Batery sensed alternator

[muzzaman]

Having studied this carefully I am sure that my alternator is "machine sensed" rather than "battery sensed".

The output when charging seems to be 13.4v and I am sure I am losing charge due to a split diode installation.

The engine is a Volvo Penta 2002 (from around 1987) and the alternator is a Paris Rhone A13N 147M (14v 50amp).

The wiring at the alternator terminals is currently as follows -

D+ : Thin Brown wire - a connection to Warning Lamp
W : Thin Grey wire - Connection to Tachometer
B- : Heavy Black wire - to engine block
B- : Thin Black wire - not sure where this goes
B+ : Heavy Black wire - main alternator output to Diode splitter.

There is also a Yellow wire which seems to be attached from the regulator to the alternator.

Is it just a case of re-routing this yellow wire so it connects to the battery rather than the alternator?

I think I have just about got my head round this but am concerned I fry something by messing up the connections.

Any advice/experiences from forumites would be greatly appreciated.

I have attached a couple of pictures.

Many thanks in advance.

Muz.

 

[muzzaman]

Battery......not Batery!

Butterfingers

 

[VicS]

When you say 13.4 volts...measured where exactly ?

You are right about all the connections..

the thin black from B- is the negative connection to the starter relay and to the control panel.
The thick black on B+ would originally have been red.. who ever fitted the diode splitter used a black wire instead of red

My guess is that the yellow wire is the sensing wire. Getting it checked and modified if necessary by an auto-electrician would be wise.

If you connect the sensing to one of the batteries you have to be very careful not to run with the battery isolator switch open.
Probably better to connect it to one of the battery terminals of the diode splitter .. that way it will always see the alternator out put ... not a disconnected battery.
If the battery isolator does not disconnect the battery from the diode splitter then no problem.

Some basics on using diode splitters and alternator sensing on http://www.tb-training.co.uk/

The engine wiring diagram is in the owners manual which you can download from http://www.volvopenta.com/volvopent...lication_search/pages/publication_search.aspx

 

[muzzaman]

Battery Sensed Alternator

Vic

Many thanks for replying.

I am measuring the 13.4v across a NASA Battery Monitor Shunt on the domestic battery bank.

As suggested I will connect the sense wire to the diode splitter battery terminals rather than directly to the battery itself.

Also, I am fairly sure that the Yellow wire is the sense wire but not 100% sure. What would be the worst outcome if I took this wire and connected it to the diode splitter terminal? Could I do some damage?

Murray.

 

[VicS]

I am measuring the 13.4v across a NASA Battery Monitor Shunt on the domestic battery bank.

I dont understand what you mean by measuring the volts across the battery monitor shunt. that should be in the negative connection to the battery such that all the current going to or from the battery passes through it. The volts across it will only be a few mV (up to 50mV at the maximum current rating of the monitor) and be dependent on the current flow.

What I wanted to know was whether the 13.4 volts is at the alternator output or at the batteries.
If the former then there is likely to be a problem with the alternator as that is rather too low.
If the latter then its that low simply because of the volts drop across the diode splitter.

I am far from sure about the yellow wire which is why I suggested getting an auto- electrician to look at at and convert it to battery sensing. I dont have any info on that particular alternator.

 

[muzzaman]

Battery sensed alternator

Vic

Apologies, my terminology is not great on these things.

What I meant was that the NASA Battery monitor is displaying 13.4v when the alternator is charging. I understood that to mean that this was the charge as measured at the service batteries. I am pretty sure it is not displaying the charge at the alternator.

With regards to the alternator itself I will have an auto-electrician look at it. I was under the impression however that to convert an alternator to battery sensing it was just a case of re-routing the sense wire from the alternator to the diode splitter terminal.

From what you say it would suggest that it is in general more complicated that this. Is this a fair assessment?

I appreciate your responses - they are extremely helpful.

 

[VicS]

Vic

Apologies, my terminology is not great on these things.

What I meant was that the NASA Battery monitor is displaying 13.4v when the alternator is charging. I understood that to mean that this was the charge as measured at the service batteries. I am pretty sure it is not displaying the charge at the alternator.

With regards to the alternator itself I will have an auto-electrician look at it. I was under the impression however that to convert an alternator to battery sensing it was just a case of re-routing the sense wire from the alternator to the diode splitter terminal.

From what you say it would suggest that it is in general more complicated that this. Is this a fair assessment?

I appreciate your responses - they are extremely helpful.

Yes That will be the volts measured at the battery. It means that the alternator output will be around 14.1 so that's fine.

I'm really am unsure about the battery sensing.. It's something I have not looked at in detail.

 

[KRG]

I have the same engine and alternator of the same era. I've stripped the alternator a couple of time to change the regulator and rectifying diode pack in the past. The regulator is potted into resin so it is difficult to be sure what the wires go to without a diagram. I have some pictures in raw format if that would help and I may be able to look out the regulator details, I'll try later today.

I had mine setup in the same way as yours with splitting diodes and the result was quite poor, the voltage output and drop was such that the batteries were never really charged properly.

I changed my setup to a relay split system with a Sterling regulator and it transformed the charging. The relay was about £40 and the reg was about £130. The relay only switches charging to the house battery once the engine battery reaches about 13 or so volts.

The alternator now outputs 14.6 volt across the batteries on bulk charge (it can be changed for sealed) and happily looks after an 80 ah start battery and 150 ah house battery.

 

[KRG]

Just played with Photoshop, hope this works!

 

[Plevier]

If the yellow wire to the regulator is attached to the main output terminal B+ then you can do what you suggest (bearing in mind VicS's caution about not going to the other side of the isolator). If the yellow wire is connected somewhere other than B+ then no.
You should use decent size wire, protect it and put a fuse - say 10A - in the wire where it is connected to the diode splitter (or isolator) as if this wire happens to get damaged and shorted to ground it will have full battery output current available to it and will melt/spark if not fused.
Note that if this connection were broken with the engine running you would be likely to do serious damage to the alternator.
Have a look at thread http://www.ybw.com/forums/showthread.php?t=115435 that gives you another possible solution, fooling the regulator with a diode, with pros and cons!