Bow thruster

[panhead56]

We own a 34HT Mainship. I’m having issues with my Intimidator AGM 8A8D (1450 CCA) battery that supplies power to the bow Side-Power SE100/185T (740 AMP, SAE 1425) thruster.

The dedicated battery is located in the engine room and supplies power to the thruster with 4/0 cable? (no markings but measured 3/4” across).

This is the second battery that cannot hold its charge any longer. The first new battery was installed in 2016, the second battery 2019. Can the battery be damaged if I use the thruster too long? Over 6 secs...during strong cross winds.

The bow thruster will perform perfectly with a new battery. But after time the battery under performs. We installed a new Pro Marina 1250 50 amp 3 bank charger back in 2019. With correct settings. Hoping that this was the problem.

I checked all terminal connections to make sure that they were tight. I came across the bow thruster positive battery cable that connects to the 500 AMP fuse plate. The terminal was burnt but tight. Possibly a bad terminal made connection. (See attached photo).

I contacted Side-Power. They stated that “if the thruster motor is not getting good voltage, below 10.5v it will Pitt the contacts in the solenoid”.

Back in 2019 I had the thruster motor rebuilt due to the brushes being worn.

Any suggestions would be appreciated.

Thanks,

 

[caltexflanc]

Does that battery power anything else? Is there a way you can get it closer to the thruster? How far away from the thruster is it today? Is it also charged by the alternator?

 

[panhead56]

The battery is dedicated for the bow thruster and windless. The battery is a little over 21’ from the bow thruster. I believe that is why the manufacturer ran 4/0 cable. According to the Side-Power cable recommendations 4/0 is adequate.

Besides the battery charger the alternator also charges the battery(s).

I considered moving / possibly installing two new smaller batteries closer to the bow thruster. It’s just that the thruster performs well with the new battery

 

[Comodave]

I put in a stern thruster. I have a dedicated AGM about 3’ away from the thruster. I used 4/0 cable for that short run. I want the absolute best voltage I can get to the thruster. If the battery only serves the thruster and windlass why not move the battery to the bow and eliminate some of the cable run? It will be easier to extend the charging cable since it will have much less current draw than the thruster. What other batteries does the charger charge? Are the all AGM type? If the other batteries are not AGMs that can be a problem. All the batteries on one charger should be the same type. I have a 15 amp charger dedicated to my thruster battery. I only charge it at the dock. It has worked well for 4 years now. So I would move the thruster battery close to the thruster and add a dedicated charger if all the batteries are not AGM. If they are all AGM then add a large cable to the charger to charge the thruster battery at it’s new location. I always calculate the size cable needed and then go at least one size larger than required for a 3% voltage loss. The larger size cable is a one time cost and will pay off every time you charge the battery or use the thruster. My thruster is rated for a 3 minute run before it gets too hot. I have never run it that long but 6 seconds isn’t too long. Good luck.

 

[AusCan]

The problem is likely your charging system. I'm not familiar with ProMarina but many of the multiple bank chargers do not do a good job of providing a proper charging profile for all batteries with varying loads. Install a dedicated charger for this battery and your battery life will be substantially increased.

 

[RCook]

My bow thruster/windlass battery bank (two 12v g31 Deka Intimidtor AGM's) are charged by an ACR connected from the house bank, which is four of the same batteries. The windlass/thruster bank is charged through the ACR whether the charging source is alternator, shore power, or generator. No dedicated or multi-bank charger needed. Wiring from bank to thruster is maybe 5 feet of 2/0.

They have worked like a charm for four summers, some 20 months of cruising. The thruster is as powerful as ever, and can be used for quite a long time with no degredation.

 

[Comodave]

Yes, I have 3 separate battery chargers on our boat. One is a 60 amp for the lithium house bank, a 15 amp for the 3 start batteries and a 15 amp for the stern thruster. It keeps everything charged. Since I have LA for the main engine and generator start, AGM for the thruster and lithium for the house bank. They all have different charging profiles so we have a dedicated charger for each type battery.

 

[panhead56]

All of the batteries are the same...all AGM’s. The new 50amp battery charger is for a 3 bank.

 

[MacPhid]

We have the identical thruster (SE100/185) installed in our Bayliner 38. Installed in spring 2015. Looked at running from the batteries in the engine room but decided cost of cable was as much or more than new batteries in the bow. Two Group 31 AGM's under the forward berth, about 4' of cable from the batteries to the disconnect/fuse to the thruster. Remember that you need to calculate the round trip for cable length to determine cable size.
Our setup is almost identical to RCook, original windlass power cable feeds an ACR to charge the thruster batteries which provide power for both the windlass and thruster. An added bonus is we installed the wireless remote with windlass control.
We're going on our 7th season with this setup and no noticeable decrease in thruster performance to date. I would try to move the battery forward.

James

 

[panhead56]

I’m looking at a photo of my battery switch and labeled the cables. The original owner wrote “#2 position normal”.

I’m thinking that this switch should be on number “1’”. Otherwise I’m using the house battery for the thruster!

Looks like the installer ran the house battery to the #2 position switch along with smaller cables to the Blue Sea automatic charging relay. Maybe their intent was to charge the thruster battery when the switch is set to #1 and NOT #2.

Unbelievable.

 

[Comodave]

It looks like you should be switching between the battery banks when you use the thruster or the windlass. That is a PITA. I would move the thruster/windlass battery to the bow and have it separate. Add a dedicated 15 amp charger for thruster battery for under $300 and be done with it. Your cable connectors look suspect. Maybe go through all the battery cables and put new connectors on them with adhesive heat shrink. I also like to use a copper conductive paste inside the connectors, like KoprShield by Thomas and Betts.

 

[Bacchus]

Gary
I have the same MS 34HT with same 8D AGM but mine serves B & S thrusters only. Also located Port side, 500 A fuses on each & with 4/0 cables run fwd & aft.
Also a 3 bank charger serving house (2- 8D AGMs) and thrusters (1- 8D AGM)
I removed a diode isolator that MS used to split Alt output to house & thrusters. A complete write up with schematics can be found on my Bacchus website in the Project section... Alt & Shore Charging system mods.
M 8D AGM were installed 2014 and still doing very well with one serving both thrusters (and now eng start) w/o any problems.
I recently moved my main eng start to the thrusters bank to shorten the cable run and leave a pure house bank.
If your thruster batty is wired over to the nirmal MS 1-2-All-Off switch on the aft deck that may be adding unnecessary run length and more connections of possible loss.

 

[Comodave]

Keep in mind that just because the boat builder did it a certain way doesn’t mean that it is correct or even the best way to do it.

 

[markpierce]

My AGM house batteries lasted 10 years. Those batteries also powered the bow thruster located about 12 feet away. It is a 24-volt system.

 

[Bacchus]

Keep in mind that just because the boat builder did it a certain way doesn’t mean that it is correct or even the best way to do it.

I would venture a suspicion that the switch wiring the OP showed is not MS factory but has been done by a previous owner. Dave it still on the mark as it might have been useful the way the previous owner used it... not necessarily optimum for others.

 

[Scottwb96]

You DEFINITELY have more of an issue than your battery just being drained... Surprised nobody else caught this, but your connector coming in is FRIED!!!
You need to check that wire, you MIGHT be able to salvage it if the scorching is limited to the connection point, but I doubt it.

Something else I would check, just to be on the safe side. Your particular thruster came in 12/24v options. Make sure you are supplying the proper power to it... Had a friend that didn't realize his bow is 24v and wired in his new batteries incorrectly... OOPS!!! Caused the motor to work A LOT harder and he got 1/2 the thrust out of it...

Also, going along with what ComoDave mentioned. I have a very similar setup. multiple chargers through the boat.
1. Starboard Alt charges 8D start battery (LA)
2. Port alt (high output) charges large house bank (AGM)
3. Magnum charger/inverter charges house bank
A. Inverter powers 15a charger in bow for thruster/windlass batteries (AGM)
B. Inverter powers 10a charger in stern cockpit for gen/thruster battery (LA)

Aside from bow, all batteries can be connected as needed, if needed...

 

[Scottwb96]

Ok, the more I look at this pic, the more concerned I get...

1. "To Battery" cable connection is fried
2. "To thruster" cable doesn't appear to be connected all that well in selector switch.
3. The ANL fuse holder (holder, not the fuse) may also not be properly sized for the amperage passing through it. I "think" the studs on that are one way of telling...
4. Lastly, this is just something, while you're in this mess, check and see what those battery switches are rated at for amps... A lot of smaller ones like the ones in your pic are only rated for 250-300amps... Another potential fire starter...

 

[TheAtomicDog]

Good catch, Scott!

 

[Bacchus]

Good catch, Scott!

Agree,.. lots to check out with this system.
I think I'd favor a KISS system for everyday use and a set of jumpers if an emergency arises.
Not having thrusters is not the end of the world!

 

[Comodave]

If you read post #11, I said the connections were suspect...

 

[Yachtman]

Keep in mind that just because the boat builder did it a certain way doesn’t mean that it is correct or even the best way to do it.

That’s why you should survey any boat. Even a new boat should have a survey of some sort, especially if they are fresh from the factory. And if large enough, or systems a-plenty, or expensive, or something to travel on or fish hard on, it should have a full survey completed prior to closing.

 

[panhead56]

Thank you for all the comments and suggestions. I need to investigate the wiring and terminals when I visit the boat this weekend.

I’m going to replace the existing terminal ends with compression fittings/heat shrink. Presently I do not have a 4/0 wire crimper or a 4/0 wire cutter. But I like the idea of a good marine compression fitting.

The Blue Sea selector switch #3002 is rated for 500A. As someone one pointed out, one of the 4/0 cable connections to the switch is showing exposed wire strands.

The Promatic 3 bank charger is working properly. I installed an optional remote Promatic monitor that indicates output,status,temperature, etc.

Don, I never did like the idea of the MS factory installed Blue Sea #7610 diode isolator. I connected a remote LED indicator light mounted next to the A/C panel in the Salon in order to monitor. I’m going to study your electrical configuration. We both basically have the same vessel.

I really like the idea of installing two smaller AGM’s batteries with its own battery charger next to the bow thruster. I might keep the existing 4/0 cable that serves the windless and connect the bow thruster to the ground of the existing house bank? as recommended by ABYC.

If I decide to place the batteries next to the bow thruster. In order to install a dedicated battery charger I will need 120volts. There is an outlet in the stateroom that I could connect to with a breaker. Hopefully the run to the bow will not be too difficult. There is an A/C unit that I may be able to tap into. I need to see what the existing power draw is along with the new battery charger.

Thank you again, I’m looking forward to researching this issue and hopefully resolve. We have strong currents and cross winds in S.W. Florida with a tight slip. Our beam is 14’-3”. We dock bow in for the view. Most days the bow thruster is required to maneuver.

 

[Roughnit]

Although I have a completely different boat I did the same thing you are considering. When I added the thruster battery in the bow I kept the undersized wiring that originally ran to the thruster. I used that wiring to to connect to a battery to battery charger instead of a 120volt charger. I found the article about battery to battery charger on marinehowto.com to be helpful. I used a Sterling because I was using AGM for the thruster but the old wiring is connected to my FLA starting battery. The Sterling charger easily allows me to set the output to what the AGM wants and allows me to charge the the thruster battery anytime the start battery is charging (alternator or 120).

 

[Bacchus]

Gary
Here is an article from Marine How To where Rod discusses how location of Alt V sensing wires can affect the V batty banks see. I dont know if any of this applies to your situation as I havent really spent the time to fully understand your system. It may be worth keeping in mind as you dig deeper. It does show a case where higher than expected V can be sent to a bank being charged with 1-2-all switches in a certain orientation. Could you thruster bank be destroyed by over charging? I do know that can be a problem with AGMs.
https://marinehowto.com/alternators-voltage-sensing/

 

[BDofMSP]

I really like the idea of installing two smaller AGM’s batteries with its own battery charger next to the bow thruster. I might keep the existing 4/0 cable that serves the windless and connect the bow thruster to the ground of the existing house bank? as recommended by ABYC.

If I decide to place the batteries next to the bow thruster. In order to install a dedicated battery charger I will need 120volts. There is an outlet in the stateroom that I could connect to with a breaker. Hopefully the run to the bow will not be too difficult. There is an A/C unit that I may be able to tap into. I need to see what the existing power draw is along with the new battery charger.

That's how ours is wired. Two G31 AGMs with a dedicated charger under the forward berth. It's outlet power follows the air conditioning plenum back to the wall to join the outlets circuit.

BD

 

[panhead56]

Great article with extensive information “https://marinehowto.com/alternators-voltage-sensing”.
I need to thoroughly read this article and wrap my head around it. The idea of using the existing 4/0 D.C. wiring to charge the batteries is interesting. I did not know that there was a D.C. to D.C. battery charger.

If we decide to install batteries next to the bow thruster. Connecting to an existing receptacle in the stateroom (for the charger) I may be able to run the 120volt cable within the A/C plenum too. Thanks for the photos.

I have many options, again looking forward to investigating the wiring on the vessel this weekend.

 

[Bacchus]

If you need or want to run new / separate 125V AC to bow there are 2 PVC pipe wire chases - 1 port 1 stbd