Campervan leisure battery not charging on ehu / mains charger?

[andyfelt]

Hi, I'm trying to work out if our leisure battery is goosed, or I'm just missing something obvious (quite possible, since i know nothing about it). When on ehu, turning compressor fridge on (Dometic CRX50) causes voltage reading to drop from 12.6/12.7 (which is where it usually stays) to below 12 in minutes (maybe even seconds) - from this I assume ehu is not charging battery? This seems to make sense in that previous time on ehu (this was only second time, didnt use fridge before), voltage stayed around 12.5/12.4 (only used for led lights/phone charging), whereas I now think it should be higher when on ehu. Power is getting into van since sockets work and RCD trips when tested. Battery voltage is generally 12.6-12.8 and charges from main battery when driving; it also seems to retain charge OK since was used without ehu for a couple of days and seemed OK (albeit minimal usage). Previous threads have mentioned a mains charge controller but I cant seem to find anything that seems like it could be this - basically theres the rcd unit (with 3-pin plug socket next to it), a single cable seems to go from here to led display and theres nothing accessible between. LED display (which seems standard) has five buttons (one is lights, one is fridge, I guess one will be water pump (although not tried it) - no idea whast other two are but I assume unlikley to have any relation to mains charger?? Its possible battery has been allowed to run down since I think van probably sat around for a good while over winter so maybe it is done, although other than the fridge draining it almost instantly, it seems OK. Or could the fridge itself be the problem? if engine on, it stays on without draining leisure battery so my guess is probably not, Any advice welcomed...

 

[TheBig1]

When on hook up, the charger would be putting out about 13.8v if it was charging

The proper way to test, and know absolutely is use a digital voltmeter/multimeter across the battery terminals directly. Measure before plugging in ehu and after and the voltage should rise. The same technique with checking the alternator is charging, check before the engine is running and when it is.

Complicating matters, a battery may show as charged, but the voltage rapidly fall if the battery is old/faulty

 

[Itsmcb]

What van do you have? Someone with a similar one could advise where your charger is located.

 

[andyfelt]

Thanks. Its a T6 conversion so I guess a charger could be anywhere (and I dont know who did conversion)...
I've tested with a multimeter; 12.63 without ehu, 12.63 with ehu, so no increase. However, it didn't increase when engine was running either, although led vodoescould 12.63 mean its fully charged anyway (in which case ehu or engine wont increase volt reading?)?

 

[andyfelt]

sorry, that last sentence was meant to read 'although could led volt reading of 12.63 mean its fully charged anyway...'

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[GeoffnDee]

Thanks. Its a T6 conversion so I guess a charger could be anywhere (and I dont know who did conversion)...
I've tested with a multimeter; 12.63 without ehu, 12.63 with ehu, so no increase. However, it didn't increase when engine was running either, although led vodoescould 12.63 mean its fully charged anyway (in which case ehu or engine wont increase volt reading?)?

If you do the same tests with some of the habitation lights switched on , to load the battery and reduce the voltage , it should show if any charging system is in place and working as it should .

 

[Raul]

At 12,65v the ehu mains charger should raise it over 13v immediately, charged or not. It will stay on float if no loads, around 13,6v or there abouts.
A CRX 50 draws about 3A and a 0,1v drop it’s not to bad.

 

[nabsim]

Does your fridge run just 12v or 12v/240v? Switch off EHU and put a load on your battery’s fridge, tv whatever you have that can use 12v.
Once batteries have dropped a bit then start engine and see if you get 14.4v on hab and start battery’s.

 

[pappajohn]

although led vodoescould 12.63 mean its fully charged anyway (in which case ehu or engine wont increase volt reading?)?

When charging from either source the voltage will show the charger voltage, around 13.6v, regardless of state of charge....if the battery is full there will be no amps flowing but the charger voltage will show.
Your charger may be part of the main control panel or may be a stand alone unit hidden away behind a drawer, under a seat or even under the wardrobe floor.

 

[Raul]

Or a fuse gone on the charger.

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[andyfelt]

Thanks for all the advice. After some detective work, I've managed to find out who the conversion company was and have spoken to someone there - apparently, ehu doesnt charge the battery since this was an optional extra and original converter didnt request it (think i'll get it added). At least that explains that. Voltmeter with engine running still only showing 12.63 though - maybe I didnt leave on long enough since something must be charging battery and i definitely saw voltage display of over 14 then 13 something when driving yesterday - will have to check again tomorrow.

 

[Outdoorrambo]

I believe your post may have just solved my own post with the same issue (no idea how to link my post ).
Saves me scratching my head so thank you.