Earlier this week I installed 3 new 110ah leisure batteries. Since then if we cruise for more than about 5 hours the battery monitor gives an 'over voltage' alarm. I checked with a digital voltmeter and it ranges from 15.6 - 16.2.

Most of the day the monitor shows 12.8 - 13.2, then it goes up to 14.4 for a while then the alarm comes on and it's over 15v.

 

Is it the regulator on the alternator that's shot ?

 

Thanks

 

Steve

What does the voltage do as soon as you stop the engine?

It drops to about 13.4

I'm thinking tomorrow of disconnecting the domestic alternator and using a jump lead to connect the two battery banks and running on the engine alternator.

I don't want to fry my brand new batteries! !

 

Steve

I am just wondering if there is a volt drop between the point where the meter is connected between the battery and the alternator and the actual battery, It would be good to measure the voltage on the battery terminals and compare it to the alarm unit.

1)Have you got an adverc or a sterling,

2) We had this problem last year and it was a cheap advec modified regulator that had gone rough it basically boiled thebatteries and cos it was over voltage the adverc couldn't regulate, ( their default is to the inbuilt reg) if your batteries are at 16.2 they will gas overheat and buckle plates. Course you could have one dead cell instead. Charge disconnect leave an hour no load and check individual voltages . Should be the same circa 12.8/9 volts.

I am just wondering if there is a volt drop between the point where the meter is connected between the battery and the alternator and the actual battery, It would be good to measure the voltage on the battery terminals and compare it to the alarm unit.

It isn't connected between the battery and alternator, it's straight onto the battery

Without any meaningful info about the alternator it sound smor to me as if the alternator is batetry sensed any you have left the sense terminal off the battery (or just possibly put it on the wrong terminal).

Without any meaningful info about the alternator it sound smor to me as if the alternator is batetry sensed any you have left the sense terminal off the battery (or just possibly put it on the wrong terminal).

That was my first thought but there doesnt seem to be a sense wire on the alternator.

I'll check again, but I was very careful putting back the connections

Without any meaningful info about the alternator it sound smor to me as if the alternator is batetry sensed any you have left the sense terminal off the battery (or just possibly put it on the wrong terminal).

Tony

Does this pic help?

You are not alone !!!

 

http://www.canalworld.net/forums/index.php?showtopic=84989&hl=

 

Maybe its the weather.

Tony

Does this pic help?

You need a regulator. That is the common or garden A127 alternator so you should find one off ebay. Simple to change, looks like yours would be simple with the alternator in situ. All you need to do to shut it down whilst you run off the other pro tem is to stick a wire from the warning light terminal to earth before starting the engine and leave it there. That alternator will then be just a belt tensioner until the link is removed.

Is the yellow/black wire the warning light terminal?

>That is the common or garden A127 alternator so you should find one off ebay

 

We're currently cruising, so eBay isn't really an option. Also we have a deadline to get son-in-law back to work!

I'll try and get one from a local motor factors.

Is the yellow/black wire the warning light terminal?

That's the one.

But presumably I need to disconnect the main terminal ?

But presumably I need to disconnect the main terminal ?

No, that link will harmlessly shut down the machine completely and the main terminal will be in the same state as if the engine wasn't running.

No, that link will harmlessly shut down the machine completely and the main terminal will be in the same state as if the engine wasn't running.

If Steve is stuck getting a bit, could he run for say 4 hrs, watching his voltage, shut the engine down and link the field to earth and then carry on for a couple of hours.

I would say that once the batteries are charged up you should be able to run fine for 2 or 3 days with the alternator shut down, IF things like electric fridges and inverters ect are switched off, and just use the water pump and lights sparingly. The starter battery should hold up all right over this period as long as the engines an easy starter.

This assuming the batteries are in fair nick.

Edited May 29, 201610 yr by bizzard

I would say that once the batteries are charged up you should be able to run fine for 2 or 3 days with the alternator shut down, IF things like electric fridges and inverters ect are switched off, and just use the water pump and lights sparingly. The starter battery should hold up all right over this period as long as the engines an easy starter.

This assuming the batteries are in fair nick.

I think they are new, the start of his problems

before I ripped things to bits and mended them I think I would want to confirm the voltages independently under charge and load.

Did as advised by Sir Nibble. All ok so far, stable at 13.9 - 14.1

Did as advised by Sir Nibble. All ok so far, stable at 13.9 - 14.1

Where are you getting your charge from then, is there a second alternator?

Where are you getting your charge from then, is there a second alternator?

Yes, I have put a jump lead from the engine battery, so the other alternator is now charging both.

Yes, I have put a jump lead from the engine battery, so the other alternator is now charging both.

OK you are ok for a bit then

I also had an overcharging problem, which I assumed was due to the alternator controller, and described here When I was back to the boat recently, I started measuring things again, and found that while the starter battery was being overcharged (19V !), the leisure batteries weren't being charged at all. So I connected the positives together as an emergency measure, and lo and behold! everything went back to normal, with both being charged at 14.5V.

 

So am I to assume that the split charge system is faulty? I've searched diligently but cannot find a relay and I wouldn't know what a diode looked like. Anyone care to enlighten me? All the relevant wires disappear into a bulkhead and only reappear behind the control panel.

Often black "boxes" with fins on the outside and three thick wires but Lucas made on that was built into an ignition coil case bit 9mm blade terminals. Now those were trouble.