time as a bonus. BTW, measuring just the voltage of battery without load gives you very little information about its actual condition (however, if the reading is low, it is almost certainly bad). Try a proper battery tester before making any definite conclusions.

 

[William_H]

As said use a multimeter to measure the voltage of the batteries and compare. Then apply a load of a few amps to each battery for say half an hour compare the end voltage of the batteries. It is possible that the voltage sensing system of one part of regulator has drifted or failed compared to the other. ie regulating too low. Try swapping the 2 outputs and see if you still get problems on one battery. ie does the battery problem move to the other battery? If same battery is down both on charge voltage and on voltage after discharge then as said battery is on the way out. Not that you should throw it away just keep an eye on it's performance and when it is not doing the job you need (engine start or powering equipment for long enough then have a new one. olewill

 

[Kelpie]

That's a good idea about swapping the batteries over,I will try that.

 

[NPMR]

After 5 years, I had, suddenly, a red warning light flashing on my Steca controller. Luckily a marine electrician looked at it for me and told me the solar panel was putting out 18v but the controller only 3v. In other words controller was kaput.

Replaced like with like, and all green lights were to be seen! I had also bought, prior to controller replacement, a battery tester to check cold cranking amps and found all OK. So it wasn't the battery, which the 'instructions' were telling me to get fixed.

 

[Kelpie]

Finally got round to looking at this. Seems that I have a dodgy connection somewhere between the controller and battery, so should just be a matter of replacing those wires. I love it when a problem turns out to simple and cheap!

And as a bonus, it's given me the impetus I needed to finally install the third battery that has been sitting in my shed since I scrapped a car last year- I'd bought it a month before the car failed its MoT so it's good as new. This will become the dedicated engine battery and the two 110ah leisure batteries will become the house bank.