Leisure battery charging problems

Niall_G

Hi. I am looking for a bit of advice. I think my leisure battery (Halfords) may have suffered from the recent cold spell. It now only charges to 12.4 volts after a long drive. What is more puzzling though is that when I plug in to mains now, it blows the ELCB in my house so I can't charge it (or do anything off mains).

The charging lead is fine, so it is something internal in the van. Before I start isolating everything, I am wondering if a "bad" battery could trip the ELCB?

The battery was previously in good condition and the charging system worked fine.

Thanks.

Jaden

Bad News First, Sounds like the battery is shagged.
Good News Next, SirLiamAlot will be along in 5,4,3....

autumnalcore

Niall_G wrote: »

Before I start isolating everything, I am wondering if a "bad" battery could trip the ELCB?

No. If you have a multimeter, disconnect the van from the mains, put multimeter on the megohm range and measure the resistance between the live and earth and neutral and earth on the mains socket in the van.

Niall_G

Thanks for that feedback. As expected, it is not the battery. Neither is it the 12v unit as I have isolated that completely. Once I turn on the main fuse in the camper it blows (the house ELCB). That main fuse in turn has three circuits. One is the 12v unit which I have disconnected. I am presuming the other 2 are the fridge and the 240v socket circuit so I will try to isolate those one by one and see how I get on. They don't make the wiring easily accessible though!

Autumnalcore: As regards resistance - 0 between earth and neutral, 8 between earth and live (or 0 if I have the main fuse off). What does that tell me?

Thanks again.

Jaden

Ah, I misread. Charge the Battery out of the van with a charger in the house. See what it reads once charged.

Niall_G

It turns out to be the fridge (which works fine on gas). That is probably the limit of my technical ability, but at least I know what I need to get fixed now. Thanks again.

jace_da_face

Give your battery a good overnight charge with a mains charger. The alternator won't have fully charged it anyway.

Your resistance figures didn't sound right. 0 between Earth and Neutral. That's zero ohms right? Not 0 volts? Zero between Earth and Neutral will trip your ELCB. But maybe now with fridge unplugged, you are not seeing a short across Earth and Neutral. If so, perhaps your fridge's mains cable is pinched or damaged.

The earth and neutral are the same thing one is allowed to conduct the other isn't.
{Edit} Actually on second thought they shouldn't be connected without the mains lead plugged in...unless you have a neutralised supply onboard which is unlikely.
Does the meter also read 0 when it's open circuit?

Probably the the fridge mains lead is contacting the chassis somewhere. It's a pretty serious fault and can be quite hazardous if there's a break in the earth or the ELCB doesn't trip (not always guaranteed).
I'd ask an electrician to look at it if you're not comfortable trouble-shooting it.

autumnalcore

Niall_G wrote: »

It turns out to be the fridge (which works fine on gas). That is probably the limit of my technical ability, but at least I know what I need to get fixed now. Thanks again.

Fridge wiring is very simple disconnect the mains lead at fridge end and see if you still have fault. If you dont check resistance between outside of mains heating element and its wires. Geating elements are pretty cgeap and easy to change.

jace_da_face

Sir Liamalot wrote: »

The earth and neutral are the same thing one is allowed to conduct the other isn't.

I disagree. They are not the same thing if one is allowed to conduct and one is not. They do eventually become the same path but that's long after your local substation meets its interconnectors. But locally, no load current should flow through your earth wires. No more than 30mA anyway which is most likely what your ELCB is set for. And yes, shorting earth and neutral at a power outlet would be enough to trip your breaker. Even with just a few tens of millivolts of trace on the neutral line, 30 mA will be exceeded.

Bottom line: Resistance across Earth and Neutral terminals feeding any of your appliances or feeding your van's EHU socket, should not meter zero.

jace_da_face

jace_da_face wrote: »

Bottom line: Resistance across Earth and Neutral terminals feeding any of your appliances or feeding your van's EHU socket, should not meter zero.

Agree. Except in the case that the meter is not displaying a reading 0Ω and continuity but instead "O" for Out of Limit or open circuit.

Earth and neutral are tied at every installation that has an RCD. This is what I was thinking of. They are both the opposite leg of the phase conductor except conduction along the neutral is acceptable where on the earth is not.

If there's a path from neutral or live to earth in an appliance downstream of an RCD/RCBO/ELCB/GFI then this is a potentially harmful fault that needs to be remedied.

jace_da_face

Agreed. I do think OP should first checkout his mains wiring to the fridge. Could be pinched.