Balmar alternator fire

[smac999]

Originally Posted by tanglewood

I would start by figuring out what's wrong with the alternator. The exact failure will likely be your best clue as to the cause. And don't just take it apart. Start by checking the windings and field for shorts to each other and to ground

I image after the fire it'll all be shorted... I would take it to an alt shop and have them open and look.

shorted field windings would just cause the regulator fuse to blow. not burn an alt

[Jammer]

Originally Posted by smac999

I don't even know what inside an alt could even burn. it's just a metal case with metal windings...

are you sure oil /gas / engine fluids or other stuff did not get into the alt? which then lit from the hot alt.

The insulation on the wires will produce fire and flame if heated up enough. It won't produce a self-sustaining fire in the absence of heat from an electric malfunction.

[Jammer]

Originally Posted by tanglewood

I would start by figuring out what's wrong with the alternator. The exact failure will likely be your best clue as to the cause. And don't just take it apart. Start by checking the windings and field for shorts to each other and to ground

It's probably a mess now and the root cause far from clear. Maybe worth checking though.

[goboatingnow]

Originally Posted by Jammer

The insulation on the wires will produce fire and flame if heated up enough. It won't produce a self-sustaining fire in the absence of heat from an electric malfunction.

There is enough flammable wire coating to make a nice fire if temps get high enough

[Lepke]

What burned inside the alternator?


The only alternator fire I've seen was from the front bearing failing and the grease burning. It was caused by too much belt pressure. Owner had a slipping problem and instead of buying a new belt or exploring a better drive setup, just used a crowbar and tightened the alternator belt as much as possible.

[goboatingnow]

Originally Posted by Lepke

What burned inside the alternator?


The only alternator fire I've seen was from the front bearing failing and the grease burning. It was caused by too much belt pressure. Owner had a slipping problem and instead of buying a new belt or exploring a better drive setup, just used a crowbar and tightened the alternator belt as much as possible.

The wire coating will burn as will certain plastic bits.

[OceanPlanet]

The only real way to put an alternator in to flaming mode is to have it open-circuited from the load (batteries). That's almost certainly what happened (have seen it before). And the fact that no output was detected supports the likelihood that it wasn't connected. Missing or blown fuse on the B+ feed to the batteries is possible.

[goboatingnow]

Originally Posted by OceanPlanet

The only real way to put an alternator in to flaming mode is to have it open-circuited from the load (batteries). That's almost certainly what happened (have seen it before). And the fact that no output was detected supports the likelihood that it wasn't connected. Missing or blown fuse on the B+ feed to the batteries is possible.

I’ve had several open circuit alternators. No way does it result in a fire. You get an initial spike about 100 mS in duration and about 100v which if you don’t have avalanche diodes will fry the diodes. Then the output drops to nothing. Current flow is relatively minor.

If the interrupted load was low to be begin with it’s hardly an event at all.

In my experience there is no way that fire was from a simple interrupted alternator.

[s/v Jedi]

I still have a bad feeling about the temperature sensor. OP confirms it has a sensor but not that it has a sensor on the alternator rather than the battery, connected to the correct pins on the regulator (for the alternator temp sensor rather than battery temp).

What is sure is that it failed. So there are two failures: whatever caused the fire and another one with the system that should have prevented it to escalate into actual flames.

[stinkpots]

Originally Posted by Tenedos

Today, roughly 20 minutes after we fired up the engine and right after we pulled up the anchor, our Balmar alternator (Balmar-AT-DF-165-K6) got on fire with flames coming out of the grills. We noticed a smell and checked the engine compartment to see the flames coming out of the alternator. We stopped the engine immediately, dropped the hook back and then I pulled the alternator fuse. After testing the temperature a bit after firing up the engine, we continued and dropped the hook in our destination. Needless to say, this was very worrisome.

We have 7x100Ah 12V LiFePO4 batteries that are connected in parallel. I also have a Balmar MC-614 controller and I have configured it with the following settings: Field reduction is 70%. High voltage/bulk limit is 14V. Absorption voltage is 13.9V and float voltage is 13.8V. There is a temperature sensor and max alternator temp is set to 100 degrees celsius. I also have a Starlink alternator protector device. I think these were relatively conservative settings.

Alternator charges the lithium batteries. Starter battery (AGM) is charged by a DC-DC charger from the lithium batteries.

We fired the engine at 16:30 and incident happened in less than 20 minutes after that. At that point battery bank was about 80% charged and solar panels were pumping in ~40A. Net current draw from the batteries was between +30A and -10A during this window. Attaching screenshots from Victron MPPT and Shunt. Looking at the output of the shunt, doesn't look like alternator ever produced anything, all power was coming from the solar panels.

So all in all, I struggle to explain this. I don't think there was a surge from the alternator. Also there was really no possibility of a BMS shutdown of any of the batteries.

This was an alternator that was installed brand new when we purchased the boat 1.5 years ago, as the original one burned during the survey and was replaced as part of the purchase. Since then, we changed the batteries, added solar etc etc and it has been running without any issues close to a year with this new setup.

Is this common? Alternator failing is one thing but it going into flames is another thing, presenting a fire hazard. Any relevant experiences?

Hi
I had a very similar alternator fire a year ago also with Balmar gear. We had only had the engine running for a few minutes when the alternator caught on fire, the same alternator and regulator we had been using with no problems for 6 years. It turned out that the circuit breaker rated at 150 amps tripped even though the alternator was outputting 100 amps. The circuit breaker tripped for unknown reasons and as soon as that happend the alternator went into meltdown!
This was a very expensive fault so we now use a 150 amp slow blow fuse between the alternator and the battery.
I have assumed the circuit breaker was faulty but there could also have been a spike from some other fault, we will never know now as all components were burnt out.

[JasonS]

I have no experience with Balmar, but it seems that emailing/calling them and speaking with someone in senior management would be worthwhile. They may be interested in having you return it for analysis and possible replacement.

Some companies are excellent like this, most are not. I just had a very positive experience with a now Garmin owned company. I “thought” (not confirmed) that the specs on a unit (which was purchased in the first few days of its intro) may not have been met. They offered me a brand new unit and paid shipping both ways. And this is 2 years later. They want to check specs on it.

A good place to start if you can’t find info elsewhere is LinkedIn. A quick search shows Chris Witzgall as the Product Manager who introduced the alternator protection device. It’s worth a try!

[CarlF]

When you replaced the alternator did you replace the 614? Regulators fail much more often than alternators and can do so in mysterious ways. And the Balmar temperature sensors fail if bent (easy to do while tightening on the battery post).

But that alternator is dangerous now since internal insulation has been damaged.

I’d replace the alternator with a Balmar XT that is better suited for Lithium and replace the 614 including a new temperature sensor.

[MerMike]

I can offer some insight, having just installed 2 drop-in LFP batteries with a 100A Ample Power alternator. I also have the MC-614 with temperature sensor. It's bolted to the back of the alternator and AL1 was set for 90° C.

After an hour of motoring I took a thermographic image of the alternator and it was eye-opening. The hottest part of the alternator reads 246°F, well above the 90°C setting.



I've been told that temperature can break down semi-conductors.

I reduced the setting to 70° C and the temperatures lowered to a reasonable level.

My takeaway is that the Balmar temp sensor does work, but it's not necessarily measuring the hottest point in the alternator.

[boatnerd]

Could it be the balmar harnesses? They often go bad over time and in turn cause havoc with the alternator. The contacts get corroded or covered in belt dust and oil residue. This can be an unseen problem in small engine area that cause phantom issues. Sometimes an alternator get replaced but the old harness gets reused.

For Lifepo4 i believe the alternator temp sensor mounted on the alternator is almost an essential item to limit output. Seven 100ah batteries at full field could put out alot of current which in turn could heat up any loose connections or undersize wiring.

Bluetooth monitoring apps are useful to see what's going on but i wouldn't necessarily trust all the data. It's should be looked at as just a reference. They too can give false readings if the sensor, wiring, or components they're connected to are not functioning properly.

[goboatingnow]

If you have a situation where an abrupt disconnect of an alternator causes a fire something else has gone seriously wrong , there simply isn’t the energy in the inductive pulse to ignite or sustain a high temperature to cause a fire.

In my experience either bearing failure , or high sustained current with result high temperature is the way to cause a fire and it’s the shellac and plastics that burn.