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Griffon Charging

Posted: Mon Mar 28, 2016 7:08 pm
by Gangesboy
I have a slightly annoying problem with my charging system, specifically the charging light stays on, even though the batteries are charging, or at best goes on and off.
(At best it goes off for two seconds then comes on for one second!)

I was at the boat today with a pal and we put a meter on each battery, number one battery is the rear battery,( I considered it the starter battery) number two is forward of it. They are wired in parallel of course.

Ok so with the isolating switch on no:1 position no:2 battery charges. On the 'both' position they both charge, and in no:2 position no:2 charges again.
Now i can live with this, batteries are charging I have all LED lights in the cabin, and as yet I haven't had a flat battery, I take them out and use a ctek charger twice a year, which keeps them in good nick, they are 85ah units.

I still have the original MD7A engine which was only intended to have a single battery as far as I can see from the manual.

We came to the conclusion I don't have a starter battery and a domestic its one big 12v battery!

Can you Guys and Ladies help or shed any light please?

P.S. The alternator belt is new and adjusted correctly.

Re: Griffon Charging

Posted: Mon Mar 28, 2016 9:51 pm
by BrightStar
Hi Gangesboy, if your batteries are physically connected in parallel then effectively you have a single battery of 12v with a capacity of 170Ahr, this would be unusual are you sure the batteries are physically connected.

In my opinion it would be better to split them so that you have a seperate starter and house battery, putting the switch to both will effctively parallel them.

If the alternator is charging the batteries correctly, the intermittent charge light might be a fault on that circuit, be worth chckng that all connections are tight including the -ve to the engine block, give all the cables a rough shaking to try to find a loose or poor connection. Better to find it n your hand rather than have a poor connection waiting to bit you

Try runnng the engine for a while, shut it down and leave it stand for 15 minutes then check the battery volts, if better than 12.6v it is probably being charged ok, this should stay lke this after a few hours.

How old are the batteries, once they are over about 5 their days are numbered.

Worst case the alternator may need a service - brushes.

I have put new batteries into my Griffon this winter and doubled up the house battery, so now I have 240Ahr house and 85Ahr high cranking starter battery. I also have converted to LED lighting

Let us know how you get on

Re: Griffon Charging

Posted: Mon Mar 28, 2016 10:35 pm
by aquaplane
I have a 1,2,Both, off switch on my Centaur (boat is not relevant).

The switch decides which battery or batteries juice is taken from.

When the engine is running the alternator charges both batteries no matter where the switch is set, so long as it's not OFF.

Flickering charging lights are the work of the devil and probably involve magic to find a fix, good luck

When my charging light was intermittent, it was accurate.
When it was on it wasn't charging, when it was off the engine note dropped and the volts went up.
That proved to be a loose terminal on the Alternator, been OK for ages now.

Re: Griffon Charging

Posted: Tue Mar 29, 2016 5:14 pm
by TyroSailor
If your alternator does turn out to need a service - and you're in the Southampton area - there's a very good chap near Botley who specialises in alternators (and starters). I don't have his details to hand at the mo, but let me know if you need them and I'll have a look.

Re: Griffon Charging

Posted: Tue Mar 29, 2016 6:23 pm
by philipstevens
I found these answers from different forums -
The flickering light means there is a difference in voltage between the alternator output and the sampled output fed back to the alternator rotor. This sample is derived via a trio of diodes and the alternator output is also derived via a second diode trio. If one of these diodes is faulty the light will flicker because it means that the rotor voltage and the alternator output are different (which should never be the case with the engine running).

With the engine running, the batteries will not be losing charge, they will be gaining charge (from the alternator). A flickering charge light means that the alternator output terminal voltage (B+) is different to the rotor input voltage(D+). This can only be the case if one of the diodes has failed or is failing OR the alternator belt is slipping.

Hope these help.

Re: Griffon Charging

Posted: Tue Mar 29, 2016 6:36 pm
by Gangesboy
Many thanks gentlemen, I have to agree with Brightstar that they need to be separated, that will be next on the list.
I will investigate further regarding your suggestions and report back.
Best Regards.

Re: Griffon Charging

Posted: Tue Mar 29, 2016 7:34 pm
by BrightStar
if you're based around the Essex / Suffolk rivers and would like a hand then let me know, I am on the Orwell :D

Re: Griffon Charging

Posted: Sat Apr 02, 2016 3:35 pm
by Gangesboy
Hi Brightstar,
Many thanks for the offer, that would have been handy but I'm on the West coast of Scotland, so a wee bit far away!

Re: Griffon Charging

Posted: Sat Apr 02, 2016 3:57 pm
by Gangesboy
Hi Brightstar,
Many thanks for the offer, that would have been handy but I'm on the West coast of Scotland, so a wee bit far away!
I had another look at the system, the batteries are connected properly neg to neg and the pos to the switch, so as you say when switched then the are connected in parallel.
Ran the engine as you suggested and after 15mins the charge on both was 12.8, they are 4 years old.
the earth was a joke so a nice new braided one was fitted.
Had a good look at the wiring for the charging light and it all looks good.
I think your idea of getting the alternator serviced is looking good.