Bad batteries or not charging?

[SlugmasterP]

In my last boat the electrical system was very simple with one 12 volt starting battery and one 12 volt house battery.

In my new to me boat it has a house bank of six 6 volt batteries which are connected to make a bank of three 12 volt batteries.

The problem I am having is that the voltage meter on the boat is reading 8.15 volts for the house bank. I know that is supposed to be reading 13-14 when it is charging. How do I know if the batteries are bad or if its a charging issue? I have already replaced two of the 6 volt batteries as the terminals were heavily corroded. When I did this the voltage jumped up to 10 or so but then dropped back down gradually. I disconnected the batteries one by one and measured the voltage they read as follows for the 6.

3.54 (old)
4.59 (old)
3.98 (old)
3.81 (old)
5.47 (new)
3.82 (new)

The reading for the whole house bank was 8.15

My question is what is the next step? I don't want to just replace all the batteries without knowing. I added a picture of the Xantrex Link 2000. When I press the "charge, power share" button when connected to shorepower the starting battery jumps to 14 volts but the house bank just sits at 8.15. Any help would be appreciated as I'm brand new to all these controllers and everything. Is it just a setting I'm missing or what?

[sailorboy1]

What did you use to measure those battery voltages? If you haven't yet, measure all of them with a volt meter.

[courageous cat]

The voltage of you house bank is way low, a six volt battery should rest at 6.30 volts
Just by what you say it sounds like the starting battery is gettin a charge but not the house bank. Problem might be wiring
How long have you had the boat. did this just start happening

[motion30]

go to the auto parts store and buy a cheap hydrometer. That'll tell you the actual shape of your batteries. Allow you to find a problem

[Scott Berg]

When the batteries are connected and the charging source is on you're reporting that the voltage isn't going up at all?? Even if the batteries were dead (and they are) there should be a large jump in voltage. Try a portable battery charger and try to bring the batteries up to charge. Also, trace the wiring on the charger (look for a blown fuse?). Might be a good time to hire a good marine electrician for an hour to trouble shoot everything.

[boatpoker]

Sounds like they are not being charged but also parallel/series wiring of of six 6vdc batteries into three 12vdc banks is a lot of wire and connections for someone unfamiliar with DC electricity .... are you sure they are wired properly.

[wingless]

What is the charger voltage when it is not connected to the batteries?

[tomfl]

Originally Posted by motion30

go to the auto parts store and buy a cheap hydrometer. That'll tell you the actual shape of your batteries. Allow you to find a problem

+1 with the qualification that you have flooded batteries. Best way to assess the condition of your batteries.

[smac999]

which bank is the xantrax hooked up to?.... if the starter one is hitting 14v when you turn the charger on it sounds like it's hooked to the engine battery... because I doubt the built in echo charger would hit 14v while the house bank is still at 8 ??

[SlugmasterP]

Thanks for the help guys.

The xantrex is hooked up to both the starter and house bank. At least I think it is but maybe that is the problem.

I measured all the batteries separately with a volt meter. Don't have a hydrometer but I'll pick one up.

How would I go about measuring the charger voltage when not connected to the batteries?

[jeepbluetj]

The hydrometer is gonna tell you the batteries have no charge - because the batteries have no charge. The new ones merely discharged into the old ones.

I'd attempt to charge up 1 pair. If you have another battery charger, I'd use that to get a "good" set of batteries. If not, measure voltage at the battery when you turn the charger on - if will go up (not to 14v). Start with the "new" batteries. Get em good and charged.

If you don't get a voltage increase on that pair - trace wires back to the charger - it's a connection or charger problem. (Maybe a fuse or something real simple)

Once you have one pair working, do the same for the other two pairs. Once they're all fully charged, and measure 12.7v or more at rest, you may be able to hook them all back in parallel. Let them rest awhile - a bad cell doesn't always react quickly.

Now you could measure with the hydrometer to find weak cells. But you need to figure out charge/nocharge and if the batteries are any good at all first. And in my opinion, that's easier with a voltmeter.

[SlugmasterP]

Originally Posted by jeepbluetj

I'd attempt to charge up 1 pair. If you have another battery charger, I'd use that to get a "good" set of batteries. If not, measure voltage at the battery when you turn the charger on - if will go up (not to 14v). Start with the "new" batteries. Get em good and charged.

If you don't get a voltage increase on that pair - trace wires back to the charger - it's a connection or charger problem. (Maybe a fuse or something real simple)

Once you have one pair working, do the same for the other two pairs. Once they're all fully charged, and measure 12.7v or more at rest, you may be able to hook them all back in parallel. Let them rest awhile - a bad cell doesn't always react quickly.

Now you could measure with the hydrometer to find weak cells. But you need to figure out charge/nocharge and if the batteries are any good at all first. And in my opinion, that's easier with a voltmeter.

So when I'm getting the new pair back to fully charged I will have the rest of the house bank disconnected correct?

[Stu Jackson]

Link 2000 - the algorithm has the F11 function, you need to read about it and see if it is set up properly. ASnd that the shunt is wired properly.

What charger is the Link 2000 controlling?

[maine50]

Is there a battery switch that combines starting and house bank? When I got current boat it took me about 6 weeks to realize I wasn't charging the house bank when engine running. I had to "combine" the banks as the wiring was set up to use the starter cables (starter battery to starter) for the charging circuit back to the batteries.

[wingless]

Originally Posted by wingless

What is the charger voltage when it is not connected to the batteries?

Originally Posted by SlugmasterP

Thanks for the help guys.

How would I go about measuring the charger voltage when not connected to the batteries?

The Xantrex Link 2000 shown in the first post is a battery monitor, used w/ a Xantrex Freedom 10, 15, 20, 25 or 30 inverter / charger.

The inverter / charger has a battery connection(s) w/ one bank for the 10, 15 and 20 and two banks for the 25 and 30.

There red input(s) / output(s) from the inverter / charger should pump out 12.5 - 15.5 VDC, depending upon ambient temperature, with the inverter / charger not connected to the battery.