QL BP1200 Voltage 12v vs 24v

[rjcgmiller]

I have a 2003 Carver 506 with a QL BP1200 bow thruster. I have had the boat for about two years now and have found the bow thruster to often be intermittent in operation. Often when I use it, I have to toggle the switch multiple times to get the thruster to run. I haven't had a lot of experience with bow thrusters on boats this size, but I have also always felt the thruster to be underpowered when it does operate. After getting caught in a cross wind with a flakey bow thruster last week, I finally decided to dig into it a little deeper knowing that there are many posts on this site citing faulty gears and seals, which I expected to be the problem.

I removed the belt cover and to my surprise, the motor and belt turned smoothly by hand with no rough operation at all. The reservoir was properly filled and looked clean with no signs of water in the fluid. Everything looked good until I checked the voltage at the motor terminals. I was reading 12 volts (actually more like 12.9) at the motor terminal when I expected to see 24 volts. I was able to reach a camera down to the motor label, and it appears to be a 24v motor unless the motor label is misleading as it states "Bow thruster BP 1200 24 V".

Does anyone have any experience to be able to tell me if my BP1200 is indeed 24v like I assume from the label? If this is the case, I assume I should be reading 24v at the motor terminals rather than 12v while the motor is at rest. I realize this might sound a little ridiculous as a question, but my battery wiring doesn't look like it has been substantially altered from factory and I don't see how it could be rewired to get 12v to the thruster rather than 24v without different battery cable lengths and so-forth. In other words, it doesn't look like a simple battery cable to swap error could have been made with the existing cables. I have 24v at the port engine bank, but it looks like the thruster source may be coming from between the two batteries at the 12v connection point rather than coming from across both series batteries. Perhaps I should be looking at accidental terminal connection swaps rather than looking at the batteries, but wanted to make a post to see if anyone had any advice.

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Thanks,
Ron

[bud37]

I have an idea you may have answered your own question ........Here is a tale from the crypt.....I had a new bow thruster installed once and it ran real slow, turned out it was a 24 volt thruster motor they installed and we were using the 12 volt system, when they changed the motor to the 12 volt, it spun as you would expect.

Perhaps during a layup previous folk have reconnected the cables incorrectly, not sayin this is the case here for you but a possibility if that thruster is in fact 24 volt.

[km1125]

Sure looks to me like it is 24v! And it would also explain intermittent operation if the control circuits (relays, solenoids, etc) were supposed to be at 24VDC and were being operated at 12VDC.

[rjcgmiller]

Thanks for the input, guys.

I was going to go ahead and switch it over to 24v, but thought I'd trow it out there to see if anyone had some story like "Carver use to do that because of xyz, so you shouldn't change it."

The wiring is also very clean and meticulous. Usually you don't see that when something is wired up so incorrectly. Somebody did a really nice job of wiring that thruster up wrong.

I'm going to go ahead and switch it over to 24v and see if that fixes my problem.