Fuse on leisure battery relay blowing.

[meggles]

I put a topic about this on here a while ago but thought I'd cured it. Anyway, the problem is that the fuse (10 amp) on the relay behind the drivers seat keeps blowing. I put a 20 amp fuse in AS A TEST and it got quite warm but did not blow even after around 30 seconds, but it did get quite warm. (I was checking for any heat in the wiring all the time!!! There was an appreciable drop in engine revs when I put the fuse in, and the revs increased when I took the fuse out. The leisure battery is/was fairly flat.
My questions: Does the autosleeper have the relay under the seat as standard or has someone fitted it later. (The wiring looks very DIY). Also does the fact that the 20 amp fuse not blow immediately and cause revs to drop give any clue as to the problem? Incidentally I took all the fuses out for the water pump, fridge etc and turned off all the lights but the same occured regarding the fuses.
Thanks in advance.

[Oldiebut goodie]

Basically it sounds like your leisure is very flat and is drawing a lot of current hence the blowing 10A fuse and warm wiring with the 20A. The alternator is working overtime to give the current needed to charge the leisure but to do that it has to increase the magnetic field which makes the alternator harder to turn. This then saps power from the engine causing the revs to drop.
In a nutshell.

[meggles]

Thanks for that. So... I'm reckoning that as the original problem was a blown fuse the leisure battery went flat and now the fuse is blowing 'cos it has too much work to do. Therefore if I charge my leisure battery off the van all should be well? My 'theory' is that it can't be a 'dead short' or the 20 amp fuse would blow immediately too.

[Oldiebut goodie]

So long as the leisure isn't goosed that is the best way to deal with it, might be time to eke out the pension a bit further for a new battery in the spring if it isn't holding the charge very well any more. (Unless you are going to do some serious camping this winter )

[meggles]

Yeah, I reckon I'll have to rid myself of the Yorkshire in me and spend a bit. It could be, though, that the battery is fine and only went flat because the fuse had blown and I hadn't noticed. I'll charge it and see what happens. (Could always sell the old battery on ebay I suppose - spares or repair ).

[Oldiebut goodie]

I got charged £5 extra once when I didn't have a battery to trade in! So they still have value.

[ghost123uk]

And invest in an "LVD" = Low Voltage Disconnect. These cut off the leisure battery at a pre set voltage to prevent it being damaged by going flat. Most folks leisure stop holding a charge, NOT because they are too old, but because they have been over discharged, so the "LVD" pays for itself in no time Plus you know your battery is not going to let you down on that one night you really don't want it to !

This HERE is the one I have. The instructions for wiring it up are not very well written imho, so if anyone needs any info, just ask me.

[kentishvanman]

Hi,
I think you will find that the relay is where Autosleeper put it ie next to the leisure battery.
Did you know there is a wiring diagram for Autosleeper in Wiki? I havn't checked but I think the fuses should be 30amp.
In my early days of ownership my relay blew and the auto elecs firm said the relay itself was only good enough if if the leisure battery was in good nick ie the original relay was to light. You might like to check/change yours.
My leisure battery is an Elecsol 100. It fits and works well and is kept topped up by a small solar panel mounted on the roof.
Don

[Oldiebut goodie]

I wouldn't just fit a 30A fuse without physically checking that the relay and wiring is suitable - dangerous practice.

[Oldiebut goodie]

Ghost - these lvd boards will only handle up to 16A - are you using it to switch a bigger relay? I am wondering also how quick they react to the voltage drop - how will it behave when something like a Webasto or Eberspächer starts up as the voltage can drop down to 11/11.5v for a short period whilst the glow plug is on when they start up? (greater than the 10 sec dropout time unless the heater has a pulsed glow)

[meggles]

Relay is at the side of the starter battery under drivers seat. Didn't know about the autosleeper wiring in WIKI, I'll check it. Thanks. Wiring looks good for 30 amps if I only look at the heavier wires, the others (to ignition) are thinner/lighter but thats why it goes to a relay... isn't it? Going to fully charge battery and see what happens. If I don't get it sorted I'll resort to spending my pension pot Thanks for replies so far folks.

[ghost123uk]

Ghost - these lvd boards will only handle up to 16A.. - are you using it to switch a bigger relay?

Aye, but you only connect it to the accessory load side of things (I guess you knew that ) it does not go near the battery to battery link. My accessory load will never get to 16 Amps, more like a 8 amp max, usually more like 5 amps (TV, Propex, LED light and the odd phone charger)

I am wondering also how quick they react to the voltage drop - how will it behave when something like a Webasto or Eberspächer starts up as the voltage can drop down to 11/11.5v for a short period whilst the glow plug is on when they start up? (greater than the 10 sec dropout time unless the heater has a pulsed glow)

They have an "anti hysteresis" circuit to circumnavigate any relatively short variations in voltage supply / demand to take care of that concern. Mind you, I don't know ( I know you will ) what current the glow plug on an Eber / Webasto takes ? It may be above the 16 Amp max ? I wonder if it can be arranged so that the glow plug is separately fed directly from the main starter battery ? That would solve any voltage drop that is longer lasting than the (short term) dropout value of the LVD.

[ghost123uk]

Relay is at the side of the starter battery under drivers seat... Wiring looks good for 30 amps if I only look at the heavier wires, the others (to ignition) are thinner/lighter but thats why it goes to a relay... isn't it?

That all sounds OK

Going to fully charge battery and see what happens

Don't forget that whilst you may be able to charge it up on the domestic charger and it then may all seem ok when on the van, if the battery is on it's way out, it will soon drop it's voltage and you will be back to square one.

Charge it for a day. Disconnect the charger and leave it for 2 hours. Then measure the voltage, it should be around 12.6 to 12.9 volts. Leave it (doing nothing) for 24 hours and measure again. If it has dropped below 12.6 then imho it is time to replace it

One of those LVD things I mention above will ENSURE that you cannot damage your new battery by over discharging it A well looked after leisure battery should last years, not the one or two years a lot of folk seem to get

[Oldiebut goodie]

I am wondering as to the best way here because I sell 24v Webastos that are using a step-up from 12v but there is one minor problem with doing this in that the step up keeps working even if the battery voltage has dropped down to 9v! Not good for your battery. The heaters inbuilt lvd circuit of course can't come into play! So the lvd is a good idea here. Some bigger heaters can hit 18A briefly on switch on but quickly settle to around 10A, others are a lot less. Of course the easiest is to have separate ldv for heater and ask Reuk if the 10 sec period could be extended easily as they say that they are open to requests.

[ghost123uk]

ask Reuk if the 10 sec period could be extended easily as they say that they are open to requests.

Sounds good, I read somewhere that they (he ?) are (is) good at special requests

This thread is diverging a bit