Alternators burning out, what are we doing wrong?

DIY
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1

We’re experiencing installation problems and could do with some help!

Basic system is a Lucas A127 80A alternator —> AGM starter battery ---- > 60A fuse — > Orion XS set to 40 Amps input/output —> 50A fuse -----> Victron Battery Isolator ---- > LiFePO4 680AH house bank (about 90% charged)

We are rapidly destroying alternators, the most recent seeing flames!

Today we fitted our last remaining alternator, while draining the starter battery by maybe 5%. After disconnecting the lithium circuit completely we started the engine and all ran well. We saw an initial current of about 10A dropping to around 4A after 10 minutes. Clearly the problem relates to the charger/settings/wiring? No fault codes from the charger.

If we reconnected the lithium circuit, I’m quite sure our last alternator would also be destroyed. Should we reduce the input from 40A? The starter load of say 10A plus the 40A for the LiFePO4 bank = 50A should be well within the capacity of the 80A alternator surely?

Any help gratefully appreciated.

Thanks in advance

Mike

2

A single 80A alternator is a bit small for recharging a 680Ah house bank.
However: You should be using a smart alternator regulator, with temperature sensing - this would enable limiting the alternator if it overheats, or too much current is demanded.
Without this: Can you limit the Orion XS charge current to a lower value, i.e.10A, and then progressively increase it from there, until the alternator starts getting hot. It would be a good move to use a clamp meter on the alternator to check the load current whilst it is running. A lot will depend on engine room ventilation, as these automotive alternators need a lot of fresh air to cool properly.

3

Thanks MikeD

Forgot to add that we already have a Sterling external regulator with a temperature sensor. The alternator failures have been quickly following the engagement of the DC to DC charger. Possibly just a few seconds after engagement, hardly time for the temperature to rise much?

It might be an idea to have a secondary temperature sensor to instantly disable the charger.

If we also consider the possibility of a heavily depleted starter battery, requiring an assist from a “charge pack”, the starter battery itself could demand a very high initial current. Much more than the 10A as above.

I read that the recommended maximum current for long continuous use (such as on a yacht on a calm day) was 50% of it’s maximum rating.

But yes, reducing the input/output current to the charger would be a good start point, keeping a close eye on the alternator’s temperature.

4

This sounds more like a wiring issue rather than overtemperature. Are you sure that theres no short in the system? Do you have a schematic?

5

lithium schematic
lithium schematic1920×2560 519 KB

lithium upgrade notes
lithium upgrade notes1920×2560 631 KB

charging board
charging board1920×2560 1.14 MB
before some tidying!

6

Are you sure that the alternators D+ can handle switching a relay coil? Does the coil have a flyback diode?

Theres no need to physically switch the input of an Orion XS, you can setup engine shutdown detection. Alternatively, you can use the remote on/off.

Where does the wire go that is connected to the energize terminal on the argofet? Since the input for the argofet comes from an Orion and not an alternator, theres no need to use the energize terminal. This could be the main issue here.

7

Thanks, the 100A relay can be removed, bit of an overkill really!

At present the D+ terminal powers the Argofet, the Orion charger and connects to the Sterling external regulator.

Could we remove the D+ supply to the Argofet and relay, and energise the Orion from Ign+ ??

This would leave the D+ connected only to the charge bulb and the Sterling external regulator.

8

We’ve discussed these issues and questions quite a few times on the Boat Forum as well, where the batteries are supposed to be charged via the drive system.
I had also linked a video about this once… but I can’t find the post right now. Basically, it’s about the charging curve of the LiFePO4 battery and the alternator, which isn’t cooled when the vehicle is stationary… but the battery still demands nearly full power from the alternator… and since the alternator isn’t cooled when the vehicle is stationary, it burns out.

9

Just my 2 cents.

An alternator of 80A is kind of slim this days, even for a small car.

Using it to power so much is the perfect recipe to destruction. This alternators have very low efficiency and are exposed to high temperatures.

Normal max. load for an 80A alternator is 40-50A, some spikes are accepted. Such battery capacity takes a lot of current for charging and if limited, takes a lot of time but, even the extra 10-20A used for battery bank charging is a burden for hours on the alternator.

Should consider a higher capacity alternator and/or much more efficient.

10

Yes, since the energize terminal of the Argofet is an input which will provide voltage on the Argofet input to energize an alternator connected to it. But in this case there is no alternator connected to the Argofet, so the energize terminal can be left unconnected. (And possibly needs to be left unconnected, since you would bridge alternator/Starting battery voltage directly to the output of the Orion)

As for the discussion of overheating, yes that can certainly be an issue. But overheating takes some time, even if as short as a few minutes. But alternators are dying here in a matter of seconds.

11

Best answer is Mike’s. Use a clamp meter to check what the alternator really delivers, set the Orion to a much lower current now and if you can, use a thermo camera to figure out when the alternator get’s hot. Running at 90 degrees should not be a problem, running 12 hours at 100 degrees could be problematic. So, measure first and then head on with conclusions. Btw; a 680 Ah LFP bank is not necessarily the problem if you don’t expect it to be seriously charged by the alternator in less time…if you are aware of the limitations and are fine with them, no worries.

12

Went to the boat today armed with all the advice from this thread.

  1. Removed the D+ connection at the Argofet Isolator.

2. Put a 30A fuse in place of the 60A one on the Input to the DC to DC Charger. Just as a temporary precaution.

3. Removed the 100A relay completely.

4. Removed the “bridge” from the Remote on the Charger, and connected the “H” terminal to an Ignition Live source.

5. The alternator D+ terminal now only connects to the Charge Warning bulb and the Sterling External Regulator.

6. Reduced the Input and output of the Orion Charger to just 5A!

Took a sharp intake of breath and started the engine. No smoke from the alternator!

After a couple of minutes the clamp-on ammeter showed about 5 Amps at the alternator. The Victron App showed about 4 Amps going through the Charger to the house bank, confirmed by the boat’s own instruments. The remainder would be going to the starter battery.

I’d already depleted the house batteries a bit and turned on several lights etc.

Gently upped the Input and Output limits on the Victron Orion Charger App to 10A and the charge rate went up to just under 10A at the alternator.

Upped again to 20A and the charge rate went up to just under 20A at the alternator.

It stayed at just under 20A at the alternator even when the limit was upped to 30A, even when taking the engine to 2000 rpm.

It might be that the state of charge of the 680Ah LiFePO4 bank caused the charge to be limited. I’ll leave the Input and Output limits at 30A for the moment.

An error message 33 came up on the App, suggesting the voltage was too high on the Input to the charger. This has now gone.

I’ll go through all the App Settings at some point to optimise them.

To add temporary confusion to the mix this morning, the charge light holder had poor contacts so didn’t work. Took a while to find this out and replace both! And the tacho didn’t work, suggesting an alternator rectifier problem. But a wire had become dislodged from the back of the instrument with all the work circuit checking, quickly remedied!

Afterthoughts

After 10 minutes the temperature of the alternator case was barely 30 degrees C. In the past, even with heavily depleted AGM batteries and sustained high charge rates, we’ve never seen it go above 80 degrees C

The Lucas A127 alternator is designed for cars, which have good cooling from passing air. But it should do an adequate job of charging our boat’s batteries, if taking a bit longer than a marine specific alternator.

There’s already a temperature sensor on the alternator for the Sterling external Regulator, which reduces the current if overheating occurs. Just wondering if there’s an additional bolt-on device which can interrupt the field-wire supply to the Sterling as a back-up?

Overall it seems that disconnecting the D+ from the Argofet has made all the difference. Thanks chrigu

I’m a bit baffled by the reasoning behind this, but it seems behind today’s great success !

Thanks for all the advice

Mike