AS battery fuse!

[Pete-B]

 

Hi, Been getting some strange readings on the Harmony panel in our 2020 Autosleeper Warwick xl. Whilst in storage, the panel showed the engine battery at 11.4v when I knew it to be 12.6v because I'd checked it with a multimeter. Also when plugged into the power at home the panel didn't show any incoming amps.

 

I contacted Sargents who told me it could be loose connections in the fuse box behind the drivers seat. I checked and found it was the actual 20amp engine battery fuse which had blown, so I replaced it, which cured the problem.

 

Now my question is, do I just leave it at that or is it necessary to find out why the fuse had blown. Sargents did suggest there may still be a loose connection at the back of the box but because of the amount of wires that go into it and the tight place it's in, it's not really a DIY job.

 

Thanks for any suggestions.

[Derek Uzzell]

It might have been better if you had added your posting to the earlier discussion about your battery-related problems.

 

https://forums.outandaboutlive.co.uk/forums/Motorhomes/Motorhome-Matters/Battery-gone-mad/57654/

 

Regarding your question “...do I just leave it at that or is it necessary to find out why the fuse had blown?”, given the complexity of the Harmony Utility Management System and Sargent’s warning, I strongly advise you to let matters rest.

 

Plainly, If the engine battery 20A fuse blows again, there’s a basic fault that will need to be adressed under warranty (and the best of luck to whoever might have to do that!) but now that everything is working properly you’d be wise to suck it and see.

 

(The Harmony system reminds me of the CI-BUS system installed in Hobby motorhomes. When it works properly everything is fine and dandy, but when there’s a fault trouble-shooting can be a nightmare and the system’s inherent complexity means that few people will have the necessary expertise to accurately diagnose the cause.)

[Pete-B]

 

Thanks Derek, much appreciated.

[Alanb]

From following the link to the previous thread provided by Derek, I see that I suggested a possible blown fuse on 24th February.

 

Fuses blow for two main reasons, either a sustained overload, or a short circuit

 

If as in this instance the cause is unknown, it is worth examining the blown fuse element, which is often visible on blade fuses.

 

A sustained overload will cause a gradual melting of the element, resulting in a small gap or crack in the element. If the cause is a short circuit, the fuse element may be completely vapourised.

 

I am having some difficulty in relating a proposed loose wire to the blown fuse. If the output side of the fuse became detached the fuse would not blow, neither would that fuse blow if the input became disconnected.

 

The fuse rating of 20A seems rather low, if it is to support habitation battery charging via a split charge relay, and the 12V element of a 3 way or AES fridge.

 

I cannot fully remember the circumstances, but I remember reading of a problem in converters fuse panel area. The cause was eventually traced by the owner to incorrect assembly of the connector for the starter battery. As I recall the connecter inserts had not been fully inserted, I think causing an intermittant open circuit, but perhaps a short circuit is also possible...... loose wire?

 

Alan

 

 

[Keithl]

Pete,

 

Did you contact either Autosleeper or your selling dealer about this fault?

 

If no then I would write to both informing them of the fault and your communication with Sargent and subsequent fix and then IF the fault recurs they at least will be aware this was not the first occurrence.

 

Keith.

[charleydog]

Same issue with our 2020 Kingham .Seemed to be (one of those things). Changed fuse with a high-quality one.no problem since.Had issues with the harmony system on our Warwick xl so not over confident with this form of control. Our chausson had on/off switches,simple and positive.Still hold my breath when I operate heating /hot water with the whale control *-)

[Pete-B]

 

Thanks for all the helpful replies. I guess the reason I originally asked was, when I contacted sargents the other day about the false readings on the Harmony screen the guy there suggested I check the fuse in the box behind the drivers seat. When I found the blown fuse I rang back to thank him and his reply was, that's OK but really the box ought to come out and the connections checked on the back but it can be a difficult job. The reason being, there's a lot of wires running in to it which are quite short and it can be very difficult to tuck them all back in when you've finished.

 

To get to the dealer is a 150 mile round trip and as everything seems to be OK now, do I just leave it for now and see what happens. I guess in all truth I'm looking for an easy way out which is perhaps the wrong thing!

[charleydog]

See the last post. If it blows again, replace, blows again, then the 150 mile trip will have value, Quality fuses are cheap, and easy to replace, Pulling wiring around better left to the dealer,

[Brian Kirby]

charleydog - 2021-03-13 5:07 PM

See the last post. If it blows again, replace, blows again, then the 150 mile trip will have value, Quality fuses are cheap, and easy to replace, Pulling wiring around better left to the dealer,

Agreed, except for replacing the fuse twice before having the issue investigated. If a fuse blows it is, as stated above, because it was defective, or has been overloaded. Replacing once should have removed the possibility of a defective fuse. If it blows again it is highly likely to be because of overload which, on a new vehicle with an (presumably) unmodified installation, points to an inherent installation or design fault.

 

Fuses are there to protect the circuit wiring from overload, consequent overheating, and possibly, fire. My take is if that fuse blows again, don't replace it and get the fault properly investigated. The suggestion that the fault may lie in the wiring behind the fuseboard sounds like someone who is aware of a possible problem in that area.