Amethyst Leisure Battery Fuse

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Amethyst Leisure Battery Fuse

Post by CJ on Tue May 31, 2016 8:32 pm

Hi all,

I've made a very silly error blushes  I bought a new leisure battery from Halford's a few months ago but didn't get around to installing it. When I did, I was fooled by the little red and blue caps on the terminals, they had been put on the wrong way around. I should have double checked with the symbols on the battery, but alas I didn't. Although I didn't fully put the clamps on the wrong way, they touched the wrong terminals and there was a spark. I immediately realised my mistake, but it was too late.

Now this is where it gets interesting, I can't find what fuse has blown, the ones in the zig unit above the door are all fine (and the one behind it), but the whole 12v system doesn't work on the battery (now installed correctly!), except for the step! The 12v system does work if it's plugged into the mains thanks to the battery charger. It must be an inline fuse somewhere. The AS manual says to look under the bonnet, I've spent ages in there, but all the fuses that I can find don't look like they belong to the 12v, and they're intact too. Could it be something in the vehicle fuse box? I've looked at the diagrams, nothing seems to be blown that I can see, but I could be missing something.

Any suggestions? confused3  I'm lost. It's a 1998 Amethyst.
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Re: Amethyst Leisure Battery Fuse

Post by logburner on Tue May 31, 2016 9:25 pm

Hi CJ,
Not familiar with your vehicle, I expect an owner of a similar model will be along later.
But meanwhile, where is your leisure battery situated ? Mine is under the bench seat/bed
behind the drivers seat. I have a block of fuses alongside the battery itself.........have you any by your battery ? scratch head
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Re: Amethyst Leisure Battery Fuse

Post by CJ on Tue May 31, 2016 9:43 pm

Hi logburner,

The leisure battery was originally located on the passenger side under the bonnet, but I have moved it into the vehicle under the seat next to the water heater to accommodate a larger battery. I've checked for fuses in both locations but no luck.  uncertain
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Re: Amethyst Leisure Battery Fuse

Post by KMRTOPAZ on Thu Jun 02, 2016 12:35 am

Hi CJ
This is a puzzle, but I have applied some lateral thinking and have a suggestion.....which could be entirely wrong !  And no doubt I will be informed so, again!
I cannot see why reversing the current would necessarily result in a blown fuse which requires a heavier than normal and sustained current flow.  What I can envisage is that a reverse current may damage an electronic component or possibly a standard component, like a relay, though I cannot suggest why it would be damaged. I quote a relay as this is a control component and there is a key relay which isolates the habitation area when the engine is running. Have you yet run the engine? It would/should energize that relay. You can usually feel the  with a finger as it opens or closes .
The step is usually fed directly from the battery and not through the Zig switch as it needs to be operable with or without habitation supply. Keith

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Re: Amethyst Leisure Battery Fuse

Post by brodco on Thu Jun 02, 2016 10:53 am

Hi wave

As it’s a Ford with the original battery under the bonnet (like mine) and about the same era as mine it may be wired similarly,  in which case the relay and fuse are in a plastic box near the starter battery. It could also be completely different of course but worth a look.


KMRTOPAZ wrote:I cannot see why reversing the current would necessarily result in a blown fuse which requires a heavier than normal and sustained current flow.

I was thinking the same way, especially as everything was presumably switched off.  

Some (but by no means all) relays do have a diode fitted across coil but the habitation relay isn’t powered from the leisure battery and it would have been “off” anyway.

One possible cause is the Zig unit itself. Its output is connected all the time so connecting the battery backwards means the output diodes will be the wrong way round possibly connecting the transformer output winding directly across the supply. Now that would draw a lot of current. shrugg

Whether there is any internal protection against that I don’t know (without looking) but I suspect not.

Brod
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Re: Amethyst Leisure Battery Fuse

Post by CJ on Thu Jun 02, 2016 11:48 am

Hi KMRTOPAZ & Brodco,
Thanks for your replies. Our vehicle looks different under the bonnet to yours brodco. I rang AS, they said to carefully trace the cable from the leisure battery across to the vehicle battery and I'd find the fuse, but it goes straight to the Split Charge Relay. It doesn’t look like anything has been changed. I've found a little inline fuse coming off the vehicle battery that goes to the relay, surely that's not F1 in the diagram below? In my van it's only 10A, maybe someone incorrectly replaced it? Anyway it's intact, so that isn't causing the trouble.



I wish we knew where all the habitation fuses and relays were in our van like your photo brodco, the only fuses I know of are the ones in the zig unit and the ford vehicle ones in the cab. The AS manual says that fuses F1, F2, and F3 are located under the bonnet, but I've spent hours looking, they don't seem to exist, but they must do somewhere!
 

Looking at the diagram, it could be that the relay R3 is damaged, that would make sense. I would feel it like you suggest KMRTOPAZ but I’m not sure where it is! It could also be the zig, but everything works fine when the battery charger is on, so it surely suggests the connection to the battery is broken somewhere. I've tried running it with the engine on and off, the 12v didn't work unless the charger is on, but I remember that the fridge does work on 12v with the engine running (makes sense though as that’s a different bit of the circuit).
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Re: Amethyst Leisure Battery Fuse

Post by logburner on Thu Jun 02, 2016 12:44 pm

May do better by tracing wires back from R3, and R2 relays to find the fuses F3, and F2.
Just an idea...... scratch head
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Re: Amethyst Leisure Battery Fuse

Post by brodco on Thu Jun 02, 2016 1:31 pm

Hi wave 



I’d be surprized if the relay was faulty, far more likely to be the fuse.
 
\"CJ wrote:I rang AS, they said to carefully trace the cable from the leisure battery across to the vehicle battery and I'd find the fuse, but it goes straight to the Split Charge Relay

 
That’s how mine’s wired as well. The feed to the habitation area and fridge comes from the leisure battery connection on the split charge relay. If you can’t find the other relays (as per logburner) you may have to trace the other wires connected to that point (not always easy I know).
Another possibility is that you may be able to trace the wire back from the Zig end if you can get to it. An even better possibility is that someone may come along that actually knows where the relay/fuses are.  confused3
 
Incidentally I wasn’t suggesting that the Zig is faulty in any way, just that it may be the reason why the fuse blew in the first place.
 
Brod
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Re: Amethyst Leisure Battery Fuse

Post by CJ on Thu Jun 02, 2016 1:53 pm

Hi everyone, problem solved! hugegrins  At last! I located the fuses and relays! They were right up under the dash next to the glove compartment. There's a little rack bolted on for the fuses, but the relays just hang loose. A real tricky spot to get to, you have to do it by feel as your arm blocks the view. Sure enough, the main 30A fuse was blown, though someone had replaced it with a 20A. A new fuse is sitting pretty and all 12v power is restored! Hurrah!  drinksallround
I've attached the photo below, important information for Amethyst owners this because it's not what AS put in the manual, or what they said on the phone. They insisted that it was located up above, below or around the vehicle battery. I can't imagine that it has been changed by a previous owner, all the wiring looks original. 



Thanks for all the help everyone!!
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Re: Amethyst Leisure Battery Fuse

Post by brodco on Thu Jun 02, 2016 2:06 pm

Hi wave

CJ wrote:Hi everyone, problem solved! hugegrins
up!

Brod
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Re: Amethyst Leisure Battery Fuse

Post by logburner on Thu Jun 02, 2016 7:41 pm

Wow !!  Great news..... up!      Seen piccies.........not what I would call user friendly.........I know they are not supposed to blow, but Hey !!   that's what they are there for.... hugegrins
Just think, if you were away somewhere...... Whistle1   At least you know, now, where they are at now......... allthumbz
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Re: Amethyst Leisure Battery Fuse

Post by KMRTOPAZ on Thu Jun 02, 2016 11:24 pm

Hi CJ
Pleased that you have sorted this problem, but still puzzled why the fuse went !! The circuit diagram above doesn't help to clear the mist circulating round my grey cells.
Perhaps someone will tell me. Cest la vie.
Keith

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Re: Amethyst Leisure Battery Fuse

Post by brodco on Fri Jun 03, 2016 10:37 am

Hi  wave
KMRTOPAZ wrote:Hi CJ
Pleased that you have sorted this problem, but still puzzled why the fuse went !! The circuit diagram above doesn't help to clear the mist circulating round my grey cells.
Perhaps someone will tell me. Cest la vie.
Keith
I have a theory! Well not so much of a theory as a guess but I can’t think of another reason at the moment (somebody else may do).

As far as I can see the only thing connected that is likely to take a large amount of current is the Zig itself. The Zig is always connected whether it’s being used or not.

Normally if there is no mains supply the output diodes block the battery voltage but if you reverse the battery, the diodes are connected the other way round putting the transformer winding directly across the battery, causing loads (to give it the technical term) hugegrins of current to flow.



Brod
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Re: Amethyst Leisure Battery Fuse

Post by KMRTOPAZ on Sat Jun 04, 2016 12:27 am

Brodco
Given that your assumptions, as explained by the diagrams, are correct, that makes good sense.
Better than anything I could produce !!
Keith

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