Bowthruster Electrics Supply

[pvb]

I see what you're saying. The return length has to be added to the overall length. In that case the chart would mirror your suggestion.
I'm going to call the supplier to check this as the chart does not seem to suggest taking the return length into account. It just shows you the minimum and recommended cable size for the length chosen, which in my case is the section listed under 7m - 14m run.

It's the total length of the positive and negative cables. Sounds like yours is 14 metres. If it's a bit more, you need bigger cables, you're just on the limit.

 

[Travelling Westerly]

It's the total length of the positive and negative cables. Sounds like yours is 14 metres. If it's a bit more, you need bigger cables, you're just on the limit.

I was going to go 7.5m (15m now) so I have some extra to play with. Oh well more expense

 

[PaulRainbow]

I was going to go 7.5m (15m now) so I have some extra to play with. Oh well more expense

SP say up to 14m should be 2x70mm If you go 2x95mm that's nearly £400 in cable alone. I'd have to ask myself if it wasn't better to fit a modest size AGM battery at the bow, cost about £100 and only weighing 17kg. Then add one of the charging methods discussed in this thread from about £100 to about £300. No issues at all with voltage drop and no having try run 4 x 95mm cables to the bow, that's a significant hassle on most boats.

 

[ip485]

Well at least you will be able to feel you have done a propoer job!

What an excellent and knowledgeable thread. I have two very large dedicated batteries for the thruster which charge directly from any of the various charge sources. I had (wrongly) assumed there wasnt a signifcant cable from the chargers, so I am now quite intrigued to see how it is put together, and will learn something more. It was an original install. Cant wait to get back on board and follow the wiring and look at the diagram.

You think you know all you should about the systems but there is always more to learn.

 

[Travelling Westerly]

SP say up to 14m should be 2x70mm If you go 2x95mm that's nearly £400 in cable alone. I'd have to ask myself if it wasn't better to fit a modest size AGM battery at the bow, cost about £100 and only weighing 17kg. Then add one of the charging methods discussed in this thread from about £100 to about £300. No issues at all with voltage drop and no having try run 4 x 95mm cables to the bow, that's a significant hassle on most boats.

Cheers Paul, was hoping you would chip in soon. The running of cable is no issue for me and I already have a dedicated battery isolator fitted for the BT.
I have to admit the cost of cable made my eyes water a bit but I thought the cable only route would keep things much simpler. Thankfully PVB gave me some pointers re cable sizing hence a re think....
Where are you seeing 95mm cable for £400? The best Ive seen so far for Oceanflex tinned 95mm is Fearneau Riddall.
What would you do?

 

[PaulRainbow]

Cheers Paul, was hoping you would chip in soon. The running of cable is no issue for me and I already have a dedicated battery isolator fitted for the BT.
I have to admit the cost of cable made my eyes water a bit but I thought the cable only route would keep things much simpler. Thankfully PVB gave me some pointers re cable sizing hence a re think....
Where are you seeing 95mm cable for £400? The best Ive seen so far for Oceanflex tinned 95mm is Fearneau Riddall.
What would you do?

"Nearly £400" was a bit ballpark, Furneau Riddall actually comes to £339.50. Personally, i wouldn't run 4 x 95mm cables forward. Not that it won't work, because it will. You will need to connect those 4 x cables directly to the batteries, then the 2 positives to a fuse/thermal breaker, then to the switch and finally forward to the thruster. That's 2 x 7m negative cables and 6 positives of varying length, bearing in mind, both positive cables will need to be fused. That'll get awkward and clumsy at the source end of things. I don't think 17kg of battery at the bow is going to be an issue one way or the other.

So, i'd fit an AGM battery at the bow, that'll give you all the instant oomph you need, right where you need it, cost about £100. You still need an isolator, but that'll also be at the bow, you could fit a thermal circuit breaker and use that to isolate the battery if needed (no real need to isolate it when not in use) such as one of these (or similar) 0-382-70 | Durite 12V-24V DC 200 Amp Manual Reset Circuit Breaker

So far, that's a neat and self contained installation, all at the bow, all done with single 70mm cables. All you need to do now is to charge the battery. A B to B charger would do the job, cost around £250 for a Victron one (others available). I'd suggest though, that as the thruster gets very limited use, it won't require vast amounts of charging. If, for instance, you use it for a minute or so to park the boat, it won't have taken much power from the battery and the battery will consequently not accept a high charge current. A 120a Victron Cyrix, connected using 10mm cable, fused at both ends, would be fine. The VSR is rated at 120a, the cable at 75a, the battery is unlikely to draw more than a few amps most of the time. At 10a charge current the voltage drop would be a mere 0.2v.

As discussed earlier, you'll want to ensure the VSR is open while you operate the thruster, to ensure the thruster doesn't draw current from the source battery. You'll be running the engine when you use the thruster and you'll likely have split charging, so whichever battery you connect the VSR to will be getting a charge, hence the VSR will be closed. So, fit a normally closed relay in the negative connection to the VSR (only a 2.5mm wire, low current draw) and connect the relay coil connection to the engine "ignition" positive. As soon as you turn the ignition on the VSR will open and you can safely operate the windlass.

If you'd prefer a B to B charger instead, no reason not to. Wiring will be similar, except you wouldn't need the relay. Still needs to be fuse at both ends though.

Some of the other suggestions in the thread would also work, but i'd go for the VSR, it's simple, inexpensive and does the job.

 

[Travelling Westerly]

"Nearly £400" was a bit ballpark, Furneau Riddall actually comes to £339.50. Personally, i wouldn't run 4 x 95mm cables forward. Not that it won't work, because it will. You will need to connect those 4 x cables directly to the batteries, then the 2 positives to a fuse/thermal breaker, the to the switch and finally forward to the thruster. That's 2 x 7m negative cables and 6 positives of varying length, bearing in mind, both positive cables will need to be fused. That'll get awkward and clumsy at the source end of things. I don't think 17kg of battery at the bow is going to be an issue one way or the other.

So, i'd fit an AGM battery at the bow, that'll give you all the instant oomph you need, right where you need it, cost about £100. You still need an isolator, but that'll also be at the bow, you could fit a thermal circuit breaker and use that to isolate the battery if needed (no real need to isolate it when not in use) such as one of these (or similar) 0-382-70 | Durite 12V-24V DC 200 Amp Manual Reset Circuit Breaker

So far, that's a neat and self contained installation, all at the bow, all done with single 70mm cables. All you need to do now is to charge the battery. A B to B charger would do the job, cost around £250 for a Victron one (others available). I'd suggest though, that as the thruster gets very limited use, it won't require vast amounts of charging. If, for instance, you use it for a minute or so to park the boat, it won't have taken much power from the battery and the battery will consequently not accept a high charge current. A 120a Victron Cyrix, connected using 10mm cable, fused at both ends, would be fine. The VSR is rated at 120a, the cable at 75a, the battery is unlikely to draw more than a few amps most of the time. At 10a charge current the voltage drop would be a mere 0.2v.

As discussed earlier, you'll want to ensure the VSR is open while you operate the thruster, to ensure the thruster doesn't draw current from the source battery. You'll be running the engine when you use the thruster and you'll likely have split charging, so whichever battery you connect the VSR to will be getting a charge, hence the VSR will be closed. So, fit a normally closed relay in the negative connection to the VSR (only a 2.5mm wire, low current draw) and connect the relay coil connection to the engine "ignition" positive. As soon as you turn the ignition on the VSR will open and you can safely operate the windlass.

If you'd prefer a B to B charger instead, no reason not to. Wiring will be similar, except you wouldn't need the relay. Still needs to be fuse at both ends though.

Some of the other suggestions in the thread would also work, but i'd go for the VSR, it's simple, inexpensive and does the job.

Nice one Paul, a very comprehensive plan - appreciate it.
Im going to look at the Victron B2B charger as suggested and get my head around that system. The VSR and relay bits confuse me a bit so I'll read up on those as well so I understand them a bit better.
Cheers Paul

 

[PaulRainbow]

Nice one Paul, a very comprehensive plan - appreciate it.
Im going to look at the Victron B2B charger as suggested and get my head around that system. The VSR and relay bits confuse me a bit so I'll read up on those as well so I understand them a bit better.
Cheers Paul

The B2B and VSR wiring is straightforward, if you have any questions about either, ask away.

 

[Travelling Westerly]

The B2B and VSR wiring is straightforward, if you have any questions about either, ask away.

Cheers Paul, will do

 

[Solent sailer]

Why not simplify things and use your main battery bank, how big is the boat? just run 95mm cables to the bow thruster, it wont be any heavier than a extra battery and wont be any more expensive than battery/charger/VRS or Relay and wont be adding weight in the bow

 

[PaulRainbow]

Why not simplify things and use your main battery bank, how big is the boat? just run 95mm cables to the bow thruster, it wont be any heavier than a extra battery and wont be any more expensive than battery/charger/VRS or Relay and wont be adding weight in the bow

Nice to see you read some of the thread before you posted Paul

Unfortunately, you seem to have missed the important bits.

 

[Dysan]

How do you currently charge the engine and domestic bank from the alternator ?

They can all be connected together via one of those rotary selector switches. I don’t know whether you can get a version that will support 3 banks? Some intelligence in that system would be nice though.

 

[PaulRainbow]

They can all be connected together via one of those rotary selector switches. I don’t know whether you can get a version that will support 3 banks? Some intelligence in that system would be nice though.

You could fit a three output Victron Argofet, connect the outputs to the same places as the mains charger, you'll only need the one set of cables going to the bow. This will allow all three batteries to be charged from the alternator, without having to fiddle with switches.

 

[Dysan]

You could fit a three output Victron Argofet, connect the outputs to the same places as the mains charger, you'll only need the one set of cables going to the bow. This will allow all three batteries to be charged from the alternator, without having to fiddle with switches.

Looks like a plan, thanks

 

[Travelling Westerly]

You could fit a three output Victron Argofet, connect the outputs to the same places as the mains charger, you'll only need the one set of cables going to the bow. This will allow all three batteries to be charged from the alternator, without having to fiddle with switches.

I like that idea too Paul. Could that possibly work for my set up? I've got a 2 output Victron Argofet at the moment so understand that system. Presumably the BT battery would only be charged whilst the engine was running as my Sterling Pro 30A charger only has 2 outputs used on the house and starter battery. What size cables from the Argofet to the BT battery would you recommend? Stay with the 95mm?
I've been reading up on the Victron B2B charger as you advised. The 12v planet shows a simple wiring diagram which does not show a VSR connected. Do I need to fit one of those?

 

[PaulRainbow]

I like that idea too Paul. Could that possibly work for my set up? I've got a 2 output Victron Argofet at the moment so understand that system. Presumably the BT battery would only be charged whilst the engine was running as my Sterling Pro 30A charger only has 2 outputs used on the house and starter battery. What size cables from the Argofet to the BT battery would you recommend? Stay with the 95mm?
Cheers

Ref cable size, see paragraph 3 in post#46. No point in 95mm cable.

If you swapped your Argofet for a three output model the alternator would then charge all the banks, great stuff. However, only charging the bow thruster battery whilst the engine is running might be an issue. Good news is, if you connected the output from the mains charger, that goes to the engine battery, to the now redundant 2 output Argofet and the two outputs to the engine battery and thruster battery, the mains charger now charges all three banks too

You'll still need to fuse the cable to the bow at both ends. 10mm would suffice, if you want to go a bit over, 16mm wouldn't hurt. Fuse for the cable rating.

So, for you, a £100 AGM at the bow (check out Hankook AGMs at Battery Megastore) and for charging, a new 3 output Argofet (BMS again ?), some 10mm or 16mm cable and a couple of fuses. Should save you around £200 and you'll have a simple, robust setup.

 

[Travelling Westerly]

Ref cable size, see paragraph 3 in post#46. No point in 95mm cable.

If you swapped your Argofet for a three output model the alternator would then charge all the banks, great stuff. However, only charging the bow thruster battery whilst the engine is running might be an issue. Good news is, if you connected the output from the mains charger, that goes to the engine battery, to the now redundant 2 output Argofet and the two outputs to the engine battery and thruster battery, the mains charger now charges all three banks too

You'll still need to fuse the cable to the bow at both ends. 10mm would suffice, if you want to go a bit over, 16mm wouldn't hurt. Fuse for the cable rating.

So, for you, a £100 AGM at the bow (check out Hankook AGMs at Battery Megastore) and for charging, a new 3 output Argofet (BMS again ?), some 10mm or 16mm cable and a couple of fuses. Should save you around £200 and you'll have a simple, robust setup.

I feel I should be paying for this advice Paul . Even better news is I acquired a brand new red top Optima AGM yesterday (long story) so that's another £100 odd saving. Great help and thanks alot

 

[PaulRainbow]

I feel I should be paying for this advice Paul . Even better news is I acquired a brand new red top Optima AGM yesterday (long story) so that's another £100 odd saving. Great help and thanks alot

No problem, glad i could help, BACS details to follow

 

[Solent sailer]

Nice to see you read some of the thread before you posted Paul

Unfortunately, you seem to have missed the important bits.

Just thought I would add my views, doesn't mean haven't read all the other views or mean I agree or disagree with them.

The fact you have expressed a view in a previous post doesn't mean no one else should have a view or disagree with you, for me running a 100a supply is a weekly occurrence and 200a or 300a quite regular so all this hassle for a 10m run with an intermittent and short duration load seem a bit over the top.

Put the control relay at the bow next to the load run a couple of big cables from the main battery bank (2 cables not the 4 as I believe was mentioned previously) nice big fuse at the source. no charger issues, no extra weight in the bows, no problems with extra battery to maintain. Most batteries are not suitable for installation in a the occupied area of the boat. Sealed AGM are generally ok but not leisure or vented, so re-using the old engine start battery may not be advisable - this may be something generally ignored but if you don't have to do it why should you ?
95sqmm or 120sqmm welding cable (several graded available before you jump on that!) is fairly cheap, you can use double insulated tinned copper if you want but with a fibreglass boat it will probably be the only bit of tinned double insulated cable on the boat. Fit the cables in flexible pvc conduit - 10m contractor pack of PVC conduit shouldn't cost you more than £10 so sleeve the cable with that readily available in 20, 25 and 32mm

 

[PaulRainbow]

Just thought I would add my views, doesn't mean haven't read all the other views or mean I agree or disagree with them.

You either didn't read the thread, or you failed to understand the issues.

The fact you have expressed a view in a previous post doesn't mean no one else should have a view or disagree with you, for me running a 100a supply is a weekly occurrence and 200a or 300a quite regular so all this hassle for a 10m run with an intermittent and short duration load seem a bit over the top.

Lot's of different views and options have been given in this thread, most of which are viable. I've even offered several different options to the two people in the thread who are fitting bow thrusters.

Put the control relay at the bow next to the load run a couple of big cables from the main battery bank (2 cables not the 4 as I believe was mentioned previously) nice big fuse at the source. no charger issues, no extra weight in the bows, no problems with extra battery to maintain. Most batteries are not suitable for installation in a the occupied area of the boat. Sealed AGM are generally ok but not leisure or vented, so re-using the old engine start battery may not be advisable - this may be something generally ignored but if you don't have to do it why should you ?
95sqmm or 120sqmm welding cable (several graded available before you jump on that!) is fairly cheap, you can use double insulated tinned copper if you want but with a fibreglass boat it will probably be the only bit of tinned double insulated cable on the boat. Fit the cables in flexible pvc conduit - 10m contractor pack of PVC conduit shouldn't cost you more than £10 so sleeve the cable with that readily available in 20, 25 and 32mm

Out of all of the options given by various people, no-one has suggested an option that wouldn't work, until now. The reason for having to run two pairs of cables, rather than single cables, is that is what the manufacturers of the bow thruster have specified, due to the fact that running a single 95mm cable will result in unacceptable voltage drop.

As for "Most batteries are not suitable for installation in a the occupied area of the boat", that's nonsense.