Request for opinions - Thruster Question

P

plewis

Well-known member
Joined
Aug 12, 2016
Messages
59
Fluid Motion Model
C-288 C
Vessel Name
Last Chance
While I'm not looking for a project it appears to me the thruster performance could be improved by moving the power source for either thruster to the house or engine battery - therefore each thruster will have its own battery. I have arrived at this thought because I have noticed when using both thrusters simultaneously the pitch (RPM) drops significantly, furthermore the battery voltage 12.7 drops to 10.5 when using one thruster to 7.5 using both. I assume this large voltage drop is due to the internal resistance of the battery. Voltage measurements were taken at the source and batteries are fairly new, eliminating the connections or the batteries as a problem. I also understand the ramifications of making above change.

Maybe this could also be a explanation why 2 years ago the stern thruster solenoid contacts were burnt/pitted beyond repair after 3 years use. Perhaps at 7.5 volts the solenoid operation could not hold a solid pick?

Has anyone tried above modification? I'm not sure how much I would gain in performance, any ideas?
 
Read all about it on Shearwater-sailing.com

I relocated the batteries, replaced the fuses w. Breakers and combined the house and thruster banks. Good results on my 2010 r25.


Stuart Bell
Ranger 25: Shearwater
(561) 352-1796
 
I agree two thruster operation on one battery is marginal. The battery rated capacity for one thruster is 300CCA and the thrust is rated at 10.5 Volts. Using two thrusters at one time most likely would reduce voltage to levels that you experienced because of voltage drops from average demands of thrusters and power cable run distances. Thus reduce thrust. The best method to increase battery capacity would be to add another thruster battery to the thruster circuit. Have two batteries wired parallel doubling your battery capacity. The next method would be to install a battery switch between the house and thruster batteries giving you the ability to isolate the two circuits when needed or combine the two circuits giving the house circuit 33% more capacity and the thruster circuit 66% more capacity ( in theory, but capacity increase will not be that much do to other component demands in the house circuit) but still a significant increase. The only draw back to this is the increased voltage drop from using both thrusters together in the house circuit may interfere with your navigation electronics from voltage drops. ( possibility) I actually did install this in my boat but for a different reason. I wanted to increase my amp hours capacity for the house battery while anchored and using an inverter. I run normally with the switch isolating the two circuits and when at anchor I switch to both. I rarely use both thrusters at the same time so 1 thruster battery has never been an issue for me.
 
Like Brian, I have joined my thruster to the house via a switch between them so they can be isolated from one another. However, I usually have them all joined and rarely isolate them from one another. I did it more for anchoring out rather than thruster performance. All electronics work well during thruster operation. I am surprised at such a drop in your battery voltage. I seem to remember during some testing I was doing on stern thruster that the voltage drop should be down to no more than 9.5 volts. That was when using only one thruster though, so perhaps using two at the same time is a significantly larger draw. I also rarely use both simultaneously. I pulse one or the other each time.
 
As there is no amp draw when not using thrusters and voltage drop when using thrusters seems to be damaging thruster motors and solenoids I don't see any downside to connecting house batteries and thruster battery. You get some more amp hours for house use and many many more amps for thruster operation where they're needed. On my R25 doing so added two batteries to the thruster circuit and now on my R29 it added four batteries.

In both instances there was a noticeable improvement in thruster performance especially when using both at the same time. This also has brought the thruster battery on line with the solar charging the house bank gets.
 
On my 2014 R-27 I added two more batteries to the house bank and wired the thruster battery to the house bank. I now have 5 100AH batteries for the house and/or thruster. Much better performance for both house and thruster loads!
 
Thanks for your responses.

Apropos of my post I just found the following in the sidepower install manual.

"If a bow thruster is also installed, we advice to use separate
battery banks for the two thrusters to avoid extreme
voltage drop if both thrusters were to be used at the same
time. Refer to the thruster manuals for advised battery
capacity and cable sizes for each thruster."
 
To Port a gee and Knotifying. As you both have combined your thruster and house batteries, could you describe or better yet, sketch over the R27 Classic power distribution wiring schematic (link to manual below see pg 32) the changes and additional wiring you installed?
Thanks Ed/
download/file.php?id=90
 
Connect the positive terminal on the thruster battery to any positive terminal on any house battery, likely they're already common grounded. Use a big fat cable. Easy peasy.
 
I have a battery switch installed so I can isolate thruster battery from House battery. 1/0 red cable attached to Pos terminal thruster battery the other cable end attached to terminal 1 of battery switch. 1/0 red cable attached to Pos terminal house battery other cable end attached to terminal 2 of battery switch. Label each cable end at battery terminal (Thruster/house jumper) As tugnnaweigh stated the negative terminals are all common grounded ( yellow terminal ). Switch is located in battery compartment. Battery switch on position batteries are combined ( batteries wired in parallel).
 
Hi Ed,

On our boat there was not room for an additional switch in the battery compartment as there is an inverter on/off switch in there. Instead, I replaced the existing thruster battery switch with the following:

https://www.bluesea.com/products/products/5511e/e-Series_Dual_Circuit_Plus_Battery_Switch/featured

The challenge however is the wiring is very tight with the large battery cables. If you have the room Brian’s solution is much easier to implement (and the switch costs less!). If space is an issue the switch above can do it in the existing space and you will have the old switch as a back-up if needed. 😀

Curt
 
BB marine":3i9hn3gv said:
I have a battery switch installed so I can isolate thruster battery from House battery. 1/0 red cable attached to Pos terminal thruster battery the other cable end attached to terminal 1 of battery switch. 1/0 red cable attached to Pos terminal house battery other cable end attached to terminal 2 of battery switch. Label each cable end at battery terminal (Thruster/house jumper) As tugnnaweigh stated the negative terminals are all common grounded ( yellow terminal ). Switch is located in battery compartment. Battery switch on position batteries are combined ( batteries wired in parallel).
Click to expand...


What position do you need to keep the factory Thruster battery switch then? On to make it parallel to house as well?
 
The thruster battery switch is independent of this cross over. Think of this additional battery switch as a parallel switch to add an extra house battery to house circuit or two extra thruster batteries to the thruster circuit. The thruster battery switch has to be on to operate the thrusters only. The house battery switch has to be on to operate house circuits only. The additional thruster/house parallel switch combines both battery combination house batteries and thruster battery together only.
 
I think you are making this more complicated than necessary - while losing significant functionality.

On the Shearwater (see http://www.shearwater-sailing.com/index.php/inverter-installation-operating-the-inverter/ ), I relocared a house battery to the bow, removed the thruster battery completely and attached the thruster to the house bank.

Since each thruster was now "close" to one battery and further from the other, both thrusters worked better than before the change - and the boat trim improved significantly.

What didn't work any longer was the switch to shut off the thrusters in the event they "ran away" or ran when the controls were off. This is an unfortunate characteristic of Side Power thrusters and the shut off must remain in the design. Since the battery moved forward and the thruster was directly connected to the battery, single switch control was no longer possible.

I achieved the same functionality by replacing the two non-standard fuse block that used expensive and hard to find fuses with standard blue sea circuit breakers that had a positive OFF position. Thus, I could securely shut off the thrusters for painting and other maintenance while preserving the short cable runs necessary for efficient operation

Both thrusters run faster, neither bothers the other, and since I always run the engine when thrusting, there is virtually no voltage drop (13.8 without, 12.2 with) at the house measurement point where the instruments are connected.

As a side effect, anchor performance also improved significantly since the anchor was wired off the bow thruster on the 2010 R-25.
 
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