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Mark65 · 19-07-2020, 15:04

Hi there! I am searching the internet for information on an issue I am having and read some great posts on similar issues on this forum, so decided to see if I can get advice here. I am an RV owner, not a boat owner, but my equipment is mostly intended for boating.

I have a Balmar 614 Regulator with what is billed as a 280A alternator - link to the kit is here -

https://www.nationsstarteralternator...280xp-er-l.htm

I have a 300Ah Lithium battery (Nexgen NG300) and a Magnum pure sine wave inverter / charger. There are also 160W of solar connected to the battery rail. The system is isolated from the factory coach 12V system.

So, I have the alternator, solar panels and the potentially shore power (via the Magnum) to charge the battery. I have had the van for about 2 years and it has been working fine as far as I know. I have never been careful or concerned about whether I idle the engine with shore power connected and its possible I have idled the engine while the Magnum is also charging the battery. It only recently occurred to me this might not be a good thing.

On my most recent trip a couple weeks ago the 10A fuse on the Balmar 12V wire was blown. I noticed this when after a day of driving the battery was not fully charged. The next morning I tried to idle the van to charge the battery, noticed no charge current and after a few minutes of poking around I saw the blown fuse.

I replaced the fuse, re-started the van and I got charge current for perhaps 5 minutes and the fuse blew again.

I read a label on the 12V wire that referenced a 15A fuse, so I installed a 15A fuse. This time the fuse didn't blow, but after a couple minutes of charge current the charge current went away and I smelled something overheating. No smoke, but a definite hot-electronics smell. I decided to drop back down to a 10A fuse. For the remainder of my traveling, I just kept the fuse out and kept the regulator dark.

I am home now and can repeat the symptoms. The best sequence I have to describe is from a test I did this afternoon.

It ran for about 7 minutes before the fuse blew again.

The current readings are coming from the Magnum controller, there is a shunt resistor to measure current in / out of the battery.

CV is 14.3V reported by Balmar. (this is the voltage target for the regulator)

For about 6 minutes –

120A of charge current reported by Magnum controller
BV reported by Balmar – 13.9 – 14.2V
BV reported by Magnum controller in the van – 13.7 – 13.8
Alternator temp – started at 34C, came up to 120C (last temp I saw reported)

Last minute before the fuse blew -

BV reported by Balmar – 13.8V
75A of charge current reported by Magnum controller

It ran this way for a little bit, then the fuse blew.

I suspect something is wrong with the alternator - any advice on further debug or perspectives on what the issue is are welcome!

CharlieJ · 20-07-2020, 13:43

Quote:

Alternator temp – started at 34C, came up to 120C (last temp I saw reported)

This is the key. The alternator should not get above about 100C so it appears that there is an internal issue, possibly in the field windings shorting to the housing when the unit starts heating up. Call Balmar Tech Support to verify.

**s/v Jedi** · 20-07-2020, 13:58

Also, do you have the alternator temperature sensor?

Google for the MarineHowTo article from Rod Collins on how to setup the Balmar 614 for Lithium banks.

Mark65 · 20-07-2020, 14:01

Quote:

Originally Posted by CharlieJ

This is the key. The alternator should not get above about 100C so it appears that there is an internal issue, possibly in the field windings shorting to the housing when the unit starts heating up. Call Balmar Tech Support to verify.

Thanks, Charlie. I am discussing with Nations (the alternator mfr) right now. Balmar folks told me they don't think its a regulator issue based on no damage to the potting compound and the regulator status indicators functioning normally.

I may be at the point now where I am convinced there is nothing I can service myself and I need to get the alternator checked out.

Mark65 · 20-07-2020, 14:03

I do have the alternator temp sensor - this is where the temp readings I am reporting come from. I will check out that article - thanks!

Scubaseas · 21-07-2020, 09:45

I would verify temp sensor reading with a pyrometer/ IR thermometer. Sounds like an alternator issue though.

smac999 · 22-07-2020, 23:19

remove the field wire from the alt. tape if off. and run motor. if the fuse still blows after a bit it would be an issue within the regulator. as no current should be drawing with no field wire to the alt.

if it does not blow. then likely it's the alt.

same idea using a meter. if you have a DC clamp meter. you can measure the current on the field wire. if you are seeing 10+ amps on the field wire when the fuse blows. then it'll be the alt that sucking too much. if you are seeing 5amps or whatever and the fuse blows. then the rest of the current (in this case 5a) causing the fuse to blow must be going wrong inside the reg.

having the motor running and magnum charging is not an issue. happens on any boat with a gen.

Mark65 · 01-08-2020, 13:11

Thanks very much for all the replies so far.

I poked around with a scope and I am seeing something I didn't expect but I am not sure if its normal.

The blue traces is the 12V rail, measured more or less at pin 2 of the Balmar regulator with probe grounded as best I could to a chasis point nearby. The Red trace is the field output of the Balmar regulator, its a pwm signal into the alternator coil. One can clearly see there is a 5V impulse drop out on the 12V rail with the rising edge of the pwm input to the field. This might be completely normal, I don't know how the alternator reacts when the field is energized step-wise, as the pwm input does. It could also be that this coupling is not supposed to be present and its causing issues with the 12V input on the regulator and this is why I sometimes blowing fuses. I have sent the image to Balmar, thought I would also post it here to see if anyone has thoughts on whether its an issue or maybe 'the' issue.

Nicholson58 · 01-08-2020, 13:23

Balmar has a very good trouble shooting guide in the manual for the 614. Download and follow it.

You might trick out the system by using the belt saving feature of the Balmar. This limits the field of the alternator.

It does sound like an alternator issue.

Mark65 · 01-08-2020, 15:20

Quote:

Originally Posted by Nicholson58

Balmar has a very good trouble shooting guide in the manual for the 614. Download and follow it.

You might trick out the system by using the belt saving feature of the Balmar. This limits the field of the alternator.

It does sound like an alternator issue.

I've read the debug guide and going down that path is what lead to me taking these scope shots. There is no magnetic field with the engine off - I can't test with the ignition on and the engine off because the 12V to the alternator is not switched on until the engine is turning, but I can see from the current draw that there is field at this time.

The next step is to full - field the alternator, which I am not comfortable doing. I am concerned that I might damage the alternator if I do that, and Nations (the alternator mfr) has advised me not to full field test the alternator. So I was digging into the field input to the alternator to try and assess if I can somehow partially field the alternator and that led me to collect these waveforms.

My thinking was/is to put a 1mA or so current source into the field, but I am not sure how much current it takes to saturate the field in the first place, so I was in the midst of seeing what I could learn when I saw as much as I have posted.

Why not take it to a shop? It has not been very straightforward for me to find someone who has experience with 2nd alternators on Sprinters, and I am hesitant to take the van to someone who might be removing and installing such an alternator on the Sprinter for the first time themselves, so I am continuing to see what I can figure out on my own while I keep looking for a mechanic. The dealer won't look at 3rd party items and the shop that did the van build for me is 200 miles away and has not yet responded to my inquiry on whether they can service this themselves or recommend someone close to me. I'd drive across town and show up at their place to discuss with them, but 200 miles is a long way to drive if they are going to end up not being able to do anything so I want to get my expectations set in advance of making that drive.

If it turns out to be a regulator issue after all, I can replace that myself very easily, or if perhaps these waveforms indicate a potential cabling issue to anyone I can try and look harder at the cable harnessing than I already have.

I may attempt "partial field" testing if I can learn from somewhere a bit more about how to energize the field (how much current) and be confident that I should expect 50 or 100A at the output with a given input field current. Its a 280A alternator and I don't want to go anywhere near that output with it even if I leave it connected to the house load.

I appreciate your response and I acknowledge your point that the best first place to start is with mfr debug procedures - I am doing that as best I can to try and get my hands around this. I realize I am quite likely to end up at a point where I need a mechanic to take the alternator off in any case regardless of what I learn.

Regards,
Mark

Nicholson58 · 01-08-2020, 19:08

My field is also switched. I have a 14 ga. X 50 foot two conductor cable with alligator clips. I use this to jumper things all around the boat for eliminating or bypassing stuff. I have full load tested the alternator on occasion. Only for a couple seconds.

You can check for field with the engine running but you say you make power until it blows. My thought is that if the alternator is suspect, take it to a shop. I have lost three to lightening. All were rebuilt at a dedicated alternator, starter shop. The shop’s main business was trucks. The windows and walls were piled high with alternators and starters. Find a place like this and take the alternator and the Balmar if you suspect it. Make sure they load test the alternator for whatever time you have determined results in the blown fuse.

I also lost an alternator to extended full load. Turns out many are not rated for continuous full load which is what is simulated if you are charging big AGM or Li banks. For this, I dropped my Balmar output to 80%.

smac999 · 01-08-2020, 20:25

Quote:

Originally Posted by Mark65

I've read the debug guide and going down that path is what lead to me taking these scope shots. There is no magnetic field with the engine off - I can't test with the ignition on and the engine off because the 12V to the alternator is not switched on until the engine is turning, but I can see from the current draw that there is field at this time.

just feed the regulator 12v to the ignition wire if you need to test with the engine off. do you not have a key? noramlly power comes when you turn the key on. if you have no key, it might come from an oil pressue swtich

The next step is to full - field the alternator, which I am not comfortable doing. I am concerned that I might damage the alternator if I do that, and Nations (the alternator mfr) has advised me not to full field test the alternator. So I was digging into the field input to the alternator to try and assess if I can somehow partially field the alternator and that led me to collect these waveforms.

you are not going to damage the alt. the balmar full fields the alt every time you start the engine.

My thinking was/is to put a 1mA or so current source into the field, but I am not sure how much current it takes to saturate the field in the first place, so I was in the midst of seeing what I could learn when I saw as much as I have posted.

field is controlled by voltage. the field coil is around 2 ohms. so in bulk mode when the reg is putting 12v out on the field output, the current will be around 6amps. in absorb if the field is say 6v the current will be 3a. 1ma isn't going to do anything. this is why putting 12v to the alt does not hurt it. the reg does it in bulk mode every time. if you want to test lower. find a way to put adjustable voltage into the field wire capable of that current

Why not take it to a shop? It has not been very straightforward for me to find someone who has experience with 2nd alternators on Sprinters, and I am hesitant to take the van to someone who might be removing and installing such an alternator on the Sprinter for the first time themselves, so I am continuing to see what I can figure out on my own while I keep looking for a mechanic. The dealer won't look at 3rd party items and the shop that did the van build for me is 200 miles away and has not yet responded to my inquiry on whether they can service this themselves or recommend someone close to me. I'd drive across town and show up at their place to discuss with them, but 200 miles is a long way to drive if they are going to end up not being able to do anything so I want to get my expectations set in advance of making that drive.

If it turns out to be a regulator issue after all, I can replace that myself very easily, or if perhaps these waveforms indicate a potential cabling issue to anyone I can try and look harder at the cable harnessing than I already have.

I may attempt "partial field" testing if I can learn from somewhere a bit more about how to energize the field (how much current) and be confident that I should expect 50 or 100A at the output with a given input field current. Its a 280A alternator and I don't want to go anywhere near that output with it even if I leave it connected to the house load.

I appreciate your response and I acknowledge your point that the best first place to start is with mfr debug procedures - I am doing that as best I can to try and get my hands around this. I realize I am quite likely to end up at a point where I need a mechanic to take the alternator off in any case regardless of what I learn.

Regards,
Mark

see comments in red

Mark65 · 01-08-2020, 20:48

@smac999 Thanks - I will test with gradually increasing voltage - appreciate the advice.

Mark65 · 04-08-2020, 09:46

Update on my issue / investigating -

I am now gaining confidence that I have a good theory on what is going on, at least conceptually.

Most of my testing is done at normal idle, so that will require the most field current to meet the regulator set point voltage. More field current means that all other things being equal, I am close to 10A on the regulator power input that I would be with lower field current. The regulator shuts the field current down when the alternator gets to 120C. This shutdown may introduce some transients that blow the fuse.

Just now, I turned on the AC to load the alternator and ran the system with the engine at high idle, 2k RPM's, not quite twice normal idle. I could see the alternator temp rising, getting to 120, the current going to zero, the alternator cooling to about 110C, the current coming back, rinse and repeat. I couldn't get the fuse to blow. I decided not to repeat things with the idle at normal because I don't really like seeing the fuse blow.

I am concluding that the basic weakness in my system is the alternator can't keep cool when its loaded and sometimes when the regulator shuts the alternator off this makes it blow its fuse. I can reduce the likeliehood of blowing a fuse by running the system at higher idles to reduce field current. If I want to make things fundamentally more robust, I need to find a way to keep the alternator cooler. It seems non-optimal to me to have the system continually limit cycling to the high temp cutoff. I was observing perhaps a 50% on-time for the alternator as it cycled to 120C, was shut off, cycled up to 126C or so before cooling down to 114C or so to get turned back on.

I may be able to track down what exactly is causing the fuse to blow under high field current conditions when the alternator shuts down, but I think I need to find a way to keep the system from getting that hot under what should be normal operation conditions.

I can limit the field on the regulator if I want to go that route - equivalent to hobbling the alternator. Since I'm already seeing a limited on time due to over temp that seems a better approach that wouldn't result in less net charging anyway. I'll give it some more thought.

I really appreciate the brainstorming / sounding board, thanks! Any thoughts on how to cool the alternator welcome as well.