Charging starter battery while isolated

[The Artilleryman]

I'm in the process of upgrading to a LiFePo4 leisure battery - along with a mppt solar controller & B2B charger.

MH is a Bailey Autograph on a Peugeot cab.

As the Victron SmartSolar controller only has 1 battery outlet, I need to find a way of charging/maintaining the starter battery, and just to complicate things also whilst the Pug isolator is in operation (parasitic discharge is too large if battery not isolated) during the Winter - at present the MH goes on EHU for 24hrs once a month to charge both batteries - but with a LiFePo4 leisure battery this probably won't be required. So was hoping to use the leisure battery to maintain the starter battery (leisure battery is permanently connected to the solar panel, even when hab. electrics shut down).
Vanbitz battery master only has 1 negative lead, does anyone make one with 2 or do I need to do something else.

 

[Jimbohorlicks]

There are other battery masters available that are more lithium adaptable ,ablemain is one ,if you go into the search facility there are numerous threads on battery masters and both vanbitz and ablemain are discussed.

 

[Hoovie]

I'm in the process of upgrading to a LiFePo4 leisure battery - along with a mppt solar controller & B2B charger.

MH is a Bailey Autograph on a Peugeot cab.

As the Victron SmartSolar controller only has 1 battery outlet, I need to find a way of charging/maintaining the starter battery, and just to complicate things also whilst the Pug isolator is in operation (parasitic discharge is too large if battery not isolated) during the Winter - at present the MH goes on EHU for 24hrs once a month to charge both batteries - but with a LiFePo4 leisure battery this probably won't be required. So was hoping to use the leisure battery to maintain the starter battery (leisure battery is permanently connected to the solar panel, even when hab. electrics shut down).
Vanbitz battery master only has 1 negative lead, does anyone make one with 2 or do I need to do something else.

I am not aware of any battery maintainers/trickle chargers that have an isolated design e.g. separate -ve connections.

As long as you have a common ground on the Starter and Leisure battery systems (which I would think is bound to be the case with a factory-built motorhome and is typical generally), you would only need one negative and then a +ve for each battery. I'm not sure why you think you need separate grounds?

 

[The Artilleryman]

The built in cab battery isolator is on the -ve terminal, hence needing 2 -ve connections.

Will have to rethink winter charging procedure.

 

[Hoovie]

The built in cab battery isolator is on the -ve terminal, hence needing 2 -ve connections.

Will have to rethink winter charging procedure.

If you want to charge your starter battery AND have it remain isolated from the van, then you would need an charger with an isolated ground.
One way to do it would be to get the smallest Victron 12V DC-DC isolated charger. It would provide a potential current much greater than a trickle charger but if you are starting off with a charged battery it wouldn't result in much more power than a trickle - especially if you set up the voltage parameters so the float was at say 12.8V.
That is the way I would go I think for your particular requirement. Have a look at the Victron Orion Smart-TR 18A.

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

 

[eddie]

Laying in bed thinking about this, why not fit a Batter Master and connect the 0VDC to the starter battery via a diode

When the isolation is on the battery will only accept charge, not be able to discharge

That said, it’s a lot of faffing about, everyone else has the same issues and unless you don’t intend to drive it for months, solar and a Battery Master works fine for thousands of similar motorhomes

Also by isolating the battery, any alarm/tracking equipment will be turned off so a potential insurance issue there as well.

 

[The Artilleryman]

Thanks for the answer eddievanbitz, was just trying to find an easy way to continue with my current (pun intended) battery maintenance schedule.

Cab battery isolated (via ignition switch), hab electrics shut down (via BCA Seattle control panel), it turns out that the solar controller is wired direct to the leisure battery - not literally, but via the PDU - and is receiving a charge from the solar panel all the time, only found this out when I fitted a Victron SmartSolar mppt 75/15 controller. EHU connected 1st of the month for 24hrs, ignition off (not isolated) BCA Seattle control panel off (NOT shut down).

Obviously I need to carry out some tests to determine what is/is not happening when BCA is shut down.

With cab battery isolated, key needed to unlock, so trying to boost key fob signal won't work and several physical deterrents fitted (you won't stop a determined thief, only persuade them there are easier targets).