Over voltage problem

[Jocklandjohn]

I've a couple of monitors on the 110, the IBS split charge system is one, which has a series voltage indicating LED's which show yellow (low v) green (ok/normal v) and red (too high v) and for a year or two the red light has flickered on and off at idle, but disappeared when running. I contacted IBS and they said the switch-over voltage might be being approached and the lamp just tickling the over-voltage threshold and all else being ok it was probably fine - I;d given them the indicated voltage readings from my meter to clearly show voltages at battery.

However today as I drove down the road the red warning light stayed on, then the red warning for over-voltage on my solar controller went on saying battery 1 and 2 receiving over-voltage, and a separate battery monitor also gave an over-voltage error message.

I could see it in real time as I quickly returned home rather than continue on my journey, and it was varying between 15v then up to 15.5v then 16v and finally 16.8v depending on RPM. One of the meter's error message indicated the voltage had gone just over 17v which is its max measuring range.

I'm assuming this is likely an alternator issue? Is this a toasted alternator or a voltage regulator issue? DO I need a new alternator or a repair? Or should I be looking anywhere else? I keep all connections tight and clean, the earth straps are regularly cleaned and vaselined too*.

*Which doesn't meant they're not culprits, as they've not been done very recently.

 

PS alternator is normal 45A version.

Edited April 25, 2022 by Jocklandjohn

[cackshifter]

This can be caused by a dodgy alternator earth contact, put a volt meter from the case to a known good earth with it charging, just about any voltage is a fault. Otherwise if you have a remote voltage sensing wire, a bad contact there can do it. After that you are maybe considering a duff regulator.

[Jocklandjohn]

34 minutes ago, cackshifter said:

This can be caused by a dodgy alternator earth contact, put a volt meter from the case to a known good earth with it charging, just about any voltage is a fault. Otherwise if you have a remote voltage sensing wire, a bad contact there can do it. After that you are maybe considering a duff regulator.

Thank you. The former I can understand. The latter is above my pay grade!

Is the "remote voltage sensing wire" a thing I'd have had to add myself at some point, or is it a standard fitment? And is the implication from it having a bad contact that it either gives a dodgy reading (to a monitor like I have) or it sends a duff signal to the alternator to allow it to deliver over-voltage?

[Jocklandjohn]

Correction: this might be a 65A alternator if the old box I found in the garage is what is fitted.

Anyway tried running engine and metered whats going on -  volts at battery with meter is high 14v's then up towards 15.8 to 16.5 with revving. Its a split charge system so checked and its same at both batteries. Readings confirmed on various monitors in the vehicle.

Then as cack suggested I connected the meter to the alternator case and to a good earth - zero readings so assume thats ok.  I also have a flying lead off the alternator rear I can meter off - tried that and and connected to a good earth and readings are same as at battery and varying with increasing revs to over 16v.

So issue is with alternator it seems.

 

Edited April 25, 2022 by Jocklandjohn

[Bowie69]

What about the thin wire to the alternator, is it in place?

[Jocklandjohn]

45 minutes ago, Bowie69 said:

What about the thin wire to the alternator, is it in place?

Aye, just been in and had a look - all the wiring is in place as it should be, all connections tight and wires look to be intact.

I pulled the alternator out anyway and it does look pretty grotty so it might be worth a replacement anyway. Sigh.

[Bowie69]

If you can just replace the regulator you can save yourself maybe £100....

[cackshifter]

Some alts have 2 thin wires, one for the ign light as usual, and one to sense the battery voltage. This means it measures the volts near the battery, irrespective of any voltage drop in the power lead. Most nowadays just assume the voltage at the power terminal is the same as at the battery or at least negligibly different, so only have 2 wires.

[Jocklandjohn]

35 minutes ago, cackshifter said:

Some alts have 2 thin wires, one for the ign light as usual, and one to sense the battery voltage. This means it measures the volts near the battery, irrespective of any voltage drop in the power lead. Most nowadays just assume the voltage at the power terminal is the same as at the battery or at least negligibly different, so only have 2 wires.

Ah ok. I've got:

W     Thin wire to tacho which I fitted.

B+   Thick wire to battery PLUS a direct feed to a landreiziger headlight loom as per their fitting instructions.

D+   Thin wire which will be the ignition warning.

[cackshifter]

Ok, forgot about the tacho wire. Yours is not remote sensing. 

 

[Peaklander]

That’s exactly the symptom I had which was the regulator. It’s a £10 part which you can change from the back of the alternator if it’s the standard model (A127 I think).

The old pulls off after removing a couple of 10mm nuts and the new one pushes on but you have to use a paper clip to hold the brushes back to allow them over the rotor. There’s little holes to facilitate that - and it’s easier when you see it.

[Jocklandjohn]

Update - I concluded that what several of you and peaklander suggested (regulator goosed) was the issue. On removal the bearings felt a bit rough too so I decided to replace the whole alternator and then at my leisure renovate the removed one.

I think this issue has been plaguing the charging system for some time but not so obvious that I really noticed. I had a period of non-charging which *seemed* to have been remedied by tightening the pulley bolt, but I suspect that may have been a red herring as the batteries appear to have been affected - presumably by the wandering voltage that was obviously too high for them. Presently doing battery testing and a recovery cycle to see what results.

Thanks for the assistance (again!).