Jump to content

High battery voltage.


jeanb

Featured Posts

We would appreciate some comments/advice please. We’ve noticed the last couple of days that both our starter battery and our domestic bank seem to be reading higher than usual following our daily cruise, as measured by meter. We tied up an hour ago and have 13.01v on starter battery and 12.82v on main batteries. The installed multimeter is reading a tad higher. As we’re only used to observing about 12.6v we’re wondering if our 4 year old batteries that have been on trickle charge all winter are on the way out. Apologies if this has been covered elsewhere. 

Link to comment
Share on other sites

Just now, jeanb said:

Thank you rusty, only the inverter and 240v fridge on and no solar. So I appear to be worried about nothing.

I would be more worried about the 12.6v to be honest. Give them a bit of exercise from their winter on hookup, see if they can support your loads at a decent voltage between 12.2 and 12. 7. I suspect they are OK. 

Link to comment
Share on other sites

I would suggest that as soon as the fridge cuts in the inverter should remove the surface charge PDQ, So 12.82V on the domestic bank is probably fine and the 13.01V on the engine bank is just surface charge. If you want to see if that is true, just spin the engine on the starter for about 30 seconds with the stop operating. I bet the 13.01 will drop to about 12.8 ish.

 

Just keep an eye on the voltage an hour after you shut down for the day and again in the morning, that will give you a fair idea about how the batteries are doing.

Link to comment
Share on other sites

Here's an explanation of why the voltage is higher immediately after a battery comes off charge, from a book on accumulator charging, see page 33 and graphs on page 34.  It was published in 1942, but I don't think lead-acid technology has changed significantly since. The graphs represent behaviour using a voltage source higher than the accumulator,  a series resistance being used to determine the charging current. On a boat, the alternator's regulator would prevent the charging voltage per cell from becoming as high as that shown in the graph.

 

 

Accumulator charging 1942.pdf

Edited by Ronaldo47
typos
Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
  • Recently Browsing   0 members

    • No registered users viewing this page.
×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.