Bow Thruster

[Lesd]

I have a Vetus 95 kgf bow thruster with a single 110ah battery located next to it in the bows. There is a 425a fuse between the thruster motor and the battery. There is then a long run of thick cable back to the domestic bank in the stern to facilitate charging, this cable is protected with a 100a fuses at both ends. A couple of months back the 100a fuse at the stern end of that cable blew. Today the one at the bow has just blown.

 

My builder says its likey that something caught in the thruster blade to cause this fuse to blow, this doesn't make sense to me as surely it the 435a fuse between motor and battery that is there to protect against such events ? Does anyone have any ideas as to what could have blown these fuses ?

 

Cheers

Les

[steelaway]

I have a Vetus 95 kgf bow thruster with a single 110ah battery located next to it in the bows. There is a 425a fuse between the thruster motor and the battery. There is then a long run of thick cable back to the domestic bank in the stern to facilitate charging, this cable is protected with a 100a fuses at both ends. A couple of months back the 100a fuse at the stern end of that cable blew. Today the one at the bow has just blown.

 

My builder says its likey that something caught in the thruster blade to cause this fuse to blow, this doesn't make sense to me as surely it the 435a fuse between motor and battery that is there to protect against such events ? Does anyone have any ideas as to what could have blown these fuses ?

 

Cheers

Les

 

Hi There

 

As you say the 100a fuse is there to protect the 'charging' cable but when the BT askes for more than the 110a battery has, it trys to take it from the stern battery's.

The 425a fuse is proctecting the BT motor/cables. It is likely that the BT motor is trying to pull to much current and the week link is the 'chargeing' cable running to the stern.

 

Alex

[ITAfloat]

Hi There

 

As you say the 100a fuse is there to protect the 'charging' cable but when the BT askes for more than the 110a battery has, it trys to take it from the stern battery's.

The 425a fuse is proctecting the BT motor/cables. It is likely that the BT motor is trying to pull to much current and the week link is the 'chargeing' cable running to the stern.

 

Alex

Hi. I think Alex may be right. The spec for the Vetus 95 kgf at 12v states minimum 1 x 165AH or 2 x 143AH. At 24v 1 x 165AH or 2 x 143AH (min/Max).

It may be drawing what it can't find locally, from the next nearest source. If it's not drawing current then there would not be a reason for it to blow.

If it has not already got one as part of the Vetus kit, you may have to put a relay to disconnect the charge circuit when in operating the Bow Thruster.

If you have space for another battery, you could always rob one of your domestics for a while and see if that does the trick before deciding.

I'd go with the spec and try another battery.

 

Jas

[stuart]

Hi There

 

As you say the 100a fuse is there to protect the 'charging' cable but when the BT askes for more than the 110a battery has, it trys to take it from the stern battery's.

The 425a fuse is proctecting the BT motor/cables. It is likely that the BT motor is trying to pull to much current and the week link is the 'chargeing' cable running to the stern.

 

Alex

 

I'd agree.

[steelaway]

Hi. I think Alex may be right. The spec for the Vetus 95 kgf at 12v states minimum 1 x 165AH or 2 x 143AH. At 24v 1 x 165AH or 2 x 143AH (min/Max).

It may be drawing what it can't find locally, from the next nearest source. If it's not drawing current then there would not be a reason for it to blow.

If it has not already got one as part of the Vetus kit, you may have to put a relay to disconnect the charge circuit when in operating the Bow Thruster.

If you have space for another battery, you could always rob one of your domestics for a while and see if that does the trick before deciding.

I'd go with the spec and try another battery.

 

Jas

 

Hi There

 

Is there a 100a diode available, that would stop current flow in the wrong direction

 

Alex

[ITAfloat]

Hi There

 

Is there a 100a diode available, that would stop current flow in the wrong direction

 

Alex

 

This will introduce a volts drop across it...on a long run already incurring voltage drop you may reduce the charge going into the batteries to an unacceptable level. If the diode had a 1v drop and the alternator was flat out at 14.8V, then that leaves only 13.8... by the time it hits the batteries, things may not be so good.

chrisW has posted on this before. I'm sure he will see this post.

If only they weren't so greedy!

[Lesd]

Thanks very much for the fast replys, what your all suggesting sounds like the cause. But even with a larger 165ah battery I assume I'd still get the same problem if the thruster had a lot of use and that battery couldn't supply the load ?

Do you think the fuse has blown under normal usage or do you think the motor got obstructed and caused the extra current draw ?

I'm wondering about the relay arrangement Jas mentioned, I wonder if Vetus do a bolt on ?

Thanks again for the quick reponse !

Les

[Ray]

I'd guess that the BT battery possibly isn't fully charged and the BT is trying to top up the supply it needs by drawing power down the line. It might be worth checking that the connections are tight and clean on the BT and its battery.

 

Give the battery a good charge if you can without using the BT whilst its charging. Then try the BT again briefly in both directions. If you can hear the BT and it appears to be working from observation at the front of the boat, then I doubt it is blocked.

 

Maybe the BT battery is getting tired.

[blackrose]

Hi Les.

 

I have the same thruster and have a 425A MegaFuse on the + cable leading to the motor. On the other side of the BT isolator switch there's a 70A fuse on the + cable from the alternator. (I have 2 x 110a/h BT batteries at the bow)

 

I think we have different set ups at the other end of the boat because my charge to the BT batteries comes from the start battery alternator - the charge is split between the start and BT batteries.

 

Anyway, there's just one other thing - do you have a Vetus BPTD on the control cable leading to the thruster? It's a device that stops you from reversing the direction of the motor too quickly - basically a 5 second delay.

 

Mike

Edited February 15, 2008 by blackrose

[pagan witch]

Technology may have moved on since my college days but I was taught that a diode was simply a 'one way valve' designed to operate up to a certain voltage / current. If you over do this then you can 'force' a supply through it the wrong way which may or may not destroy it depeneding on its' design and how much 'force' you'd applied.

 

If this understanding is correct then as I see it a diode of any size isn't going to help.

 

What you need to do here is prevent the charging cable from being required to deliver BT operating current. A diode, depending on which way you installed it would either :-

 

1) allow current to flow from the BT battery to the boat

 

2) allow current to flow from the boat to the BT battery.

 

Option 1 has no use at all - you are hopefully never going to be in a position where you want BT battery to feed boat.

 

Option 2 is what is already achieved without having a diode in.

 

I concur with previous replies that your BT is underpowered and is therefor trying to draw from the boat and the fuses are doing a great job in protecting an overload of that cable.

[ITAfloat]

I'm wondering about the relay arrangement Jas mentioned, I wonder if Vetus do a bolt on ?

Thanks again for the quick reponse !

Les

Taken from the Vetus 95Kgf site...

Series/Parallel switch

Where a 12 Volt circuit is fitted the installation of a series- parallel

switch can be used to: ..."connect the 2 (12 Volt) batteries in parallel to the 12 Volt charging system during charging.

Vetus can supply a series/parallel switch that is already fitted with the necessary help relay to allow a simple connection to

the Vetus bow thruster, Vetus art. code: BPSP.

 

- The maximum continuous current that may flow through the charging contacts of the series/parallel switch is 60 A.

The way in which the bow thruster is controlled remains unchanged after installation of the series/parallel switch!"

 

If I read this right Les, yes they do have something that does it, which you may or may not have, we don't know, but sounds more likely you don't. You could do it with a good relay (including the voltage sensitive types), and come off the control circuit when you power it up.

 

First chance you get ask Vetus what they recommend and also confirm what battery bank you should have, then if this differs from what you have, ask the builders why they fitted only one battery against Vetus recommendations. You may get a second battery out of them or the BPSP. Never hurts to ask.

Good luck Les. PM me if needed 'on site'

[blackrose]

Les, try this bloke:

 

Ray Browning

02380-454507

RBrowning@vetus.nl

 

 

Vetus Den Ouden Ltd

5 Compass Point

Ensign Business Park

Ensign Way, Hamble

Southampton, SO31 4RA

tel: +44 (0) 23 8045 4507

fax: +44 (0) 23 8045 4508

email: RBrowning@vetus.nl

internet: www.vetus.co.uk

[Yoda]

Have you all missed something here?

 

What is the point of having very heavy cables to the BT battery from the starter battery with all of the associated problems when you could just do away with the BT battery altogether. You might as well have twin starter batteries.

[Ray]

With respect, I think you'll find that the voltage drop over the length of the boat from the engine would stop the BT from performing to the optimum otherwise I'm sure a lot of people would have done it.

[blackrose]

I don't have very heavy cables from the start/BT alternator to the BT batteries - they're about 25mm2. The short cables from the BT batteries to the BT motor are much thicker. I think the idea is that the BT motor needs instant power without voltage drop hence the thick cables, but the BT batteries have plenty of time to get charged from the alternator while the BT isn't being used (which is most of the time), so the thinner cables suffice despite the length of cable run. I think I'm restricted to about 3 minutes of button pressing/hour without running the batteries down, which is plenty.

Edited February 15, 2008 by blackrose

[chris w]

Technology may have moved on since my college days but I was taught that a diode was simply a 'one way valve' designed to operate up to a certain voltage / current. If you over do this then you can 'force' a supply through it the wrong way which may or may not destroy it depeneding on its' design and how much 'force' you'd applied.

 

If this understanding is correct then as I see it a diode of any size isn't going to help.

 

You won't cause a diode to "reverse-breakdown" using the voltages available from boat batteries (unless it's specifically designed to do so, like a zener diode - which is not what we are talking about here).

 

A diode would be a bad option for the reasons given above - you will lose a volt across it and up to about 50W in power across it. Your charging of the BT batteries would be hopeless.

 

Chris

 

--------------------------------------------

 

Les

 

If the boat builders didn't follow Vetus specific guidelines, then legally it's up to them to sort it out at no charge to you. (Sale of Goods Act - Fitness for Purpose). Don't let them take an inch.

 

Chris

[ChrisPy]

With respect, I think you'll find that the voltage drop over the length of the boat from the engine would stop the BT from performing to the optimum otherwise I'm sure a lot of people would have done it.

that's what I've done - twin welding cables 475x0.40 giving a voltage drop of 1.3V. I can live with that. It cost about £100.

[DHutch]

Alternatively could you stick a 100amp relay in the charge line, that opened when the bow thruster was working?

[Lesd]

Guys

Thanks again for the tips. I dont hink I have the time delay gizmo mike mentions in the circuit and here's notthing fouling the blades (I have a bow weedhatch to get to it) and he propellor turns freely. These were the same symptoms as the first time the fuse blew. I have email the contact Mike passed on and will let you know how things progress with him / the builder.

Rgds

Les

PS Jas, thanks for the offer, we're moored near where ypu saw us before (waiting for the winkwell stoppage to clear) so pop in for a brew any time !

[ChrisPy]

I'm restricted to about 3 minutes of button pressing/hour without running the batteries down, which is plenty.

enuff for doing a few pirouettes, actually .....

[Lesd]

update, I got an answer back from Vetus. Yes the battery needs to be upgraded, Im ''in discussion'' with the builder about that, but Vetus also say I should connect the bow thruster battery to the dometic bank/alternators via a diode (!!!!) to make sure the thruster cant pull current from the domestic bank. Its currently connected via a smartbank relay.

 

Im worried that a diode in line will screw up the charging of the bow battery if I follow their advice. (that seemed to be your combined expert opinion). So is there a simple way of wiring the charge line via a large relay that triggers when the thruster operates. Any tips on how to wire that in ? Any alternatives you can think of ?

 

Thanks

les

[sideways]

update, I got an answer back from Vetus. Yes the battery needs to be upgraded, Im ''in discussion'' with the builder about that, but Vetus also say I should connect the bow thruster battery to the dometic bank/alternators via a diode (!!!!) to make sure the thruster cant pull current from the domestic bank. Its currently connected via a smartbank relay.

 

Im worried that a diode in line will screw up the charging of the bow battery if I follow their advice. (that seemed to be your combined expert opinion). So is there a simple way of wiring the charge line via a large relay that triggers when the thruster operates. Any tips on how to wire that in ? Any alternatives you can think of ?

 

Thanks

les

There is a very simple way. Use a Blue Sea Systems PN 7600 Automatic Charge Relay to charge the battery and everything else is taken care of. www.bluesea.com

We have several hundred in use and not one problem. The thruster battery or batteries need to be double the amp draw for the ACR to work properly. If the draw is 500 amps then the battery needs to 1000 CCA

[ITAfloat]

Hi Les,

As the bow thruster cannot be used without blowing fuses, I'd be asking the builder to rectify this at their expense - at least that way it's covered by warrenty. Looking at the wiring diagram there is a control circuit with a smaller fuse to operate the control relays. This connects to pin 2 on the relay block (as they have it labeled on their circuit diagram). From memory there is a small control box which the switch block connects to. It may be in there. The other way is take off the positive feed from the switch, through a new fuse to a Voltage sensitive relay (VSR). Merlin sell them - 125A, 12v £41.41 +VAT. Also available at other outlets

That way when the switch has power fed to it the batteries don't.

I'm sure there are other ways to achieve the same end. You can always stick a meter on the switch and find the right cable. Did Vetus state their paralleling device would or would not do this?

I'd be concerned not to invalidate any warrenty you may have as it's new.

 

Jas

[chris w]

update, I got an answer back from Vetus. Yes the battery needs to be upgraded, Im ''in discussion'' with the builder about that, but Vetus also say I should connect the bow thruster battery to the dometic bank/alternators via a diode (!!!!) to make sure the thruster cant pull current from the domestic bank. Its currently connected via a smartbank relay.

 

Im worried that a diode in line will screw up the charging of the bow battery if I follow their advice. (that seemed to be your combined expert opinion). So is there a simple way of wiring the charge line via a large relay that triggers when the thruster operates. Any tips on how to wire that in ? Any alternatives you can think of ?

 

Thanks

les

 

Les

 

They acually mean a diode in EACH line, ie: one in the bowthruster line and one in the domestic line. A single diode won't solve the issue of isolating the two battery banks from each other. ie: the same as splitter diodes for starter/domestic batteries.

 

If you do this, you CANNOT use machine-sensed charging (eg: most alternators using their own regulator). You would need an external alternator controller to make the charging battery sensed.

 

Chris

[Lesd]

Hi Les,

As the bow thruster cannot be used without blowing fuses, I'd be asking the builder to rectify this at their expense - at least that way it's covered by warrenty. Looking at the wiring diagram there is a control circuit with a smaller fuse to operate the control relays. This connects to pin 2 on the relay block (as they have it labeled on their circuit diagram). From memory there is a small control box which the switch block connects to. It may be in there. The other way is take off the positive feed from the switch, through a new fuse to a Voltage sensitive relay (VSR). Merlin sell them - 125A, 12v £41.41 +VAT. Also available at other outlets

That way when the switch has power fed to it the batteries don't.

I'm sure there are other ways to achieve the same end. You can always stick a meter on the switch and find the right cable. Did Vetus state their paralleling device would or would not do this?

I'd be concerned not to invalidate any warrenty you may have as it's new.

 

Jas

 

Sounds complicated Jas (to me anyway). I've asked the specific question just now by email !

I like the sound of this Blue Sea device that sideways mentions, sound like it will do what I need without changing anything else. As its inline with the charge cable i wont by messing with what the builder has done and so guarantee will be complete.

 

Chris, thanks I wasnt sure exactly what he meant. I dont want to have to change too much, the smartbank seems to be doing a good job (apart from this issue which may or may not have anything to do with it).

 

The builder wont pay for this work (apart from the battery) as he didnt spec the set up, I did (oops).

 

Sideways, do you know where to buy these devices ? Midland and aquafax dont seem to have them. I cant even find a price on the net although there is an example of blue seas web site showing exactly the same set up as I have ! so thanks for the tip.