Charging Both Batteries

[wotme]

I've just been looking through the book of words on my 2007 Elnagh and it appears both the starter and leisure battery are charged via the EHU, just wondered if this is the norm because I'm not 100% convinced. I suppose someone with more knowledge than me could test it but I thought if any one would know its you guys,

 

[PhilandMena]

I'm sure the manufacturers and designers of your motorhome don't have a clue how it works and put any old rubbish in there manuals.

 

[jockaneezer]

Most decent vans charge both batteries when on hook up, but with some you might have to manually select which battery you want to charge, usually by a toggle switch labled "cab or aux".

 

[two]

Under normal circumstances, you shouldn't need to charge your starter battery. A problem may arise if you leave the van unused over winter with security devices draining them, though.
Chargers, nowadays, are supposed to be 'smart' and charge according to a special regime appropriate to the battery they are managing. Since the battery technology for starter and habitation batteries is usually different (as well as their capacity and state of charge at any time) any charge offered to a second battery can only be a token offering. In most cases, that's all that's needed, so no matter.
The best way to charge the vehicle/starter battery is to use an independent charger.

 

[PhilandMena]

After reading the above posts I decided to look at what is actually stated in the manual and have formed the view It's self explanatory.

The starter battery can only be fully charged with an external charger. If a 240 V power supply is used, the transformer/rectifier charges the starter battery with a float charge only. Even in mobile operation, the vehicle engine alternator is not capable of completely charging the starter battery. 9.4.1 Charging using a 240 V power supply If the vehicle is connected to the 240 V power supply, the living area battery and the starter battery are automatically charged by the charger module on the transformer/rectifier. The starter battery is charged with a float charge of 2 A. The charging current is adapted to suit the charging condition of the battery. This ensures that it is not possible to overload the battery. To make use of the maximum output from the charger module on the transformer/rectifier, switch off all electrical appliances during charging. 9.4.2 Charging using the vehicle engine When the vehicle engine is running, the vehicle alternator recharges the living area battery and the starter battery. When the vehicle engine is switched off, the batteries are automatically disconnected from one another by a relay in the transformer/rectifier. This prevents the starter battery from being run down by electrical appliances in the living area. The starting capability of the vehicle is thus preserved. The charging condition of the living area battery or the starter battery can be read on the panel. 9.4.3 Charging with an external charger When charging the living area battery and the starter battery with an external charger, proceed as follows: Turn off the vehicle engine. Switch off 12 V main switch on the panel. The indicator lamp will go off. On the transformer/rectifier, move the battery cut-off switch to the position "Batterie Aus" (battery OFF). Disconnect the mains plug from the transformer/rectifier. Switch off all gas appliances, all gas isolator taps and close the regulator tap on the gas bottle. There is a danger of short circuit when disconnecting the battery poles. For this reason, first disconnect the negative terminal on the living area battery or the starter battery and then the positive. Remove the living area battery or the starter battery from the vehicle. Check that the external charger is turned off. Connect the external charger to the living area battery or the starter battery. Pay attention to the polarity: First connect the positive terminal "+" to the positive pole of the battery, then connect the negative terminal "–" to the negative pole of the battery. Switch on the external charger. See the instructions for use of the connected

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[pappajohn]

I'm sure the manufacturers and designers of your motorhome don't have a clue how it works and put any old rubbish in there manuals.

Even in mobile operation, the vehicle engine alternator is not capable of completely charging the starter battery.

And there's the proof they don't know what they're talking about.

 

[PhilandMena]

And there's the proof they don't know what they're talking about.

Not quite I think. It does say in their manual that insufficient charge comes from the alternator to fully charge the cab battery and that it only receives a float charge of 2 Amps.

 

[pappajohn]

Not quite I think. It does say in their manual that insufficient charge comes from the alternator to fully charge the cab battery and that it only receives a float charge of 2 Amps.

The alternator will provide whatever the battery needs to keep it fully charged.

If the battery is fully charged and no electrical items are turned on the alternator will be outputting a very low amperage, more than a couple of amps just to power the engine electronics, but if the battery needs charge current it will get it at whatever rate it needs to FULLY top it up.

It may be a 2amp float charge to the HABITATION battery via an electronic split charge but float will only take effect when the hab battery is fully charged anyway.

They are talking tosh.

 

[PhilandMena]

The alternator will provide whatever the battery needs to keep it fully charged.

If the battery is fully charged and no electrical items are turned on the alternator will be outputting a very low amperage, more than a couple of amps just to power the engine electronics, but if the battery needs charge current it will get it at whatever rate it needs to FULLY top it up.

It may be a 2amp float charge to the HABITATION battery via an electronic split charge but float will only take effect when the hab battery is fully charged anyway.

They are talking tosh.

From the manual.
The starter battery can only be fully charged with an external charger.
The starter battery is charged with a float charge of 2 A.

 

[HandyAndy]

Yes you've already said that, doesn't make it correct though

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[PhilandMena]

Yes you've already said that, doesn't make it correct though

Why not !

 

[jockaneezer]

For normal running, the van alternator will take care of charging the vehicle battery. The 2amp reference is from the on-board charger, not the alternator which will provide well in excess of 2amps. If, due to inactivity/storage your vehicle battery became flat, it's saying that the on-board charger probably doesn't have the capacity to fully recharge it and expects you to put a separate battery charger onto your battery to recharge it in a reasonable amount of time ?

 

[PhilandMena]

I must have been right with my first post then.

 

[pappajohn]

From the manual.
The starter battery can only be fully charged with an external charger.
The starter battery is charged with a float charge of 2 A.

Which manual.... Cab or Hab?

Regardless... Its wrong.

 

[pappajohn]

For normal running, the van alternator will take care of charging the vehicle battery. The 2amp reference is from the on-board charger, not the alternator which will provide well in excess of 2amps. If, due to inactivity/storage your vehicle battery became flat, it's saying that the on-board charger probably doesn't have the capacity to fully recharge it and expects you to put a separate battery charger onto your battery to recharge it in a reasonable amount of time ?

That's exactly what it means.

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[Jev88]

1) Buy a multimeter
2) Connect EHU
3) See what voltage is going to all batteries by touching to + and - of the battery..... Should see 13+ volts if charge is going to the battery you are testing........

 

[PhilandMena]

Which manual.... Cab or Hab?

Regardless... Its wrong.

I posted the relevant statement from the manual in post #5 of this thread. You can make of it what you will. I'm fed up now and will post no further on this thread. Not as if it's my motorhome anyway.

 

[Captain Yoghurtpot]

Dear Pappajohn,
So just that I can understand this and being a newbie, but learning fast, when I am on EHU, only my 230v sockets will work and NOT charge the habitation battery, UNLESS I switch ON my 12v switch on my control panel marked as “lights”, and then all my 12v circuits will work ( pump etc) and only at this point will my habitation battery be charging.
I do not believe I have a split charging system to also charge my cab battery when in 12v mode, only a system to charge the hub battery.
I ask because at home I like to run a small heater in the motorhome which is 230v temporarily to keep things in order, but don’t want to overcharge or “ cook” the Hab battery with overcharging.
Our van is a 2001 model ci type on a fiat Ducato base.
Much appreciated your response and knowledge. Thanks.

 

[pappajohn]

I posted the relevant statement from the manual in post #5 of this thread. You can make of it what you will. I'm fed up now and will post no further on this thread. Not as if it's my motorhome anyway.

Up to now you still haven't said which manual... HAB or CAB

 

[pappajohn]

Dear Pappajohn,
So just that I can understand this and being a newbie, but learning fast, when I am on EHU, only my 230v sockets will work and NOT charge the habitation battery, UNLESS I switch ON my 12v switch on my control panel marked as “lights”, and then all my 12v circuits will work ( pump etc) and only at this point will my habitation battery be charging.
I do not believe I have a split charging system to also charge my cab battery when in 12v mode, only a system to charge the hub battery.
I ask because at home I like to run a small heater in the motorhome which is 230v temporarily to keep things in order, but don’t want to overcharge or “ cook” the Hab battery with overcharging.
Our van is a 2001 model ci type on a fiat Ducato base.
Much appreciated your response and knowledge. Thanks.

On hookup, so long as your charger is turned ON it will charge the leisure battery.
The 12v split charge system is to charge the leisure battery from the engine alternator ONLY when the engine is running.

To charge the engine battery from the mains charger depends on your control panel, some do... Some don't.

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[Captain Yoghurtpot]

On hookup, so long as your charger is turned ON it will charge the leisure battery.
The split charge system is to charge the leisure battery from the engine alternator ONLY when the engine is running.

To charge the engine battery from the mains charger depends on your control panel, some do... Some don't.

Thanks Pappajohn,think I’m getting it now.
So what I need to do now is find a way of getting a charge put into my CAB battery when on EHU , either at home or on site to keep things topped up, via my motorhome charger, if such a thing is possible and find out if I can just charge the CAB battery or if I have to charge both the HAB and CAB at the same time, via switching on the 12v switch.
Had some other good advice given on this group recently and have followed it and got some 12v led readout meters from eBay and made a test lead which I can plug into the cigarette lighter to check the CAB battery voltage condition or plug in at the rear socket to read and check the HAB voltage condition, so don’t have to keep getting the voltmeter out and scramble under seats etc or under the bonnet to get to the battery terminals to check things.

 

[Captain Yoghurtpot]

Dear Pappajohn, this might seem daft, but what is to stop me making a lead up of positive and negative with a in line fuse and some form of good yet removable connections, like crocodile clamps, and attaching them to the HAB battery and then onwards to the CAB battery, so that when I switch on the Charger it will charge both albeit the CAB battery charge rate I would guess would be greatly reduced as the secondary receiver of charge, but receiving a charge none the less , enough to just help with starting the engine.
Does this sound dangerous?

 

[autorouter]

I ask because at home I like to run a small heater in the motorhome which is 230v temporarily to keep things in order, but don’t want to overcharge or “ cook” the Hab battery with overcharging.
Our van is a 2001 model ci type on a fiat Ducato base.

Most MHs have a smart charger, which monitors the voltage and amps of the battery, and goes into 'float mode' when the battery is fully charged. It will not overcharge the battery, and can be left on indefinitely. The question is, does your MH have a smart charger? If you can tell us the make and model of the electrics box, or post a picture, I'm sure someone will know.

 

[pappajohn]

Dear Pappajohn, this might seem daft, but what is to stop me making a lead up of positive and negative with a in line fuse and some form of good yet removable connections, like crocodile clamps, and attaching them to the HAB battery and then onwards to the CAB battery, so that when I switch on the Charger it will charge both albeit the CAB battery charge rate I would guess would be greatly reduced as the secondary receiver of charge, but receiving a charge none the less , enough to just help with starting the engine.
Does this sound dangerous?

There's just one drawback.... You forget to disconnect and start the van and the link wire between batteries melt due to 3 or 400 amps passing through.... Or the fuse blows, which it will, then you THINK its charging the battery but it most definately isn't.

The best and safest option is a battery master from vanbitz.
Only 3 wires to connect and fully automatic in function.

 

[Captain Yoghurtpot]

Most MHs have a smart charger, which monitors the voltage and amps of the battery, and goes into 'float mode' when the battery is fully charged. It will not overcharge the battery, and can be left on indefinitely. The question is, does your MH have a smart charger? If you can tell us the make and model of the electrics box, or post a picture, I'm sure someone will know.

Thanks autorouter
Will return to thread tomorrow when have had chance to photograph the electrics box and found it’s type.
I’m fairly sure it does NOT have a smart charger, being of 2000 / 2001 vintage.Think it might be an Electrobloc but willcheck properly tomorrow.
Thanks for the reply anyhow and interest to help a newbie out.

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[HandyAndy]

EBL 99 goes to float of 13.7, checked it not two days ago as I was worried it was stuck on 14.4 v from a check I did about three weeks ago.

 

[Captain Yoghurtpot]

There's just one drawback.... You forget to disconnect and start the van and the link wire between batteries melt due to 3 or 400 amps passing through.... Or the fuse blows, which it will, then you THINK its charging the battery but it most definately isn't.

The best and safest option is a battery master from vanbitz.
Only 3 wires to connect and fully automatic in function.

Point noted Mr. Pappajohn Sir!
Will look up vanbitz bit of kit.
Thanks for the advice. Will check again to see if I have not definitely got a smart charger type of charger.
I suspect not, what with the boiler system for hot water being coal fired!?

 

[autorouter]

There are two problems with a wire joining hab and cab batteries.

First, you do not want them joined when the starter motor is cranking. Starter motors draw a huge current from the starter battery, and if the hab battery is connected a huge current will flow along the connecting wire.

Second, if you leave the wire connected when the charger isn't working, the starter battery drains at the same rate as the hab battery. If you flatten the hab battery you won't be able to start the engine.

There's nothing inherently dangerous about joining the hab and cab batteries. The split charge relay does exactly that, but only when the engine is running, after the starter motor has finished starting the engine.

A BatteryMaster is an electronic device that joins the hab and cab batteries, but it has a 'one-way valve' that only allows flow towards the cab battery, and restricts the flow down to about 1 amp.

 

[Captain Yoghurtpot]

Thanks to all who gave advice.
Have checked both cab and hab batteries and the hab charger dies NoT charge the cab battery but does charge the HAB battery.
Cab is at 12.4v but can get to over 13v with external charger, and HAB at 13.2 on 12v and 13.5 on EHU from our Nordelettric Mod. Tel 41? Onboard control panel.
Definitely think a vanbitz charger is the way to go.
Are they really that simple to fit or would I be better going to vanbitz.
Bearing in mind I live in Nottingham and I think they are in Bristol?
All advice appreciated, I'm learning fast!
Thanks