Leisure battery not charging

[Maisy]

Our motorhome is a 2005 Transit based Chausson Welcome 27, fitted with a CBE PC-100 together with DS-300UK.

Problem;-
Leisure battery is not being charged by the alternator, also, the indicator lights on the PC100 for alternator AND mains 240V connection do not work.

Observations;-
The leisure battery IS being charged when the motorhome is connected to the mains. (The leisure battery is new as of three days ago!). Also, the fridge "finds" the mains when connected, and 12v when not on mains.

The engine battery IS being charged via the alternator.

Is there a relay and/or fuse secreted somewhere by Chausson that needs checking? - all the fuses in the DS-300 are OK.

All the 12V circuits in the motorhome (inc fridge) operate when the engine is running.

Any ideas, anybody?

 

[mitzimad]

have a look around your vehicle battery compartment for any fuses holders that dont look factory fitted

 

[Maisy]

Thanks Mitzimad, but the leisure battery is under a bunk with nothing else in sight! and the vehicle battery is under the drivers seat, again nothing else near - looks like I'll to take a few carpets up!

 

[autorouter]

Problem;-
Leisure battery is not being charged by the alternator

How do you know the leisure battery is not being charged by the alternator? Are you looking at the display panel or using a multimeter on the battery?

If you take the cover off the DS300, there are three big terminals at the bottom, where three thick wires come in, labelled B1, B2 and GND.

Check that the voltage between B1 and GND is exactly the same as the Starter Battery voltage.
Check that the voltage between B2 and GND is exactly the same as the Leisure Battery voltage.
When the engine is stopped, the voltage between B1 and B2 should be the (small) difference between the battery voltages.
When the engine is running, the voltage between B1 and B2 should drop to zero.

The black plastic box between B1 and B2 is the relay that connects them together when the engine is running.

 

[Maisy]

Thanks for that. I knew that the leisure battery was not being charged by the alternator as its voltage (using a multimeter) did not increase once the engine had been started, whereas the vehicles battery voltage did. All the checks you suggested also demonstrated the same result. Perhaps it could be the relay. More messing in the DS300, I feel, is the next task!
Thanks again, autorouter.

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[andy63]

Is there a relay and/or fuse secreted somewhere by Chausson that needs checking? - all the fuses in the DS-300 are OK

If everything that has been mentioned so far checks out..check the small fuse I think its labeled d+ in the ds300 ..
Andy..

 

[autorouter]

All the checks you suggested also demonstrated the same result. Perhaps it could be the relay

If the voltage between B1 and B2 drops to zero when the engine is running, that means the relay is operating correctly, so the fault is somewhere else. If the relay is not functioning but everything else is, then B1 voltage will go up to about 14V, but the B2 voltage will stay at the leisure battery voltage.

If the relay is not operating, then as andy63 suggested, check the D+ signal which is what triggers the relay. That signal should be about 12V when the engine is running, and about zero when it is not running.

Another thing worth checking: the voltage between the GND terminal of the DS300 and the leisure battery negative terminal should be zero.