Issues with Balmar Digital Duo Charge charging the thruster bank.

I'm in Klemtu with a short burst of cell service. I discovered my thruster bank was no longer being charged while under way. The equipment:
1) Wesmar 24 volt thruster.
2) 2XNorthstar Battery Company NSB M12-210, CCA 1830 amps, MCA 2350 amps. These are 12 but are connected in series with what looks to be a relay.
3) Balmar Digital Duo Charge to charge the thruster bank.
4) Victron Centaur 40 amp charger, shore power and genny.
Thruster Bank:

Relay

Charging buss bar, Digital Duo Charge is the smaller gauge wire.


So, my layman's understanding is: when the thruster is toggled at the helm, the relay trips, combines the batteries in series to 24 volts and the thruster is engaged. This is what is working now. However, I believe the draw on the Duo Charge exceeds threshold and the fuse pops. I would have thought that the Duo Charge would shut down and wait until the demand is stopped before continuing the charging procedure.

I have discovered that the inline 30 amp fuze "popped" on the house bank side of the Digital Duo charge when the thruster is engaged. Otherwise the Duo charge works. I don't have a spare 30 amp fuze right now, but the 20 amp fuses definitely "pops".

The Balmar DDC manual covered this on page 4:

"Solenoid Drive:

In applications where the Duo Charge is used to support larger capacity starting batteries (such as 4D and 8D models) or windlass and/or thruster batteries, there may be instances when the 30-amp capacity of the Duo Charge’s circuitry may not provide sufficient current to satisfy demands. When used as a stand alone charge source, the Duo Charge is designed to discontinue charging when demands exceed its capabilities. At that point, the Duo Charge will wait for a short period and query if the demand has diminished to below its 30-amp capacity. If so, the Duo Charge will continue charging. If demand continues to exceed capacity, the Duo Charge will continue to shut down, while checking periodically to see if demand has diminished.

If your application requires frequent charging levels in excess of 30 amps, it may be necessary to add a solenoid as a method to manually bypass the Duo Charge’s internal circuitry. Keep in mind, the Duo Charge will not automatically activate the solenoid if the demand exceeds its capacity. As such, it is important to monitor charging voltage closely at the battery being charged by the Duo Charge. To utilize the Duo Charge’s solenoid drive function, it will be necessary for the user to supply an appropriate-capacity solenoid and a toggle or other ON/OFF switching mechanism to control the bypass function."

So either the Duo charge has issues, the Relay is no longer functioning properly, or the Thruster is requiring more power than can be accommodated. Thoughts? Is there a more current decide than the relay that would be more appropriate in this application?

The 30 amp charge limit is one problem (there are others) with a Balmar Duo Charger. I happen to like them and use one to charge my thruster bank and another to charge my genset battery. However, this should not have caused your fuse to be blown. Because of this, I would first check all your wiring to see that there is not a short in the system somewhere.

As for the 30 amp limit. The Duo Charge should be configured to the type of battery that you have. However, as the manual states, if the demand is greater than 30 amps, the Duo Charge will shut down until the demand is less than 30 amps. I have never run into this problem with my setup. My thruster bank is large enough that I have never depleted the bank down to the point where its charge demand as exceeded the 30 amp limit. This is even with both thrusters, windlass, and crane all being connected to that same bank. Did you use the thrusters a LOT, to drain the battery bank down significantly?

I have some cables on the boat that I could combine the thruster bank with either the house bank or the starter battery should I drain the thruster bank to low. The house bank is charged via shore charger, alternator, or genset so would also then charge the thruster bank if they were paralleled. The start battery is charged via an Echo Charger which will only charge at a 15 amp rate but doesn't have the limit issue the Duo Charger does.

You might see if you can temporarily parallel your thruster bank with your start or house batteries to get them charged up. However, I think the 30 amp Duo Charge limit is not related to that blown fuse.

Thanks Dave. The Thruster bank is nowhere near discharged. The batteries are near 13 VDC, according to the Victron meter as well as my own measurements with my multimeter. So why isn't the Duo Charge shutting off at the 30 amp limit? It's supposed to. I agree something else is going on as well.

If I get the Duo charge working, at least I can prevent further sulphation of the batteries, if there is a danger of that. And it seems to work for the time being, providing I don't use the thruster. For now, I'm mostly anchoring and can work without the thruster.

Do I use the thruster? Yes. I do because I can. And it hasn't been a problem until now. But I and and do dock the boat on my preferred side without it, even in current.

Will your clamp on DC ammeter record? Some meters will record the highest current and voltage if they have a record mode although not simultaneously.

I don't think yours will unfortunately. Something I forgot about and used to use a lot.
You have a good meter otherwise, just unfortunate this is one function it does not appear to have. I did look it up.

Regardless you might try that new meter to measure the current periodically to see how high the current level goes. Especially soon after thruster use.
If the Duo Charge is intended to actually limit the current to 30A or shutdown if the pass through is greater than 30A then it may be the unit is faulty.

Although I cautiously mention this, a slow blow fuse might be appropriate IF the Balmar is working properly but just not fast enough. The slow Blow fuse would give a bit more time. I would ask Balmar first though since I'm not an electronics tech. and have no experience with this unit.

The meter should help determine what level is tripping the fuse.
I have seen fuse holders that caused fuse tripping. If the contacts between fuse and holder are oxidized or the least bit loose they can cause the fuse to heat up and trip when it should not. The fuse is a heat sensitive device. Try feeling the fuse holder in operation. If hot that may be the problem.

Other wise you might fit Balmars relay suggestion.
I can see if the thruster bank is somewhat discharged the draw could be over 30A but another question would be for how long.
A regular fuse will trip depending upon how much overload exists after a long time or quite quickly.

You may need to contact Balmar and do the mod. I suspect a Cole Hersey relay could be used , continuous duty unit, of about 80A but use that meter to attempt to find out how much current is passing.

But that maybe begs the question that for your purposes the Balmar is the wrong unit if it cannot handle a legitimate high load like this. Rather use an ACR which will simply close upon the primary battery reaching an appropriate voltage and will remain that way untill the primary battery voltage drops to the opening point.

Thanks "C". There is definitely more trouble shooting I need to do and one is to find out what the draw is from the thruster when engaged. I can check that with the Blue Seas clamp meter. Anyways the unit has worked fine for several years now, so something has changed. I have a Mastervolt voltage regulator that sends charging to the house bank, starter bank and gen start batteries. The Gen start battery hardly needs this at all, since it is charged during the generator use. That can be relocated to the thruster bank.

I can't help but think tho' that something else is going on, either with the relay or something else. I only wish that the programming of the BDDC was with dip switches rather than some stupid reed switch. What a silly concept. Basically means you gotta get some technician to work through this.

If it was all working before,then obviously something has changed. Since the fuse pops when you activate the thrusters, and is otherwise fine, I would start with the solenoids. I'd start with understanding how the duo is wired to the batteries, and how the solenoid rewires them for thruster operation. Perhaps the fault is allowing the duo to see 24V rather than 12V, even just briefly?

It's also possible the duo has failed and rather than shutting down, is going over current and blowing the fuse.

Any blinking lights on the duo that might give a clue?

The only blinking lights I have observed indicated that the "house bank voltage" was too low. This indicated an issue on the house bank side, and I checked the fuse. House bank is charging normally.

The Duo is cabled to the batteries on the charging buss bar together with the Victron charger.

I had the genny on this morning and topped up the Thruster batteries, but not to float charge. I will be able to charge later today with the Duo charge.

So, with the main engine off, I ran the bow thruster for a four X 5 second bursts and identified -39 amps leaving the thruster bank as measured at the shunt and the Victron battery monitor. Battery voltage declined to below 11. The monitor does not indicate anything near 24 volts, so I presume combining the batteries in series occurs outside of where the shunt monitors the voltage. Voltage is back up to 12.96 five minutes later and is continuing to slowly rise. We are at anchor and there is no charging source right now.

I want to resolve questions about the solenoid relay, but am uncertain how that can be tested with my limited knowledge. I believe it to be working as the bow thruster is working, but cannot be certain if it is sending some sort of power surge that the Duo charge cannot handle.

JD, your issue is way over my head but I would agree that if this system has been working well for a few years, something has changed.

I wonder about the Duo Charger seeing 24v as was mentioned above. I don't know what happens in that situation.

Maybe a call to Balmar would be in order to answer that question. If you are fortunate, maybe CMS will see this and chime in.

I don't think there is any evidence for the Duo Charge seeing 24 volts when the thrusters are in operation. The Victron monitor indicates well less than 13 volts during the operation with no charging source. One good "test" will be when I can get replacement 30 amp fuses.

If the "relay" tests out fine, then the DDC may be on its way out. As I mentioned, fortunately I can move that cable that connects the Mastervolt voltage regulator to the genny battery and move it to the thruster bank. That voltage regulator should be more than capable of handling the demands of the thrusters. I hope!

Duo charge is putting out 3 A into thruster bank at 13.3 V. House Bank is at 14 V and is accepting 56 A at ~95% SOC. at. Least something is going into the thruster bank. It was nearly at full charge, I think. Leaving cell service soon. TTYL.

Second pic to the right is the series/parallel solenoid. Common on engines where 12v system and 24v starters. When energized, it changes the two batts from parallel to series, then back to parallel when de-energized.

In this system, only one batt needs to be connected to charge source. When sol is in par mode, the other batt should charge too.

When thruster is energized, charge source is going to be overloaded and if it does not shed load itself FAST, could see it popping the fuse.

Some charge systems have a lead that can be connected to starter (or thruster, in this case) solenoid lead that when energized, sheds the charger load to protect it. Might look into the duo charge lit and see if such a feature exists.

Check both batt term volts and make sure they are exactly equal in par mode. Also, if at 13v, there is/was some charging gooing on from somewhere.

JDCAVE said:

Duo charge is putting out 3 A into thruster bank at 13.3 V. House Bank is at 14 V and is accepting 56 A at ~95% SOC. at. Least something is going into the thruster bank. It was nearly at full charge, I think. Leaving cell service soon. TTYL.

Click to expand...

That sounds right. The charge voltage from the Duo Charge is determined by the charge profile. If the bank is close to be fully charged, very little current should be going into them.

Thanks guys. I'm in Shearwater and am on my way to pick up some fuses. I'm going to start with 30 amp and if that pops I may then try 40 amp which will indicate whether the Duo charger is the issue or not. The Duo charger may not be shutting down at 30 amps.

I have not used the bow thruster since my tests, since I have been at anchor and have not needed it. The thruster is functioning fine it seems, but I am not certain if the AGM's are on their way out.

Bow thruster update: replaced the fuse indicated above with a 30 amp fuse as stipulated in the BDDC manual, and the fuse does not pop. Not sure why it popped the first time with the 30 amp fuse, but I suspect perhaps overuse of the bow thruster might have been responsible. Still, I think the batteries may be on their way south so will continue to monitor.

Thanks to all for your thoughts!

Jim

I have seen fuses that fail from frequent use at their capacity or if slightly over capacity.
The little element heats and bends each time and eventually fails, not from overcurrent, but mechanically.
Use infrequently and at less than capacity and they last fine.
I can see that happening in your application.
Try using you meter with someone monitoring it just as a check.

C lectric said:

Try using you meter with someone monitoring it just as a check.

Click to expand...

Thanks "C". Yes, I have been checking things with the meter and have concluded that the shunt that provides info to the Victron monitor, monitors only one of the batteries, as the "amps" indicated on the meter are about half of expected when the thruster is engaged, and also about half of the charge current from the BDDC, as measured by by the clamp meter.

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