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Post by **rednip120372** » 26 May 2007, 20:17

https://www.expeditionexchange.com/cart ... ctid=18441

Found this near the leisure battery, the fuse had melted !! What's it do ? nothing seems to have stopped working

Website · Post by **dbroada** » 26 May 2007, 20:37

they are often used as the split charge relay and are not always up to the job.

Put a voltmeter on the leisure battery then start the engine. If the voltage stays the same the split charge system isn't working.

Post by **rednip120372** » 26 May 2007, 20:44

Thanks for that -I'll check that in the morning. If it's not working right then can I just replace the fuse or do I need to replace the relay?!

Would this effect the Eberspacher as the fan in this has stopped working since yesterday?

PLUS!!! I also have no main beam and front fog light on one side...are all these things connected or am I just having a run of niggles?!

Website · Post by **dbroada** » 26 May 2007, 21:05

The problem is those relays are rated at 15A which is a bit low for a split charge system. I have seen several that have had the 15A fuse replaced with a 30A and then had the relay melt. I would start with a 15A fuse but if that blows I would replace the whole thing with a 40A relay. These can be bought from Maplins or a motor factor but they are much cheaper from under the bonnet of just about any car in a breakers.

One of the main reasons that the split charge relay gets overloaded is because the leisure battery has been allowed to discharge too far. When the relay closes you get a surge from the alternator AND the starter battery. If your LB is measuring below 12,5 volts I would recommend that you charge it from the mains before you replace the fuse.

I don't think this would have had an affect on your lights but it is possible the heater stopped working because the LB voltage dropped too low. And the low voltage was either because the fuse had blown or the fuse blew because the voltage dropped too far.

Post by **rednip120372** » 26 May 2007, 21:18

Many thanks !!!!!

Will check it out asap will let you know how i get on

Post by **Rozzo** » 26 May 2007, 22:46

ahhhhh now you've given more info in here than your post elsewhere and if that is the split charge relay and your liesure battery is low on voltage then the eber may not work as they have low voltage protection to stop them flattening your battery. i think it kicks in if the battery drops below 10 volts.

Website · Post by **dbroada** » 27 May 2007, 06:02

I hope it cuts in at rather more than 10v - that would be a VERY flat lead acid battery and would just about guarantee a blown split charge fuse. A fully charged battery is about 13,5v and anything below 12v can be considered flat for our purposes.

If you are regularly going to discharge your battery you would be better of using a different charging regime. Also you would probably benefit from a true (deep cycle) leisure battery. Deep cycle batteries will take more deep discharges (still not many, just more) than a normal car battery and NEITHER type like sitting discharged. With a split charge relay we have already established that the fuse can blow which will leave the battery discharged when you get home. This is not good.

Post by **Rozzo** » 27 May 2007, 06:55

errmm no, the eber low voltage cuts in at 10v as stated. a typical engine battery will just about start your engine at 10v with a struggle. thats why they did it.

Website · Post by **dbroada** » 27 May 2007, 07:37

OK, I've never tried - mine has problems fully charged!

However....

State of Charge

State of charge, or conversely, the depth of discharge (DOD) can be determined by measuring the voltage and/or the specific gravity of the acid with a hydrometer. This will NOT tell you how good (capacity in AH) the battery condition is - only a sustained load test can do that. Voltage on a fully charged battery will read 2.12 to 2.15 volts per cell, or 12.7 volts for a 12 volt battery. At 50% the reading will be 2.03 VPC (Volts Per Cell), and at 0% will be 1.75 VPC or less. Specific gravity will be about 1.265 for a fully charged cell, and 1.13 or less for a totally discharged cell. This can vary with battery types and brands somewhat - when you buy new batteries you should charge them up and let them sit for a while, then take a reference measurement. Many batteries are sealed, and hydrometer reading cannot be taken, so you must rely on voltage. Hydrometer readings may not tell the whole story, as it takes a while for the acid to get mixed up in wet cells. If measured right after charging, you might see 1.27 at the top of the cell, even though it is much less at the bottom. This does not apply to gelled or AGM batteries.

suggests that 1,75 volts per cell = 6 * 1,75 = 10.5v is 100% discharge. It also suggests that fully charged is 2,15 * 6 = 12,9v so my earlier figure differs too.

that was from http://www.windsun.com/Batteries/Batter ... 20Voltages