Which battery for windlass/ bow thruster.

[Jannie Radiance]

I want to have a dedicated single battery up forward for my bow thruster and windlass. ( at this time it is connected to the house batts). Should I use a 105ah class 31 starting battery? I have an automatic charging relay to install between house and this batt.
What bothers me is the time duration of the windlass operation. The bow thruster is now problem . ( quick 5 sec bursts 10 at most). My 12V house battery is 690 Ah golf cart 6 V’s.
Windlass is Quick 1000W. Does 80 Amps sound about correct?
Do I calculate with CCA?

[john61ct]

No, deep cycle usage, forget CCA.

Get one new pair matching the House bank, see if that's enough. If not, add another pair within a week or two.

[smac999]

don't use an ACR between a house battery and bow thruster battery.

what is your bow thruster amp draw? many are 300-500a. from my experience half will come from the house bank through the acr. so you'll have 150-250a flowing down the acr wires and through the acr. if it fused (like it should be) it'll blow.

something like an echo charger will limit charging to 15a. and allow you to run small cable to the bow, and fuse normally. the battery will drain while running the windlass or thruster but be charged slowly back once off.

if you want to run an acr you'll need the 500a model and you'll still be running 2/0 or so to the bow, vrs 10 awg

[john61ct]

Blue Sea 7600 old current limiting ACR was designed for this, much higher 60A engineered limit. I pick them up on eBay pretty regularly, $50-90.

The big 500A ML version is a better solution if you can run the fat wiring.

And of course a switch / relay can open / isolate the charging connection while the thruster or windlass are operating.

Just writing "don't use an ACR" is overstating the case, Echo Charger 15A is a pretty limited charging current, depending on bank size, and imposes a major voltage drop in addition to that of the long wiring run.

[Jannie Radiance]

Smac999. I dont quite understand how this current goes through the open circuit relay. The voltdrop on the ACR ( when using windl or thruster) switches the ACR open circuit . That in my understanding. When does 120A flow through? John61ct makes sense to me. But I dont want to blow the forepeak bunk to infinity....and beyond.

[Jannie Radiance]

Pic of my ACR cant seem to attach pic . M-ACR 7601 Blue Sea Systems.

[john61ct]

Originally Posted by Jannie Radiance

Smac999. I dont quite understand how this current goes through the open circuit relay. The voltdrop on the ACR ( when using windl or thruster) switches the ACR open circuit . That in my understanding. When does 120A flow through? John61ct makes sense to me. But I dont want to blow the forepeak bunk to infinity....and beyond.

The engine running - or any active charge source - keeps the connection closed.

Unless you open it manually.

Or automatically wired into the windlass / bowthruster switches.

[Jannie Radiance]

Originally Posted by Jannie Radiance

Pic of my ACR cant seem to attach pic . M-ACR 7601 Blue Sea Systems.

yes john62ct . I will wire it to the Windlass and thrust on switch. Windlass up /down .. power to ACR . Cuts dedicated battery from housebank . I actually think I got it now.

[stormalong]

I am sure to open a can of worms with this post but here goes.

Don't do a bow mounted battery bank. Use appropriate heavy wiring back to your house bank. When using your bow thruster or windlass you want as much power coming from your alternator as possible, not the least which is what you are proposing.

The disadvantages of batteries up forward far outweigh the supposed advantage.

Your boat is about the same length as mine. With the anchor, chain, windlass and bow thruster forward you already have a lot of weight concentrated there.

The bow is the place with the most motion in your boat. Any batteries forward will need to be very solidly secured.

The moment you engage the windlass or thruster the heavy load will cause a voltage drop. With an ACR you will be disconnected from the best power source you have - your alternator.

Best solution to your power needs is heavy wiring back to your house bank which is fed from a large alternator. You can use large wire from an electrical supplier rather than paying the marine premium. The cable is stiff and hard to bend but you only have to do it once. The conductors are heavy gauge and with good crimped terminals and heat shrink sealed ends water intrusion is not an issue. I did this on my boat in 1991 and it is still good.

[JOHNMARDALL]

Hello, this is John Mardall of Vetus Maxwell. For these installations, we recommend locating an appropriately sized AGM battery as close as possible to the bow thruster and with the thruster and windlass circuits fused separately. The thruster will pull much more power than the windlass, so size the battery in accordance with the thruster manufacturer's recommendations. If you'd like to tell me the make and model of your bow thruster, I'll look up the recommended battery for you - jmardall@comcast.net. Cable sizing is also important, as these devices pull a lot of current.



All the best
John Mardall
Vetus Maxwell Boat Equipment.

[Dougtiff]

I have a group 27 up forward to power a electric toilet and the windlass, originally i had a combiner, but it burnt out, so removed it, and went straight to house bank, no problems now, the thing is, when your using the thruster, ect., your running your engine, so all batts. are charging, do have the wire from house bank to bow batt. fused.

[john61ct]

I agree **if** it is practical to run the required heavy wiring to beef up the existing House bank for these consumers rather than using a separate forward bank.

Fewer points of failure, overall simpler design.

But that will be a very fat heavy expensive hunk of copper!

[Frankly]

Just cover the bases. On my ship I have 4 GC2s midships and 2 more on the fwd bilge. They are all electrically connected in series parallel and normally operate as a single bank. The bow thruster and windlass (and a few other small local loads) are tapped directly from the fwd bank (with appropriate ckt protection). Sure when I start the engine, thrust, or retrieve, the loads are not shared equally by all on the supply side. But where there is a potential difference (even a few millivolts) then current will flow. After 30 minutes the voltages all read the same. The batteries all seem to get along fine (better than some crew members). The fwd and main banks are connected with #2 cable and positive fused on each end. The only real current measurement I have ever made is that the 300 amps for the thruster comes 200 from the fwd pair and 100 from the main bank. Switches on each of the three banks allow me to test them out a couple of times each year by individually starting the 3GM.

Running like that for 13 years, typically change out Sam's best every 5 or 6 years.

[Jannie Radiance]

Originally Posted by JOHNMARDALL

Hello, this is John Mardall of Vetus Maxwell. For these installations, we recommend locating an appropriately sized AGM battery as close as possible to the bow thruster and with the thruster and windlass circuits fused separately. The thruster will pull much more power than the windlass, so size the battery in accordance with the thruster manufacturer's recommendations. If you'd like to tell me the make and model of your bow thruster, I'll look up the recommended battery for you - jmardall@comcast.net. Cable sizing is also important, as these devices pull a lot of current.



All the best
John Mardall
Vetus Maxwell Boat Equipment.

Vetus 9512 650 Amp Model EC 5,7/1,2/39-02
Double solenoids on the side.
Can you please email me jannie@radiance43.com. I have a question about my bowthruster.

[Jannie Radiance]

Originally Posted by Dougtiff

I have a group 27 up forward to power a electric toilet and the windlass, originally i had a combiner, but it burnt out, so removed it, and went straight to house bank, no problems now, the thing is, when your using the thruster, ect., your running your engine, so all batts. are charging, do have the wire from house bank to bow batt. fused.

Thanks .. 200amp fuse for thruster and breaker for windlass.