Volvo Alternators

[dragoon]

Maybe someone can help me with a little advice.


Recently my 12v (175Ah) house battery gave up the ghost and I replaced it with a new one from LSUK (who incidentally closed down across the UK the following day /forums/images/graemlins/frown.gif

The thing is, the battery sits at around 12.76 V when not charging. If I start the engine, the voltage comes up gradually to around 13.8V.

If I use anything electrical, quickly the voltage falls - e.g. running with the Nav lights on, the GPS and the radio (listening only) brings it down to around 13.2.

If I put the fridge on, it comes down to 12.9 or so.

It looks to me that somehow the output of the alternator is not able to keep up with a fairly low current demand.

So my question is, what output is the alternator supposed to put out ? The engines are TAMD40s and the alternators were renewed a few years ago just after I bought the boat.


Any thoughts or pointers most appreciated.

Cheers,
Paul

 

[volvopaul]

If you have a split charge diode as most volvo set ups do then you loose a slight amount of voltage through this, as lone as it doesnt drop much more then the alternator is still charging, take a reading from the alternator positive terminal rather than at the battery that will give a true reading.

Is the boat twin engine? if so it may have a double diode pack either on the alternator itself or remote mounted on a bulkhead.

Ive just been down a similar route with my new boat, the problem was with some emgineer that will remain nameless as he is southcoast based, basically he fitted 2 new alternators to my boat for the previous owner but fitted non genuine single pack diode alternators from a non volvo supplier and wired the engine start batteries into the domestic charging side, net result all batteries drain down together, very clever it could also have caused a fire hazard when I tried to start the engines with the cut off in the off position as the current supplied through the alternator still supplied the ignition system!!!.

 

[dragoon]

Hi Paul,
thanks for the reply.

I've tried, but never been successful in identifying a seperate split charge diode (or a double diode pack) with this installation.

It's a twin engine setup, and the system is wired as follows - port engine charges starter battery and starboard engine charges the house battery.

There is a link switch which seems to be nothing more than a mechanical switch between both systems, mounted close to the batteries.

The alternators were supplied by Volvo a few years ago - from memory they were a Valeo equivalent of whatever was in there from new.

The boat is a 1980's Storebro if that helps throw any light on how it could be wired.

I'll try and measure voltage at the alternator as you suggest. Any thoughts on what current these are likely to supply?

Thanks,
Paul

 

[Andrew_Fanner]

>>>
LSUK (who incidentally closed down across the UK the following day
>>>

That is a pain, my local source of sensibly priced oils, filters, belts and injector servicing etc. Nadgers. Any recommended Portsmouth area alternatives?

 

[dragoon]

Agreed, these guys were very good. We've even kept my father-in-law's JCB running with parts from this company - from memory a brand-new (not reconditioned) dynamo was something like 29 pounds!!

Unfortunately, I've no idea who could replace them. Maybe some other locals will have an idea? Anyone?

Cheers,
Paul

 

[VicS]

The alternators fitted to the MD40, TMD40, AQD40, TAMD40, AQAD40 range of engines mostly appear to be 35A at 14V

There does appear to be a "charge distributor" available (part #840638) that fits directly to the alternator for charging two batteries. A diode splitter I guess.

 

[dragoon]

Thanks Vic.

Cheers,
Paul

 

[pande]

The best (and most helpfull) motor factor in the Portsmouth area is Southsea M F, Grove Road, Southsea. Phone 02392751121.

(I have no conection with these guys) /forums/images/graemlins/grin.gif

 

[BartW]

probably your volt meter is connected on the supply side of the electrical switches / distribution at the dashboard.
If the supply wire to these switches is not oversized, there might be some voltage drop over this wire, in the range of figures you give.
Good advise to measure the voltage at the alternator, if you have 13,8 or more at that point, I guess you have no problem.

 

[Kawasaki]

Yep tiss a diode splitter as VicS says.
Your origional alternators would have been fitted with such.
The Valeo replacement would accept the D Splitter from your old alternators.

Then again surely the set up has been correct for a while?
As You mention You have owned the Vessel for some time.

BartW and volvopaul have it right.
Measurment at the Alt is the thing.

 

[volvopaul]

Thanks kwacker!

 

[Kawasaki]

No.
Thanks to You for all Your advice on ere, ref those Damn Green Thinghies /forums/images/graemlins/grin.gif

 

[NorthUp]

Your vee belt is slipping.

 

[Kawasaki]

Ooh err Matron!

 

[dragoon]

Thanks to all who replied.

Kawasaki, I do have some documentation that suggests it was originally fitted with a split charge system - I just find it so I suspect it either failed or was removed at some time.

Would this likely have been set up so that one (or both) engines could charge both batteries simultaneously?

And is it okay to include 2 split chargers (one per engine), so that both batteries are charged in all cases?



Yes, you're right I've had the boat for sometime - when I bought it I put in a new bank of house batteries (2 x 175Ah) and 2 new alternators. Since the batteries failed I've only replaced one of them - I'm convinced I don't need that much Ah as we're almost always hooked up to shore power, and I have a 45A mains charger installed.

During the last 6 months (as the batteries failed) I saw increasingly weaker voltage readings, and even the radio started reporting "low voltage". Hence when I replaced the 2 with 1 brand new one, I expected to see better at all times, but I don't.

.... and yes, the V-belt is tight and not slipping /forums/images/graemlins/tongue.gif


Cheers,
Paul