Habitation battery

[AGC]

I’m new to Hymer but have just purchased a new Whiteline BMCI 600 (22 plate)
Really just getting to grips with it - main issue at the moment is the habitation battery which seems to discharge very quickly
Dealers have said to isolate the battery at the EBL (which works) but then you lose date / time in the Truma control
Do I really need to isolate the battery & will it be damaged if left permanently connected to mains ?
Any advice gratefully received

 

[pappajohn]

How large (AH capacity) is the battery?
How long does the battery last when not on mains hookup?
Your van should have a smart charger so can be left on hookup indefinitely.

 

[paddymcc]

If it's discharging quickly with no significant load on it then it's likely to be a duff battery and needs replacing. What make and size battery is it? You shouldn't need to isolate it by turning of the 12v side.

 

[autorouter]

Really just getting to grips with it - main issue at the moment is the habitation battery which seems to discharge very quickly

It's hard to decipher what you mean by 'very quickly'. Is that a day, a week, a month or what? The best thing is to first find out if the fault is an unknown load draining the battery, or an internal fault inside the battery. Is there a display panel that shows the amps to/from the battery - I'm assuming there isn't so maybe you can use a clamp meter to measure the amps in the positive cable to the battery terminal. The dealer should be able to do such a test, if you don't have a suitable meter yourself. Or a local auto electrician could do it if that's more convenient than a drive to the dealer.

 

[AGC]

Hi all
Many thanks for the all the comments
Firstly apologies for being less than specific on some points - my wife said keep the post short so I did !
The battery is a Varta 12V 95A / 85A
In terms of ‘quickly’ the battery had discharged to the point where it had switched itself off via the EBL in around 6 days
Lastly, when the vehicle is parked I switch off the 12V at the control panel which as I understand it only leaves essential services (like the Truma control) connected
When connected on hookup the battery comes up to around 13V and shows around 12.5V off hookup then drops over a matter of days
I do agree entirely that it shouldn’t be necessary to isolate the battery at the EBL but this was the advice from the dealer
I still have more investigation to do in terms of ‘hidden’ loads
I can easily arrange a permanent hookup when parked but was a little reluctant in case I did any damage
We’re going away in the vehicle this weekend so hopefully will get a bit more into the detail
Again many thanks to all

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[headlight]

Surely if it's a new van you should take it back to the dealer for them to sort the problem out.

 

[autorouter]

A lead-acid based battery needs to be fully charged to 100% every week or two to stop it deteriorating by sulphation. If it's at 12.5V with no charging and no load (resting voltage) then it's not 100% charged, I'd expect more like 12.6V or 12.7V. Put it on hookup and watch the voltage.

A smart charger constantly monitors the battery voltage and amps, and takes it through at least three stages of charging. The voltage will gradually rise up to about 14.5V, this will take a few minutes or several hours, depending on how flat the battery is. When it reaches a limit (the absorption voltage) it will stay at that voltage for another period of time, until it's 100% full. Again, that might take a few minutes or a few hours. When it's 100% full, the voltage will drop to about 13.5V. This is 'float charging', where the charger puts in just enough to stop the battery discharging, but doesn't overcharge it. It can be left in this state indefinitely.

The exact voltages depend on the type of battery (flooded, sealed, gel, AGM etc).

With all the added devices on most motorhomes, like Truma/fridge controls, audio systems, etc, the leisure battery often only lasts a couple of weeks before it needs charging again. If the battery was never being fully charged in the first place then it won't even last that long. So maybe there's nothing wrong at all.

 

[Tombola]

85ah lead acid discharging somewhat in a week with various std auxillary loads Isn't a big concern. Plug in on the drive or if you have solar system lave that switched on.

 

[BILL 875]

I'm no expert but if u have solar and its left on/charging the 12v panel or battery panel should be showing 13.5 all the time, well mine does anyway. Bill

 

[AGC]

Thank you all for the very helpful feedback - this is all useful stuff & good background for when I speak to the supplier
The consensus seems to be that it’s OK to permanently hookup so I’ll run this past the dealer
Just wanted to be speaking from a position of knowledge as to date their advice has been a bit suspect
Again many thanks to all

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[VXman]

What EBL to you have? Most modern control units will smart charge to battery when on Hook up. It will charge til full and then automatically stop charging, trickle charge, float etc etc. You shouldn't need to do anything just leave it plugged in.

If the battery is not being used I wouldn't expect it to die in 6 days. If in use then yes, probably - depending on what use age it has had.

 

[Lenny HB]

It's an AGM battery when on hookup it should charge up to 14.7v once at 14.7 should hold there for 4 hours then drop to a float charge of 13.7v.

Was the van a new factory order or has it been in stock at the dealers for while?
If a stock one I suspect the battery has been allowed to go flat and it's now goosed.

If the dealer is replacing it try and get a Gel battery far more reliable than AGM, EBL setting will need changing.