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Battery charging


Dave 2

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Hi I have a Sterling inverter battery charger I’ve just discovered that it’s not charging the bow thruster battery when it’s connected to the Shoreline (don’t know if it was charging before)I’ve checked it with a volt meter and the only time it’s charging is when the engine is running is that normal, One other point I found this out after blowing the 100 amp battery charging fuse and my battery went  flat I replaced the fuse it’s charging ok from the alternator,Is there anything else I should check.

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2 minutes ago, Dave 2 said:

Hi I have a Sterling inverter battery charger I’ve just discovered that it’s not charging the bow thruster battery when it’s connected to the Shoreline (don’t know if it was charging before)I’ve checked it with a volt meter and the only time it’s charging is when the engine is running is that normal, One other point I found this out after blowing the 100 amp battery charging fuse and my battery went  flat I replaced the fuse it’s charging ok from the alternator,Is there anything else I should check.

 

 

When you want to charge different battery banks from a single source you need some form of charge splitting. You obviously have this for alternator charging but doubt you have it for charging from the inverter charger. probably the easiest way to solve this is to fit a separate mains charger at the front for the bow thruster batteries powered from the shore line only (not from the inverter because using battery power to charge batteries is nit a very bright idea.

 

Not sure what you mean by a 100 amp battery charging fuse. I suspect you may mean a 100 amp fuse in the 12V inverter lead because 50 amp fuse would be large for most battery chargers. More info needed on this so I understand what this is about.

 

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1 minute ago, sbainbridge said:

If it's any comfort mine is the same.

Charged by the engine battery alternator, originally through a diode splitter which has now been replaced with a Cytrix Voltage Sensitive Relay.

A very sensible arrangement and if you charge your engine battery from a charger there is a good chance the thruster battery will be charged as well. The reason I dod not suggest adding a VSR in because I am far from sure what the OP's set-up is.

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8 minutes ago, Dave 2 said:

Re the 100amp fuse it’s on the power charging  lead it’s fitted just before the positive terminal.

I have now had a look at the Sterling online instructions and as I said that fuse is in the 12V supply to the inverter. It just so happens those leads are also the leads that the charger uses to pass current to the batteries.

 

You need to know why it blew. It could be shorting cells in the battery, excessively heavy mains load on the inverter or the fuse is not of sufficient capacity. However fuses are there to protect the cable, not the batteries or the inverter and on the sheet I downloaded the smallest fuse they list for a 12V system is 250 amps BUT you an't just uprate it.You MUST ensure the cable size is large enough.

 

If it is all charging now then no damage has been done but to me it indicates an amateur installation - on the info given.

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When I got my boat it was set up so the big alternator charges the leisure  batteries  and the little alternator charges via a split charge diode the engine start battery and the bow thruster battery.  I thought about replacing the diodes with a VSR (voltage sense relay) but realised that if the relay was closed when the bow thruster was operated a very large current could flow from the starter battery to the thruster battery, burning out the relay or even supply cables, so I kept the diodes for now.

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Just now, Alan de Enfield said:

Why would you want to 'waste' power charging the BT battery from the land-line ?

You won't be using the BT unless you are moving (will you ?) and if you are moving then the engine is running and charging the BT battery.

 

Seems a very sensible method of 'wiring up'.

 

Yes, until as in this case, the bow thruster battery went flat and we know how many hours of cruising that would take to fully charge. Also a mains charger at the front of the boat would not need the huge cables that charging from the back of the boat would entail

 

As for "wasting power", have you not heard of a mains socket with a switch on it? IN any case I doubt the "wasted power" would be noticeable when compared with other mains poleward devices that are typically left on for long periods.

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6 minutes ago, Alan de Enfield said:

Why would you want to 'waste' power charging the BT battery from the land-line ?

You won't be using the BT unless you are moving (will you ?) and if you are moving then the engine is running and charging the BT battery.

 

Seems a very sensible method of 'wiring up'.

Much less voltage drop at 240V than 12V if the bowthruster battery bank is 50+ feet away from the alternator. I know quite a few boats that run a small mains charger off the inverter, but only when the engine is running.

Edited by TheBiscuits
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Just now, TheBiscuits said:

Much less voltage drop at 240V than 12V if the bowthruster is 50+ feet away from the alternator. I know quite a few boats that run a small mains charger off the inverter, but only when the engine is running.

and I specifically said from the shore line so the existing charging system would charge when out cruising and the shore line would fully recharge the battery and then keep it charged when in the marina.

 

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1 minute ago, Tony Brooks said:

Yes, until as in this case, the bow thruster battery went flat and we know how many hours of cruising that would take to fully charge

One might wonder how it became 'flat' ?

Is it not just used for a 'few seconds' and is recharged in 'minutes' (similar to the starter battery) ?

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5 minutes ago, Chewbacka said:

When I got my boat it was set up so the big alternator charges the leisure  batteries  and the little alternator charges via a split charge diode the engine start battery and the bow thruster battery.  I thought about replacing the diodes with a VSR (voltage sense relay) but realised that if the relay was closed when the bow thruster was operated a very large current could flow from the starter battery to the thruster battery, burning out the relay or even supply cables, so I kept the diodes for now.

But if it tried to do that woudl it not pull the voltage below the 13.6/13.8 so the relay dropped out?

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1 minute ago, Alan de Enfield said:

One might wonder how it became 'flat' ?

Is it not just used for a 'few seconds' and is recharged in 'minutes' (similar to the starter battery) ?

with a skilled helmsperson then yes but I would rather an hour or so to recharge but typically ----- I think not. It seems may people use the bow thruster to steer to a degree.

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Just now, Alan de Enfield said:

One might wonder how it became 'flat' ?

Is it not just used for a 'few seconds' and is recharged in 'minutes' (similar to the starter battery) ?

Have you never seen people extensively use their bowthruster when coming back into their moorings then switch off the engine and go away for months leaving a flat battery bank? 

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Just now, Dave 2 said:

the boats just over a year old professional fit out all the electrical work carried out by an electrical engineering company.

 

Have you got a fault that has drained the BT battery ?

 

Just now, TheBiscuits said:

Have you never seen people extensively use their bowthruster when coming back into their moorings then switch off the engine and go away for months leaving a flat battery bank? 

No.

I have never seen a BT used for more than a few seconds - but then I am not on the canals.

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2 minutes ago, Dave 2 said:

the boats just over a year old professional fit out all the electrical work carried out by an electrical engineering company.

 

Well in that case have a look in your RCD file an dig out the instructions for installing the inverter/charger and see what those say. Alternatively download the relevant Sterling instructions, you have not given us the model number so I guessed.

 

https://cdn.shopify.com/s/files/1/0658/7343/files/Combi_Q_S_fitting_instructions_USA_EURO_ba72847f-0490-44d2-98b3-957275f333ac.pdf?789

 

This may not be your unit.

Edited by Tony Brooks
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But normal use of a bow thruster is maybe 5 seconds  two or three times at say 150amps.  So 150x3x5=2250 amp seconds which is less than 1Ah, so you only need a small charge current.  So I wonder if anything else is connected to the thruster battery to drain it.

4 minutes ago, Tony Brooks said:

But if it tried to do that woudl it not pull the voltage below the 13.6/13.8 so the relay dropped out?

It would, but the contacts would open with a very large current, so either a big relay or burnt contacts.

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6 minutes ago, Chewbacka said:

But normal use of a bow thruster is maybe 5 seconds  two or three times at say 150amps.  So 150x3x5=2250 amp seconds which is less than 1Ah, so you only need a small charge current.  So I wonder if anything else is connected to the thruster battery to drain it.

That was my point, but you have kindly filled in the 'numbers'.

If you 'held the button in' for half an hour it might flatten the battery - but even a 'few minutes' shouldn't draw too much, and the engine will be running whilst using the BT

Edited by Alan de Enfield
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It’s a Sterling Pro combi s 360va 2500w the fuse blew whilst leaving my moorings, when I changed it I found the battery was dead so I charged it with my car charger all seems well whilst cruising, but I was asking should it be charging on the land line I’d ask the builder be the company went bust within weeks of delivery.(that’s another story)

 

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There should be a wiring diagram in the RCD owners handbook.

 

 

The documentation shall contain so far as relevant for assessment:
(a) a general description of the type,
(b) conceptual design and manufacturing drawings and schemes of components,
sub-assemblies, circuits, etc.,

(c) descriptions and explanations necessary for the understanding of said drawings and
schemes and the operation of the product,
(d) a list of the standards referred to in Article 5, applied in full or in part, and
descriptions of the solutions adopted to fulfil the essential requirements when the
standards referred to in Article 5 have not been applied,
(e) results of design calculations made, examinations carried out, etc.,
(f) test reports, or calculations namely on stability according to section 3.2 of the
Essential Requirements and on buoyancy according to section 3.3 thereof (Annex I.A),
(g) exhaust emissions test reports demonstrating compliance with section 2 of the
Essential Requirements (Annex I.B),
(h) noise emissions test reports or reference boat data demonstrating compliance with
section 1 of the Essential Requirements (Annex I.C).

Edited by Alan de Enfield
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1 hour ago, Chewbacka said:

 

It would, but the contacts would open with a very large current, so either a big relay or burnt contacts.

Not if you limited the size of the BT charger cables. Volt drop at high currents down that long run would mean that you’d pull very little through the VSR. Obviously this would limit the start of the charge cycle but it would all catch up in the end. 

 

 

Edited by WotEver
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