Disconnecting Leisure batteries - help please. (1 Viewer)

[Vanman]

Please see picture below. I want to put a volt meter with a 'shunt' onto the negative terminal. Is the correct sequence to - Disconnect the 1st battery Negative at A; Disconnect the 2nd battery Negative at B; Attach the meter to Live at C and the meter/shunt to the Negative that's disconnected, then finally connect the Shunt to B and the 2nd Battery back at A? Thanks.

 

[Derbyshire wanderer]

Ideally your power outlet to the habitation circuits should use positive C and negative A and use the same posts for your volt meter shunt.
This way both batteries are always getting an even discharge and charge as they are both connected evenly.

 

[Vanman]

Ideally your power outlet to the habitation circuits should use positive C and negative A and use the same posts for your volt meter shunt.
This way both batteries are always getting an even discharge and charge as they are both connected evenly.

Thanks, that's a good point. But as far as 'messing' with it just now, is it right to disconnect the x2 Negatives first and then reconnect them last afterwards?

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

 

[Lenny HB]

Thanks, that's a good point. But as far as 'messing' with it just now, is it right to disconnect the x2 Negatives first and then reconnect them last afterwards?

Yes in a car it's only so you don't short the positive lead to earth, not so important in a Motorhome where nearly everything is timber.

 

[Vanman]

Ideally your power outlet to the habitation circuits should use positive C and negative A and use the same posts for your volt meter shunt.
This way both batteries are always getting an even discharge and charge as they are both connected evenly.

It looks like A might be the 'main' Negative after all. Do you think it will matter which I attach to the Shunt to take the readings from?

 

[Derbyshire wanderer]

It looks like A might be the 'main' Negative after all. Do you think it will matter which I attach to the Shunt to take the readings from?

To get totally accurate results then the shunt should be connected as o said earlier otherwise you will only read the condition of a single battery and that can be influenced by the second one.
As you are undoing the connections anyway it should be easy to wire as described.

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

 

[DBK]

I'm confused, which admittedly is my normal state. I understand a "shunt" to be a type of fuse and probably a very thick one. The meter will read the voltage drop across this "fuse" and because it knows the resistant of it can calculate and display the current flowing.

Your batteries should be connected like the lower picture below though they could be connected like the upper picture.

The battery monitor I have is wired as shown in the diagram below.

Although this shows only one battery it makes no difference if you treat your two linked batteries as one. Your meter may not use as many wires as this one but the principle is the same, you need to break into the cable which is feeding the power from the batteries to the MH. You should not need to disconnect any cable joining the two batteries together and most of all, don't connect the shunt between a negative and positive terminal.

 

[Derbyshire wanderer]

I think the shunt he is fitting also reads battery voltage which is why it also needs a positive feed.
@DBK as your post well illustrates that the correct connections are required to ensure even draw and therefore correct meter readings

 

[Infinity31]

As diagram posted above.


Leave the link that’s already there between A & B.


Remove the output from A and connect to the shunt.


Add a link cable from other end of shunt to A


Connect fused lead to C.

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

 

[Vanman]

There's a video here, showing the exact same model. My confusion was really with the two Negative terminals on my two batteries (and that he doesn't show the moment of fitting to see the sequence of events - but I'm reasonably OK with that now).

 

[Vanman]

Thanks again for all the helpful advice - looks like we got there in the end!

 

[Infinity31]

With so many threads simply left hanging, it's good to see one successfully stitched up

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