Inverter Question - 2 Batteries not connected.. (1 Viewer)

[MichaelT]

Was thinking of fitting an inverter and have read several posts on here so have a fairly good idea of whats needed. However I have come across an issue that I am not sure what to do about. At the weekend I found the wire for the SP had come out of the crimp so was looking about where I could fit the Inverter and run wiring etc.

We have 2 leisure batteries in the van one under each of the front seats however they do not seem to be connected together in the conventional sense but seem to have wires from each going to the electro block where there is a terminal for B1, B2 and negative. So the question is where would I connect the Inverter to, was thinking just connecting to one battery would drain it quickly as they are only 85AH or would I have to have wires coming from each battery to the Inverter then I would have to have wires coming across the walkway between the seats. Anyone had the same problems, van is a 2016 Knaus Sky TI.

 

[Richard n Ann]

Is one battery for the engine?

 

[MichaelT]

No its a second leisure battery.

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[hilldweller]

No its a second leisure battery.

Which electroblok is it ? Our B1/B2 is leisure and starter battery.

The starter battery is of course charged, at a low rate by the B2 connection. It does not feed enough current to keep a leisure battery up to scratch.

 

[MichaelT]

Looks like one battery is connected to B1 and the other to B2 so any load is taken from both batteries at the same time and as far as I know the engine battery is under the floor. When @eddievanbitz fitted the SP and battery master they connected these to the electro block, but I guess they must have wired the battery master to the engine battery but I cant see where the wire goes.

 

[hilldweller]

Looks like one battery is connected to B1 and the other to B2 so any load is taken from both batteries at the same time.

That's why I asked for the electroblok number. Our old one is as I said with only B1 serving as a leisure circuit and B2 just charges the starter battery but others with later models may be able to chip in with advice on a different configuration. If by chance I'm right you have been running a single leisure battery and have a spare battery that never passes an amp.

Never for a second assume because that's how something arrived out of the factory that it is right, it just does not work like that in motorhomes.

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[MichaelT]

Well when the engine starts it shows 2 batteries on the control panel and both batteries are the same type so I am sure they are leisure batteries. As I said as far as I am aware on the 2016 Ducato the engine battery is under the floor though I have never looked to confirm this...

 

[DBK]

Assuming you are fitting a reasonably large inverter which needs its own cables then I don't think you have any choice - you need to link both batteries together and run the inverter off both, connecting it to the positive terminal of one battery and the negative terminal of the other.
To tidy up the cables they could be run under the floor but if you have a garage then you could move the batteries into it and mount the inverter next to them.

 

[two]

I’d start by finding out why the two batteries are not already joined.

Inverters take a lot of current, so cable runs need to be as short as possible, and thick.

What are you planning to use from your inverter and will you be off-grid and stationary for long?

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[MichaelT]

Will use it for the obligatory ladies hair dryer and a nespresso machine mainly. Sometimes off grid for 5 days at a go but have 130w solar panel so that should be OK. Only short bursts on the Inverter.

They both supply the 12v (as far as I know) but I guess because of location they feed the electro block separately rather than being joined together first then supplying the 12v.

 

[Lenny HB]

Doesn't matter how many leisure batteries you have they will only show as one battery on the control panel the other battery will be the engine battery.

 

[Reallyretired]

I think your first move is to find the engine battery, if you can't then one of the two you have found is the engine battery. At only 85Ah a single battery isn't going to run your inverter for long e.g. average hairdryer (1500w) for 10 minutes will consume around 25Ah and you will only have around 40Ah available from your battery.

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[MichaelT]

Will try and get to the storage yard at the weekend and check.

 

[two]

You may be OK so long as you realise that inverters have only a modest, finite, supply. Not like mains at home.
Check out those batteries first, though, because what you have described does not make a lot of sense.
Place the inverter as close to the battery as possible and use thick cable.

 

[hilldweller]

You may be OK so long as .........

...... he doesn't ask simple questions on FUN. He must be mighty confused by now.

We do our best.

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[Lenny HB]

Your van is on a Fiat so engine battery will be under the drivers footwell (passenger side on a RHD). Lift the mat/carpet and you will see a removable panel.

 

[MichaelT]

Your van is on a Fiat so engine battery will be under the drivers footwell (passenger side on a RHD). Lift the mat/carpet and you will see a removable panel.

That's is what I understood Lenny which is why I am certain the batteries under the drivers and passenger seats are leisure batteries. And I do know how inverters work and the need to have a big enough battery bank which is why I posted this as all the information and forums I have seen the batteries are strapped together and the inverter connected from there.

 

[Lenny HB]

I'm sure you will find they are connected in parallel, cables probably under the floor timber between the seats.

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[Bobby22]

Looks like one battery is connected to B1 and the other to B2 so any load is taken from both batteries at the same time and as far as I know the engine battery is under the floor. When @eddievanbitz fitted the SP and battery master they connected these to the electro block, but I guess they must have wired the battery master to the engine battery but I cant see where the wire goes.

The battery master will have one wire going to B1 one going to B2 and a third going to an earth.

B1 will be the vehicle B2 will be hab x 2 earth is common for both.

Solar will come into B2 from sloar controler and to earth.

The battery master is there for the solar charge to get to the engine battery

Your engine battery will be under the floor panel on the passenger footwell (rhd)

 

[MichaelT]

OK so I took some pictures today and confirmed that the engine battery is in fact under the passenger floor as Lenny suggested.
First picture is the battery under drivers seat which I think is the second one, as you can see there is a black lead coming off it but it does not seem large enough to be a connecting one to the other battery I thought the wire would be thicker. Next the second battery and charger then the battery master which is connected to both B1, B2 and the negative terminal so maybe the batteries are linked and there is a connection back to the engine battery so the voltage can be displayed on the panel.

Sorry for piccy quality it is dark under the seats...
Think I may need to take professional advice where it can be looked at...

 

[two]

So the two batteries are, indeed, part of the habitation bank. It may be best to remove the seats (4 bolts + wire to disconnect, but awkward and heavy) and take a good look at the connections. I have a feeling that the second one under the driver's seat has been added at a later date in an unconventional manner. It may be worth changing the wiring arrangement for best results, especially if adding an inverter.

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[MichaelT]

So the two batteries are, indeed, part of the habitation bank. It may be best to remove the seats (4 bolts + wire to disconnect, but awkward and heavy) and take a good look at the connections. I have a feeling that the second one under the driver's seat has been added at a later date in an unconventional manner. It may be worth changing the wiring arrangement for best results, especially if adding an inverter.

It was a factory fit option so hoping they are connected properly but I'm not sure they would take the load of an inverter so will get someone to look at it and advise on best way forward.