Urgent: Victron DC2DC cut off input voltage is low but isn‘t

[CaptainRivet]

Hi all,
Supporting a buddy boat as shore support during Atlantic crossing and he is facing a strange behavior from the Victron DC to dc 12 30/30 and cannot charge his Lithium via it.
He has 420AH of Gel as starter/backup house where the Victron DC2DC is connected charging 560AH lithium. 90A mastervolt alternator on a Volvo d2-55 with regulator for gel, charging gel.
When he switches on the Orion, the Orion starts and then over course from 2 min the input voltage drops from 14,78V to 10V.
If he puts a 30A load (not the dc2dc) on the gel the gel stays stable.
When he puts the 30A from the input voltage on DC2DC dropes to 10v over 2 min and dc to dc switches off. But measuring at the gel it’s stable.
What can that be?

[s/v Jedi]

Originally Posted by CaptainRivet

Hi all,
Supporting a buddy boat as shore support during Atlantic crossing and he is facing a strange behavior from the Victron DC to dc 12 30/30 and cannot charge his Lithium via it.
He has 420AH of Gel as starter/backup house where the Victron DC2DC is connected charging 560AH lithium. 90A mastervolt alternator on a Volvo d2-55 with regulator for gel, charging gel.
When he switches on the Orion, the Orion starts and then over course from 2 min the input voltage drops from 14,78V to 10V.
If he puts a 30A load (not the dc2dc) on the gel the gel stays stable.
When he puts the 30A from the DC2DC the voltages dropes to 10v over 2 min and dc to dc switches off.
What can that be?

Which model Orion? Is it a Smart model? 12 30/30 doesn’t exist.

Are the voltages and currents measured or confirmed with a multimeter? Where were the meter probes connected during the measurements?

[donradcliffe]

Just use jumper cables to charge the lithium.

[Scubaseas]

Do the lithium batteries have a low voltage cut out? Sounds like the BMS on the LiFePo4 battery is not letting voltage in? Or is there a fuse between the Orion and the LiFePo4 bank? I'd call Victron and see what they think.

[SV Confianza]

Assuming that all this info is correct, and the gel bank indeed is stable over that same two minutes, the problem really can only be the cables or the dc/dc itself.

If he has extra cables, he can swap them out (the ones to the dc/dc) to eliminate that problem at least. Or he can try to swap the cables the run to the dc/dc to a different battery in the bank. It could be connected to the one bad battery that the others can’t compensate for but that seems like a reach with that size bank.

I don’t use a dc/dc on my setup so I shouldn’t try to comment on the problems that could arise with the victron itself.

[CaptainRivet]

Originally Posted by s/v Jedi

Which model Orion? Is it a Smart model? 12 30/30 doesn’t exist.

Are the voltages and currents measured or confirmed with a multimeter? Where were the meter probes connected during the measurements?

Yes orion TR Smart 12V/12V 30A
Gel is directly connected to a mastervolt shunt and battery manager, confirmed with measuring at the poles of the battery and poles of the argofet, who is splitting bowtruster and gel starter/backup house.
Then on input of the Orion shows the Same then the app.
Well the only thing in between is 50cm cable and a fuse.
Told him now to just use a new piece of cable without a fuse to the DC2DC and just reconnect all new to the battery.
Installation is a month old, I helped him to do and we did 3 days together all the use cases that could happen, all was fine and DC2DC was working correct.
It’s the Orion itself that’s cutting out, gel is at 14V and 100% full and LFP is at 13,4V. Taking the 30A.

[s/v Jedi]

Originally Posted by CaptainRivet

Yes orion TR Smart 12V/12V 30A
Gel is directly connected to a mastervolt shunt and battery manager, confirmed with measuring at the poles of the battery and poles of the argofet, who is splitting bowtruster and gel starter/backup house.
Then on input of the Orion shows the Same then the app.
Well the only thing in between is 50cm cable and a fuse.
Told him now to just use a new piece of cable without a fuse the DC2DC.
Installation is a month old, I helped him to do and we did 3 days together all the use cases that could happen, all was fine.

It sounds like maybe the BMS is disconnecting the house battery?

If he measures 10V on the terminals of a gel start battery then either the battery is defective, or there is a very large load, like a near dead short.

[wholybee]

You state that the voltage at the AGM is stable, but at the input to the DCDC it slowly drops to 10V. Assuming that is confirmed by a voltmeter, there is a bad connection, that is heating up, and as it heats, gets worse. It is probably a crimp connector somewhere between the AGM and the DCDC. But it could be something else, and could even be a bad connection (cold solder joint) inside the DCDC.

But 90%, it's a bad crimp connection between the AGM and DCDC. It could be either the positive or ground, so check both.

[Scubaseas]

Originally Posted by CaptainRivet

Yes orion TR Smart 12V/12V 30A
Gel is directly connected to a mastervolt shunt and battery manager, confirmed with measuring at the poles of the battery and poles of the argofet, who is splitting bowtruster and gel starter/backup house.
Then on input of the Orion shows the Same then the app.
Well the only thing in between is 50cm cable and a fuse.
Told him now to just use a new piece of cable without a fuse to the DC2DC.
Installation is a month old, I helped him to do and we did 3 days together all the use cases that could happen, all was fine and DC2DC was working correct.

There may be a special restart situation with the battery if the house bank went below a certain voltage. Try checking wiring and fuses. If they're OK try making sure ALL the house loads are off then try turning on the Orion and see if the House will start to accept a charge. If you have a 10.2V or lower house and a lot of stuff on you need to remove the load by turning stuff off and let it charge up some first. To put it another way you are drawing more off the house than the DC2DC can put back in.

I have Renogy LiFePo4s which if run below 10.2V need a special power supply to turn the BMS back on. Not sure what that means and I've never let the bank go that low but there may be special voltage considerations if you ran the house down below what the BMS allows.

[CaptainRivet]

So one issue is found, it was the breaker in the input line to the DC2DC.
Input breaker 13.3V, output breaker fluctuate between 13 and 5V, the longer on more 5V.
Replaced and now at least voltage is stable.
But output alternator is 14,78V=input gel but the input voltage on the DC2DC is 12,78V.
It looks like DC2DC is taking the 30A out of the gel as the gel is very slowly dropping in voltage but should actually show the 14,78V from the alternator.

BMS is not involved at all and not shutting off the Orion. All ok on LFP side.

[Captain Bill]

What Wholybee said. 30 amps through a bad crimp or solder joint will do exactly what you describe. I could also be a damaged wire but not as likely. If he has a laser temperature sensor, a quick scan of the wires will show a definite hot spot.

[CaptainRivet]

Thank you everyone, problems solved:
Issue 1 was a faulty 60A breaker in the input to the DC2DC
Issue 2 was a cable break in the field wire to the alternator.
After issue 1 was found the voltage was high from alternator because it was not delivering any amps as field wire just got contact from time to time means the DC2DC took the 30A partly from the starter/backup 420AH gel when field wire didn’t have contact. We couldn’t see that before due to faulty breaker. And when we tested the alternator delivered 30A to the gel and breaker was ok…assume partly because that happened now after longer time motoring.
Replaced the field wire and all working as it should, 57A from alternator, 32A for DC2DC, Rest for bowtruster battery, normal house loads and autopilot.
That’s the advantage if you DIY your system, you know it and can troubleshoot it.

[s/v Jedi]

Originally Posted by CaptainRivet

Thank you everyone, problems solved:
Issue 1 was a faulty 60A breaker in the input to the DC2DC
Issue 2 was a cable break in the field wire to the alternator.
After issue 1 was found the voltage was high from alternator because it was not delivering any amps as field wire just got contact from time to time means the DC2DC took the 30A partly from the starter/backup 420AH gel when field wire didn’t have contact. We couldn’t see that before due to faulty breaker. And when we tested the alternator delivered 30A to the gel and breaker was ok…assume partly because that happened now after longer time motoring.
Replaced the field wire and all working as it should, 57A from alternator, 32A for DC2DC, Rest for bowtruster battery, normal house loads and autopilot.
That’s the advantage if you DIY your system, you know it and can troubleshoot it.

You mean the blue wire between the regulator and the alternator field terminal? Yes, if that is intermittent then that will throw everything off.

I was fearing there were faulty diode or FET isolators hidden somewhere

[smac999]

if input battery is 14v and orion input is 10v. there is only 2 options. cables / conectinos from battery to orion is bad. or orion is bad internally and it it really has 14v at the posts but only sees 10 inside.

both can be confirmd with a volt meter by measuring battery and orion posts.

[CaptainRivet]

Originally Posted by smac999

if input battery is 14v and orion input is 10v. there is only 2 options. cables / conectinos from battery to orion is bad. or orion is bad internally and it it really has 14v at the posts but only sees 10 inside.

both can be confirmd with a volt meter by measuring battery and orion posts.

Correct Jedi..The cable break in the field wire was kinda randomly connecting and not. Most likely that cable break is old and was even present when we tested the new installed LFP system 6 weeks ago. There breaker worked and DC2DC too.
But it needed the breaker to get faulty additionally that this could discovered…Murphy is calling…it’s mostly several things that need to go wrong till you realize something is wrong.
If that breaker wouldn’t have been faulty that issue with the field cable wouldn’t have been detected that easy.
And doing that via iridium communication on a new install when in the middle of ocean is quite challenging.
What helped is the fact that all switching of BMS is done via optocopler so with one quick view you can see if the BMS was involved and switched or not. Each source has its own optocopler, so what is on shines red…
Means I put I acrylic sheet as cover on my BMS Box so I See this optocopler too.

Thanks again for prompt help.