B2B question

[AMK]

I fitted a Sterling B2B a while ago and was reading some old threads today that mention disconnecting the split charge to ensure the B2B works correctly.

Is disconnecting a must do.

Or by leaving the Split charge running would it just charge the bats quicker.

On another note should I also isolate the solar mppt when the engine is running to maximise the B2B.

I’m confused.

 

[Ivory55]

I fitted a Sterling B2B a while ago and was reading some old threads today that mention disconnecting the split charge to ensure the B2B works correctly.

Is disconnecting a must do.

Or by leaving the Split charge running would it just charge the bats quicker.

On another note should I also isolate the solar mppt when the engine is running to maximise the B2B.

I’m confused.

Don’t worry 12v confuses a lot of us, haha

 

[Pausim]

Probably a bad idea to leave the split charge relay operating but it depends on how you wired up the B2B. If you have wired the B2B directly to your leisure battery then the split charge relay will be making a second connection to the battery but the electricity will probably be flowing the wrong way through it back to the engine battery.

1. Engine battery powers B2B at say 13.8V
2. B2B boosts voltage to say 14.4V for the leisure battery.
3 Split charge relay then has 14.4V on leisure side and 13.8V on the engine side so the current flows backwards through it to the engine battery.
4. B2B is now in effect feeding the leisure battery, the engine battery and itself through a loop.

The result is the B2B can’t monitor the leisure battery properly and the ECU can’t monitor the engine battery properly. The leisure battery probably gets some charge but not as efficiently as it should. In motorhomes with poor original wiring there may be sufficient voltage drop to disguise the problem.

 

[AMK]

Looks like I need to have a look at this.

Hopefully it’s just a fuse or breaker I can pull out or switch off.

But then again when do these things ever seem to be that simple,

Would it be in issue leaving the solar on.

 

[Pausim]

I can’t answer the solar question but I suspect it is not a problem. As to how difficult stopping an unwanted charge loop is, depends on the 12V distribution system installed by the manufacturer.

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[Lenny HB]

If you have a decent size split charge relay 60 or 100 amp with suitable size wiring you can simplify the instalation by feeding the B2B in series with the split charge relay.
If you have an Elektroblock you can remove the starter battery feed and connect that to to the B2B input and connect the output to the EBL.

 

[autorouter]

It all depends on how complicated and interdependent your system is. On some systems you can disconnect the trigger wire of the relay to stop it activating. Some systems you disconnect the starter battery feed to the distribution box. Or as Lenny HB says, wire the B2B into the starter battery feed.

Where it gets complicated is if the starter battery feed is used for other things as well, like the fridge 12V power, or the battery voltage sensing. There is always a workaround, but each solution is specific to the particular system.

 

[the1andonly]

. There is always a workaround, but each solution is specific to the particular system.

With a CBE System the precise method will depend on age and model. The experience and knowledge is here, but as aurorouter says the system in fo is required preferably manufacturer and type /model number.

 

[steveh57]

Must admit I kept mine separated I.e B2B and SCR , just pulling the fuse on the starter battery feed to the SCR kept all other functions intact. So I could have wired it in series before the SCR but I thought should the B2B fail or I move it to a new van reverting to the original setup is a simple as putting the fuse back. Plus the additional wiring for the B2B was very straight forward

 

[AMK]

Must admit I kept mine separated I.e B2B and SCR , just pulling the fuse on the starter battery feed to the SCR kept all other functions intact. So I could have wired it in series before the SCR but I thought should the B2B fail or I move it to a new van reverting to the original setup is a simple as putting the fuse back. Plus the additional wiring for the B2B was very straight forward

That’s sounds like a plan.

Just need to work out how to find the fuse.

Anyone out there know where this would be on 2016 elddis encore.

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[steveh57]

Well there should be a fuse at the beginning of the cable that feeds the SCR relay adjacent to the starter battery. What I did was remove this fuse and checked the step retracted and the Fridge still operated when the engine started. That confirmed to me that the power to these was supplied by the leisure battery in the presence of a D+ feed.

I'm not sure what you do if either of these don't work as expected with the fuse removed.