Split charge relay help (faux?)

[67westy]

I got a split charge relay off Jon last year and have just got round to fitting it 10 months later :shock:

Got it all wired in correctly (I think!) but it keeps blowing a fuse, can someone give me a sanity check and make sure I've got this all right. Pretty sure I have as the kit was clearly labelled and checking against wiring diagrams it seems ok.

I have

85: earth
87: Leisure battery +
86: coil 15
30: Main battery +

Leisure battery currently reads 12.34V
Main battery reads 12.94V with the engine off and 13.4 when charging
Terminal 87 reads 12.34V with the ignition off as expected

The 10A fuse near the main battery keeps blowing, can't find any shorts. Should I up this to a higher rating or is something wrong?

I've been trying to test the voltage across the leisure battery terminals with the engine running to make sure it's charging, I presume this wouldn't cause the fuse to blow?

 

[bluenose]

have you gone straight to earth with 85 and does it happen when you crank the engine??

If you have the relay would be on as soon as you turn the ignition on then your starter motor is drawing off the leisure battery when you start and blowing the fuse.... you need to take that earth off your alternator/generator wire.. the one that turns the genny light out on your dashboard.

EDIT: sorry i think i got that back to front ... you do go straight to earth but take the live (85) off the alternator instead of the coil

have a look at this;
http://www.keithandsylvia.co.uk/tech pages/splitcharge.htm

 

[67westy]

Yup 85 is straight to earth and it's blown as soon as the engine is started, I guess I need to get the wiring diagram out then.

Would it be the fuse nearest the main battery that blows though? I would of thought if it was drawing from the leisure battery the fuse nearest the leisure battery would blow?

 

[bluenose]

Yup 85 is straight to earth and it's blown as soon as the engine is started, I guess I need to get the wiring diagram out then.

Would it be the fuse nearest the main battery that blows though? I would of thought if it was drawing from the leisure battery the fuse nearest the leisure battery would blow?

i got it backwards see the edit lol, 85 should go to earth but the live should come of the alternator because you don't want the leisure battery connected when your cranking the engine, have a look at that link i posted, it also says to use 30amp fuses

 

[67westy]

Beat me with the edit

That is a bit different to how it was labelled then, 86 and 85 seem the opposite way round although I don't think what would make a massive difference from my limited understanding of relays. So I guess I need to change from 15 on the could to 61 on the regulator then. I'll have a look at bumping up the fuses as well

Cheers for the input, I'll have a look at it tomorrow

 

[six]

also if your main battery is weak then current will flow the other way, from the lesuire batt to the main when the relay is on.

ive got a diode or something inline to stop this happening.. ill ask my bro what he put int there. im just reciting.

also the opposite is true.. if the lesuire batt is low and there is a drain on it ie a radio and other bits it may blow a 10amp fuse.

just a though

 

[67westy]

A diode would make sense, will have to look into that. At the minute the leisure battery is quite low so will be drawing more. Going to bump the fuses up after I've checked the wire gauge, looks beefy enough though.

 

[six]

you got a multimeter? chuck that in and measure the draw.

also if the battery is low yes it will draw more as the cells try to balence. this is why usually manufactures of lil toys tell you not to mix new and old batterys, in my experence a plit charge will charge ok up to a bout a 50% drain on battery (depending on size and application wrie etc etc)

try charging the battery full then try again

 

[six]

oh.. and i have a 40 Amp Blocking Diode in my split charge setup

 

[67westy]

Cheers for all the help with this. I swapped the coil wire to a feed from the alternator and bumped the fuses up to 25A and it's all working now 8) Just need to finish the wiring to the new fusebox tomorrow and I'll be able to have the lights on without worrying about flattening the battery

 

[faux]

Sorry I haven't replied til now, busy not sleeping :mrgreen:

A couple of people have mentioned this to me so I had a look into it. It only seems to happen to some and not others.

As others have said on here it is the high draw as ignition turns live. Upping the fuse should do the trick. I have started using 20a fuses now and no problems reported.

Regards

Jon

 

[simo]

Sorry Jon- havnt fitted mine yet but should be soon so can you just confirm what i need to connect to and should i change my fuse?
thanks
simo

 

[67westy]

Thanks for the reply Jon, I read your thread about your new arrival so wasn't expecting a rapid reply hope you get some sleep soon!

Simo, I swapped the coil wire to go to the alternator warning light and then upped the fuses from 10A to 25A and I've had no problems since. I think you could probably get away with keeping the wire to the coil but I preferred the other option as it will mean the batterys aren't linked until the engine is running which means the leisure battery wont be drawn from whilst the starter is turning.

 

[Pete B]

I had no end of trouble with blown fuses but swapping the relay supply to the regulator from the coil and upping to 20A from 10A fuses seems to have done the trick.
Another thing that seemed to not help matters was having something drawing a high current (such as a cool box) plugged in when cranking the engine, particularly when the leisure battery is getting low on charge.

 

[froggy]

As said it better to take the live feed from the dynamo / charging light output as this stops the leisure battery and start battery from being in circuit when cranking (this is usually what blows the fuses)

 

[loweredlight]

:?: got mine wired as per instructions from Faux so how can I tell if the fuse has blown?

Cheers

 

[67westy]

You can check the voltage across the leisure battery with the engine running, should be about 13.5 - 14V or you can take the fuses out and look at them