12v problem off EHU, ideas please...

[Andacami]

It's now beyond my understanding. We had no problems with LB 12v until a few days ago, symptoms are:

• LBs seemingly not charging on alternator
• LBs seemingly 100% having been on EHU
• LBs take a charge from the Victron Solar unit
• Unhook and drive for a couple of hours to next site
• Set up and switch on 12v, all seems fine
• After an hour or so voltage drops to 11ish
• Then the Sargent 480 starts to report low voltage everywhere including starter battery
• Water pump will come on at 10v and run constantly (it's fine at 12v and on EHU)
• Starter battery is healthy and does charge from alternator but Sargent reports as low as 3v
• Turn the master switch of the Sargent PSU off for 20mins, then on again and it seems ok for 5mins before going back to reporting low voltage everywhere
• LBs are actually about 11v with a multimeter, starter is fine
• No significant drain reported at the control panel and everything unplugable is unplugged
• All fuses that I can locate are good

Something is awry, seemingly no alternator charging, a drain that takes the LBs down within an hour...

Could it be a knackered Sargent charger/psu?

Could it be knackered LBs (They are not that old and have performed well so far)?

 

[ivorantony]

LB batteries are shot is my first thought!

 

[TheBig1]

if the LBs off charge read 11v, they are knackered. What you see when plugged in is the charger voltage which the batteries are not taking. Once the surface charge voltage dissipates you see the true voltage. The control may be being confused so is not reading the starter right

water pump is seeing the low voltage drop as an open tap

 

[Jev88]

Sounds like LB allowed (not blaming you) to go too low and dead. Have the output from your charging systems checked or risk destroying the new LB.

 

[Andacami]

Thanks very much, makes sense.

I'll disconnect the LBs and get an hour by hour multimeter reading later, if they drop then I have to agree with you that they are knackered.

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[scotjimland]

concur.. LBs goosed

 

[Boldly]

There have been several similar threads recently where leisure battery is duff. They seem to go wrong very quickly when I would have thought a gradual decline in performance would be more likely. Am I wrong to expect some warning before they expire?

 

[AdrianChen]

There have been several similar threads recently where leisure battery is duff. They seem to go wrong very quickly when I would have thought a gradual decline in performance would be more likely. Am I wrong to expect some warning before they expire?

Is it a case that the battery's capacity is slowly declining, but that decline is masked by regular alternator, EHU and solar charging until the point where the it is so small that it becomes noticeable and insufficient even for a couple of hours?

 

[Andacami]

Is it a case that the battery's capacity is slowly declining, but that decline is masked by regular alternator, EHU and solar charging until the point where the it is so small that it becomes noticeable and insufficient even for a couple of hours?

Could be, that's what seems to be happening to me. The batteries have the telltale window to show charge state, always been green but further tests required methinks...

 

[pappajohn]

Your leisure batteries are in excellent condition but your vans knackered

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[Andacami]

Your leisure batteries are in excellent condition but your vans knackered

It might be, we've thrashed it in France since 3rd Sept

 

[GeoffnDee]

Could be, that's what seems to be happening to me. The batteries have the telltale window to show charge state, always been green but further tests required methinks...

The green state of charge tell tale is only relevant to one cell of the battery and can still show green even if one or more of the other cells of the battery is faulty.