My 15amp fuse keeps blowing in my split charge relay. Is it ok to put a 20amp fuse in instead? I think it's blowing just as the engine starts as the first surge of electricity rushes down the wire. I have just tried it and it seems to be ok, I'd just like a little reassurance that I'm not going to burn my van down to the ground.
20 amp is fine. It'll blow anyway if anything's wrong. Are you sure a) your relay is working and b) the main batt isn't flat?
Is the LB flat or very low charge? if it is, when you start the engine the surge will be power flowing from the starter battery and the alternator into the LB. For what its worth I use a 40A fuse. put as large a one as you need as long as the cable and the relay are up to it
Cheers for the help guys. The main batt is 12.6v and the LB is, or was 7.8v but that was because all the way up from london last weekend I had the radio on but the batt wasn't being charged. When I tried it just now at the camper fuse box fed from the LB the voltage was 12.8v with the engine running.
Dont change the fuse for a bigger one unless you know what the relay is rated at and that the cable is the right size taking in to account the length as well A spilt charge system on a bay needs to be 30amp or your fuse will blow Also the relay should get its switch feed from the alternator and not the coil as i suspect yours is if it blow when you are starting
Cheers for the reply Matty. My relay is the blue one from Just Kampers and if I remember correctly came with a 15amp fuse. I had it connected to the coil+ last year and you're right the fuse blew a few times. Late last year I connected it to the alternator and it's been fine ever since. I think the problem may be connected to me fitting a propex heater a couple of weeks ago. I was camping at the weekend and ran my leisure battery completely flat for the first time ever. I've got nice big fat cables and their not very long.
Might be for the best to give your LB a good charging on a plug in charger unless you intend to drive around for hours. It's good for them to get an eight hour charge from time to time to clean up the plates and lengthen the battery life. Leave it on for another 4-6 hours even when the charger says it's charged.
The cheap JK relay is rubbish. Don't waste your money, doesn't do what it's supposed to. OK for a trickle charge but our leisure battery's need more than that.
Ha Ha great minds think alike. I'd just been looking at beefier relays in response to Matty's post and was about to post a reply asking his opinion of this relay http://www.split-charge-relays.co.uk/contents/en-uk/d58__voltage-sensing-split-charge-relay.html Then I read your post, went and read the thread you linked and blow me down if post 45 leads me to exactly the same relay. From the company I found it costs £50.79 to my door. Your link it costs £45.05 to my door. Cheers guys and thanks for being so patient when with a bit more thought I should have done a search.
Have a look on fleabay those Durite 140A intelligent split charge relays are £27.99 +£2.99 postage search for "intelligent split charge"
I know i have said it befor but Why spend £30 on a relay plus heavy awkward to fit cable when a £7 one is more than capable http://www.vehicle-wiring-products.eu/VWP-onlinestore/relays/relays.php Part R30AF
One reason for me is so I can have both batteries on charge at the same time using one charger, not easy to do with a traditional relay.
So, just to make sure I've understood it correctly This one http://www.vehicle-wiring-products.eu/VWP-onlinestore/relays/relays.php = more expensive but if I connect a mains battery charger to the engine battery it will charge both batteries in one sitting. The engine one first then leisure battery afterwards through the fully charged engine battery, in addition to keeping the lesiure battery charged while the engine is running. This one http://www.split-charge-relays.co.uk/contents/en-uk/p299_voltage-sensing-split-charge-relay.html = much cheaper, adequate for the job, wired up to the same places as my present JK relay. Both = 2 inline 30amp fuses 1 in wire from +engine battery to the relay and one in the wire from the relay to leisure battery+
The normal relay is just a switch When the engine is running the relay is switched so that both battery's are joined together so charging both battery's. The self switching relay When the main battery reaches a set voltage 13.3 volts it switches so that both battery's are joined Pros/cons Normal relay needs signal wire from alternator cheep Charges both battery's as soon as the engines running Self switching easy to install not cheep charges main battery first (if your battery or alternator is not in good condition it may not reach switching voltage) may not charge leisure battery on a short journey For the best system you want a battery to battery charger but they are £215 http://www.ctekchargers.co.uk/ctek-d250s.php
