NT37 - Engine starting glitch

Greetings from the UK, hope you are all managing to keep well in these torrid times.

Please see a couple of photos of the 12V DC panel on my Nordic Tug 37, the 2 readings are the amps being drawn, one with the Battery switch off (0.4amps) and the second showing 10.3. The 10.3 amp picture was taken just before it trips out as the switch is only rated at 5 amp.

So my learned friends what is causing the amps to surge? Engine start has been working faultlessly until this problem and no other electrical works have taken place.

Thanks and stay safe

I'm confused. What exactly does the battery 1 switch power? Is it some type of solenoid or relay that in turn powers the engine start battery? 5 amps is way too low for an engine starter.

Tator

Hi Tator

The Engine 1 switch goes to a solenoid, please see some other pics of the set up.

Thanks

It seems like the coil in the solenoid has shorted. Or something else unknown is on the same breaker. I'd disconnect the control line from the solenoid (documentation here) and see if you can turn on the breaker without it tripping. It is only supposed to draw a few amps, even on inrush. That is an obsolete part, but Blue Sea (generally very good equipment) has suitable replacements.

Is the starter current going through that solenoid? Engine won't start unless it is energized?

Thanks for the reply.

If I forcibly hold the Battery 1 switch on the engine will start with no problem, the switch will then trip again with the engine running...

Thanks

I've had the breakers (sensing part) go bad before, but your meter shows the actual amps through the shunt (actual likely reduced by resistance of light 5A wiring), so that is not it.

*I* wouldn't HOLD the breaker to make it work. Probably pulling more current through it (and the sensing part) than it is rated for. May be damaging (at least) the sensor/trip part.

You likely have a load (solenoid) or wire problem. Find that and fix it. Start by disconnecting the solenoid and make sure the current goes to zero.

There may be a connection that is allowing the voltage to drop below the threshold
for the accurate function of your ammeter. Or, the starter may be drawing too much.
The breaker may also be tired and need replacing. They do wear out.

ACR failure

Our 2008 NT-42 had that ACR and it failed. I replaced it recently with a Blue Seas ML-7266 ACR. This unit replaced the one that failed that is no longer available. There is a bit of re-wiring for the parallel control switch at the dash board.

New solenoid switch fitted, now all working OK, bit of a heat mark from where the old solenoid was fitted, and there was a hairline crack on the back of the unit.

Unfortunately lock down here means no leisure boating at all, and its a beautiful light wind Easter weekend, stay safe everybody.

A quality rotary switch may require more effort than a solenoid to operate , but many last the life of the boat.

I couldn't agree more to the tried and trusted rotary switch for battery banks, all my previous boats have had them.

But as this appears to be a standard fit for Nordic Tug I decided to fit like for like, however, I do have a question regarding this switched solenoid set up.

The on/off switch for the solenoid on the DC panel has one of those protective covers that prevents accidental turning off as you would expect for bilge pumps etc. See picture in my first post.

Should this switch be left permanently on, or only turned on when using the boat?. I believe the previous owner left it on all the time, but the solenoid failure (after 11 years of use) got me thinking that I should turn it off after shutting down the engine. Thoughts?

Thanks

The main battery switch was always 'off' when I left the boat for any length of time.
Bilge pumps were on a separate circuit and the battery chargers were left 'on' on the AC panel.

Personally , it depends upon how the charging system is setup and the battery type.

If you have a multi output 120V charger and both battery banks are charged from it when plugged in then the ACR could be turned off. THe charger will recharge both banks and the ACR is not needed..

If you have two different types of batteries and one charger for each bank set for those batteries then the ACR is not needed.

When you are running the boat and the alternator is intended to recharge
both battery banks then the ACR is needed.

That's what I do with mine.