question

reno avatar image
reno asked

Circuit breaker vs Smartshunt

Hello,

I'm about to add a Smartshunt on my installation in my campervan. I'd also like to add a general circuit breaker to be able to easily isolate the battery if necessary (i.e. working on the installation, winterizing, etc...)

So here is my question : is it ok/safe to place this circuit breaker between the battery and the Smartshunt ? Or should it be placed after the smartshunt (but in that case, the smartshunt is still powered) ?


Thanks !

SmartShunt
2 |3000

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

2 Answers
Alexandra avatar image
Alexandra answered ·

@Reno

Ideally nothing should be between the negative and the shunt.

The answer depends on if your battery can take the drain of the smart shunt over the expected time you are leaving it unattended.

You could always disconnect the positive power cable anyway if it is on the battery side.

If it is a good lithium it will likely go to sleep and stop the parasite draw. If lead acid you might return to a dead undercoverable battery.

Don't forget there is also battery self discharge as well.

12 comments
2 |3000

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

reno avatar image reno commented ·

Thanks for your answer. Ideally, it's to leave no consumer at all (it's a Gel Battery).

My concern - assuming I place it between the battery and the shunt - is the fact that in case of shut off/shut on, the smartshunt will be "wired" in the inverse order of the manual indications, i.e first battery minus, and last positive wire. Could it damage the shunt ?


0 Likes 0 ·
Show more comments
reno avatar image
reno answered ·

Hi again !

So, on your advice - and my doubts - I went with the recommended solution, that is placing the smartshunt between the battery and the switch (reminder : negative circuit breaker in my case).
So far so good, I can live with that... BUT !! I then plugged the V.aux cable to monitor the main battery (starter battery), and I'm facing a new problem : when I switch off the circuit breaker, the Shunt is no longer connected to the common negative, and so the V.aux is something erratic (23v in the present case).


Do you think it's something to worry about ?


I wonder if the best solution was to place the switch between the battery and the Shunt actually...

3 comments
2 |3000

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

cybermaus avatar image cybermaus commented ·

Well, lets first remark that I was giving observations rather than advise. For a negative disconnect, I think I would have done it like you did, but I also did not think it would matter much.


But yes, it means you cannot read the aux battery (mine has a temp sensor). But had you place the shunt on the other side of the disconnect, you could read the aux, but not the main battery.


I guess if you want them both readable, you'd have to move the disconnect to the positive side. Like is more common nowadays, rather than the tractor example.

0 Likes 0 ·
reno avatar image reno cybermaus commented ·
Yes you're right, and no worries about observations vs advice, I thank you all for those ! ;-)

Next step is to add a switch before the loads on the positive side, so I won't have to use the main negative switch except for maintenance/emergency.

So far, I'm ok with this installation, but I just would like to be sure that keeping the Aux plugged while switching off is safe and harmless for the Smartshunt.



0 Likes 0 ·
regman54 avatar image regman54 reno commented ·
Even the smallest SmartShunt can handle up to 500 amps (current) so from what I can tell you should be good.
0 Likes 0 ·