Batteries not charging when driving Help!!! (1 Viewer)

[gazza280]

Hi Guys

Have a problem I need help with.
A few weeks ago I installed 2 new 110amh batteries in the van in readiness for a trip in Europe soon. The batteries installed correctly have been charging up on EHU, no problem.
Now I have taken the van out for a long run today and returned home to find the batteries only have 11.6v charge. How can this be?

I only used the fridge on battery whilst driving and the lights on for about 10 minutes. I know that they were fully charged this morning with 13.7v.
Drove about 150 miles so I would have thought that the batteries would still be nearly full.
So why would the batteries discharge so much?

My first instinct was, the alternator is not charging the leisure batteries, but no. I have a plug in meter that tells me the state of charge of the batteries. When I turn the engine over it shows a jump to 14.1v so I am assuming that the alternator is charging the batteries.
So I don't think its a fuse issue either.

I don't know much about the electrical system but I am assuming this also means that the split charger is working. Am I wrong?

The cab battery was also fully charged, well according to my electrics panel anyway.

Do I need a more powerful alternator? Do I need a new split charger? Do I need a new charger?
I was thinking of a smart charger as I have heard some good things but how do I replace the original vehicle panel charger?

I am so frustrated so please anyone, Help!!

Many thanks
Gary

 

[TheBig1]

it depends where you are testing the voltage to see 14.1v. the alternator is obviously working but not getting to the batteries, either duff relay used for split charge or fuse or a faulty earth connection to the leisure batteries

 

[Terry]

a COUPLE OF SIMPLE things to test if you have a multi meter is switch off your on board charging unit -leave a couple of mins -take reading from batts then turn engine on and re test:thumb: if no different then either split relay (if van has one) a fuse , or you may have a switch on control panel - basically what Big one said
Are you sure it used to charge battery from engine before?It could be that no split relay has been fitted to charge the L/B it may just run the fridge -Swift have been known to do alsorts of silly things
don't forget to turn your on-board charger back on
terry

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[gazza280]

Am I right in thinking that the fridge works from the cab battery when traveling and then the changes to leisure battery when engine is not running.
Obviously I use gas when off hookup for extended periods.

 

[Larby]

The fridge should NOT work on 12v unless the engine is running.
When the engine is running a split charger charges both the vehicle and leisure battery, also the fridge if showing as 12v on selector.
When on EHU, you run the fridge on gas or 240v, switching to 12v [HI]shouldn't allow it to work [/HI]unless wired incorrectly as it would flatten batteries in no time.
The place to measure if leisure battery is getting a charge is across the terminals of the battery when engine running, hopefully showing 14.4volts or thereabouts. If not the fuse may have blown or the relay has failed. I enclose a picture of mine and the fuses. You can try swapping relays if the same type, also check fuses.
It is unlikely to be alternator but check voltage across terminals on vehicle battery when engine is running. If 14.4v or so and leisure battery isn't, then fault lies between.

 

[pappajohn]

remove hab control panel....throw in bin.
fit mechanical switches.
problem solved.

i detest electronic panels....absolutely no need for such 'advanced' technology in a motorhome.

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[DavidG58]

Hello, I cant offer technical input better than above, but am surprised that the voltage drop could be as big as you have recorded, unless the fridge was running off the leisure batteries while you were driving. You would have needed to have virtually everything on to drop the voltage so much in such a short time, unless there is something very seriously wrong somewhere

 

[Reallyretired]

Possibly a red Herring, but on a MH of mine many years ago a fuse between the vehicle battery and a two pole relay (the split charge relay) had blown. The relay still closed when the engine was running, but because of the blown fuse and the way the relay was wired, the fridge was running on the leisure battery, while the leisure battery was receiving no charge. After driving for a couple of hours the leisure battery was flat, and the fridge wasn't too happy either. Replacing the fuse meant all was well again.

 

[Terry]

remove hab control panel....throw in bin.
fit mechanical switches.
problem solved.

i detest electronic panels....absolutely no need for such 'advanced' technology in a motorhome.

Nothing like keeping it simple
terry

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