DC -DC charger with Inovtech battery charger

[SwissBob]

Yet another electric question. We have an Inovtech battery coupler that works ok and was installed when we had agm batteries. I now want to add a dc - dc charger for the battery which is now changed to lifepo4. My question is, can these two things, Inovtech coupler and dc-dc play nicely together?

 

[autorouter]

Do you know what the Inovtech battery coupler is supposed to do? I can't find any actual information on this item, and a 'coupler' can mean several things. If it joins the batteries together when the engine is running then it's not compatible with a DC-DC charger.

 

[SwissBob]

Do you know what the Inovtech battery coupler is supposed to do? I can't find any actual information on this item, and a 'coupler' can mean several things. If it joins the batteries together when the engine is running then it's not compatible with a DC-DC charger.

I struggled too until I had the clever idea of searching in French, it being a popular option on vans here.
"
(13)
The battery separator coupler allows you to parallel your starter battery (engine battery) and your auxiliary batteries. It automatically connects and disconnects the batteries installed in parallel according to predefined voltage thresholds. It ensures that the engine battery never completely discharges so that you can restart without any problem. It protects your batteries from a complete discharge which could damage them. The separator coupler ensures the charging of all batteries by giving priority to the engine battery and as soon as the engine battery goes above 13.5 volts, all batteries are charged simultaneously. The maximum charging current is 70 amps. Suitable for batteries with individual capacity up to 300 Amps." We have the posh version that includes something to do with the fridge.

So now I'm thinking it's similar to a dc to dc charger but I think no option to change the charging profile. More investigation required ...

 

[Lenny HB]

Yep it's a B2B with a few additional features, unless you can set it for LifeP04 it would best to replace it.
Worth contacting the manufacturer before you do anything they may be able to reprogram it.

If it's been set up for AGM don't use it with Lithium voltage will be far too high.

 

[SwissBob]

Managed to find the contents of the user manual - in French but translates ok on googly.

Analyse du Coupleur séparateur Inovtech Réf 480721 - Casa Trotter

Not suitable for lithium so some rewiring and a dc to dc needed.

^{_{Subscribers  do not see these advertisements}}

 

[Lenny HB]

I've scanned through the instructions quickly it looks like a sofisticated split charge relay rather than a B2B.
The fridge is run from it so you could leave it just to run the fridge or fit a seperate relay for the fridge.

 

[autorouter]

My question is, can these two things, Inovtech coupler and dc-dc play nicely together?

I agree with Lenny HB, it looks like a split charge relay with extras. So no, it doesn't work with a DC-DC charger, it would basically short circuit the DC-DC input and output so the DC-DC charger would have no effect. The good news is that it is accessible, not buried inside a box with a circuit board like many split charge relays.

The wiring diagram shows two leisure batteries, Aux1 and Aux2. I think that's more intended for boats, most motorhomes have one leisure battery bank, which can of course consist of two or more batteries in parallel. So I think you just disconnect whichever output (Aux1 or Aux2) you are using, and connect it to the output of the DC-DC charger.

For the input of the DC-DC charger, you could either split the wire going to the Inovtech unit, or run a separate wire to the starter battery - depending on whether the wire is up to the job. It depends on your DC-DC charger. If it's a 30A then probably you can use existing wires, if it's 70A you'll need new wires probably.

 

[SwissBob]

Update: talking to the supplier they have new versions that support lithium but not lifepo4 according to the guy I spoke to. Seems daft to me so now after a second opinion but the actual manufacturer seems impossible to track down.

 

[SwissBob]

I agree with Lenny HB, it looks like a split charge relay with extras. So no, it doesn't work with a DC-DC charger, it would basically short circuit the DC-DC input and output so the DC-DC charger would have no effect. The good news is that it is accessible, not buried inside a box with a circuit board like many split charge relays.

The wiring diagram shows two leisure batteries, Aux1 and Aux2. I think that's more intended for boats, most motorhomes have one leisure battery bank, which can of course consist of two or more batteries in parallel. So I think you just disconnect whichever output (Aux1 or Aux2) you are using, and connect it to the output of the DC-DC charger.

For the input of the DC-DC charger, you could either split the wire going to the Inovtech unit, or run a separate wire to the starter battery - depending on whether the wire is up to the job. It depends on your DC-DC charger. If it's a 30A then probably you can use existing wires, if it's 70A you'll need new wires probably.

Thanks, good advice and that does seem like a plan. Would the dc to dc charger need a -ve back to the starter battery or just the common one?

 

[Lenny HB]

Thanks, good advice and that does seem like a plan. Would the dc to dc charger need a -ve back to the starter battery or just the common one?

You can take the negative for the B2B from either battery.

^{_{Subscribers  do not see these advertisements}}