Battery chargers won't work on genset, work fine on SP

[Mischief Managed]

My boat suddenly has a strange issue. Both my Inverter (Xantrex SW3012) and my battery charger (Promariner 1250P) will not charge my batteries on 1992 Cummins Onan 8kw diesel genset power.



Every other 120V system on the boat works fine on genset power and both chargers work perfectly on shore power. The genset puts out a steady 118.3VAC (plus or minus .1V measured with a DMM using MIN and MAX function) at 61.25 Hz at the furthest outlet from the generator on the boat. An analog volt meter does not display any voltage fluctuations. The genset is running smoothly and works perfectly under heavy load (water heater and all three AC units running). I have not looked at the waveform yet with an oscilloscope, but that's the next step.


Any thoughts or ideas would be appreciated.


I called Xantrex tech support and they assured me that the inverter only looks at voltage, waveform, and frequency to qualify AC input power. It does not care about bonding, floating grounds, stray current, or any common issues like that one may find on a boat.


My gut says the genset os putting out a funky waveform that none of my other 120V devices care about or monitor. The genset has approximately 1240 hours.

 

[rslifkin]

Check the brushes on the generator head and anything else that's mentioned in the manual and would be easy to check. Also, was that 61.25hz at no load, some load, or?

 

[Mischief Managed]

Check the brushes on the generator head and anything else that's mentioned in the manual and would be easy to check. Also, was that 61.25hz at no load, some load, or?

Thanks, 61.25 Hz was with no load. I will check again under load, but I am certain it will be well within normal. Portable handheld oscilloscope is on the way; always wanted one and this is as good an excuse as any to add one to my tool kit.

 

[rslifkin]

Definitely re-check with as much load as you can manage. Ideally, you'll be no more than 62 hz at no load, no less than 58 at full load. 63 - 57 is the outer end of the acceptable range.

 

[fryedaze]

If the genset has an alternator it could be charging at a higher voltage than the battery charger causing the charger to back off.

 

[ranger58sb]

My boat suddenly has a strange issue. Both my Inverter (Xantrex SW3012) and my battery charger (Promariner 1250P) will not charge my batteries on 1992 Cummins Onan 8kw diesel genset power.

Is this a recent change?

If not... is the 1250P actually hooked up to charge 3 banks? (One being th genset battery?)

Is the 1250P properly charging other banks at the same time?

Is the generator's alternator charging the genset battery?

If so, is the genset battery fully charged, therefore not showing much current from the 1250P?

-Chris

 

[Mischief Managed]

Is this a recent change?

If not... is the 1250P actually hooked up to charge 3 banks? (One being th genset battery?)

Is the 1250P properly charging other banks at the same time?

Is the generator's alternator charging the genset battery?

If so, is the genset battery fully charged, therefore not showing much current from the 1250P?

-Chris

The 1250P does not charge the genset start battery and never has. It will eventually, but right now it charges the main starting battery, the house GC battery bank, and the Mathers Micro Controller (shifter/throttles) GC battery bank.



The only normal charging for the genset battery is the generator alternator and it's never been a problem. My boat has a paralleling switch so that I can start the genset from the house bank and I use that once a month over the Winter to combine them for charging via the 1250P (which is also only used once a month in the Winter until all batteries are in float).



I do not think the genset starting battery can have anything to do with this. Even if the batteries are all fully charged, the inverter and 1250P will still turn on and simply go to float. In my situation, they will not turn on at all. The inverter just stays in inverter mode and the 1250P goes right into fault mode. As soon as connected to shore power, they act normally.

 

[Mischief Managed]

Is this a recent change?

There have been no changes at all in wiring since it worked normally and now. It started on Sunday morning when I ran the genset to charge the batteries and do some cooking after an overnight at anchor. Fortunately, the FLA house batteries were still at 12.4V (75ish% SOC) so the alternators had no trouble topping them up on the 6 hour cruise back to the marina. The genset worked fine for cooking and coffee.

 

[kchace]

I assume the inputs to the inverter and charger are separate? If so, it’s unlikely either device is at fault. Is it possible you lost a leg that feeds both, perhaps through a switch or breaker?

I have a scope I can bring to the boat Monday if you’d like to borrow it.

Ken

 

[tiltrider1]

I am going to suggest the obvious. Under generator did you measure voltage at the inverter Or battery charger. I’m just wondering if there is some way the power is not getting to the inverter. This is a long shot but I couldn’t tell if it had been ruled out.

 

[ranger58sb]

The 1250P does not charge the genset start battery and never has. It will eventually, but right now it charges the main starting battery, the house GC battery bank, and the Mathers Micro Controller (shifter/throttles) GC battery bank.

The only normal charging for the genset battery is the generator alternator and it's never been a problem.

There have been no changes at all in wiring since it worked normally and now. It started on Sunday morning when I ran the genset to charge the batteries and do some cooking after an overnight at anchor. Fortunately, the FLA house batteries were still at 12.4V (75ish% SOC) so the alternators had no trouble topping them up on the 6 hour cruise back to the marina. The genset worked fine for cooking and coffee.

I think I misunderstood; thought you meant the 1250P wasn't charging ONLY the genset battery.

Instead, you mean it's not charging any battery when being powered by the genset, yes?

-Chris

 

[Mischief Managed]

I think I misunderstood; thought you meant the 1250P wasn't charging ONLY the genset battery.

Instead, you mean it's not charging any battery when being powered by the genset, yes?

-Chris

That is correct. Both the inverter and 1250P seem to need to qualify the AC input before they will activate charging mode and neither of them will do so, so there is no charging at all, except for the alternator on the gen set charging the genset starting battery.

 

[Mischief Managed]

I am going to suggest the obvious. Under generator did you measure voltage at the inverter Or battery charger. I’m just wondering if there is some way the power is not getting to the inverter. This is a long shot but I couldn’t tell if it had been ruled out.

I did not, only because it's a pain and they both work fine on shore power, so know the wiring from the AC breaker panel to the inverter and to the charger has to be OK.

 

[Mischief Managed]

I assume the inputs to the inverter and charger are separate? If so, it’s unlikely either device is at fault. Is it possible you lost a leg that feeds both, perhaps through a switch or breaker?

I have a scope I can bring to the boat Monday if you’d like to borrow it.

Ken

The inputs to both devices are indeed separate and are also on opposite legs in the AC panel. FWIW, the previous owner did a good job keeping the two charger circuits as separate and redundant as possible. I normally just run one charger but now I can't run any...



I should see if the 1250P will run on the sine wave output of the Inverter, not because it would solve my problem, just to see if the sine wave output is truly clean, since it seems to picky...

 

[DDW]

Small gensets can have really horrible wave forms, many inverter type chargers will operate at reduced capacity or not at all on them. I don't have any idea why it would have changed, but looking at it with the o'scope is a good plan. The voltage output should be 110 - 120V RMS, so the peak waveform should be around 165V. If your meter was really measuring peak-to-peak, your voltage is low.

 

[sunchaser]

MM
Unplug the Pro mariner and see if inverter charger does any better. Can you then bypass the inverter charger to see if PM then works better?

Do you have a BMK for the house bank? They are great tell alls if hooked up correctly. Also consider a dead battery cell somewhere. But, given it all works fine on shore power it points to a genset sending a bad wave form. 30+ years degrades electrical components just when sitting.

 

[Bacchus]

Is this a recent change?

If not... is the 1250P actually hooked up to charge 3 banks? (One being th genset battery?)

Is the 1250P properly charging other banks at the same time?

Is the generator's alternator charging the genset battery?

If so, is the genset battery fully charged, therefore not showing much current from the 1250P?

-Chris

This raises a related question for me but I'll that a separate thread re Multi Bank Charger Operation to avoid hijacking this interesting thread.

 

[twistedtree]

Have you metered the input voltage right at the terminals to the two devices?


Also, I think the SW "Meters" menu will let you see what it's seeing at the input.

 

[kchace]

Portable handheld oscilloscope is on the way; always wanted one and this is as good an excuse as any to add one to my tool kit.

That's awesome. Now you have me thinking, I keep a lot of tools and spares on board but even *I* don't carry one of those! Should I? (I already own one)

Ken

 

[CharlieJ]

Just to be sure, recommend you check the ACIn settings on the SCP. These units will accept 85VAC to 135VAC and 45 to 70Hz. It is possible that the acceptance band was tightened for this installation and the genset freq or voltage has wandered out of the tighter band.

 

[tiltrider1]

Have you metered the input voltage right at the terminals to the two devices?


Also, I think the SW "Meters" menu will let you see what it's seeing at the input.

OP said he had not done his. Until he does I think he is chasing his tail.

 

[MYTraveler]

Portable handheld oscilloscope is on the way; always wanted one and this is as good an excuse as any to add one to my tool kit.

Which did you buy? I had wanted one since high school in the 70's (very expensive then), but purchased a Rigol a few years ago just because I was so impressed with the power / cost ratio. Although I didn't have a specific use for it then, I have found many uses since, including decoding (from bits to hex) NMEA sentences.

 

[Mischief Managed]

Which did you buy? I had wanted one since high school in the 70's (very expensive then), but purchased a Rigol a few years ago just because I was so impressed with the power / cost ratio. Although I didn't have a specific use for it then, I have found many uses since, including decoding (from bits to hex) NMEA sentences.

I got a Hantek 2D72

 

[FlyWright]

Let us know what you see for input voltage on your charger (AC w/ genset on) and your inverter (DC).

 

[Mischief Managed]

Let us know what you see for input voltage on your charger (AC w/ genset on) and your inverter (DC).

Will do.



I ordered a bunch of ferrite beads in case the oscilloscope shows some high frequency noise on the line that the charger and inverter don't like.



Perhaps a dumb question, but I assume the genset has brushes for the exciter coils, is this correct?

 

[Choices]

I had an issue with worn brushes.

Brushes would bouncece the contact and cause an irregular frequency that the charger chopping circuit could not handle.

Chatter was two fast and irregular so a/c and frig still worked, seeing the 60hz wave still there.

Easy fix.

 

[MYTraveler]

It would be great to see pics of the waveform(s). Does your device do triggering? You may need to look at the wave form with the genset under load.

 

[Delta4242]

Gen set volts

The Onan Generator needs to put out its nameplate voltage. This should be 120vac. Try adjusting it up to 120 exactly (within .1volt. )
The procedure is in the owners manual.
?

 

[greatpapabear]

Hi Mischief Managed.

I had an issue with my Onan when I installed a new 4 burner stove (hob in the UK). Found the issue was that the stove had a very tight Hz tolerance. I was able to increase the Onan's Hz to the stove's top limit so when other items kicked in, dropping the Onan's RPM and therefore the Hz, it still stayed in tolerance.

The manual will show you how to adjust the Onan's Hz, but if it doesn't, I can show you how I did mine.

 

[Swfla]

Hi Mischief, it's been 10 days since you posted the issue. What was the outcome/issue?