Engine rewire, wiring diagram ?

[xeitosaphil]

Hi all , I am in the final stages of my engine rewiring job which seems to have taken forever to sort out, but I have had loads of help from the guys/galls on the forum and hopefully this will be my last diagram which I am hoping will be deemed as workable?
My basic requirements are to monitor the charge and discharge rates of my house and engine start batteries using a smart gauge and two digital ammeters and shunts. In additional to that I would like to be able to isolate both sets of batteries when going ashore but leave two chargers on shore power to keep things going while away. There is also the need to be able to start engine from either battery while isolating the flat one if necessary. All circuits need to be fused for protection of wiring and I need to be able to charge both batteries as well, I just hope I have covered all the bases?
All starter cables are now 50mm2 and VSR and Dis/Panel wiring is 10mm2, Windlass - 35mm2 as recommended by Lofrans

The text re starting procedures on the photo may not be absolutely correct as I wrote them in haste, but circuit measurements are correct.

I would be interested and grateful for any constructive feedback with regards to the workability and safety of my diagram, as I am eager to get the job finished now so I can go onto the next job!

Philip

 

[BabaYaga]

I have not followed your previous postings on this subject, but one thing that struck me looking at the sketch is the lack of a fuse in the pos lead from alternator to starter battery. Also the leads from the two shore power chargers are unprotected.
The point of having both a 1-2-both-switch AND a VSR is not quite clear to me, but I suppose this was already discussed.

If I understand correctly the ammeter on the house battery is only for max 50 A? Will it still be able to handle starting current?

I think the requirements you have set up for your system are not so easily met.

 

[Bilgediver]

If I understand correctly the ammeter on the house battery is only for max 50 A? Will it still be able to handle starting current?

I think the requirements you have set up for your system are not so easily met.

I think the 50A meter only measures house and is bypassed by the starter circuit.

 

[pvb]

There are numerous basic errors in your proposed diagram, which also seems over-complicated. I don't really know where to start, but here are a few observations...

All positive connections on your engine battery should be made to the load side of the fuse, not to the positive terminal.

Similarly, all positive connections on your house battery bank should be made to the load side of the fuse, not to the main positive terminal.

The VSR is wrongly wired; it should be wired to the load side of the engine battery fuse, rather than to the common terminal of the 1-2-Both switch, and to the load side of the house battery bank's fuse.

The VSR should be wired with heavier cable than 10 sq mm - in some situations there could be a very high current through the VSR circuit.

The ammeter shunt for the engine battery is wrongly located. As you've shown it, this ammeter will measure both engine and house battery current.

Similarly, the ammeter shunt for the house battery bank is wrongly located. As you've shown it, this ammeter won't show engine charging current, although it will show mains charger current to the house battery and domestic load from the house battery. However, it will also show the current being delivered to the engine battery by the other mains charger - which presumably isn't your intention.

Why do you need a second charger for the engine battery? Why not just let the VSR handle shorepower charging current, from one charger?

There frankly isn't any point in having an engine battery ammeter, as unless there's a major problem the engine battery should always be charged. In any case, if you're planning to use a SmartGauge, why bother with an ammeter in the house battery circuit?

The whole thing would be a lot simpler if you dispense with the 1-2-Both switch and the separate isolator switch, and just have 2 simple on/off switches - one for the engine battery, and one for the house bank. There's almost nothing to go wrong or set wrongly, just arrive at the boat, turn both switches on, enjoy, turn off both switches, leave boat. If you're worried about the engine battery going flat (and if it's correctly wired there's almost no chance of this happening anyway) you can always have a third on/off switch to use the house bank for starting.

 

[VicS]

I have not followed your previous postings on this subject, but one thing that struck me looking at the sketch is the lack of a fuse in the pos lead from alternator to starter battery. Also the leads from the two shore power chargers are unprotected.
The point of having both a 1-2-both-switch AND a VSR is not quite clear to me, but I suppose this was already discussed.

If I understand correctly the ammeter on the house battery is only for max 50 A? Will it still be able to handle starting current?

Yes A fuse could/should be put in the alternator connection to starter battery. Also in the battery charger positive connections.

The starter current, as said below, does not pass through the 50amp shunt


I think the requirements you have set up for your system are not so easily met.

I think the 50A meter only measures house and is bypassed by the starter circuit.

You are right I am sure

There are numerous basic errors in your proposed diagram, which also seems over-complicated. I don't really know where to start, but here are a few observations...

All positive connections on your engine battery should be made to the load side of the fuse, not to the positive terminal.

Similarly, all positive connections on your house battery bank should be made to the load side of the fuse, not to the main positive terminal.

The VSR is wrongly wired; it should be wired to the load side of the engine battery fuse, rather than to the common terminal of the 1-2-Both switch, and to the load side of the house battery bank's fuse.

The VSR should be wired with heavier cable than 10 sq mm - in some situations there could be a very high current through the VSR circuit.

The ammeter shunt for the engine battery is wrongly located. As you've shown it, this ammeter will measure both engine and house battery current.

Similarly, the ammeter shunt for the engine ???? battery is wrongly located. As you've shown it, this ammeter won't show engine charging current, although it will show mains charger current to the house battery and domestic load from the house battery. However, it will also show the current being delivered to the engine battery by the other mains charger - which presumably isn't your intention.

Why do you need a second charger for the engine battery? Why not just let the VSR handle shorepower charging current, from one charger?

There frankly isn't any point in having an engine battery ammeter, as unless there's a major problem the engine battery should always be charged. In any case, if you're planning to use a SmartGauge, why bother with an ammeter in the house battery circuit?

The whole thing would be a lot simpler if you dispense with the 1-2-Both switch and the separate isolator switch, and just have 2 simple on/off switches - one for the engine battery, and one for the house bank. There's almost nothing to go wrong or set wrongly, just arrive at the boat, turn both switches on, enjoy, turn off both switches, leave boat. If you're worried about the engine battery going flat (and if it's correctly wired there's almost no chance of this happening anyway) you can always have a third on/off switch to use the house bank for starting.

I think it is has become complicated in the attempts to satisfy all the objectives

The starting current goes through the Mega fuse, The windlass has its own fuse. Lighter loads with lighter wiring should have their own fuses. One is required in the battery charger connection

Again the staring current goes through the Mega fuse . Lighter loads with lighter wiring should be separately fused. A fuse is shown for the distribution panel. Another should be put in the battery charger connection. Maybe if the wiring is appropriately sized ( the battery charger leads may not be!) one fuse could serve both purposes.

If you check back with the original thread i think you will find that the proposed VSR wiring is as suggested by Halcyon ( Brian of KDD Powercentre). IIRC he explained the logic at the time.

The VSR should be wired with cable suitable for the full alternator output plus an allowance to avoid voltage drop. I believe there is info on cable sizing for the VSR on the BEP website

Maybe the positive connections should be fused although I don't recall see that suggested in the instructions for wiring the VSR on the BEP website

The VSR should be wired with cable suitable for the full alternator output plus an allowance to avoid voltage drop. I believe there is info on cable sizing for the VSR on the BEP website

The 500amp ammeter will show the total charging current from the alternator. I think you will find if you want separate readings for both battery banks you will need two ammeters, or at least two shunts with switching of the meter connections between the two. I think the OP has opted to put the ammeter in the common negative to avoid buying two 500 amp ammeters

The engine battery charger negative should perhaps go directly to the battery negative but is OK where shown. However if the 500amp ammeter is required to show the charging current from the battery charger then the negative should go to the end of the shunt furthest from the battery

I believe the OP already has the 50 amp ammeter so he has included it to show principally the consumption via the domestic distribution panel. As he has shown it it will also show charging current from the battery charger.

I think the Op has already bough both chargers as a special double pack offer. IIRC I suggested earlier that a smaller one would adequte for the starter battery but if he has them He might as well use them!

The Smartgauge does not show current .. hence reason for an ammeter.

I think you will find that the 1,2 , both switch is already in existence. So it is being used so that the house battery can be selected for starting if required.
I forget without going back to the original thread but the other isolator may also alraedy be fitted.. The same logic applies on arrival at the boat. Switch both switches on ( selecting the battery required for starting in so doing) .... etc etc.
The need for a third switch for emergency starting ( or even paralleling the batteries) is eliminated .. it can be done done by the existing selector switch.

 

[pvb]

Thanks for highlighting my typo Vic - should have read "house" rather than "engine" - careless cut & paste job! I've edited my post.

The VSR wiring certainly needs revising. At the moment, if the OP starts the engine using the house battery, the VSR won't operate at all. Additionally, if the house battery charger is on, it will also charge the engine battery (assuming a bidirectional VSR) unless he manually disconnects the VSR, which he then has to remember to reconnect later.

The ammeter shunts are wrongly positioned because the OP said he wanted "to monitor the charge and discharge rates of my house and engine start batteries", and they don't do that.

 

[VicS]

Thanks for highlighting my typo Vic - should have read "house" rather than "engine" - careless cut & paste job! I've edited my post.

The VSR wiring certainly needs revising. At the moment, if the OP starts the engine using the house battery, the VSR won't operate at all. Additionally, if the house battery charger is on, it will also charge the engine battery (assuming a bidirectional VSR) unless he manually disconnects the VSR, which he then has to remember to reconnect later.

The ammeter shunts are wrongly positioned because the OP said he wanted "to monitor the charge and discharge rates of my house and engine start batteries", and they don't do that.

I think the logic is that normally the domestic battery would be charged via the VSR.
If it was necessary to start the engine from the domestic battery one would switch back to the starter battery bringing the VSR back into operation
Its not how I would have wired it but for Brian's suggestion See his post at #30 and #40 in this thread http://www.ybw.com/forums/showthread.php?341682-Fuse-board-to-Engine-Ground.

I dont think the intention was to use a dual sensing VSR although I think I would have done so with the alternator charging the start battery as priority and a single battery charger charging the house battery as priority.

I think you will find that the single 500 amp ammeter shunt measuring the total charging current is simply the result of not wanting to fit two of them. I am sure I did diagram showing two shunts at some stage Perhaps it did not make it to the forum.

It was the diagram below ( A and B being the shunts) A lot of other detail is not included but which the Op has added in his diagram at the start of this thread

 

[xeitosaphil]

Thanks Vic for a detailed explanation and breakdown of the drawings intended use in answer to some of the queries.

I do seem to remember you saying that I could monitor both batteries with one gauge and shunt and suggested I put the 500amp shunt where it is on the diagram unless I misunderstood.
I assume that fitting two shunts on the negs as shown will give readings of both battery charges using the Alternator, even if the house reading is only when the VSR is closed charging the house battery using the 500amp shunt. If not I can revert to the first suggestion of fitting them one in the dis/brd circuit, and one right next to the engine battery.

The 50amp gauge and shunt should give charge and discharge hopefully.

Just to answer a few of the others questions, the Battery chargers are Ctek M300 8 stage 20amp intelligent Shore based chargers- one engine maintenance charger and one 8 stage intel/ charger for the House bank. They need to be fitted direct to the battery terminals and are supplied with 6mm ring type terminals which fit to my 2 x Numax 110 Ah Dual post battery http://www.tayna.co.uk/Numax-CXV31MF-P3694.htm.

VSR is connected to load side of batteries via 1-2-both switch when either or both are selected.

VSR current, limited to 55amp Alternator mounted within 150mm cable run of 1-2-both switch and isolator also 1.5mtrs from Distribution fuse panel.

10mm Tri rated cable for VSR and Distribution Panel rated at 75amps so should be ok ( didn’t think VSR were designed to take heavy duty cables anyway no provision to terminate on the rear? maybe wrong)

Have disconnected engine bats mains charger Neg, and fitted it to common Neg shunt “ A “ see drawing, not sure if I should fit fuses to charger cables, all cabling supplied by manufacturer including terminals already fitted- 13amp fused supply shore power and fused plug tops in sockets, Via a RCD consumer unit, do I really need more?

The idea of VSR being fitted to 1-2-both common terminal – to be able to isolate VSR when charging from mains shore power chargers also charge independently.

VSR –no fuses require or advised on manufacturer’s web site, Merlin Dual Sensing Bi- Directional.

Note on the 1-2-both switch, I am using Bat 2 as engine start, and Bat 1 as House battery so as not to confuse the crew, as is existing orientation.

Question: When starting on BAT 2 of 1-2-Both switch with isolator ON, VSR and alternator will charge engine battery YES! With VSR open, - Will the 500amp Digital Ammeter shunt at “ A “ measure the charge voltage from the Alternator to engine battery.
When VSR closes at 13.8v and charges the House batteries via the isolator switch, will the 500amp Digital Ammeter at “ A “ then measure the charge voltage going to the House battery.

I have amended the diagram to see if this is ok now?

At the end of the day I would like to be able to monitor discharge rates from House Batteries and charge rates into both sets of batteries when the alternator is charging either battery bank, along with all the isolation scenarios as previously mentioned. Anything else is a bonus

Thanks for the many thanks for the comments and keep um coming. Philip

 

[pvb]

Question: When starting on BAT 2 of 1-2-Both switch with isolator ON, VSR and alternator will charge engine battery YES! With VSR open, - Will the 500amp Digital Ammeter shunt at “ A “ measure the charge voltage from the Alternator to engine battery.

The ammeter measures current, not voltage. Before the VSR closes, it will measure the current going into the engine battery.

Question: When VSR closes at 13.8v and charges the House batteries via the isolator switch, will the 500amp Digital Ammeter at “ A “ then measure the charge voltage going to the House battery.

When the VSR closes, the ammeter will measure the current going into both the engine battery and the house batteries, plus any current being used via the distribution panel.

I have amended the diagram to see if this is ok now?

The windlass power should be connected to the load side of the engine battery fuse - at the moment you have unprotected cable.

When the house battery charger is on, ammeter B will show shorepower charging current into the house batteries (and the engine battery, unless you first remember to turn the 1-2-Both switch to either 1 or Off, or unless you turn off the isolator switch supplying the distribution panel, or unless you turn off the VSR negative switch). Ammeter B will not show any engine charging current.

However, when the house battery charger is off, ammeter B will only show current being used via the distribution panel.

When the engine battery charger is switched on, it will also charge the house batteries, unless you first remember to turn the 1-2-Both switch to either 1 or Off, or unless you turn off the isolator switch supplying the distribution panel, or unless you turn off the VSR negative switch.

Similarly, when the house battery charger is switched on, it will also charge the engine battery, unless you first remember to turn the 1-2-Both switch to either 1 or Off, or unless you turn off the isolator switch supplying the distribution panel, or unless you turn off the VSR negative switch.

As I said before, the whole thing is over-complicated and the opportunities for you or one of your well-meaning crew to put one or more of the various switches in the wrong position at the wrong time are endless. You could have a much simpler system.

 

[VicS]

When the VSR closes, the ammeter will measure the current going into both the engine battery and the house batteries, plus any current being used via the distribution panel.

This is a consequence of trying to use only one 500amp ammeter. The alternative is two of them as in my diagram in #7.

The windlass power should be connected to the load side of the engine battery fuse - at the moment you have unprotected cable.

The windlass has its own fuse. This should be positioned as close as possible to the battery terminal. It will then protect the windlass and its wiring. If wired through the 250 amp mega fuse then the 100amp fuse should as close as possible to that (or connected with the same size cable as the battery cable)

When the house battery charger is on, ammeter B will show shorepower charging current into the house batteries (and the engine battery, unless you first remember to turn the 1-2-Both switch to either 1 or Off, or unless you turn off the isolator switch supplying the distribution panel, or unless you turn off the VSR negative switch). Ammeter B will not show any engine charging current.

However, when the house battery charger is off, ammeter B will only show current being used via the distribution panel.

When the engine battery charger is switched on, it will also charge the house batteries, unless you first remember to turn the 1-2-Both switch to either 1 or Off, or unless you turn off the isolator switch supplying the distribution panel, or unless you turn off the VSR negative switch.

Similarly, when the house battery charger is switched on, it will also charge the engine battery, unless you first remember to turn the 1-2-Both switch to either 1 or Off, or unless you turn off the isolator switch supplying the distribution panel, or unless you turn off the VSR negative switch.

I think all these situations are avoided if the selector switch is off and/or the VSR disabling switch is open when the battery chargers are in use although curious current readings could be avoided by routing the battery charger negative connections directly to the batteries rather than through the shunts.

My preference, I think, would be to connect the VSR to the batteries rather than to the switched side of the selector and isolator. If the battery banks are not adjacent to each other this can be done conveniently by connecting it between terminals 1 & 2 of the selector switch.

I think I would have used just one battery charger, connected to the house battery bank, together with a dual sensing VSR to control the charging of both batteries from the alternator or the charger.

As I said before, the whole thing is over-complicated and the opportunities for you or one of your well-meaning crew to put one or more of the various switches in the wrong position at the wrong time are endless. You could have a much simpler system.

Its complicated I think as a result of trying to satisfy the original objectives.
Crew members should not be allowed to operate the master switches! although with the alternator feeding the engine batter directly the usual pitfall blowing alternator diodes by opening the wrong switch while the engine is running is avoided.

I expect the OP is looking forward to seeing a diagram of your idea for a "much simpler system". Post it because I'd like to see your ideas too.

 

[pvb]

I expect the Op is looking forward to seeing a diagram of your idea for a "much simpler system"

I doubt that he is. But it certainly could be made much simpler. I'm not prepared to spend endless time doing wiring diagrams for people, but I've knocked up a quick diagram to give an indication of how much simpler it could be.

I've only included one mains charger - there's no need for two. The VSR will ensure that the engine battery gets charged as a priority, before switching in the house batteries. Importantly, the mains charger will work regardless of the switch positions.

The 1-2-Both switch has been consigned to eBay (or thrown overboard) and I've included 3 simple on/off switches. One switches on the house circuits. One is used to enable the engine to be started. The third is an emergency switch, to connect the house batteries to the starter in the event that the engine battery is flat (which is extremely unlikely). I'd suggest that the operating key for this switch is normally removed - in the event that it's needed, using the key from the engine switch will work and will ensure that the flat engine battery isn't parallelled with the house bank.

Most importantly, no damage can occur by having the switches in the wrong positions. It's simple - arrive at boat, turn on engine and house switches, use boat, turn off switches, leave boat. Nothing to worry about, nothing to remember, nothing to be set wrongly.

I've only included one ammeter shunt, to show the current in and out of the house bank. There's really no need for one on the engine battery, although one could be added if desired. Starting the engine uses very little power, and the engine battery has priority of charging by both alternator and mains, so it's going to be fully charged almost all the time.

I've shown the windlass feed coming from the house bank, as this has greater capacity. If using the windlass when the engine isn't running, this will preserve the engine battery. Or, if the engine is running, the house bank will be receiving charge from the alternator. I haven't shown a separate fuse for the windlass, as the sort of cable used to wire a windlass will be fine with the main fuse on the house bank.

 

[Steve C Cronin]

There are numerous basic errors in your proposed diagram, which also seems over-complicated. I don't really know where to start, but here are a few observations...

All positive connections on your engine battery should be made to the load side of the fuse, not to the positive terminal.

Similarly, all positive connections on your house battery bank should be made to the load side of the fuse, not to the main positive terminal.

The VSR is wrongly wired; it should be wired to the load side of the engine battery fuse, rather than to the common terminal of the 1-2-Both switch, and to the load side of the house battery bank's fuse.

The VSR should be wired with heavier cable than 10 sq mm - in some situations there could be a very high current through the VSR circuit.

The ammeter shunt for the engine battery is wrongly located. As you've shown it, this ammeter will measure both engine and house battery current.

Similarly, the ammeter shunt for the house battery bank is wrongly located. As you've shown it, this ammeter won't show engine charging current, although it will show mains charger current to the house battery and domestic load from the house battery. However, it will also show the current being delivered to the engine battery by the other mains charger - which presumably isn't your intention.

Why do you need a second charger for the engine battery? Why not just let the VSR handle shorepower charging current, from one charger?

There frankly isn't any point in having an engine battery ammeter, as unless there's a major problem the engine battery should always be charged. In any case, if you're planning to use a SmartGauge, why bother with an ammeter in the house battery circuit?

The whole thing would be a lot simpler if you dispense with the 1-2-Both switch and the separate isolator switch, and just have 2 simple on/off switches - one for the engine battery, and one for the house bank. There's almost nothing to go wrong or set wrongly, just arrive at the boat, turn both switches on, enjoy, turn off both switches, leave boat. If you're worried about the engine battery going flat (and if it's correctly wired there's almost no chance of this happening anyway) you can always have a third on/off switch to use the house bank for starting.

I agree with all of that but would add one (seemingly radical) comment.

On my first seagoing boat I had ammeters run across shunts but for the last three I have dispensed with these due to the unavoidable voltage losses. Instead, I have (& very sucessfully) relied upon volt meters which show me the RESULT of a discharge, ie, that the battery voltage(s) are dropping if I am loosing current, or that they are rising if I am doing well in the electricity supply stakes by getting an excess charge going INTO the batteries.

My current system is monitored by Mr Sterling's nifty little panel.

 

[VicS]

I'll go along with that too

A clean sheet of paper works wonders. Id got to the point where I could not see the wood for the trees.

I think he already has a dual sensing VSR so I' d connect the battery charger to the house battery, as that is the one most likely to require charging. (He could always use the other charger for the starter battery should the need arise.)

I think he envisaged supplying the windlass from the starter battery but that can still be done by moving the positive connection. A separate fuse in its supply might also be a good idea although I guess, to avoid volts drop, its cables will be fairly heavy. The windlass manufacturer might recommend a fuse size

He already has the 50 amp ammeter so it will still be possible to use that to measure the current used by the circuits connected to the distribution board if desired.

All along he seemed to want to retain old selector switch but as you say it's better with three separate switches esp because its is possible to select either battery for all purposes while isolating the other one or to parallel them if appropriate

 

[pvb]

I agree with all of that but would add one (seemingly radical) comment.

On my first seagoing boat I had ammeters run across shunts but for the last three I have dispensed with these due to the unavoidable voltage losses.

It is a bit radical. Many shunts work on a maximum voltage drop of 50mV when they're handling hundreds of amps current. So at typical levels of current, the voltage drop is infinitesimal and can be ignored.

 

[VicS]

Fuse required in the battery charger connection !

 

[pvb]

A clean sheet of paper works wonders. Id got to the point where I could not see the wood for the trees.

I think he already has a dual sensing VSR so I' d connect the battery charger to the house battery, as that is the one most likely to require charging.

The whole point of having a separate engine start battery is to ensure that the engine can always be started. In that case, charging the start battery must be the priority, both by the alternator and by the mains charger. That's why I'd connect the mains charger to the start battery and let the VSR take care of the house bank.

 

[pvb]

Fuse required in the battery charger connection !

I said it was just a quick diagram!

 

[Steve C Cronin]

The whole point of having a separate engine start battery is to ensure that the engine can always be started. In that case, charging the start battery must be the priority, both by the alternator and by the mains charger. That's why I'd connect the mains charger to the start battery and let the VSR take care of the house bank.

Certainly SHOULD be connected that way; the starter (starter and windlass in my case) getting the direct charge with the VSR bringing in the house batts at the appropriate voltage level. My 110watt solars are connected to the house only to minimise the fridge drain but I have a bridging switch in case of a starter battery failure. At the moment, laid up ashore 1500 miles away,with a marina ban on unattended boats being connected to the mains, this switch is closed to allow the solars to keep both banks of batteries conditioned.

 

[lenseman]

I am still trying to get my head round the fact that you need a 250 Amp fuse in the house supply???

Do you really have wiring which will handle a continuous current of 250 Amps (500Amps peak)!

Your wiring will get hot, melt and short out long before that fuse will blow.



.

 

[pvb]

I am still trying to get my head round the fact that you need a 250 Amp fuse in the house supply???

Do you really have wiring which will handle a continuous current of 250 Amps (500Amps peak)!

Your wiring will get hot, melt and short out long before that fuse will blow.

The OP wanted a system which allowed the engine to be started from the house battery bank, in the event that the engine start battery failed. To enable that, the cable from the house bank has to be heavy enough to take starter loads, and fused accordingly.

You'll note that the supply to the domestic distribution panel is indicated in thinner cable, and is separately protected by a 40A fuse. The 40A value is notional, it could be more or less, depending on cable choice and likely loads.