SO43 DS Alternator charging question

[Amun Ra]

Hello,

I have a 43DS with the 75hp turbo engine, an 85Ah alternator and 330Ah (3x110Ah) house bank.

Over the last few weeks I have felt that running the engine has not been putting charge back into the batteries at anything like the rate that it used to. I accept that's an entirely subjective view, but after an hour and a half today I had only managed to take the bank from 76% to 83%. (approximately 12.15V to 12.5 or so)

I would suspect the Mastervolt charger, and if no current was flowing it would seem to be the answer. But it is charging, albeit more slowly than I expect.

The instruments all suggest that the alternator is pushing out 16-18Amps.

is it just me, I wonder? If anyone can offer any words of advice I would be very grateful!

Best wishes

Julian

[MartyB]

While it could be the charger, or the wires have gone bad, or the battery bank is starting to go bad!

I should be one of the three. I swag would be my option 3 if you have original batteries!

Marty

[Amun Ra]

Thanks Marty. Batteries were new last year, so they should be good. I will recheck the wiring.

Best wishes

Julian

[MartyB]

Julian

If you replaced the batteries last year, my first thought would then be connections. Something has come loose, or a wire is slightly fried.........

which is what it sounds like you are going to look for.

Marty

[Amun Ra]

Marty,

I'm hoping by starting at the easiest, cheapest checks first I will find the solution! I have seen a couple of similar situations described on the web where a temp sensor wire had come adrift. The charger thought the batteries were too hot, therefore restricted the charge current.

I'll report back!

Best wishes

Julian

[rxc]

Julian,

Is our mastervolt charger a separate voltage regulator for the alternator, or something else? If it is the VR, then I would check the voltage at the alternator outlet, because bad connections usually make the VR think that the battery voltage is LOWER than it actually is, and they try to increase the alternator voltage. If the voltage at the alternator is low, then I would suspect the alternator - maybe a diode has died, and it is time to take it in for repairs.

Ralph

[Amun Ra]

Ralph,

Thank you - good point. I will check the alternator voltages and see if that reveals where the problem lies.

Best wishes

Julian

[davidknell]

I'd start off by taking the Mastervolt thing out of the circuit if I were in your position and it was relatively easy to do. I started ours today to top the battery off (that's battery singular - there's a bunch more indoors) and had about 25A into the one battery at 14V+ at ~1200 rpm on the engine to start with. The current (as expected) dropped off after a few minutes. I'd expect significantly more than that into 12.5V, so something's definitely up.

One question - does the Mastervolt doobrie control charging to both the house bank and service battery?

--Dave

[Amun Ra]

Hi Dave,

Thank you for that. Useful to hear what you are getting in your system. I will look at taking the Mastervolt unit out of the loop when I am back down this weekend.

The answer to your question is that I don't know - and I should! On my last boat I refitted all the electrics and the house bank and eng start were both definitely connected to my Sterling Alt/Batt charger - I had assumed this was too, but it may just be that that the eng start is isolated. Shouldn't be, I would say, as I expect the box of tricks to be bright enough to top up the eng start very briefly before turning its attention to the house bank.

Best wishes

Julian

[Amun Ra]

Thank you to everybody for their suggestions and advice. I was on the boat on Saturday and did some investigating. I wanted to try and determine if something is wrong, or I have reached the limits of my charging system.

To recap, I have an 85Ah alternator charging three battery banks through a multiple battery isolator. The banks are House (3x110Ah), Engine Start and Bowthruster.

Engine off - readings:
House bank 12.36V
Engine start 12.75V
Bowthruster 12.74V

Engine on - readings:
Alternator 15.00V
House bank 13.92V
Engine start 14.12V
Bowthruster 14.08V

Charging currents, taken from a shunt in the system were:
On Engine Start - 21.3A,
+5 minutes 19.0A
+30 minutes 18.8A
+60 minutes 17.6A

To check, I also fired up the generator, which produces 240V to power the mains battery charger. This produced a charging voltage of 13.81V and 18A.

It seems that all the components in the system appear to be working properly – batteries are healthy; alternator is producing good voltage, battery isolator is working in correct sense, so I’m not sure what to deduce from this - do I have a problem, or is this as good as the system gets!

I think I have two options.
1. Replace the Battery Isolator with a similar isolator, but a better device that has a lower, near zero voltage drop; and/or
2. Add in an ‘alternator to battery’ charger to improve the efficiency of engine charging system.

Any thoughts, observations or recommendations are most welcome!

Best wishes

Julian

[electricmonk]

You seem to have a good handle on most of it and most of it seems to be working but here's my contribution; back to some basics that you may have missed out.

Alternators don't like high resistance, and even though you have some healthy looking currents I would check the resistance across the battery isolation switches (it depends upon how the alternator output is connected - as to whether these are in the circuit or not) lets assume they are in the circuit and check them. A high resistance here plays havoc with the charging system. Mine were very high, cycling them a couple of hundred times restored their continuity - its now part of the annual maintenance regime.

If you have bypassed the isolators disregard the above.

Some further observations

Your house bank is/could be low

I assume you are using the Jeanneau panel for your readings - if yes then the House bank is VERY low.

Your engine on readings for AMPs suggests that the batteries are not getting charged - the current should have tailed off to almost nothing after an hour.

The more I look at the numbers the more I think there is a high resistance somewhere, and this could be a faulty battery.

[Amun Ra]

Thank you Electricmonk, I really appreciate your thoughts.

Current readings were/are taken from the Mastervolt panel, cross referenced to the Jeanneau ammeter on the panel. It is the low current that is foxing me, as all else seems to be working more or less as it should.

Voltage readings were taken at the batteries.

I did also read the voltage across the terminals on the Multi Battery Isolator, and the alt to house bank was 13.0V, alt to engine start 13.8V, alt to bowthruster 13.8V.

I had not considered the battery isolator switches could be a problem. It's easy enough to cycle them a hundred times! (I have three children under 10 who would love that task!) I will do that first - always prefer to start with the easiest and cheapest solution!


I think my next step must be to do some more analysis by isolating some parts of the system, and to try and track down why the current is so low.

Thank you.

Julian

[rxc]

Julian,

Sorry I have not commented sooner - I have been without a reliable internet connection for 4 weeks.

Could you explain what the Mastervolt unit does, in your system? Is it a voltage regulator for the alternator, a battery charger that is powered by shorepower/genset, or something else? I have seen some literature on these, but some components have not been explained very well (probably translation issues), and I have a trawler friend who has one that has been driving him crazy, but he is a non-engineer, and does not understand what it does either.

My first suggestion would be to replace the isolater with a combiner. It appears that your alternator is putting out the correct voltage, and there is about a 1V voltage drop between the alternator and the battery. This is consistent with a simple diode battery isolator, where the voltage drop across the diodes is about 1V. If it is the original Jeanneau-supplied unit, then it is a diode unit, and you should replace it with a combiner. Actually, you need two - one for the starter battery and one for the windlass battery, because you don't want any of these batteries in parallel unless they are all being charged, or unless you want them paralleled to boost the power, e.g., to start the engine. You will also likely have to move some wires around to make sure that they are actually isolated from one another, except when the engine is running and the combiners are paralleling them. You will also have to make sure that the windlass breaker is open at all times, except when you are using the windlass, to keep it's battery isolated.

Also, do you have separate leads from the shore-powered battery charger to each battery? And do you have a bow-thruster up forward using the windlass battery? (This is what I have done - one battery serves both high-demand devices, which do not (normally run at the same time)

This setup is a bit complicated, but necessary, I think.

[Amun Ra]

Rxc,

Thank you for your post, very helpful. I think I'm getting there slowly with this.

Yes, I do still have the original Jeanneau fitted Battery Isolator and swapping it for a better unit - perhaps a combiner, is certainly an option I am considering.

One advantage of digging into this system is that I have learnt a lot about how my 12v charging system works!

The Mastervolt charger (actually I have two, a main one and a much smaller one which I think charges the generator battery) sits in the system, not as a alternator controller, but simply as a Mains charger. I have spoken to an excellent ex-Mastervolt engineer about the unit and he's happy it is fitted correctly and working according to spec. It has a charging cable coming in, and three out - house, starter and bowthruster. I measured voltage at these points under three different situations:

All Off Engine/Alt On 220V/Mains

House 12.34 14.16 14.37

Start 12.75 14.24 14.29

Bow 12.37 14.08 14.30

You make a good point about how the windlass is powered and I do not know. I don't see any heavy duty cabling heading up to the bow, so I suspect that the windlass runs off the bowthruster battery.

I will cycle the battery master switches 50-100 times on Saturday and see if that makes a difference to the charging voltage at the batteries and current flowing.

If not, it's then a question of what to do. I'm giving serious thought to a Sterling 12V 50A battery to battery charger. Simple to fit and relatively easy to find space for next to the house bank.

Best wishes

Julian

[davidknell]

Probably too late to save you a job, but you could just measure the voltage drop across the isolator switches with the engine running and alternator generating some current - if it's appreciably more than 0, then they could possibly do with some attention. If not, no need to wear them out..

--Dave

[Amun Ra]

Dave,

Thank you for that. I will when I am down later this week.

Had a night in a marina with shorepower and was able to charge the batteries back up to 13.1v. Motored home and all seems fine.

I will measure across the switches - and hopefully prove no need to wear them out unnecessarily!

I'm pretty much convinced that I have run up against the limits of the Jeanneau alternator charging system. Sterling B2B ordered.

Impressed by the sound of your LiOn set up.....

Best wishes

Julian

[Amun Ra]

In the belief that I have a functioning system, but one that isn't very good as delivered by Jeanneau, I fitted a Sterling 12v 50A Battery to Battery charger yesterday.

It was an extremely tight squeeze, but it is now in the port battery box with the Engine Start and House 1 battery.

I will report back on how I fare with it. My expectation is that it will allow me to charge my House bank far more efficiently. The only remaining uncertainty in the system is the Battery Isolator and whether or not I swap that out. Same again, but better or a zero drop isolator seem to be the options.

Best wishes

Julian

[davidknell]

The charging splitter (thing with the diodes in) gets it in the neck unfairly, I think. The alternator's output is split three ways - house, starter and feedback to the alternator/field winding - so the alternator will increase its output voltage to overcome the diode drop, and, incidentally, that of the shunt for the ammeter.

I made some measurements on ours today - 75A charge (engine at 1500 rpm), and the voltages were:
- input from alternator: 14.58V
- ouputs to batteries: 13.58V and 13.68V
- feedback to alternator - 13.88V

The thing does dissipate some 70W under these conditions. To put this in perspective, it's about 0.1HP; the specific fuel consumption of the engine is on the order of 200g/kWHr, so the splitter increases fuel consumption by 1 litre for about every 70 hours that the batteries are being charged flat out.

So the thing does no real harm, does the job its supposed to do, mine hasn't blown up yet (so I'm quite happy with it) and so I'd suggest leaving it be unless there's evidence of its having malfunctioned.

[Amun Ra]

Thanks David. I'm impressed by your 75A of charge! I would be happy to see 20A into my house bank - it will be interesting to see what difference an 'intelligent' multi-stage charging unit has on the house bank charge time to charge.

Your figures on the Isolator are reasonably similar to mine, and I am reluctant to swap out something that seems to be working fine.

I'm heading out tomorrow for three weeks on board, with a fair proportion of time at anchor so it will be interesting to see how I fare.

Best wishes

Julian

[davidknell]

Hi Julian -

Having read all of this again, I'm beginning to wonder if you actually have much of a problem. Firstly:
- your mains charger charges the batteries at about the same rate as the alternator
- battery voltages on charge from the alternator don't look wildly out of kilter (13.8V is 2.3V/cell)
- the Jeanneau shunt for alternator current output measures exactly that - charging current is this figure less alternator field coil current, current consumed by gubbins around the engine (fan...?) and current consumed by everything else. Only the last of these is shown on the meter on the console.

One thing you could try (at your own risk.. and bearing in mind the possibility of sitting at anchor for three weeks in the dark if it all goes wrong ;-)) would be to move the output of the charge splitter which goes to the house bank to the input to the thing - so the house bank gets charged directly from the alternator, but everything else stays as it is - and see what happens to the charging current then.

I just tried this on mine; everything worked as expected, but the engine alarm came on the moment I turned the negative battery isolator on for reasons which aren't entirely clear from Jeanneau's schematic, which doesn't look terribly complete when it comes to the engine control panel thing.

--Dave

[davidknell]

Oh, and having looked at the battery isolator, it's rated for 70A max alternator current.. if mine were supplied from the factory with the 80A alternator that's currently there, then tut, tut, Jeanneau..

[Amun Ra]

Mine's 70A max isolator on a 75A alternator......

[royhb]

Jul 26, 2013 7:50:12 GMT davidknell said:

Oh, and having looked at the battery isolator, it's rated for 70A max alternator current.. if mine were supplied from the factory with the 80A alternator that's currently there, then tut, tut, Jeanneau..

If I'm not mistaken, the house bank connects directly to the alternator output and the isolator feeds the start battery.  At least that's how my boat was wired when delivered.

If that is correct, then the isolator would never need to pass more amps than the single start battery can absorb.  The start battery wouldn't ever exceed 15-25 amps (and usually much less) , so the isolator is operating within it's capacity.

Having said all of that, I've replaced the isolator on my boat with a voltage sensitive relay (for simplicity).  I've also replaced the fairly puny original house bank with 590AH of AGM's.  I also replaced the factory alternator with an alternator designed for emergency vehicles that is rated for continuous full output and added a Balmar regulator.

Removing the Tudors, installing the AGM's and tweaking the Balmar regulator has dramatically improved the recharge rate.  It's pretty much doubled the initial rate and extended the duration of high volume charging noticeably.  Most of the difference is due to the better batteries.  The alternator and regulator are just icing on the cake.

Cheers;
Roy

[davidknell]

Jul 27, 2013 12:17:57 GMT royhb said:

Jul 26, 2013 7:50:12 GMT davidknell said:

Oh, and having looked at the battery isolator, it's rated for 70A max alternator current.. if mine were supplied from the factory with the 80A alternator that's currently there, then tut, tut, Jeanneau..

If I'm not mistaken, the house bank connects directly to the alternator output and the isolator feeds the start battery.  At least that's how my boat was wired when delivered.

Ouch. The isolator drops about a volt so such an arrangement would result in overcharging the house bank or undercharging the start battery, depending on whether the alternator had an external feedback connection and, if so, where it was connected.

On the other hand, the house bank would be able to aid the start battery via the diode in the combiner with starting the engine.. this might well exceed its 70A rating, though..!

--Dave

[royhb]

It's been a while so I don't recall the exact number but the isolator I removed didn't drop anything like a a volt, I measured it at more like 20-50 mv.  It was a mosfet isolator that looked like the attached picture.