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Bow thruster with relay for charging ?


moiuk

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7 minutes ago, nicknorman said:

Yes but that is on leaving the mooring (after which lots of engine running) rather than arriving (after which many hours of no engine running).

Agreed, but it was more the point that a BT shouldn't be needed, let alone destroying the bank-side by trying to push the boat away with a 'water-jet'.

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20 minutes ago, nicknorman said:


 

A boat being moored on the towpath really doesn’t require a BT to be operated.

Some times a quick squirt can be useful to stop the bow swinging out as the stern nears the bank and the recess prop wash starts to push the bow out.

The answer to the charging at a 20 watt solar panel at the front connected to the batteries, they are nicely trickle charged every day.

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1 hour ago, Tracy D'arth said:

But with sensible size cables the bow batteries will receive a sufficient charge to fully charge the batteries.

Purely out of curiosity, what would you suggest as "sensible size cables" - 25mm csa?

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1 hour ago, Tony Brooks said:

That is what the BSS specifies for battery cables?

As they are connected to batteries, yes should be 25mm2.

In reality less would be enough, to carry charging current but it has to be considered that they may have to carry current from the starter battery to flat bow batteries,  volts drop will limit the maximum current in that case.

I think I would be happy with just 16mm2.

  • Greenie 1
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6 hours ago, Jen-in-Wellies said:

Not necessarily. There could be leaves, plastic bags and crud blocking things up for example. The bow thruster will still whine, but little thrust generated. The shear pin that protects the thruster if the prop gets jammed could have been broken. Again, motor noise, but no thrust.

Jen

So how would you clear it? Doesn't seem to have a weed hatch system to gain access..

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6 hours ago, nicknorman said:

Yes but that is on leaving the mooring (after which lots of engine running) rather than arriving (after which many hours of no engine running).

For me the main time I have needed them is going through bridges and the tight corner before/after.  I am fairly capable at the tiller, but some areas are not possible without a bit of thrust at the front.  Having said that, I am trying to move a very long widebeam.....

15 minutes ago, Tracy D'arth said:

If there is no weed hatch, the whole motor must lift out, hopefully without sinking the boat.

that is something I will hope to avoid.... 

 

I will look again in case I missed the weed hatch.

Edited by moiuk
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6 hours ago, Bod said:

Get the BT batteries' fully charged by an external source, before relying on the alternator charging.  This will be much quicker, and enable you to check the condition of the batteries.  The combination of large capacity batteries and thin charging cables, and a surprisingly low alternator output, (think 5-10 amp rather than the 50-90 amp alternator rating) then you may require in excess of 60 hours engine run time.

 

Bod.

not really an option for me as I am never plugged into a mains source.  I intend to not use the Bt again until the voltage on their batteries are reporting something heathly again. They stopped working when it dropped down to 12.1, so not terrible. Will wait until they are up to 12.5 at least before using them is my plan.

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11 minutes ago, Tracy D'arth said:

They need charging much longer than when at 12.5v

Charge until the current drops to less than an amp, terminal voltage after standing should be in excess of 12.8v.

Thanks, might need to get the generator working then if I want to be using them anytime soon. Its an 80amp battery charger,  I assume that will get me there a bit quicker than the alternator? 

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3 minutes ago, moiuk said:

I assume that will get me there a bit quicker than the alternator? 

Probably save about 5 minutes.

It is the batteries that control how much charge they take, not the alternator.

A 70Ah alternator will not put in 70Ah.

 

As the battery charges it will take less and less amps, until when it gets to about 90% it may only take 5 amps and another 5 hours later it may be down to 1 amp, It doesn't matter how big the alternator or battery charger is, that is how batteries work.

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9 minutes ago, Alan de Enfield said:

Probably save about 5 minutes.

It is the batteries that control how much charge they take, not the alternator.

A 70Ah alternator will not put in 70Ah.

 

As the battery charges it will take less and less amps, until when it gets to about 90% it may only take 5 amps and another 5 hours later it may be down to 1 amp, It doesn't matter how big the alternator or battery charger is, that is how batteries work.

 

Thanks, will need to think of another solution then, perhaps wiring up my solar panels/charge controller for a day is the way forward.

 

I also remembered that the generator wouldn't help anyways, as the relay to charge them is energised by the alternator being on.  That's assuming that the battery charger is wired to charge both the leasure and the starter battery which it might not be..

 

Engine running or solar seems to be the only options to get it back up to 100%.

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9 minutes ago, moiuk said:

I also remembered that the generator wouldn't help anyways, as the relay to charge them is energised by the alternator being on. 

 

That sounds strange, is it not just a 'generator' and it produces 230v, you plug your battery charger into the socket and it charges the battery ?

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Just now, Alan de Enfield said:

 

That sounds strange, is it not just a 'generator' and it produces 230v, you plug your battery charger into the socket and it charges the battery ?

Yes it is, and it charges the leisure batteries just fine. Just haven't checked that it is split to also charge the starter battery, and even then the relay will stop the BT batteries from charging unless the alternator is running.

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1 minute ago, moiuk said:

Yes it is, and it charges the leisure batteries just fine. Just haven't checked that it is split to also charge the starter battery, and even then the relay will stop the BT batteries from charging unless the alternator is running.

 

How about taking your battery charger to the bow and connecting it to your BT Battery, use a 230v extension lead to get power from the generator to the battery charger.

 

It may need a few wires disconnecting / reconnecting but it sounds like the only (simplest) way to get your BT battery charged.

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3 minutes ago, Alan de Enfield said:

 

How about taking your battery charger to the bow and connecting it to your BT Battery, use a 230v extension lead to get power from the generator to the battery charger.

 

It may need a few wires disconnecting / reconnecting but it sounds like the only (simplest) way to get your BT battery charged.

Battery charger is mounted in the stern,  a sterling invertor/charger multi.  But you might be on to something if I use a standard car battery charger perhaps.

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3 hours ago, Tracy D'arth said:

You could pick up on the cables going to the bow batteries at the stern, the positive will be on the relay, the negative will be common to all the batteries.

Yes I think I will do this.

 

Easiest thing with the wiring in place is to move the solar charge controller positive from the lesuire batteries to the BT side of the relay.  I'll limit the current on the charge controller down to 30amps (its a 100amp charge controller) as its the wrong side of the fuse where I will be attaching it and the cables are quite small (Between 10mm-15mm).

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26 minutes ago, moiuk said:

Yes I think I will do this.

 

Easiest thing with the wiring in place is to move the solar charge controller positive from the lesuire batteries to the BT side of the relay.  I'll limit the current on the charge controller down to 30amps (its a 100amp charge controller) as its the wrong side of the fuse where I will be attaching it and the cables are quite small (Between 10mm-15mm).

Disconnect the panel from the controller or cover the panels before removing the controller to battery cable. Or the controller may die.

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7 minutes ago, Tracy D'arth said:

Disconnect the panel from the controller or cover the panels before removing the controller to battery cable. Or the controller may die.

Thanks.

 

Yes I have an isoloation switch between the panels and the charge controller which I will ensure is off before moving the cables.

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On 05/08/2020 at 18:17, Tracy D'arth said:

You could pick up on the cables going to the bow batteries at the stern, the positive will be on the relay, the negative will be common to all the batteries.

Hi,

 

Just switch it over.  The solar controller has gone directly into absorbtion mode, with only 10/20 amps flowing to the BT  batteries.  The volatage at the solar charger is showing 14.2 amps (my absorbtion set voltage), the voltage on the BT batteries is showing as 13.2.  Is this due to the long length of wire and the  votage drop?  Could I get more into it by setting a higher absorbtion voltage on the solar controller to compensate for the voltage drop?

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You meant 14.2 VOLTS? You could take that up to 14.8v with open lead acid batteries or 14.4 with sealed LA or gel batteries,

 

The volt drop will get less and less as the current falls as the batteries charge, don't fret.  Ohm's law Volts =Amps * resistance.

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3 minutes ago, moiuk said:

Hi,

 

Just switch it over.  The solar controller has gone directly into absorbtion mode, with only 10/20 amps flowing to the BT  batteries.  The volatage at the solar charger is showing 14.2 amps (my absorbtion set voltage), the voltage on the BT batteries is showing as 13.2.  Is this due to the long length of wire and the  votage drop?  Could I get more into it by setting a higher absorbtion voltage on the solar controller to compensate for the voltage drop?

Yes I would think it is down to the voltage drop in the cables. 14.2v is a bit low anyway, so I would increase to 14.6v, at least while it’s attached to the BT batteries.

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