BCS BT55N Bow thruster not working

[Nb Ceann Caslach]

The bow thruster worked last time I used it, we haven’t been out for a year.  I switched it on this morning and when I switched the isolator on the thruster motor ‘kicked’ for a second or so and the control panel showed the Fault light.  I switched it off at he isolator and back on again and the relay on the thruster clicks when the switch is switched on or off.  The Fault light shows when it is on.  Can anyone suggest where I should look/test with the meter?  I suspect a wiring issue somewhere.

[Chris G]

Flat battery?

[Momac]

Knackered battery.

[matty40s]

99 % battery, 1%, any other cause

 

[Nb Ceann Caslach]

Thanks for the suggestions.  Battery hadn’t occurred to me but I’ll check it as soon as I get the meter out of the van. 

[cuthound]

When my BT stopped working it took me a year or three to look at it.

 

It turned out that condensation in the BT compartment had caused the motor to rust and size.

 

Cox Auto.Electrics of Atherstone refurbished the motor for me for about a quarter of the price of a new one.

 

https://www.coxautoelectrics.co.uk/marine-leisure

 

Since then I leave the BT compartment open (under the cratch)  to ventilate it over winter to prevent condensation forming.

[DaveR]

The BUS electric motor has a blade fuse tucked in beside the motor. On mine it was helpfully spray painted the same colour as the motor body. The fuse is in the control circuitry & may be  a contributory cause of your problems.

Auto correct changed BCS TO BUS, sorry about that.

[Nb Ceann Caslach]

I’ve checked the battery voltage and, when the relay energises it only drops from 13.7 to 13.3 so I’d suspect that it isn’t the battery.  Once I get some stuff cleared off the foredeck I’ll trace the wiring and check voltages closer to the motor.  It may be a bit before I update the thread again as we’re going away in the van for a couple of weeks but I’ll post findings when I do check it.

 

Thanks to everyone for the very helpful responses so far.

[Tracy D'arth]

How do you get a resting voltage of 13.7V on LA batteries (not on charge) please?

Edited October 1, 2023 by Tracy D'arth

[Nb Ceann Caslach]

It is sitting on its own trickle charger connected to the 240V supply so I assume that 13.7 is the float voltage for that charger.  I’ve never actually put a meter across it before.

[Tracy D'arth]

24 minutes ago, Nb Ceann Caslach said:

It is sitting on its own trickle charger connected to the 240V supply so I assume that 13.7 is the float voltage for that charger.  I’ve never actually put a meter across it before.

That is no way to evaluate a battery.   It needs to be off charge for several hours to establish the resting voltage.

[Nb Ceann Caslach]

I wasn’t looking at resting voltage, I was looking for voltage drop when the relay kicked in as the only way the fault light could illuminate due to battery condition would be if it saw an excessive voltage drop, which you’d get of it had lost a cell and a heavy load was applied. Clearly if the meter sees that voltage then that’s the voltage which the controller will see and it wouldn’t then illuminate the ‘Fault’ light because the battery was low.  Unless, of course, I’m missing something in its fault detection logic?

Whether the relay should engage as soon as the isolator is switched on is another matter as, at that stage, I’m not sure that anything apart from the controller should be energised?  I’ll dig deeper when I get back and, as a matter of course, will drop-test the battery once I get sufficient access to disconnect it and get the tester on it.

[matty40s]

You cant test a battery that is connected to an active charger , period.

 

[magnetman]

Brushes. 

[Tony Brooks]

Dirty/corroded contactor contacts.

[Nb Ceann Caslach]

21 minutes ago, matty40s said:

You cant test a battery that is connected to an active charger , period.

 

Neither can the control panel, I wasn’t testing the battery.  I was testing the battery VOLTAGE which the control panel sees as, for the fault light to be the result of a low battery, the controller would have to see low voltage.  All the controller knows is the voltage which it sees at the time.  Perhaps I should have been clearer about this in my initial statement.   If the control panel only ever sees ~13V how could the Fault light be because the control panel believed the battery to be low/dead?

 

As I said, I’ll dig deeper in a couple of weeks and, as soon as I get access to the battery I will test it but I’ll also investigate why the panel is showing a fault light.  It would be useful to know if the relay is supposed to energise as soon as the isolator is switched on as, if not, then that will probably be a part of the fault.  I’d suspect that the relay is only supposed to energise when the motor is engaged but need to either see, or reverse engineer, a circuit diagram to confirm that unless someone on here knows the answer.

[Tony Brooks]

The contactors will certainly only energise when you try to energise the motor. This may well be via a pair or relays.

Edited October 1, 2023 by Tony Brooks

[Nb Ceann Caslach]

3 minutes ago, Tony Brooks said:

The contactors will certainly only energise when you try to energise the motor. This may well be via a pair or relays.

Thanks, that’s what I suspected and that, along with the fact hat the motor kicked when I initially switched it on, suggests that there is a fault in the controller circuit somewhere which is trying to energise the motor before the controller has even been switched on.  Clearly in this state the control panel would be expected to detect a fault.  ‘All’ I have to do now is find the short 😉

[Alan de Enfield]

3 hours ago, Nb Ceann Caslach said:

when I get back and, as a matter of course, will drop-test the battery

 

What do you expect that to tell you ?

[Tractor]

On 30/09/2023 at 12:01, Nb Ceann Caslach said:

The bow thruster worked last time I used it, we haven’t been out for a year.  I switched it on this morning and when I switched the isolator on the thruster motor ‘kicked’ for a second or so and the control panel showed the Fault light.  I switched it off at he isolator and back on again and the relay on the thruster clicks when the switch is switched on or off.  The Fault light shows when it is on.  Can anyone suggest where I should look/test with the meter?  I suspect a wiring issue somewhere.

Brushes stick in the holders with corrosion?

Give them a wiggle, or rub down, and a good run to clean the commutator.

[magnetman]

19 hours ago, Alan de Enfield said:

 

What do you expect that to tell you ?

How hard the casing is. 

 

It depends how high you drop it from

Yars ago I split a 220ah SLA dropped from about a foot. 

 

 

Its like the traditional test for a flat battery. You get a metal straight edge such as a stainless steel 1ft ruler and if you can hold it across the battery terminals then the battery is flat. 

 

(take advice before trying this)

Edited October 2, 2023 by magnetman

[Alan de Enfield]

8 minutes ago, magnetman said:

How hard the casing is. 

 

It depends how high you drop it from

Yars ago I split a 220ah SLA dropped from about a foot. 

 

 

Its like the traditional test for a flat battery. You get a metal straight edge such as a stainless steel 1ft ruler and if you can hold it across the battery terminals then the battery is flat. 

 

(take advice before trying this)

 

 

I just use a jump lead and look at the sparks - we used to use a length of welding cable and a battery to cut holes in the roof of the tow-cars at the gliding club. One cable clamped to the battery and the other end to the vehicle, then a longer length clamped to the other battery terminal, the 'loose end' was then dragged across the car roof making a reasonably neat 'sun roof'

 

I know what the drop test is and what supposedly tells you about the battery health - I'm just wondering what the OP will think it actually tells him about his batteries.

[magnetman]

If it is a load tester then it does give an indication of the state of the battery. Ability to supply current and a low voltage over time.

 

I'd want a load tester, a conductance tester and a refractometer if the acid is accessible to get a true idea of the battery health for a wet lead acid battery. 

 

Without all of these there are weaknesses but the three work well together. 

 

Conductance tester is a particularly interesting device. I've got an old Motorola moving coil conductance tester somewhere. 

 

 

[Tony Brooks]

Remember that the currant capacity of the load ester needs to be matched fairly well to the capacity, or more accurately the CCA/MCCA of the battery. If you did a drop (load) test on a typical narrowboat battery with a car tester it is unlikely to load the battery sufficiently so could well pass a duff battery. Just like if you did it on a well discharged battery, it would stand a good chance of condemning it, even though a good charge may sort the battery out.

 

I fear most boaters that have a load tester will find it is a car one suitable for (say) a 35 or 40 Ah battery, not the 100 Ah plus boats usually use.

 

The need to match to CCA/MCCA really says they are for start batteries, not so much for true deep cycle ones.

[blackrose]

I still don't understand why the OP isn't testing the battery voltage off charge? He's asking for advice and then dismissing it.

 

I'm assuming the controller he refers to is a solar controller and he's expecting the batteries on float voltage to be powering the BT? That isn't going to happen if the batteries are knackered and the voltage drop he's measuring is irrelevant if the batteries are being charged.

 

What you're measuring is the voltage drop with volts coming out of the controller. PLEASE DO WHAT OTHERS HAVE SUGGESTED: TAKE THE BATTERIES OFF CHARGE, LEAVE THEM FOR A FEW HOURS AND THEN TEST THE  RESTING BATTERY VOLTAGE. I would actually press the BT button to take any surface charge off the plates. If when you test the voltage it's 12.7v or 12.8v then fine at least you know the basic condition of the batteries and can look for other causes, but without that information you're wasting everyone's time.

Edited October 2, 2023 by blackrose