Battery discharging

[canalman1946]

My engine battery is discharging unless I switch engine battery master off, any clues?

[Robbo]

My engine battery is discharging unless I switch engine battery master off, any clues?

 

Glow plug stuck on?

[blodger]

My engine battery is discharging unless I switch engine battery master off, any clues?

 

You do not say what sort of current is flowing or if anything is staying warm. Since the engine batt is principally connected to the starter and alt both of these need checking out to see if a short/problem has developed. If you disconnect one and then the other you may determine which if any is responsible.

 

The ignition has to be on to energise any relays (inc heater plugs) for charging the domestics but perhaps it is possible for the relay or diode, if that's what you have, to be defective and allowing the start batt to feed the domestics. So isolating the relay/diode would be another stage in diagnosis.

 

Hope that helps for now.

Edited July 18, 2011 by blodger

[bottle]

Battery is 'duff' and self discharging, check levels (if you can) otherwise there is a load/short, as others have said.

[WotEver]

Battery is 'duff' and self discharging, check levels (if you can) otherwise there is a load/short, as others have said.

If that were the case, then switching it off wouldn't help as stated in the OP.

 

Tony

[canalman1946]

Thank you for the replys, still investigating and the battery is brand new.

[bottle]

Battery is 'duff' and self discharging, check levels (if you can) otherwise there is a load/short, as others have said.

 

 

If that were the case, then switching it off wouldn't help as stated in the OP.

 

Tony

 

 

Ooops !!!!!!!

[dor]

If it is anything like the Vetus panel, they have been known to develop a fault which leads to self-discharging. I think it is due to a diode somewhere breaking down and conducting in the reverse direction, even when the ignition switch is 'off'.

[canalman1946]

could there be a diode on the alternator itself? I did notice it was warm the other day well after the engine was shut down?

[WotEver]

could there be a diode on the alternator itself? I did notice it was warm the other day well after the engine was shut down?

Yep, three of them. It could well be the culprit.

 

Do you have an ammeter to show how it's performing? In the mean time, try disconnecting it and seeing if the problem goes away.

 

Tony

[blodger]

could there be a diode on the alternator itself? I did notice it was warm the other day well after the engine was shut down?

As I said disconnect the alt from the batt and see if the batt still discharges with batt isolator on afterwards. Obviously, the rectifier works such that there should be no current flow through the alt when it is connected and not running, if there is there's a fault.