Bow Thruster Batteries

[Tireless]

I am sure that there are a number of members that have the VP QL Bow Thruster in your boat.

I have one and it is currently being powered by a single group 31 Cranking Battery. At the time I purchased the boat it appeared that they may have been 2 group 31 cranking batteries running the thruster. This would have been a 12 volt set up and not 24 v.

I would be interested in hearing views on the issue and what any of the members may have powering their Bow Thrusters. I have been considering getting a second battery, if thats what is required. The thruster seems to be working okay, however, I wonder if it would be more efficient with 2 batteries, not sure.

Thanks in advance.

Greg

[Viper]

Two batteries is better Greg, minimizes voltage drops during operation which can lead to other issues. A good check would be to do a voltage drop test with a meter while operating the unit for a typical duration of actual use. Should be short bursts, maybe no more than 10 sec each. This will tell you how the bank is handling the load. Do you know if that bank is charged by the engines?

[Tireless]

Viper, thanks for your comments. I assume that the alternators charge the thruster battery. I will put a meter on that battery when the boats get in the water. Hopefully soon.

As for the load when the thruster is in use, I will check that’s as well.

I get the sense from you that one battery will work,however, two batteries will be better.

Thanks again

Greg

[Midnightsun]

From the factory mine was setup up with dual group 31 battery banks for both the engines and thrusters. In other words the port engine has 2 group 31 batteries which are connected together to form a bank, the bow thruster is also connected to this bank. Same situation for the Starboard engine and stern thruster. So yes, lots of juice available as all 4 batteries are 1000 CCA rated.

[pepmyster]

The more the merrier. Having 2 will take a lot of strain off the single one for sure!!!!!!

[Viper]

I'm not a fan of running thrusters and engines off the same bank, or anything else off the engine batteries for that matter. The CPUs in today's engines don't like brownouts which can occur for various reasons under load when the voltage drops far enough. This is pretty common as batteries age, connections corrode or loosen, something jams the prop in the thruster, etc. The factory setup is easy for production but keeping such system power sources isolated from others is the best way to do it, in fact in some engine applications is a must.

[Tireless]

I have noticed since I bought the boat that moving the boat to the starboard after a couple of bursts starts to fail, however, moving the boat to the port seems fine. Maybe a result of the voltage drop you speak of, or the connections require cleaning.

Also wondered if the switch is faulty or requires cleaning.

Thanks for the feedback

Greg

[Midnightsun]

I thought is was a little odd also after discovering how Carver did this however after all these years it has been extremely reliable and powerful. Sometimes it works well thinking out of the box.

After putting thought into how Carver set this up, I have 2000cca available to start each engine. Even if the batteries were half way worn out, I would still have the recommended 1000cca to start the engines. Normally thrusters are for docking when arriving and you will plug into shore power any way. When leaving the dock using thruster, your alternators will replenish the small amount used while under way and again the engines are already operational at this point. Thrusters do require a lot of juice to operate at their intended power rating but again, for only shorter bursts. All in all it make a lot of sense what Carver did when you think about what is actually happening under normal usage. Backup is always the generator which has its own 1000cca battery independent from it all and a large efficient on board charger none of which has ever been required except for normal charging/power on the hook.

[bud37]

Windlass wired the same....it even suggests to only use when engines operating....that is why having two batteries in parallel is desired in this case......keeps certain engine control circuits happy with very minimal voltage drop if the batteries are good.

I corrected that very problem by paralleling the boat engine batteries....also used two for the thruster.

A load test while operating will show the battery and circuit health.......good luck on launch day, coming soon to a marina near you.....

[km1125]

Source of the post I have noticed since I bought the boat that moving the boat to the starboard after a couple of bursts starts to fail, however, moving the boat to the port seems fine. Maybe a result of the voltage drop you speak of, or the connections require cleaning.

Also wondered if the switch is faulty or requires cleaning.
Thanks for the feedback Greg

Not due to voltage drop. You might have a switch or relay that is having issues, especially after some current has run through it.

You should also inspect the condition of your thruster prop(s). A ding on one edge of the blade or on one prop out of a paired set could cause better performance towards port than starboard (or vice-versa).