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[VanWithMan]

Hi All,

I am having issues that my battery is reaching 16V when I charge using my mains charger. It is a Paco, 7 stage, 12V charger that is advertised as plug and forget. So it switches off when the battery is fully charged and should only give a maximum of 14.4V when charging.

My solar controller is set to stop charging at 14.4V.
So why am I sometimes getting the 16V reading?
The mains charger is connected directly on the battery and obvioulsy the solar panels go through the MTTP controller. I got the mains charger because in the cloudy uk winter I was only getting between 6-10Ah of charge from the panels which isn't enough to power what I need.
I have a basic understanding of electronics so I have a couple of ideas on what may cause it;

1.   The mains controller is seeing the 14.4V from the panels and is trying to "charge them up?" Sort of like how a solar panel connected to a battery at night will draw current from a battery if you don't have the solar controller to prevent this.
2.   The solar panels are seeing the mains charger and trying to charge that up by allowing 16V from the panels? I don't think this is the case because the solar controller is set to 14.4V and when the mains charger is connected I would have thought that the panels will be disconnected.

I have thought that maybe I should connect the mains controller to the solar input on the MTTP controller. That way the mains controller becomes a 2nd solar panel.
I have also thought I should just disconnect my panels while I'm on electric Hook up and just allow the mains charger to do its thing.
If anyone can help that would be great. If you have a mains charger and solar panels I would love to know how they are connected.

Thanks for reading

[Camper_Dan]

Greetings!

I think I would isolate each, and see what they're charging at.  When dosconnecting the solar, make sure you disconnect the panels before the controller.  When reconnecting, the controller gets hooked up to the batteries first, and the panels last.

My guess would be a faulty charge controller, I went through many before ditching solar altogether.  Now I mainly charge while driving, or with a cheap battery charger connected to shore power or my generator. 

I once had an expensive multi-stage battery charger, and the guy at the battery shop suggested a cheap 2/10/50 amp automatic charger.  Seems like it may have been around $30.  At that time, I didn't have an isolator, and was charging my batteries only with my generator and fancy battery charger.  The batteries were lasting me about 3 years, about 2 years longer than when using solar.  When I switched to the cheap battery charger, my battery lifespan more than doubled.  Later, adding an isolator almost totally eliminated my need for the generator, but didn't lower the battery life.  Now my generator is mostly a backup and to help charge up other people's batteries.

After years of experience and trial and error, today my power system is very minimalistic, a 110amp deep cycle battery from a junk yard for under $20, in a plastic boat box, connected to my starter battery via a solenoid.  Taped to the outside of the battery box I have a 4 port ciggy outlets thing.  That's it.  From that I can run all the 12v and USB accessories I want or need.  I no longer have an inverter, and if I want shore power, I can just fire up my generator.  By design, I use very little power, and now consider it a luxury instead of a necessity.

I'm in the USA, and in some parts of the country are large groups of Amish and other people who live their lives without electricity of any kind.  Many don't even have cars and still use horses & buggies.  While I'm not interested in going to that extreme, I think learning to live comfortably without electricity, batteries, or electronics, is a good skill to have.

Cheers!