Second Alternator +ve Cable and Sterling Charger?

[demonboy]

Last time I used a local electrician who sorted the problem out, though he made the comment that there was not enough power coming in. He didn't go into detail as his English was limited and we were off back to the UK the next day. When I returned after monsoon nothing was working again so I replaced the starter, stop and glow-plug push buttons. There's 12.6 volts coming into the circuit but it drops at starter switch X2, which in turn feeds the alternator lamp, where the voltage drops further. Only 11.5v is being fed to the alternator lamp. I don't understand this.

I checked the starter relay earlier today and have it on my list of things to check again because there is definitely a voltage drop there too. I did try a new relay to see if this was the problem and it didn't appear to make any difference. I'm going to go through it all again tomorrow to see if I can make more sense out of it.

 

[demonboy]

Just starting to tackle this again. As a short-cut I am attempting to energise the alternator by using a feed from the battery via the solenoid. This is as per the original set-up. That cable normally shows 12.6v, yet when I attach it to my B+ terminal on the new alternator, the reading drops to 3v. Why is this? Are the internal diodes protecting the alternator? If so, how can I energise the alternator if it is refusing to accept current?

For the record the alternator looks like this:



Second question: I can't start my engine with just the start button, I have to press the glow-plug switch for at least 10 seconds. I never had to do this before, so is it possible the starter relay is not working but somehow the glow-plug over-rides this and allows the engine to start with minimal voltage? A cursory check is suggesting that the 'G' terminal (I think this is now called 87) is not receiving power when the starter button is pressed.

Third question: when the ignition circuit is off, 12v can be read on the solenoid +ve, which is coming from the battery. When I turn the ignition circuit on, the voltage drops to 2.5v. Is this normal?

 

[pvb]

Second question: I can't start my engine with just the start button, I have to press the glow-plug switch for at least 10 seconds. I never had to do this before, so is it possible the starter relay is not working but somehow the glow-plug over-rides this and allows the engine to start with minimal voltage? A cursory check is suggesting that the 'G' terminal (I think this is now called 87) is not receiving power when the starter button is pressed.

To operate the starter, 12v+ has to be applied to the 50 terminal on the starter solenoid; this makes the solenoid close and allows high current 12v+ to flow to the starter motor. The 50 terminal should be powered from the starter relay's G terminal. If this isn't outputting 12v when the starter button is pressed, the starter relay could be faulty. I assume you've checked that there's 12v+ on the N terminal of this relay.

When you press the glow plug switch for 10 seconds, does the starter operate by itself?

 

[demonboy]

Hi again. Sorry to waste your time on this. I replaced the old starter relay with a new one and it appears to be working more efficiently. Rather than pressing for 20 seconds I can get away with a couple, though I suspect this is the engine warming up. One of the things that might have been throwing me over the inconsistency of the starter is the AC we have running on the boat. With the engine and diesel pipes exposed the diesel is probably being cooled down quicker than normal.

More to the point, I think I've completed the installation of the AB unit and got the alternator excited so it's putting out the correct voltage. One thing I need to find out from Sterling is how the float system works. After starting the engine the starter battery appears to be receiving a charge, but a slow one taking it from 12.5v after start up towards 12.7. It quickly moved to 12.8 when I engaged the gear and applied revs, but I'm moored up so it was a quick test. After turning off the engine the starter battery dropped back down to 12.6, which is what I would expect. However I would have thought it would show 14v, as is the case with the old alternator regulator. Is this the Sterling AB unit being clever in float mode, or is there an alternative explanation?

I don't expect an answer to this, I've emailed Sterling directly. However I should thank you all for answering a few questions for me and helping me work my way through this logically. Appreciate the time.

Cheers,

Jamie

 

[pvb]

One thing I need to find out from Sterling is how the float system works. After starting the engine the starter battery appears to be receiving a charge, but a slow one taking it from 12.5v after start up towards 12.7. It quickly moved to 12.8 when I engaged the gear and applied revs, but I'm moored up so it was a quick test. After turning off the engine the starter battery dropped back down to 12.6, which is what I would expect. However I would have thought it would show 14v, as is the case with the old alternator regulator. Is this the Sterling AB unit being clever in float mode, or is there an alternative explanation?

Yes, there's an alternative explanation. The A-B charger has 2 outputs; one for the start battery, one for the domestic batteries.

The output for the start battery isn't boosted at all. And, to ensure that the start battery is isolated, the start battery output has a diode protecting it - this will drop the starter battery charge voltage. After an hour or so of running the engine, you should see the start battery back up to 13+ when the engine's running.

The diode in the starter battery output circuit prevents the alternator "seeing" the battery voltage, which is why you've needed to add the wire to provide a start-up excitation voltage for the alternator.

The output for the domestic batteries is electronically boosted and has a 4-stage charging cycle control. As I recall, this output doesn't start until a few minutes after starting the engine, in order to allow the engine to warm slightly before loading up the alternator.

 

[demonboy]

That's encouraging, though the green flashing boost light (14) continues to flash, even after running the engine for 15 minutes in gear. According to the instructions this means

the unit is on but on standby, ie the high alt temp trip or some other trip has switched the boost aspect off and the unit is waiting to reset if possible

The question is, will it reset itself, and what has tripped it? I have installed the alternator and battery temp sensors (both going to -ve).

 

[pvb]

That's encouraging, though the green flashing boost light (14) continues to flash, even after running the engine for 15 minutes in gear. According to the instructions this means


The question is, will it reset itself, and what has tripped it? I have installed the alternator and battery temp sensors (both going to -ve).

Are the house batteries connected to the A-B charger?

 

[demonboy]

Yep

 

[pvb]

Yep

OK, I don't have the installation instructions for the A-B charger you've got, only for the original A-B charger. It does say in there that "Under no circumstances will the system allow the starter battery to drop below 13V."

You said your starter battery was at 12.5v, which is rather low, and that when running it rose to 12.8v. It could be that your starter battery is quite discharged and that the A-B charger is doing what it says and not boosting until the starter battery reaches 13v.

 

[demonboy]

Indeed. One oddity is the difference between the manual and the actual unit. I am now in touch with the man himself so I hope to get some further answers.

 

[demonboy]

Well, the usual friendly response!

this unit is not working , this needs returned for repair or replace

Planning to leave India for the Maldives in five days! Fortunately I have a Balmar alternator regulator as back-up. Maybe I should have stuck with this in the first place. New thread, methinks.

 

[pvb]

Indeed. One oddity is the difference between the manual and the actual unit. I am now in touch with the man himself so I hope to get some further answers.

Are you saying that you've got the unit with the red plastic ends, but have the manual for the original square black charger?

 

[pvb]

Well, the usual friendly response!

Have you tried charging the starter battery, maybe with your mains charger, until you know it's topped up? Then run the engine again and see if the A-B charger goes into boost after the start battery voltages exceeds 13v.

 

[demonboy]

The link that was provided above to the online pdf, which is better explained, is for the black unit, but the one I received with the unit has both models on the cover. The diagrams (Fig 7 and 8) appear to correlate to my unit, but the LED lights make no sense. For example, I have a green light for high temp (17), yet the manual I have shows red. Do they alternate between green and red? The manual doesn't suggest this.

 

[demonboy]

Have you tried charging the starter battery, maybe with your mains charger, until you know it's topped up? Then run the engine again and see if the A-B charger goes into boost after the start battery voltages exceeds 13v.

The mains charger has been on and off over the last week as I've installed the unit and tested it, but to make sure I will leave it on over-night and start the engine first thing tomorrow. Even if I disconnect the mains charger the standing voltage should be around 12.8v, so it will still need some time to get up to 13v. I haven't left the engine running long enough to do this yet. I described the lighting configuration I was getting (both 12.5 and 13v green LEDs were on at the same time and the green boost charge light (14) was on constantly) and that's when he responded by saying the unit was faulty.

 

[pvb]

The mains charger has been on and off over the last week as I've installed the unit and tested it, but to make sure I will leave it on over-night and start the engine first thing tomorrow. Even if I disconnect the mains charger the standing voltage should be around 12.8v, so it will still need some time to get up to 13v. I haven't left the engine running long enough to do this yet. I described the lighting configuration I was getting (both 12.5 and 13v green LEDs were on at the same time and the green boost charge light (14) was on constantly) and that's when he responded by saying the unit was faulty.

If the start battery is reasonably charged, the charge voltage when the engine's running will soon exceed 13v, and you'll then be able to see if the boost function works on the A-B charger.

In post #26, you said "That's encouraging, though the green flashing boost light (14) continues to flash, even after running the engine for 15 minutes in gear." Now you're saying the boost light is on constantly. I'm confused.

 

[demonboy]

So am I. According to the manual the flashing light suggests a trip that "the unit is waiting to reset if possible". I am assuming this has reset itself but I've no idea what had tripped. How long would you expect the unit to hit the 13v for the starter battery? This afternoon it ran for 15mins in gear and slowly crept up from 12.6 to 12.8. I can try running it tomorrow until it hits 13v and see what happens.

 

[pvb]

So am I. According to the manual the flashing light suggests a trip that "the unit is waiting to reset if possible". I am assuming this has reset itself but I've no idea what had tripped. How long would you expect the unit to hit the 13v for the starter battery? This afternoon it ran for 15mins in gear and slowly crept up from 12.6 to 12.8. I can try running it tomorrow until it hits 13v and see what happens.

If your starter battery was reading 12.5v this morning, it's quite low. Can't you charge it from mains overnight?

 

[demonboy]

Yep. I think you missed a post or I didn't explain properly: I've put it on mains charger and will leave it over night. I'll wait till it's fully charged tomorrow and start again. It's 10pm here now so hope to have the battery up tomorrow morning. Thanks very much for all your help.

 

[demonboy]

Good morning. The starter battery was charged up over night and I started the engine. The charge coming into the battery is jumping up and down. It started at around 13.4/13.5, but has settled down to around 13.15 volts. This happened within the space of a few minutes. As far as I can make out the house batteries appear to be receiving the same. Bear in mind both house and starter have been charging on mains over night so should be fully charged. Float is supposed to be 13.3v for open lead-acid so this could make sense.

All the while the far left green LED boost (14) has remained on. At no point has the green float (16) LED come on. Bear in mind the house has been charged by the mains charger and has solar with reg charging it too.

The High Temp light is on. On my unit this is LED (20) but in the guide book it says High Temp is (17). It also says it should be red. Mine is green.

Also, the 13.5, 13 and 12.5v LED lights are all on. There is no explanation for this in the book.

There doesn't appear to be any boost/high charge happening. Assuming the batteries are fully charged I should be seeing 13.3v. Exactly how constant this charge is I've no idea, but if between 13.15 and 13.3 is float, why has the float mode light not come on?

It's like the unit is working with a fully charged bank, i.e. floating, but the lights don't correlate to this. In fact the lights just don't make sense even compared to the instruction manual.

Next test is to run down the house bank and then monitor the voltage going to them to see if it boosts (14.8).