C-26 Thruster Battery Dead

[koedding@comcast.net]

We just had the thruster battery (#3) replaced on our 2016 C-26, which we dry-stack. It was dead and wouldn't hold a charge. We have 150 hours of engine running time and both the engine and house batteries are able to maintain a charge and check out okay. Not that this matters, but in the C-26/C-28 Owner's Manual, the #2 battery (engine) is positioned aft and the #3 battery (thruster) is positioned forward, in the port battery box. However, these positions are switched on our C-26 or the Owner's manual is labeled incorrectly.

Having reviewed the posts regarding batteries, it seems that the post "tatoweb on Mon Apr 09, 2018 12:00 am" is more reflective of my issue. I asked our repair shop (Cutwater Dealer) to make sure there was nothing draining battery #3, since bilge pumps 1 & 2 are wired to the thruster battery. They found nothing wrong. Is it possible that the charger relay is not working correctly, since both the engine and house batteries are getting and holding a charge?

 

[Red Raven]

Is the Thruster ACR LED lit when the charger is on?

 

[BB marine]

The fact that you are rack stored. I would assume that the battery charger is not used while the boat is not in use. This would indicate that your issue may be caused from- 1) battery draw when not in use and discharges battery.2) Battery is no longer holding a charge and may need to be replaced. ( I have a 2016 Cutwater and have noticed our house batteries are not maintaining a full charge anymore and may need replaced. The boat was built in 2015, so the batteries are 3 years old. I use the 3 year battery replacement plan and use maintenance free wet cell batteries less expensive). 3) Charge relay not working or not wired properly. There is a spade connector that has to be attached to the Ground connection on the Relay. If it is attached to the remote spade connector the relay will not work. Also if the Thruster battery for what ever reason was low on voltage which from your description it is. The relay will not connect to thruster battery to the battery bank for engine charging. You have to excite the battery with a high enough voltage for the relay to connect to the bank and charge the battery. ( this is the simplified explanation). First is to answer Red Raven question light on working no light its not connected . If battery is near dead or very low I doubt the light will be on regardless.

I would change the component set up. I have all accessories attached to the house battery, auto bilge pumps, everything on board . Nothing goes to Engine battery or thruster battery. In the event that the house batteries fail the bilge and other accessories can be powered with the engine battery by using the cross over switch for emergency.
There are several topic post on Tug Nuts for trouble shooting the ACR relays with good explanations of how they work.

 

[Cutwater28GG]

Perhaps the propane solenoid or co2 detectors are wired to the thruster battery

 

[stwendl]

My pet peeve on the tugs (and possibly cut water) is the setup for charging by either motor, solar or shore.

My shore charger has three outputs and is wired to each battery individually. However, when the shore charger is on, so are the ACRs defeating the shore chargers smart charge profile for each individual bank. The acrs should be disabled during shore charging by means of the inhibit input on the acrs.

 

[Cutwater28GG]

agreed I do not like the charging circuit.

 

[Osprey]

Stwendl writes:
"My shore charger has three outputs and is wired to each battery individually. However, when the shore charger is on, so are the ACRs defeating the shore chargers smart charge profile for each individual bank. The acrs should be disabled during shore charging by means of the inhibit input on the acrs."

I am assuming here that the charger being discussed is a ProMariner Pronautic 12nnP series (nn could be 20, 30 40 ...). The instruction manual states: "THE PRONAUTIC SERIES ON-BOARD MARINE BATTERY CHARGER INCORPERATES INDUSTRY LEADING TECHNOLOGY, DELIVERING FULL AUTOMATIC AND SEQUENTIAL MULTI-STAGE CHARGING THAT PROVIDES ELECTRONICALLY CONTROLLED CHARGING, CONDITIONING AND MAINTENANCE OF ALL BATTERIES AND BANKS CONNECTED". Pay particular attention to the "ALL BATTERIES AND BANKS CONNECTED". It does not mean that each output can be set to a separate profile or be on a separate stage. During the charger setup the user chooses a profile which applies to all 3 outputs . During charging each output has the same stage voltage at the same time. For example, connection 1 cannot be on a bulk stage voltage while connection 2 or 3 are on absorption or float voltage. If, say the house set is significantly discharged relative to the other banks, the relevant ACR will be open and the house set will draw more current than the other banks. More current because the differential voltage between the house battery and charger is greater. Once the house set is sufficiently charged the ACR closes. The ACRs provide isolation when battery voltages are low and combines banks when safe to do so.

 

[stwendl]

I have read that section and it makes no sense that having three separate output intended for three separate banks (of potentially different soc not to mention capacity) are charged at the same regimen. Perhaps in sequence, but not in parallel. Having a multi level charger assumes the levels adjust to the state of charges of that particular bank and do not ghost other banks along forcing a charge that is inappropriate onto a battery. Thusly the ACRs should not be connected either when a smart charger is connected. They do make sense if a simple alternator supplies the charge which is not really good for batteries. Having said that, I admit that millions of car batteries are being charged that way every day. However there is no reason not to apply a bit of effort to treat the batteries gently

 

[koedding@comcast.net]

Thank you all for the feedback and putting this in layman's terms. Since we dry-stack, we are only able to use the charger when we are connected to shore-power on overnight cruises. I would like to think that Fluid Motion had setup the electrical systems on the boat to ensure that the batteries are properly charged by the engine and/or solar panel, rather than by shore-power. Per the solar wiring schematic, the thruster battery is not connected to this charging circuit. Therefore, the only way that it could receives a charge is while we are underway. I'll double check the ACRs.

 

[stwendl]

I had an email conversation with pronautics tech support confirming that each bank is charged at the same time and based on the individual banks need

Yes, each bank will have amperage distributed based on what each bank is calling for. The unit will distribute current based on each bank's needs in an effort to have them all top off at the same time.

 

[stwendl]

Stwendl writes:
...
I am assuming here that the charger being discussed is a ProMariner Pronautic 12nnP series (nn could be 20, 30 40 ...). The instruction manual states: "THE PRONAUTIC SERIES ON-BOARD MARINE BATTERY CHARGER INCORPERATES INDUSTRY LEADING TECHNOLOGY, DELIVERING FULL AUTOMATIC AND SEQUENTIAL MULTI-STAGE CHARGING THAT PROVIDES ELECTRONICALLY CONTROLLED CHARGING, CONDITIONING AND MAINTENANCE OF ALL BATTERIES AND BANKS CONNECTED". Pay particular attention to the "ALL BATTERIES AND BANKS CONNECTED". It does not mean that each output can be set to a separate profile or be on a separate stage. During the charger setup the user chooses a profile which applies to all 3 outputs . During charging each output has the same stage voltage at the same time. For example, connection 1 cannot be on a bulk stage voltage while connection 2 or 3 are on absorption or float voltage. If, say the house set is significantly discharged relative to the other banks, the relevant ACR will be open and the house set will draw more current than the other banks. More current because the differential voltage between the house battery and charger is greater. Once the house set is sufficiently charged the ACR closes. The ACRs provide isolation when battery voltages are low and combines banks when safe to do so.

Warming up an old thread. I am currently monitoring batteries with a graphing industrial grade voltage monitor. The graphs confirm that the pronautics 3 bank charger charges all battery banks in multiple stages at the same time but with different voltages as needed by battery. Meaning if one bank is on float, another one can be on bulk and a third on on float. It is however true that all batteries must be on some chemistry/type. You shouldn't mix flooded with maintenance free or agm.
The term "sequential charging" is either incorrectly used in the manual, or refers to different charge stages in sequence.

These tests were done with the ACR disabled. AS soon as the ACRs are enabled the entire scenario changes. ACRs close as soon as either voltage reaches 13.0V and open when the fall below 12.75V (after some time delay to eliminate short spikes or drops).

So what does this mean and why should I care. If a battery is charged it is floated at about 13.2V-13.4V. if another bank is still on bulk of 14.2V-14.4V and the ACR is closed the same voltage will be applied to the floated battery and that battery can start gasing out (battery cooking).

The batteries can be in one of four situations.

1) disconnected
2) connected not charged
if any battery connected to an ACR is over 13v then ACR will close and the higher voltage will charge a battery with lower
voltage until the voltage reaches 12.75V
3) charged by single source (alternator/solar)
if the charge source provides 13V+ the ACR will close and charge both batteries, possibly not in a multistage way.
As the ACRs close, a higher charged battery will contribute to the charging of depleted batteries along with the
shore charger. As both batteries equalize to each other, they will then continue to be charged as a single bank.
4) charged by shore power
as soon as shore charger is connected, voltage on all batteries will be over 13V and the ACRs close forcing the voltage
charge regimen of the most depleted battery on all battery. As the ACRs close, a higher charged battery will contribute
to the charging of depleted batteries along with the shore charger. As both batteries equalize to each other, they will
then continue to be charged as a single bank. The 3-bank charger is pretty much useless with the ACRs installed and
engaged. To benefit from 3-bank charging, the ACRs must be inhibited or disconnect the ground connector at the ACR.
When all my batteries are charged after 3 bank charging and ACRs open, Voltages will be different with maybe a .5v
difference. When the ACRs are then closed there will be a drain from the higher voltage battery to compensate a lower
voltage battery. Over time, batteries of different usage will develop different capacities/voltage at rest. When the ACRs
are then closed you will lose capacity when batteries try to compensate that difference.

The process of one battery being charged by another one when the ACRs are connected will cause as much amperage
being delivered to the lower charged battery which may shorten life of the one or the other battery. Multistage charging
is designed to extend the life of batteries. What is the real benefit? Haven't done the testing yet. Would require hundreds
of charge and discharge cycles. From a manufacturing point, costs could have been saved by installing a single bank charger
if there was no easy way to disable the ACRs and just use all batteries as a single bank. Unfortunately, at least on my R27, there are 3 deep cycle batteries for house and thruster, and one start battery for the engine. I consider those different batteries which should not be parallel for long time (like the ACRs do)

 

[Red Raven]

Thanks Stwendl!

This maybe answers the last remaining question I had. Based on the manual and literature (and common sense!) there had to be a reason for three separate outputs. What Is not clear is whether each bank can be in separate stages (by program) or if the independent outputs just allow the different voltages based on the battery state and current flow (by physics). The charger indicates the “state” it is in. So if each bank can be in a different stage then which one is indicated on the charger?

Would you mind sharing the graphs? It would ideal if you also new the SOC of each bank when put under charge and the “stage” indicated by the charger during the charging cycle if you have it.

The Blue Seas web site also has instructions for how to install a simple ACR isolation switch. I think this would solve the problem you are concerned about. See link below.

https://www.bluesea.com/support/art...lti-Program_Multi-Output_Charger_Interference

Curt

 

[Osprey]

The Pronautic charger has one digital voltage meter and one digital ammeter. The voltage displayed is, I believe, the voltage output present at each of the three outputs. The current displayed is the sum current. I have confirmed the current relationship by measurement. When the ACRs are closed the current from each output is equal at 1/3 of the meter reading. When the ACR's are open the current out of a given output will depend on the difference between the charger voltage and the battery voltage to which the output is connected. (With the sum limited by the charger's maximum current rating).
As stated above, with our tugs' factory setup, very early in the charging cycle the ACRs close to form essentially one multiple battery bank. And yes, if some of the batteries are initially charged more than others , then an equalization takes place between the batteries until all are at about the same SOC. The charger now delivers current, via all connected outputs, to the bank based on the smart charger's programming. Batteries initially at a higher SOC the others do not get "cooked " while the charger works at bring batteries initially of low SOC up to full charge. The equalization prevents such an outcome.
On our tugs do we really need a 3 output charger? Not essentially. On my tug I have two chargers. One rated at 20A and the other at 30A. The 30A is connected with separate outputs to starter, thruster and house batteries. The 20 charger has a single connection to the house (only one of the charger's outputs is connected). I can operate the chargers singly or as a pair. If the house is at a low SOC I operate the pair. The ACRs quickly close and the sum current is 50A. The currents then moderate as the SOC of the bank increase (absorption and float stages).
Is there an advantage to having a 3 output Pronautic charger coupled with ACR action? One advantage is that the current delivered is via 3 wires so wire diameter of each can be less that for single wire setup. Another is if one output fails there are still two others outputs to carry the load.
At present I have the original AGM batteries installed at the factory in late 2011. A couple of weeks ago they all passed a load test. Yes, load testing can be unreliable, but so far they have been working fine in "field" use. Well, they have a somewhat reduced capacity, but this has not been an operational problem. I may take note of advice received and replace them as a matter of an abundant of caution. However, a point I want to make here, is that the Ranger setup has worked well for me over many discharge/charge cycles, so what is the concern with charger and ACR functions?

 

[Osprey]

I have followed the Blue Sea link provided by Curt relating to "ACR / Multi-Program Multi-Output" chargers. This link relates to chargers capable of having a separate program for each output. The Pronautic charger in our tugs is only capable of having one program selected at a given time. For example, during charger setup I selected the "AGM, Profile -2" mode of operation. This applies to all 3 outputs.
There also seems to be some uncertainty relating to capability of individual outputs can have different voltages at a given time. I think not. Note that the voltage display is labeled "System DC Output".

 

[stwendl]

If you read my previous posting it would have answered your question. I can confirm, with graphs, that the pronautic can have different voltages on each output. However, as mentioned before, if you have ACRs between the banks, they will combine all batteries when voltage is over 13V on any output which pretty much defeats that feature.

A diagram is in my album labeled tug nuts charge discharge and is in PDF format which allows zooming. You can see the discharge time over night until 8 in the morning, then the charger was turned on and separate voltages can be seen for each battery. The spikes seen in there are from the refrigerator kicking in. As it turns out the house battery is a candidate for replacement. Originally the batteries were installed improperly, the starter battery was in parallel with a deep cycle battery and the thruster and start battery were both deep cycle batteries.

 

[Red Raven]

Stwendl,

Thanks for providing the graphs! Very interesting. The graphs confirm a few things for me.

First, all banks are in the same charging stage at the same time. The voltages are slightly different (more on this below) but not enough to indicate a different stage. This means that even with the ACRs disabled the start and thruster banks will stay in (or drop back into) bulk charge mode a bit longer than needed. I don’t believe this would occur long enough to “cook” (or otherwise harm) the batteries (though I am not 100% sure).

Second, you are correct in noting that when the ACRs are disabled each bank receives a different amount of current according to its needs. This is the benefit of the three output charger (with disabled (or no) ACRs. The voltage difference is due to this difference in current flow in each output. There is a small resistance in each output between the charger supply and the battery terminal. This resistance includes connections at the charger, the charging cable, and the battery terminal connection. The higher current going to the house results in a greater voltage drop across that resistance and thus a slightly lower voltage applied to the house bank.

Adding a relay to disable the ACRs during shore power charging may still provide some benefit by allowing independent charge current to each bank. It will not, however, stop fully charged banks from experiencing longer bulk charge periods than required. In addition, the value of independent charge current is offset by the initial equalization that occurs when the ACRs tie the banks together. During this equalization the more fully charged banks provide extra current to the less charged bank(s) as both you and Osprey pointed out. So...for me, I don’t think it is worth the effort or even worrying about so I will not be making any change to my charging system.

Thank you providing the excellent graph data. It clarifies what is going on and sheds some light on the confusing and vague ProMariner marketing claims.