I am using the second battery connection to trickle charge my starter battery when connected to shore power. I have read elsewhere that it may be that both battery banks are somehow cross connected even when ac power is off, so that it is claimed a charged starter can top up depleted domestic banks, which would be unwanted and surprising. Anyone know if thats the case? I don't want the effect of either bank trying to pass charge to the other.
@BobB, which battery connection are you referring to - the second battery connection right next to the first, or the specific trickle-charge spade connection?
The second battery connection that's right next to the first is of course not isolated from the first because -as you can see upon visual inspection- the two connections are using the same contact plate, so they can't be isolated from each other.
So long as you use the dedicated trickle charge spade connection, however, you should not be seeing any cross-communication between the two battery banks.
the connections I'm using are the small pin plug situated between v sense and t sense connections as in the "G" block on the attached image
Oh, @BobB you shouldn't have any problem then; the trickle charge connection is only active when on shore power - that is, it's not charging your start battery from your leisure bank, or vice versa. Do you know where you read otherwise? I'd like to visit that thread to establish whether there was just a misunderstanding in the device's operation or if there was another problem at play there.
It was a canal boat forum, I can try and find it but it was a few years ago (when it was published). It wasn't a victron forum that is, although the author claimed to have got it from Victron. They were going to install an isolator switch, which made me think having a blue box of sophisticated electronics seemed rather pointless. Next step was to take the domestic battery connection off and see if there was any potential on it, but it did surprise me if that were to be the case.
Yeah I have to suspect that in that particular case there was some other variable -or perhaps just normal but misunderstood operation- that was causing a condition which was then erroneously attributed to the MultiPlus.
An example of that is here: https://community.victronenergy.com/questions/25252/multiplus-trickle-charge-connection-depletes-the-s.html
in which the OP sees his two separate battery banks returning to their healthy resting voltage and, since they're doing it relatively in tandem, assumes that it must mean they've been paralleled by the Multi but in fact all it shows is that at the end of any charge cycle, all batteries "settle" and batteries of similar chemistry and age will tend to settle at the same rate.
