Easiest/cheapest way to charge a separate 12v battery onboard?

[PaulRainbow]

I was thinking that you were suggesting a much cheaper option than a B2B or thick cables, so as I read it I was expecting you to link the VSR to the windlass motor power supply so only disconnects the charging cable when the windlass is actually letting out or hauling in chain. I thought, “That’s really neat”, but then realised I’d misunderstood.

As an example in my setup the engine battery is only ever charged by the motor running. Solar and very very occasionally shore power charge the house only.

My bad for assuming the engine battery was charged by means other than the alternator. Still a few ways to achieve the Ops desire of a cheap solution.

If the engine battery gets charged by other means, post #11 is sound. If not, a pair of normally closed relays can be fitted in series, so the VSR negative passes through both relays if the are closed, if either opens the VSR opens too. Then connect the relay coils to the windlass control circuits, one to "up" and one to "down".

It would also be acceptable to connect the VSR to the domestic bank, using the relays as above. This would allow the windlass battery to be charged by any other charging source connected to the domestic bank (in your case, solar or shore power).

 

[Finbar]

I'll be fitting my 1.5kw Tigres windlass soon, and will need a way of filling it with electrons.
At first I thought that the best/simplest way would be to have it directly wired to the engine bank. I'm unlikely to be using it without running the engine, so that would make sense. Except when I priced up the 18m of tinned 95mm2 cable I would need I had a small fit.
Using the house bank presents the same problem.

The old but still usable 110Ah battery that I have sitting around looks like a better option if I stick it in the bow. But how to recharge it? If I just run skinny cables to it from an existing bank, I'll be warming up my bilges every time I run the windlass, thanks to the voltage dip on the battery. Is there some way of limiting that current flow?
What's the simplest/cheapest way of recharging a lead-acid battery from another 12v source? I know you can use a B2B charger, but they're fairly pricey.
I could even throw a £20 solar panel in there but obviously that has limitations.

This all seems very complicated.
I fitted a Lofrans Tigers winch to a 36 ft boat, using 35mm welding cable from the house batteries and it has worked fine for years. Batteries were about midships and the cable is inexpensive

 

[PaulRainbow]

This all seems very complicated.
I fitted a Lofrans Tigers winch to a 36 ft boat, using 35mm welding cable from the house batteries and it has worked fine for years. Batteries were about midships and the cable is inexpensive

That's great if you want to run your windlass at about 10.5 volts.

 

[JumbleDuck]

Fit a VSR near the engine battery, run a 10mm negative cable from the engine battery to the windlass battery and a 10mm cable from the VSR to the windlass battery, fuse at both ends. Connect the VSR negative to a normally closed relay. Connect the coil circuit of the relay to a power source that is only live with the "ignition" on. This way, the VSR will charge the windlass battery whenever a charging source is present at the engine battery, but not when the ignition is on, so the windlass won't try and draw too much current through the 10mm cable or the VSR.

Wouldn't that try to supply the windlass through the VSR if the anchor was raised with the engine running? I'd trigger the relay from the windlass circuit, so that when ever the windlass is used the VSR cuts out. My apologies if I haven't followed you properly - I was AstraZenecaed yesterday amd the side affects are a bit distracting.

 

[PaulRainbow]

Wouldn't that try to supply the windlass through the VSR if the anchor was raised with the engine running? I'd trigger the relay from the windlass circuit, so that when ever the windlass is used the VSR cuts out. My apologies if I haven't followed you properly - I was AstraZenecaed yesterday amd the side affects are a bit distracting.

No, the relay is normally closed, so allows the VSR to also close. The relay coil is connected to a source that becomes live when the ignition is turned on, so the relay open, breaking the VSR negative.

It's also possible to use relays connected to the windlass control, as you suggest, you'd need two relays in series, one for "up" and one for "down", as in post #11

Hope you feel better tomorrow

 

[rich]

I used welding cable, heavy and cheap and very flexible.

 

[JumbleDuck]

No, the relay is normally closed, so allows the VSR to also close. The relay coil is connected to a source that becomes live when the ignition is turned on, so the relay open, breaking the VSR negative.

Oops. My bad. Seems a shame not to be able to charge the thruster battery from the engine, unless I have that wrong too.

Hope you feel better tomorrow

They say two days, possibly, but it clears up after that. It's like a stinking cold - aching joints, dry eyes, no temperature regulation, splitting headache - but still worth it!

 

[PaulRainbow]

Oops. My bad. Seems a shame not to be able to charge the thruster battery from the engine, unless I have that wrong too.

Have a catch up on the thread when you're back to yourself

They say two days, possibly, but it clears up after that. It's like a stinking cold - aching joints, dry eyes, no temperature regulation, splitting headache - but still worth it!

I've spoken to a few people who have had the jab, some say no effects at all, others have felt like you for a couple of day. My first one is booked for next week, so fingers crossed.

 

[Kelpie]

To do that, you'll need hefty cables going to the bow, as the windlass
Perhaps the OP could say how his engine battery gets charged ?

It gets charged from solar as well as the alternator.

 

[William_H]

I would suggest OP search again for high current cable. Try "Welding cable" Run the winch off the engine battery so alternator will contribute to winch current and immediately recharge when winch is stopped. As said if you set up for battery in the bow it will die soon and so further cost to replace it. Keep it simple. ol'will

 

[PaulRainbow]

It gets charged from solar as well as the alternator.

In that case, post #11 will work, the bow thruster battery will get charged when the engine battery is being charged by solar, but not by the alternator.

If you wanted it to be charge by the alternator too you could fit a pair of normally closed relays in series, so the VSR negative passes through both relays if they are closed, if either opens the VSR opens too. Then connect the relay coils to the windlass control circuits, one to "up" and one to "down".

 

[JumbleDuck]

Have a catch up on the thread when you're back to yourself

Much better this morning, thanks.

I've spoken to a few people who have had the jab, some say no effects at all, others have felt like you for a couple of day. My first one is booked for next week, so fingers crossed.

Good luck. I am much relieved to have had it, though of course it is three or four weeks before I can clear high buildings in a single bound, outrun an express train and so on.

If you wanted it to be charge by the alternator too you could fit a pair of normally closed relays in series, so the VSR negative passes through both relays if they are closed, if either opens the VSR opens too. Then connect the relay coils to the windlass control circuits, one to "up" and one to "down".

That sounds like a curiously familiar scheme ...

 

[PaulRainbow]

Much better this morning, thanks.

Good luck. I am much relieved to have had it, though of course it is three or four weeks before I can clear high buildings in a single bound, outrun an express train and so on.

Glad to hear it and thanks.

That sounds like a curiously familiar scheme ...
[/QUOTE]

I read it somewhere

 

[RupertW]

I read it somewhere

I won’t claim the credit as a CSR suddenly feels like a much simpler scheme

 

[Finbar]

That's great if you want to run your windlass at about 10.5 volts.

Has never been a problem. With engine running, voltage at the windlass is probably close to 12v after drop. Windlass runs fine, although I would always use the engine rather than try to move the boat ahead using the windlass alone

 

[Kelpie]

I would suggest OP search again for high current cable. Try "Welding cable" Run the winch off the engine battery so alternator will contribute to winch current and immediately recharge when winch is stopped. As said if you set up for battery in the bow it will die soon and so further cost to replace it. Keep it simple. ol'will

At 1500w my Tigres is a pretty hungry beast. It's also a 16m round trip from the engine battery.
According to the voltage drop calculator I used, anything less than 95mm2 isn't good enough, and the cheapest I can find that is about £10/m

I think most welding cable is lighter than that?

 

[TernVI]

It's worth being aware that high current '12V' motors are often designed in the real world where cables are not zero resistance.
They are also often designed to run from normal sized batteries.
So if you've got a stout battery bank, the allowable cable voltage drop might be more than you think.
£160 for 16m of cable sounds a lot, but even using a local battery you're going to be shelling out a few quid for cables, the difference starts to look less than another decent battery. Don't forget to price up all the odds and ends like fuses and holders, isolators.

Actually running the cable through the boat may be quite a challenge though!

 

[Ammonite]

Just curious as everyone seems to have written this off as a cheap and cheerful £20 solution, although personally I'd favour the VSR / relay approach as it keeps the banks seperate. Why is that?

https://www.mouser.co.uk/ProductDetail/Bussmann-Eaton/CBC-50?qs=GM6gGTqOQCs2wg64her3TQ==

It would use either the starter or house batteries to charge the bow battery via the existing cables and as soon as you operate the windlass and the current hits 50amps the CDC-50 would break the circuit to protect the charging cables. It would then reconnect automatically when you stopped operating the windlass. The only other thing you'd need is a 70 amp midi fuse just in case the CDC-50 failed closed.

 

[TernVI]

Just curious as everyone seems to have written this off as a cheap and cheerful £20 solution, although personally I'd favour the VSR / relay approach as it keeps the banks seperate. Why is that?

https://www.mouser.co.uk/ProductDetail/Bussmann-Eaton/CBC-50?qs=GM6gGTqOQCs2wg64her3TQ==

It would use either the starter or house batteries to charge the bow battery via the existing cables and as soon as you operate the windlass and the current hits 50amps the CDC-50 would break the circuit to protect the charging cables. It would then reconnect automatically when you stopped operating the windlass. The only other thing you'd need is a 70 amp midi fuse just in case the CDC-50 failed closed.

Actually it will cycle on and off the whole time the windlass is running.
It might not last ever so long.

Type I - Automatic ResetCircuit breaker automatically resets after opening. If the fault still exists, thebreaker will continue to cycle between ON and OFF positions until the overload is corrected. These devices are sometimes called "cycling breakers." Type I/Automatic Reset circuit breakers do not address, or correct, overcurrent or fault conditions. They only react by cycling OFF andON. Any overcurrent or fault condition that causes any Type I circuit breakerto operate should be corrected as soon as possible. Continual vehicle operation under an overcurrent or fault condition (causing the Type I circuitbreaker to cycle) is NOT recommended.

 

[Ammonite]

Actually it will cycle on and off the whole time the windlass is running.
It might not last ever so long.

Type I - Automatic ResetCircuit breaker automatically resets after opening. If the fault still exists, thebreaker will continue to cycle between ON and OFF positions until the overload is corrected. These devices are sometimes called "cycling breakers." Type I/Automatic Reset circuit breakers do not address, or correct, overcurrent or fault conditions. They only react by cycling OFF andON. Any overcurrent or fault condition that causes any Type I circuit breakerto operate should be corrected as soon as possible. Continual vehicle operation under an overcurrent or fault condition (causing the Type I circuitbreaker to cycle) is NOT recommended.

Perhaps but a minute or so isnt the same as continual vehicle operation. Its also rated to 1500amps but even if it did weld itself shut the midi fuse would blow. Worst case you are down £20