Installing a bow thruster need electrical help

[Striper Blues]

Guys,
I'm thinking of installing a Lewmar 140TT2.2 electric thruster in my Wellcraft 290 Coastal and I am getting educated on the use of Automatic Charging Relays instead of adding another battery charger with the install of the new thruster battery. Although I have plenty of experience with other electrical items I'm not familar with ACR's or adding additional batteries to an already complex electrical system.

At present I have an Alltech Flyback 10-3 charger with three outputs, two go the motor/house batteries and one to the gen set battery. I need some coaching on what a logical and safe solution looks like whether I do the ACR install or hire a pro to do the whole thing.

I am told by the thruster dealer that I should hook the new battery up using a Blue Sea ACR. But I have a ton of questions about this approach that I can't find answers for on their website. For example...

If I go with an ACR will the charge from my AC charger pass on from the Alltech thru the ACR to the thruster battery when I have shore power attached (it should based on what I've read). If thats the case then I'm good to go as it would charge the thruster battery whether it was coming from the alternator or the Alltech charger.

I am also confused about the charging amps. Some ACRs are 60 others are variable from 60 to 120. We're talking about me charging a 12 volt battery that will be seldom used.

Any insights are greatly appreciated.

 

[Bifflefan]

Re: Installing a bow thruster need electrical help

I say skip the web site and the FAQ's. and call them direct. If they are any kind of company and they are selling you their product then they should be able to talk to you on the phone a time or two.

 

[Silvertip]

Re: Installing a bow thruster need electrical help

The short answer to your question is NO. The AC charger outputs are not connected to the fourth battery (the one for the thruster). Therefore it cannot charge that battery. The ACR is fed by the engine charging system and has a dedicated output going to the thruster battery. So for all practical purposes you have several independent systems. 1) House, 2) Starting, 3) Thruster. You didn't say whether you had a dual battery switch or some other system for charging both the house and starting batteries from the engine but that probably wouldn't matter. The only "gotcha" here is if some creative wiring was done by someone who did not fully understand switches, isolators, ACR's etc. The only time the thruster battery would be charging is when the engine is running, and only after the starting battery has reached full charge. The ACR would then switch the thruster battery on-line.

 

[Striper Blues]

Re: Installing a bow thruster need electrical help

Silvertip,

Thanks for the feedback. I guess I can install a separate charger just for the thruster battery. I actually have a spare Alltech flyback 10-3 charger but it seems like over kill for just one battery? Maybe not.

Given that I almost never use the gen set battery, if I could tap into that battery and just run 1AWG wires from the gen set battery the 10 feet to the thruster? I would have to put a battery switch on the thruster loop to shut if off when I'm not on the boat. In that case the thruster would just use the Kohler generator starting battery. If I did that would I have to put in a dual switch that forced me to choose either the genset circuit or the thruster circuit, or do I even have to bother doing that?
Thanks again,
Pat

 

[Silvertip]

Re: Installing a bow thruster need electrical help

Anytime you connect one battery to another as you are suggesting, you are placing batteries in parallel. Unless you use a switch to separate them, and especially if they are different capacities, different types, and different ages, the weaker of the two batteries will suck the life out of the better one until both are equal. The thruster battery needs to be a large deep cycle so the generator battery would very likely be a plain starting battery. So here is a possible solution. Remove the generator starting battery. Replace it with the largest deep cycle that will meet the requirements for your thruster. Wire both the thruster and the generator to that battery. Generators should be exercised periodically so use it to keep that battery topped off. You still have just three batteries, you don't need the ACR and you don't need another charger or a switch.

 

[Striper Blues]

Re: Installing a bow thruster need electrical help

Silvertip,
Thanks again for your help.

So it sounds like it is possible to upgrade the battery to the level required by the thruster and then just run wires directly from the battery terminals to my thruster install? (The thruster installation directions require a battery on/off switch and a fuse in the positive lead which I will certainly install.)

One other point I should raise is that the gen-set battery is hooked to the Alltech charger and gets charged both when the generator is running and when I'm plugged into shore power. So unless there is an issue with that arrangement. I am delighted to hear I can go this route without having to install another charger.

Thanks again,
Pat

 

[Splat]

Re: Installing a bow thruster need electrical help

I agree with ST. The easiest solution here would be to eliminate the current gen batt, and replace it with a large deep cycle, then wire both the gen and the bow thruster to this new battery. This will allow you to use your current charging setup, and will eliminate the need for more complex circuits, and quite frankly things to troubleshoot when they go wrong.

The new deep cycle battery will charge in the same way the current generator battery does. Either through the onboard AC charger, or the generators charging circuit.

Also the battery switch I believe should go in-line between the battery and the bow thruster. This would allow you to totally "disarm" the bow thruster for instances where you may need to work on or near the unit.

Bill

 

[Striper Blues]

Re: Installing a bow thruster need electrical help

Thanks Bill, that is my plan. Now all I need to do is figure out how to get a 5 1/2" hole thru my hull. There isn't a lot of room for me to put it given the need for it to be the right distances from the water line and the bottom of the keel line.

Thanks for you input.