Balmar MC 612 Issue

[K4309 269]

We have a Balmar MC612 alternator regulator. It has a voltage sensing wire to the house batteries with a 1 amp fuse.

The 1 amp fuse is blowing, and the alternator is giving both the start and house batts 15.6v. Any ideas on what to check? Everything keeps running with the fuse blown. It appears this fuse has been blown for some time. Replaced it today and it failed asap...

We have a bunch of other related issues we are working through:

1) Parasitic loads on both the start and house batts. Start is about 4 or 5 mA (if I've got my units right). House is about 10mA with the isolator off (most of this is the battery monitor and screen). With the isolator open it can be anywhere from 0.13A to 0.25A ish.

2) We recently determined the isolator switches had shat themselves. The plastic casings had failed, so the screws holding the rotor backing had popped off, meaning the copper rotator bar wasn't hard up against the contacts. A whole new BEP set of switches and VSR has been installed. We hoped that was the primary cause of our issues, but on commissioning and running checks today, it appears the gremlin has moved.

3) We recently killed the house batts. I left the isolator switch on one day, and about a month later the batts were at 7v. FLA's that were 3.5yrs old.

4) We thought the start batt was in good condition. It is normally floated with a 25w panel. I sat it out fully disconnect over this week, and it dropped to 10.75v. Clearly not in as good a condition as I thought.

The Balmar is correctly programmed and should be doing 14.8v in the bulk phase. We have substantial concerns about it squirting our 15.6v. Based on the history of issues, it may have been doing this for some time. We are concerned this is what killed out batteries. Very closely related to the other topic "how to make a bomb".

The Balmar unit itself is fairly old, maybe 20yrs. Having replaced our engine 160 hrs ago we did not immediately re-connect it (needed to get a 'thing' put in the alternator to make it work). The MC612 has been running for approx 70 hrs in the current set up. It ran for 18 odd years on the old engine without issue.

[K4309 269]

Edit, tomorrow we are planning on running a series of tests as per the Balmar manual to check for faults in the regulator, wiring harness or alternator. This will include a full check on the voltage sensing wire, field wire and ignition wire.

We expect the alternator to be fine, as it is putting out more than enough ergs. As per the opening sentence in the Balmar manual, the majority of faults are in wiring and connections, so we are hoping to find the gremlin there somewhere. Really don't want to replace the regulator, they aren't cheap.

These tests should be just like defusing a bomb. We have to find if the fault is in the blue, red or brown wire...

[K4309 269]

The update is that I've fixed the problem, but I have no idea how...

If the sense wire fuse is in place and not blown, everything runs fine, and the batts receive 14.8v, and the regulator sees the the correct voltage. If I pull out the 1 amp sense wire fuse, the regulator thinks it sees 14.8v (no idea how) but the batts receive 15.6 ish.

All the diagnostic tests on the regulator passed. So no problems with our 20yr old regulator

I checked the resistance on everything I could find, pulled every wire off the regulator and checked resistance there. Then pulled the alternator off the engine and checked everything there. No obvious issues. Outside chance I fixed something by pulling it off and putting it on, but I doubt it (its not a PC that needs to be turned off and turned o again)

I'm just reading this article on the mysteries of voltage sense wires.

Alternators & Voltage Sensing - Marine How To

And yes, I found that SA thread as well, the joys of google.

I'm most interested in this voltage differential thing you mention. The start batt was at 10.7 yesterday for some reason, and the sense fuse blew. Having charged the battery overnight at home, the fuse did not blow today. Looks like we may have killed the start batt too, somehow. Come to think of it, I just paralled the batts before starting the engine today, and the house is two brand new 240Ah AGM's, so bugger all voltage differential. If I tried starting on the flat start batt by itself yesterday, that would put out a big voltage differential. I better finish reading that article...

[CarpeDiem 431]

Going to 15.6v if the v.sense is disconnected would give me cause to throw it out.

[K4309 269]

11 hours ago, CarpeDiem said:

Going to 15.6v if the v.sense is disconnected would give me cause to throw it out.

Throw which bit out? the regulator?

[CarpeDiem 431]

9 hours ago, Guest said:

I would have thought that balmar would limit the regulators output in the instance where the sense fuse blew or became disconnected to avoid fully fielding the alt so a limit of 15.6 stator output is reasonable? Where sense voltage is zero. Just surmising here. Don't really want to try it to find out!

I assume that the sense delta (to a limit ) gets added to the configured Vset to compensate for Vdrop.

1. if the vsense dies it should use the voltage coming out of the alternator as backup and alarm

2. if it sees no voltage at the alternator or does not have this feature, then it should ideally shutdown the field and alarm;

3. or it should just alarm, warning you it has lost the v.sense - you could then still leave it charging and just monitor the voltage.

Sending 15.6v into a LA battery long term is a recipe for a thermal runaway - if you are lucky you will destroy the battery, if you are unlucky you will destroy the boat.

At the very least an alarm is the minimum you should have.

My engine will alarm at 15v, there are aftermarket high voltage alarms available if your engine doesn't or the setup requires such.

[K4309 269]

1 hour ago, CarpeDiem said:

1. if the vsense dies it should use the voltage coming out of the alternator as backup and alarm

2. if it sees no voltage at the alternator or does not have this feature, then it should ideally shutdown the field and alarm;

3. or it should just alarm, warning you it has lost the v.sense - you could then still leave it charging and just monitor the voltage.

Sending 15.6v into a LA battery long term is a recipe for a thermal runaway - if you are lucky you will destroy the battery, if you are unlucky you will destroy the boat.

At the very least an alarm is the minimum you should have.

My engine will alarm at 15v, there are aftermarket high voltage alarms available if your engine doesn't or the setup requires such.

We have a battery monitor that we are setting an alarm up from. To a light on the dashboard. The first time we had this issue (15.6v) there was an alarm going. That was when we were trying to charge the batteries up from 7 volts. I assumed that was an under voltage alarm. The key issue that we need to resolve, is that the regulator is seeing 14.8 when the batteries are getting 15.6. That is why the regulator isn't triggering an alarm (although it doesn't make sense why the 15.6 happens to be the high voltage limit) At the same time, we have parasitic loads we are trying to identify. It is possible there is a short or cross connection somewhere that is foxing the regulator and giving us our parasitic loads. I'm yet to check through all the wiring to and from the ignition switch. And a few other places.

Whilst I agree it is an issue, I wouldn't just go and through out an $800 piece of kit for shits and giggles (the regulator). It passed all of its diagnostic tests, and as the first para in the manual says, the majority of issues with regulators are wiring and connection issues, normally associated with corrosion or loose connections. It'd be really friggin funny if I drop $800 on a new regulator, and the problem was a $2 wire connection somewhere else.

[CarpeDiem 431]

10 hours ago, Guest said:

15.6 v to my LiFePO4 would be worse than to his AGMs. So I have 4 levels of alarms starting at regulator with the highest, but still with headroom.

No it wouldn't.

Ignoring the fact you have a BMS. 

LFP can be safely charged to 4.2v / cell. While personally I have never done this, there's plenty of people online who have experimented with this. And that includes Rod @ Marine How To.  This is what he charged his first pack too, many times in the beginning when he was experimenting with this tech and that pack is still going strong after many cycles. 

Because there's less than 1% capacity between 3.6v and 4.2v there's just no point charging to this voltage. 

At 15.6v AGM is equalizing, beginning to gas and will eventually cook itself if left long term. 

For LFP at 15.6v you're 1.2v away from the absolute maximum and you might knock a few years off its life. Assuming you cycle the battery every weekend that's 32 years instead of a 38 years lifetime.

But it's never going to happen unless your BMS is also faulty.

 

[K4309 269]

11 hours ago, Guest said:

 

Is the Cv setting a preset AGM setting not configurable on the 612? And there is no "custom" setting?

If the preset AGM setting is corrupted, why not try setting to a lower Cv chemistry, powerup and check output. If correct Cv fo that chemistry, reconfigure back to AGM and see if output is correct on reboot? This is assuming sense fuse is intact of course. This should bea data point on regs functioning.

Maybe the Balmar trouble shooter suggests this and you have done it already.

 

 

It is only a problem when the sense fuse has blown. Everything works fine (as it has for the last 20 odd years) when the fuse is in place.

Someone on here posed the question the other day, why is the regulator not alarming / telling us its lost the sense wire? I think if I can resolve that question, it will resolve / explain the basic issue.

Yes, we can programme the Regulator. It is actually on Pro2, FLA. (The old house batts were FLA). BUT, it has always given a bulk charge of 14.8v, and Pro2 doesn't use 14.8v. It uses 14.4 I think. So it is likely my father did a user programme at some stage and has forgotten the details. I'm going to review and reset those, but I've no reason to believe the programme is causing the issue. The issue is the voltage is not as per the existing programme when the fuse has blown, AND the regulator is not telling us the fuse is blown.

Thanks for the offer to test your spare unit. I don't think I need to do that yet. I need to understand the alarm states on my current unit, and confirm I don't have a wiring cross connection somewhere. My first place to look is if the ignition wiring is back feeding a voltage that the regulator is seeing when the fuse goes. 

[Island Time 1,239]

OK; You guys are expecting the (OLD) Balmar reg to be smarter than it is. It WILL NOT throttle the field back without voltage sense OR battery temp sense. For it to be blowing the voltage sense fuse repeatedly indicates a failure in the regulator. It's encased in resin and is not normally economically repairable.  It's trying to full field the alt as the v (sense) is below target voltage. By the time the batts got too hot at >15v they would likely be damaged, possibly severely. Replace the reg. Sorry. 

[K4309 269]

2 hours ago, Island Time said:

OK; You guys are expecting the (OLD) Balmar reg to be smarter than it is. It WILL NOT throttle the field back without voltage sense OR battery temp sense. For it to be blowing the voltage sense fuse repeatedly indicates a failure in the regulator. It's encased in resin and is not normally economically repairable.  It's trying to full field the alt as the v (sense) is below target voltage. By the time the batts got too hot at >15v they would likely be damaged, possibly severely. Replace the reg. Sorry. 

Hi IT,

What is the regulator supposed to do when the sense fuse blows? And is there any tests or a 'recreation' I can run to confirm there is a problem with the regulator?

[Island Time 1,239]

2 hours ago, K4309 said:

Hi IT,

What is the regulator supposed to do when the sense fuse blows? And is there any tests or a 'recreation' I can run to confirm there is a problem with the regulator?

The fuse is not supposed to blow. It's there to protect the wire and prevent a fire - it's doing that. Oh, and you have done the test - replaced the fuse. Remember that the sense wire is connected directly to the battery, and could carry ANY current the battery can supply if it is connected to neg directly. To be like this would be a failure of a component in the reg, which is not serviceable. Replace it.

[K4309 269]

23 hours ago, Island Time said:

The fuse is not supposed to blow. It's there to protect the wire and prevent a fire - it's doing that. Oh, and you have done the test - replaced the fuse. Remember that the sense wire is connected directly to the battery, and could carry ANY current the battery can supply if it is connected to neg directly. To be like this would be a failure of a component in the reg, which is not serviceable. Replace it.

Hi IT,

I haven't been able to get the fuse to blow again. Would this change your recommendation on replacing the unit?

Started and ran the engine several times today, behaved normally. If I take the fuse out it will run at high voltage. Put it back in, runs fine.

Note that we did have the sense wire on the house batts, which is behind the VSR and therefore can't be 'seen' by the alternator when it is closed. I've shifted the sense wire to the start batt, which can always be seen by the alternator.

We've also determined why we don't get a high voltage alarm. The lead from the appropriate terminal on the regulator doesn't actually connect to the dash lamp. Amature hour!

I successfully got into the programming functions and documented the current set up, and changed the programme. From that I've found that the regulator is putting out about 0.3v more than the bulk set point. i.e. it was putting out 14.8/14.9v on Pro2, where the bulk set point was 14.6v. I changed to Pro1 which has a set point of 14.1v and the regulator and the batts were all saying 14.5. This appears to be the compensation limit. I'm yet to work out what that is and what is going on.

But in terms of replacing the unit, it appears to work in that all the lights come on, I can access and change the programme, it passed the diagnostic tests, and puts out current. There is this question about going to the compensation limit, and I'm yet to sit down and watch it go through and entire charge cycle and confirm everything is fine.

Noting that last week we found our isolator switches had shat themselves. the backing screws had fractured the plastic housing, so the copper rotator was not hard up against the contacts. There is a possibility this was causing voltage spikes, and how do you say "load shedding events". I suspect if anything was going to damage the regulator, that sort of stuff would have achieved it.

If I need a new regulator, I need a new regulator, (I've already sussed price, supply and model etc) but I'm keen to understand and confirm this one is not working properly / what is wrong with it.

[K4309 269]

I believe I've worked out the compensation limit question. It is temperature compensation. Mid point is 25degC.

Ambient temp currently is about 15degC, i.e. 10 deg lower than mid point.

My new batteries have temperature compensation of 30mV/C. A random example Victron VRLA battery has 24mV/C. At 10 degrees cooler, the regulator is adding 0.3v / 0.24v to the target voltage to compensate for the cooler ambient temp. I expect that if I warmed up the temp probe to 35degC, the regulator would reduce the bulk charge voltage by 0.3v.

If this is correct, A. I can test it really easily by warming the temp probe, and B. my regulator is actually working properly and without any apparent issues. 😀

[Black Panther 1,591]

Toilet hoses i would replace rather than try to clean.

[K4309 269]

1 hour ago, Black Panther said:

Toilet hoses i would replace rather than try to clean.

I thought you old skool types just used a bucket?

[Island Time 1,239]

OK, so this is a progression. I thought the sense wire blew it's fuse all the time?

Turns out it doesn't.

The install manual was not followed. The sense wire MUST be connected to the battery that the alternator can see, ALL the time, as when disconnected it will go to full field to try to raise the (sense wire) voltage to the specified voltage. Do not connect a sense wire anywhere else but to the battery - that's why its's fused.

This is the issue with remote diagnostics. Without an accurate circuit diagram it can lead you down the wrong path very easily.

Yes the .3v is most likely temp compensation, and the device is working as designed,