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post #21 of 27 (permalink) Old 16-10-2020, 11:54
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Originally Posted by Yvonne and Ward View Post
Thx so much for this Rayc-- when I multimeter test the leisure battery itself it reads 12.75 volts. When I took the cover off the distribution box as you suggested, the multimeter test of leisure battery through B2 bolts is only 11.37v. What does that mean to you? Again, really grateful for your know-how!
I think that the control unit disconnects if the battery voltage drops below a pre set voltage [the drop dead voltage]. I thought it was 10.8v but with a cheapish multimeter a reading of 11.3v may be near enough.
In any event the question has to be where is the 2v or so from the battery being 'lost'? At the 50A fuse or the terminal connectors?
What I would do is run a wire directly from the battery positive to terminal B2+ and see what happens. It may be prudent to insert a 20A fuse in the wire.

Just a question, are you absolutely sure the battery voltage you are measuring as 12.7v is the leisure battery and not the cab one?

Can you confirm that when on EHU that the voltage from the charger measured at B2+ and B2 - is the same as at the battery terminals i.e. the charger is charging the battery.
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Last edited by rayc; 16-10-2020 at 12:00.
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post #22 of 27 (permalink) Old 16-10-2020, 12:49 Thread Starter
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Originally Posted by rayc View Post
I think that the control unit disconnects if the battery voltage drops below a pre set voltage [the drop dead voltage]. I thought it was 10.8v but with a cheapish multimeter a reading of 11.3v may be near enough.
In any event the question has to be where is the 2v or so from the battery being 'lost'? At the 50A fuse or the terminal connectors?
What I would do is run a wire directly from the battery positive to terminal B2+ and see what happens. It may be prudent to insert a 20A fuse in the wire.

Just a question, are you absolutely sure the battery voltage you are measuring as 12.7v is the leisure battery and not the cab one?

Can you confirm that when on EHU that the voltage from the charger measured at B2+ and B2 - is the same as at the battery terminals i.e. the charger is charging the battery.
Thx again. Oh, wow, this time when doing the checks you suggested I realized what I hadn't thought about before, that I was checking the leisure battery at B2 on distribution box while the motorhome was plugged into EHU. When I check B2 without being plugged in, it is really low, like 3.65v.

You asked me to confirm I was definitely checking leisure rather than engine battery, and I can confirm that (it's a Numax DC25MF back underneath the bed whereas the other is an Exide Excell EB950 under the hood).

You made another suggestion: I haven't yet run a wire directly from leisure battery to distribution box. I could figure that out and get 'er done if that's the key to the secret, but I haven't gotten that far yet.

So it sounds to me like I've got two charged batteries (leisure and automobile) but am getting next to nothing from leisure battery at the distribution box...

Thx again
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post #23 of 27 (permalink) Old 16-10-2020, 12:56
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Originally Posted by Yvonne and Ward View Post

So it sounds to me like I've got two charged batteries (leisure and automobile) but am getting next to nothing from leisure battery at the distribution box...

Thx again
That is why you should check the 50a fuse that should be somewhere between the battery positive and B2+
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post #24 of 27 (permalink) Old 17-10-2020, 12:02 Thread Starter
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That is why you should check the 50a fuse that should be somewhere between the battery positive and B2+
Thx to everyone who gave us such helpful information. I found and replaced the 50a fuse, but it's still doing the same (registering 12.7 v at the leisure battery, only 3.7 at the B2), so I think we'll give up, have a drink , and see if we can get an auto electrician to look at it next week.

All the info shared with us is much appreciated. See you all out there sometime soon.

Best, W
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post #25 of 27 (permalink) Old 17-10-2020, 14:12
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Will you come back n tell us what the solution was please? All good info for future readers.
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post #26 of 27 (permalink) Old 17-10-2020, 14:28 Thread Starter
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Will you come back n tell us what the solution was please? All good info for future readers.
Great idea-- yes, I will come back to post again once I sort it out.
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post #27 of 27 (permalink) Old 17-10-2020, 14:36
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Originally Posted by Yvonne and Ward View Post
Great idea-- yes, I will come back to post again once I sort it out.
Before giving up and calling the electrician you could try a couple of things if you wanted to.

Can you confirm that the 50a fuse was definitely in the leisure battery supply and not cab battery?

Can you remove the fuse and test the voltage on the fuse holder contacts, with the meter negative connected to battery negative? What do you read on the contact coming from the battery? What do you read on the contact going to B2+? [with EHU disconnected]

Can you use a test wire from battery positive to B2+? [with EHU disconnected] Does everything spring into life?

Last edited by rayc; 17-10-2020 at 15:23.
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