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We have just bought a rather youthful for us (10 year old) narrowboat, with lots of new fangled equipment that we're not used to, including a Sterling invertor.

 

We have 4 domestic batteries, all of which are undercharged, currently showing 12 volts on the invertor, less on the panel thing with all the switches. This is after about 10 hours cruising over 2 days. When we visited before purchasing, fridge, webasto etc were all working fine, but things had been left switched on in the months before we actually got on board and now the fridge switches itself off, I assume due to lack of power, and I am unable to chill the wine.

 

We currently have access to a shoreline, but the invertor keeps switching itself off because it shows that the starter motor battery is overcharged at 16 volts.

 

We've tried isolating the starter motor battery but it still knew that it was there and switched off again. We've tried starting the engine and switching it off again several times to try to lose some of the charge but it didn't make much difference.

 

Any ideas how we get it to charge the domestic batteries from the shoreline? When we were cruising, it didn't seem to mind about the starter battery, the invertor stayed switched on and was charging the domestic batteries, we just ran out of time to charge them up fully.

 

Any suggestions welcome, thank you.

 

 

 

 

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I'd not trust any battery monitor/voltmeter unless it has its own sense wires to the battery itself (suitably fused). If it doesn't have these, its not a "battery monitor" but a "somewhere along the circuit monitor" for its voltage readings.


Also, its nigh-on impossible that the inverter, or even an inverter/charger, was charging the batteries while you were cruising. Much more likely that the alternator was charging (or maybe it wasn't......or maybe there's 2 alternators and only 1 was working.......) etc etc

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"We've tried isolating the starter motor battery but it still knew that it was there and switched off again. "

 

Then you haven't isolated it!

 

It would help people help you if you could give a better description of the total set up.

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OK, sorry if I haven't explained it very well, this is all new to me.

 

Yes, I have a manual, which says it's a "3 in 1 combined pure sine wave inverter UPS/ battery charger (solar and shore)" although we don't have solar. There is a Sterling user manual which I have read but struggled to understand.

 

We have twin alternators which I understand charge the domestic / starter battery when cruising. I thought that the inverter was still functional whilst cruising, but maybe this isn't the case?

 

Thank you for the quick responses.

 

Christine

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Christine

 

I think you may be confusing your self, you have what is known as a 'combi' it is an inverter to give you 240v ac from your domestic 12or24v dc batteries, it also has a charger in the same box that will charge your domestic batteries only when on shoreline or a generator is available.

 

To charge your domestic batteries you can either use shoreline or generator via the 'combi' (charger) or run the engine and the alternator will do it.

 

 

the invertor stayed switched on and was charging the domestic batteries,

 

This is not or should not be possible, the inverter may be ON to supply the 240v ac but it will not be charging the batteries the charger does that.

 

Remember the charger only works when on shoreline or generator.

 

Without shoreline or generator then the alternator on the propulsion engine does the charging.

 

If you were using 240v ac whilst cruising the alternator will be supply the 12or24v dc to the inverter and then the 240v ac,

 

If the load is greater than the alternator can supply then your batteries will not be charged, all the alternator power will be going to the inverter to supply the 240vac.

 

I do not know the Sterling but if it has an output for domestic and start battery (charging) you could disconnect the charge wire from the start battery and connect to the domestic battery with the existing charge lead. You may wish to get this confirmed by someone that knows the unit.

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I think you need to buy a multimeter and measure the voltage of both battery banks during various states of operation:

 

1. Everything off

2. Engine running

3. On shoreline with combi on (and charging - don't know if it has different modes)

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I hadn't realised it only charged when on shoreline/ generator, and that the 'combi' would just be needed for any 240v things when cruising, that's helpful, thank you.

 

The only thing we have on 240v is the plug sockets which don't seem to work (tried a phone charger) but I assumed this is because the domestic batteries are not sufficiently charged.

 

I think it may be the boat's way of saying she wants to go out cruising again.

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I hadn't realised it only charged when on shoreline/ generator, and that the 'combi' would just be needed for any 240v things when cruising, that's helpful, thank you.

 

The only thing we have on 240v is the plug sockets which don't seem to work (tried a phone charger) but I assumed this is because the domestic batteries are not sufficiently charged.

 

I think it may be the boat's way of saying she wants to go out cruising again.

 

That could also be because your combi is switched to 'charger only' or similar. That is, the inverter is off.

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I hadn't realised it only charged when on shoreline/ generator, and that the 'combi' would just be needed for any 240v things when cruising, that's helpful, thank you.

 

The only thing we have on 240v is the plug sockets which don't seem to work (tried a phone charger) but I assumed this is because the domestic batteries are not sufficiently charged.

 

I think it may be the boat's way of saying she wants to go out cruising again.

 

It may well be that you are not getting 240v ac from the 'combi' inverter because he batteries are discharged

 

If you only have one or more sockets and they were not in use, when cruising (engine running) then the batteries should have charged from the alternator

 

Now you have shoreline then the batteries should be being charged from the 'combi' charger.

 

Paul C is on the correct track, lots of checking ( engine not running, engine running, shoreline connected and On) with a multi-meter to check voltages at different points and possibly amps also.

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The usual way that a battery gets to 16v (assuming a 12v system) is when it's lacking in electrolyte, Have/can you top the batteries up properly with pure water to the correct level. Can you determine the presence of charging current going into any of the batteries?

 

You will have to read and understand the boat's manuals and circuit diagrams, it's not an option if you want to do repairs.

 

Do you actually know the age (date code!) of the batteries, If there is a likelyhood that the batteries are over a year old then fit new ones. A battery that's been stood discharged for long usually doesn't hold it's full charge properly. If you are going to leave the boat for months then look into fitting a 5 - 10w panel for the starter battery and a 25 - 100w panel for the house battery. These will not create much power for use but will protect against natural self discharge.

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We have just bought a rather youthful for us (10 year old) narrowboat, with lots of new fangled equipment that we're not used to, including a Sterling invertor.

 

We have 4 domestic batteries, all of which are undercharged, currently showing 12 volts on the invertor, less on the panel thing with all the switches. This is after about 10 hours cruising over 2 days. When we visited before purchasing, fridge, webasto etc were all working fine, but things had been left switched on in the months before we actually got on board and now the fridge switches itself off, I assume due to lack of power, and I am unable to chill the wine.

 

We currently have access to a shoreline, but the invertor keeps switching itself off because it shows that the starter motor battery is overcharged at 16 volts.

 

We've tried isolating the starter motor battery but it still knew that it was there and switched off again. We've tried starting the engine and switching it off again several times to try to lose some of the charge but it didn't make much difference.

 

Any ideas how we get it to charge the domestic batteries from the shoreline? When we were cruising, it didn't seem to mind about the starter battery, the invertor stayed switched on and was charging the domestic batteries, we just ran out of time to charge them up fully.

 

Any suggestions welcome, thank you.

 

 

 

 

Seems to me a lot of wiring systems tend to overload the batteries with watts with charging considerations not too realistic.

 

Sometimes I wonder if inverters are really needed. I took mine out of circuit for the time being and just use the charger function. It charges at 10 amps. If I recall more or less correctly many batteries give about 120 amp hours so you need about 12 hours charging to bring the bank to full capacity.

 

Modern inverters will now be better than mine but some inverters draw a good few amps just being switched on. Why run a D.C. device from D.C. battery bank, to A.C. output and then back to D.C. again through the device transformer?

 

Put bluntly, the trick is to use low wattage appliances, a moderate battery bank (300 amp hours is fine) and to make sure the charge is replacing fully the output drain.

 

 

 

 

 

 

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That could also be because your combi is switched to 'charger only' or similar. That is, the inverter is off.

Its also possible if the inverter has a power saving mode a phone charger may not be a big enough load to switch it on.

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  • 2 weeks later...

With all the helpful replies, we have now discovered that 2 of the 4 domestic batteries looked to be well overdue topping up (the 2 that were difficult to get to strangely enough) so 2 new batteries are on the shopping list and hopefully this will fix it, thank you. Having had sealed gel batteries on our last boat, we didn't know to check for this. I did wonder what the de-ionised water was for and thought it must be for the webasto as it was in the same cupboard, but we certainly know now.

 

On a related question, the man we bought the boat from said that you shouldn't run the webasto while the engine is running, although the webasto manual doesn't mention this. Is this right?

 

Thanks again for the help.

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