Habitation batteries not charging when driving

[Robert P]

The problem, I think, is that the alternator won’t deliver more than 12–12.5 V. Engine off, voltmeter across engine battery terminals reads 12.5 V. Start the engine (3L Ducato) and the voltmeter stays at 12.5 V instead of rising to 14–14.5. The B2B charger needs in excess of 13.5 V to charge the habitation batteries (2×100 Ah LiFePO4). The hab batteries charge ok from the solar panels and EHU. The engine starts immediately without needing jumping and there is no trouble with cab electrics – lights, wipers, air con, etc.

If I am right, will a new alternator solve the problem? Anybody any experience? I’m reluctant to get a new alternator straightaway in case the trouble is caused by a faulty voltage regulator or a bad connection. It’s not helpful that the engine has a cover so you cannot even see the alternator!

 

[Richard n Ann]

My Seat Arosa alternator stopped working, it was just the voltage regulator on the end of the alternator. Simple job

 

[Steve and Denise]

Not to long ago you could change the voltage reg in the alternator now all they want to do is sell you a alternator or worse an engine or worse still a new van

 

[ctc]

Had the same problem, it was a 50amp fuse next to the starter battery that supplied alternator current to the leisure batteries.

 

[autorouter]

What year is your Ducato? Is it possible that it has a smart alternator? This doesn't charge the starter battery if it's over a minimum limit. A B2B with a voltage activation to trigger it won't work in that situation, it needs a D+ alternator signal.

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[Robert P]

Thanks for all your thoughts. I'm pretty sure it's not a smart alternator - 2011 vintage and Euro IV rating.

 

[autorouter]

The engine starts immediately without needing jumping and there is no trouble with cab electrics – lights, wipers, air con, etc.

You'd expect some trouble with those things if the alternator wasn't working. Is it possible that the solar is charging the cab battery,and disguising the alternator problem. As it gets to winter (less solar, more lights and heater fan) that might show up the problem. I'd get that alternator checked out.

 

[Robert P]

I had an appointment with an autoelectrician for tomorrow, but he's just had to self isolate for a week or so!

 

[GeoffnDee]

If you have a jump lead try a temp. earth connection between the alternator body and the chassis/bodywork to see if there is any improvement in its output when running.

 

[NicM]

if no jump leads you can also try a volt meter on the Battrey terminal out from the Alternator to the Alternator body and see what you get if you can get to it!

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[autorouter]

If you can't get at the alternator, it's worth trying a jump lead between the battery negative terminal and somewhere on the engine body. That will bypass a possibly faulty earth strap. If the voltage springs back to 14V or more then it's a faulty earth strap.

 

[Alan]

I had a 2006 Cheyenne and I had to choose vehicle battery on the control panel instead of leisure when I wanted to keep it topped up, Just remember when you switch to vehicle battery every thing on the leisure side will be using vehicle battery.

 

[Alan]

I had a 2006 Cheyenne and I had to choose vehicle battery on the control panel instead of leisure when I wanted to keep it topped up, Just remember when you switch to vehicle battery every thing on the leisure side will be using vehicle battery.

I forgot to say when on hookup

 

[82125]

Had the same problem, it was a 50amp fuse next to the starter battery that supplied alternator current to the leisure batteries.

same here when i bought my van (from a dealer ), hab batts werent charging from the alternator, fuse on the engine battery that links to the hab batteries blown (glad they did all the pre-purchase inspections correctly, everything ticked off as checked).

Dont know if its the same for you as I dont have B2B (yet)

 

[bigwood]

We used to change the brush pack and regulator on alternators because it was sometimes easier than changing the alternator. This was ok on better quantity alternators but the cheaper ones could have knacker bearings by the time the brushes were worn out.
A quick check for older alternators as follows. They must have a battery live (Large terminal), ignition feed (Small terminal) and a decent earth.
Unfortunately the more recent alternators are controlled by a black box and not something I have had to deal with.

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[Robert P]

Finally got this sorted. The leads to and from the starter motor had got water inside the insulation and this had corroded the Cu leads. New leads and the voltages came up to what they should be and a healthy rate of charge was going into the hab batteries (and the fridge works). The leads replaced are not earthing straps, which were all ok. The new leads are hefty cables 3 or 4 ft long and very heavy gauge (much more substantial than the earthing straps). Unfortunately the corroded leads were discovered after fitting a new alternator, but I'm happy to have a new one.