Van Bitz Battery Master doesn't keep vehicle battery topped up.

[Andy MacD]

I see the value in the battery master over the winter or periods of non use.

What I wouldn’t want is to be off grid in the van for say a week and the battery master “stealing” precious amps from the leisure battery when there’s no risk of the cab battery failing.

I presume you could wire a switch to disable it?

 

[RogerIvy]

I see the value in the battery master over the winter or periods of non use.

What I wouldn’t want is to be off grid in the van for say a week and the battery master “stealing” precious amps from the leisure battery when there’s no risk of the cab battery failing.

I presume you could wire a switch to disable it?

Yes you could.
But …. if you forget to turn it back on and can‘t start your engine you’d appreciate losing a few AH each day.
You really don’t notice the difference (other than the fact that your engine always starts )

 

[AshVanBitz]

It depends if the LiFePO4 is being charged (and what the difference is).
The BM activation is based on difference between Leisure and Starter battery, when it exceeds 0.75 the starter battery is then trickle charged.
So let’s say your healthy starter battery is sitting at 12.8v, add 0.75v to that and the leisure battery needs to be at 13.55 or higher to activate charging. That happens usually when the leisure is being charged, as most LiFePO4 will rest at around 13.4 to 13.5 (and some a bit less).

IMO the 0.75 diff is a good compromise and in our experience keeps a starter battery in good nick without draining the leisure battery. If however you have a staring parasitic drain on your starter battery it won’t help.

I‘s sure AshVanBitz can provide more info and correct me if I’m wrong

Couldn't have said it better myself

 

[Dolmen]

It’s simply Works better than any magic trick. My cab battery would drop from 12.8 to 12.3 in only a couple of weeks. When I changed the leisure battery to lithium I added a battery master (votronic model), and the cab battery now sits rock solid at 12.9 and the drain on the lithium is so low I calculated I could leave it for at least 6 months if anything untoward was to happen. There is no solar in the equation.

 

[funflair]

I see the value in the battery master over the winter or periods of non use.

What I wouldn’t want is to be off grid in the van for say a week and the battery master “stealing” precious amps from the leisure battery when there’s no risk of the cab battery failing.

I presume you could wire a switch to disable it?

If there is no risk of the cab battery failing it won't be pulling amps from the leisure battery anyway unless you have a charger on the Leisure battery raising the voltage then you don't care anyway.

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[Andy MacD]

risk of the cab battery failing

I must not have been clear.

When off grid say for a week there is absolutely no danger of the cab battery going down.

What I do NOT want is the leisure battery needlessly sending power to the cab battery when I need that power for off grid living.

Hence my question about a quick way to disable the battery master when it’s not required.

 

[funflair]

I must not have been clear.

When off grid say for a week there is absolutely no danger of the cab battery going down.

What I do NOT want is the leisure battery needlessly sending power to the cab battery when I need that power for off grid living.

Hence my question about a quick way to disable the battery master when it’s not required.

Yes I understand what you are saying but I still say that if the cab battery isn't going down over the week it won't be taking power, or certainly not until the leisure batteries are charged and the power is surplus anyway, but if you want to switch it off the option to fit a switch is there but I wouldn't.

 

[Lenny HB]

Yes I understand what you are saying but I still say that if the cab battery isn't going down over the week it won't be taking power, or certainly not until the leisure batteries are charged and the power is surplus anyway, but if you want to switch it off the option to fit a switch is there but I wouldn't.

Agree, you can live with a low leisure battery but a low starter battery you are stuffed.

 

[headlight]

I must not have been clear.

When off grid say for a week there is absolutely no danger of the cab battery going down.

What I do NOT want is the leisure battery needlessly sending power to the cab battery when I need that power for off grid living.

Hence my question about a quick way to disable the battery master when it’s not required.

I go not on hook up (off grid) exclusively.
I can be "off grid" for 3-4 weeks at a time.
For the starter battery to be trickle charging from the Battery Master then either the leisure batteries are being charged, in which case there is no issue with draining the leisure batteries, or the starter battery voltage has dropped in which case it needs charging or you won't be able to start the vehicle.
I have had my Battery Master for nearly 2 years and have never had a problem including in UK winter.