using a neutral from another battery

[simonfraser]

i disconnected the neutral from the house battery with some minor house stuff still switched on
expected all the house power to switch off
but as the neutral is all on a bus bar and shared with the starter battery the house stuff stayed on

bit odd, not quite what i expected

obviously not how i would normally use the batteries
any harm in doing this long term ??

 

[Aurai]

In the first instance, the convenience of isolating circuits when you leave the boat.

 

[Alan S]

I guess you mean negatve, not neutral.
If there were no cabes on the house battery neg, then some of your "house stuff" postives must be connected to another source of 12v, starter battery possibly.
Al

 

[bedouin]

That is odd - for the power to stay on there needs to be a circuit from the positive through the device to the negative of the same battery.

If the neutral is disconnected then that battery cannot provide power to anything so what you are saying is that the positive supply from you starter battery was powering the domestic circuits which would be very odd wiring indeed - unless you have a 1-both-2 switch set to both or some form of VSR to parallel the two batteries,

I think conventional wiring is to connect all negatives from all banks to a common bus and to switch individual positives.

 

[PaulRainbow]

That is odd - for the power to stay on there needs to be a circuit from the positive through the device to the negative of the same battery.

If the neutral is disconnected then that battery cannot provide power to anything so what you are saying is that the positive supply from you starter battery was powering the domestic circuits which would be very odd wiring indeed - unless you have a 1-both-2 switch set to both or some form of VSR to parallel the two batteries,

I think conventional wiring is to connect all negatives from all banks to a common bus and to switch individual positives.

Well done that man!

Simon has a VSR and some solar panels, i guess the solar charge has closed the VSR.

 

[TernVI]

Should people learn the very basics of electrical circuits before fiddling with this sort of thing?

 

[RichardS]

Should people learn the very basics of electrical circuits before fiddling with this sort of thing?

Sometimes the best way to learn is to fiddle .... but it can be taken beyond a point of no return.

Richard

 

[Garythetruck]

You must have another power source connected some where. You need both Positive +, and Negative -, to get a circuit. I would have another look.

 

[WoodyP]

Sometimes the best way to learn is to fiddle .... but it can be taken beyond a point of no return.

Richard

How very true. I often start with the premise of "what's the worst thing that can happen". Sometimes I unfortunately find out.

 

[PCUK]

The fact is that your house battery positive is connected somewhere to the starter battery positive. That is the only way that this can happen.

 

[PaulRainbow]

You must have another power source connected some where. You need both Positive +, and Negative -, to get a circuit. I would have another look.

The fact is that your house battery positive is connected somewhere to the starter battery positive. That is the only way that this can happen.

See post #5

 

[PaulRainbow]

It's worth remembering to isolate batteries before removing leads. Disconnecting under load can damage some equipment. Disconnecting under load when batteries are on charge, as would be the case in this instance, can lead to a spark and an explosion.

 

[simonfraser]

yeh ofcourse the VSR is connecting the two ....

the battery area is v well ventilated, but take your point re sparks

always worth posting here

 

[rogerthebodger]

Disconnecting under load when batteries are on charge, as would be the case in this instance, can lead to a spark and an explosion.

Would that also apply to sealed batteries

 

[LittleSister]

Should people learn the very basics of electrical circuits before fiddling with this sort of thing?

No. It would reduce the excitement of boating, and the entertainment value of this forum.

 

[simonfraser]

No. It would reduce the excitement of boating, and the entertainment value of this forum.

indeed, basic ciruits, well i thought i understood this reasonably well but am happy to be advised on this forum
i tell my wife that i am perfect and never make mistakes, however you guys and girls know better

 

[bedouin]

Well done that man!

Simon has a VSR and some solar panels, i guess the solar charge has closed the VSR.

Doesn't that mean there is a risk you could try to start the engine from the domestic bank through the VSR?

 

[simonfraser]

connect the starter and the voltage of the starter battery drops below 12.70 as a result of which the VSR disconnects
the fuse on the VSR is 80A
my KAD 44 needs a tad more to turn over, would blow the fuse instantly