Batteries & Charging

[Andt The Fiddler]

Hi all,

 

I am hoping you guys (and gals) will come up with some suggestions or tell me everything is Ok?

 

I've just had to changed my batteries after only 2yrs and 5 months, a costly excersise as we all know.

 

Last time they were changed I also had to change the mains charger to a Victron Centaur.

 

I have put my schematic at My Schematic so you can all have a look and see how it is all configured.

 

Basically the question is - have I got it right - could it be better - am I risking overcharging the batteries from the alternator - The Centaur should sense the absorbtion and cut back charging?????

 

Any helpful comments would be appreciated - I was an Architectural assistant in real life, then an IT geek, before I retired and am a tad wary of engineering aspects such as this, I know basic theory but detail knowledgfe is limited and errors are probable.

 

Thanks in anticipation

 

Andy

[by'eck]

Well a quick look suggests that your wiring will work. A few comments though.

 

1) Whilst it may seem pedantic, live & neutral refer to the two legs of an AC mains feed. Since your diagram includes AC & DC it may be better to refer to the latter as the conventional positive & negative.

 

2) It may be safer to have the battery isolator(s) in the positive feed (one for each battery). Generally battery negative(s) are connected to boat ground (the steel hull). This may cause your present installation to present you with an active circuit that you thought was switched off.

 

3) There will be a significant volts drop (0.5 to 1 volt) across the diode splitter you use to feed alternator output to both the starter battery & service bank. A couple of solutions are to use a zero volt drop splitter or fit the alternator with a smart controller that will allow sensing of battery volts downstream of the splitter. This will adjust the alternator output to compensate for the splitter induced volts drop.

[Iain_S]

As above, plus move Charger and inverter connections to same battery post as "boat live".

 

Iain

[blodger]

Well a quick look suggests that your wiring will work. A few comments though.

 

1) Whilst it may seem pedantic, live & neutral refer to the two legs of an AC mains feed. Since your diagram includes AC & DC it may be better to refer to the latter as the conventional positive & negative.

 

2) It may be safer to have the battery isolator(s) in the positive feed (one for each battery). Generally battery negative(s) are connected to boat ground (the steel hull). This may cause your present installation to present you with an active circuit that you thought was switched off.

 

3) There will be a significant volts drop (0.5 to 1 volt) across the diode splitter you use to feed alternator output to both the starter battery & service bank. A couple of solutions are to use a zero volt drop splitter or fit the alternator with a smart controller that will allow sensing of battery volts downstream of the splitter. This will adjust the alternator output to compensate for the splitter induced volts drop.

 

The charger does not appear connected to diagonally opposite positive and negative but to a single battery in the bank so it could overcharge that battery and undercharge those furthest away. Cannot tell from the drawing but possible the inverter is connected likewise (because its a charger/inverter) so you wouuld get the same effect in reverse when using?

Edited May 16, 2011 by blodger

[Chalky]

 

2) It may be safer to have the battery isolator(s) in the positive feed (one for each battery). Generally battery negative(s) are connected to boat ground (the steel hull). This may cause your present installation to present you with an active circuit that you thought was switched off.

 

 

Standard automotive practice is to switch the positive supply on every circuit (where possible).

 

Consider adding a maxi or mega fuse to the +ve battery connections. I've got a 250A fuse - it's the last line of defence in case of a catastrophic short circuit.

 

The 12V system should float with respect to the hull - it should not be connected. Connecting it can lead to problems such as hull corrosion. Only the 240V earth / ground should be connected to the hull either via a galvanic isolator or as part of an isolating transformer circuit. The BSS does not allow/recommend that the hull is used as an earth return for any circuit.

[ditchcrawler]

Standard automotive practice is to switch the positive supply on every circuit (where possible).

 

Consider adding a maxi or mega fuse to the +ve battery connections. I've got a 250A fuse - it's the last line of defence in case of a catastrophic short circuit.

 

The 12V system should float with respect to the hull - it should not be connected. Connecting it can lead to problems such as hull corrosion. Only the 240V earth / ground should be connected to the hull either via a galvanic isolator or as part of an isolating transformer circuit. The BSS does not allow/recommend that the hull is used as an earth return for any circuit.

Not an earth return but negative bonded to hull surly.

[Gibbo]

The 12V system should float with respect to the hull - it should not be connected.

 

Oooo fight time.

 

You're wrong

[coreng]

Connecting it can lead to problems such as hull corrosion.

 

Same for me. Wrong too... (Sorry Ditchcrawler, I was aiming Chalky. Missed something.)

Edited May 16, 2011 by coreng

[blodger]

The charger does not appear connected to diagonally opposite positive and negative but to a single battery in the bank so it could overcharge that battery and undercharge those furthest away. Cannot tell from the drawing but possible the inverter is connected likewise (because its a charger/inverter) so you wouuld get the same effect in reverse when using?

Basically the question is - have I got it right - could it be better - am I risking overcharging the batteries from the alternator - The Centaur should sense the absorbtion and cut back charging?????

 

Am I reading this right as 5 questions

 

have I got it right - not quite as per posts

could it be better - yes as per posts and a few finer details

am I risking overcharging from the alternator - not on schematic but do some volts & amps monitoring

The Centaur should sense the absorbtion and cut back charging - reply as above

[WotEver]

It's all been said but I'll post for the sake of repeating Iain's point in Post #3. Moving your battery connections will give you the quickest 'bang for the buck' improvement to that layout. Do it sooner rather than later.

 

See here for some in depth info about battery connections.

 

Tony

 

The 12V system should float with respect to the hull - it should not be connected. Connecting it can lead to problems such as hull corrosion.

Knowing that Chalky knows his stuff, I suspect that he was confusing using the hull as a return path with bonding neg to the hull. Obviously the advice above remains wrong, however.

 

Tony

[Timleech]

 

 

Knowing that Chalky knows his stuff, I suspect that he was confusing using the hull as a return path with bonding neg to the hull. Obviously the advice above remains wrong, however.

 

Tony

 

May not be all that obvious - isolated return and floating dc systems used to be the norm for marine installations, quite likely still are for big stuff, though the accepted wisdom these days is that a single -ve bond is best at least in our small world.

 

Tim

[by'eck]

The 12V system should float with respect to the hull - it should not be connected. Connecting it can lead to problems such as hull corrosion. Only the 240V earth / ground should be connected to the hull either via a galvanic isolator or as part of an isolating transformer circuit. The BSS does not allow/recommend that the hull is used as an earth return for any circuit.

 

Brave words but how do you avoid fitting an engine with starter motor that has its negative feed through body which in turn is firmly bolted to the block, without having at least starter battery negative effectively strapped to hull. Whatever the pro's & cons you can't avoid it. Note this doesn't preclude the need to have cable connections from devices to battery negative though.

 

Good advice re AC earth though.

Edited May 17, 2011 by richardhula

[Timleech]

Brave words but how do you avoid fitting an engine with starter motor that has its negative feed through body which in turn is firmly bolted to the block, without having at least starter battery negative effectively connected to hull. Whatever the pro's & cons you can't avoid it. Much safer to strap to hull. Good advice re AC earth though.

 

You get an isolated return starter motor

Probably not an option for small modern diesels, should be for your JP though!

 

Listers used to fit two external solenoids, so that the system was only 'earthed' while the starter was actually running, to some of their marine engines but the JP was usually fitted with a BS5 starter which is inherently isolated.

 

Tim

[RobinJ]

Basically the question is - have I got it right - could it be better - am I risking overcharging the batteries from the alternator - The Centaur should sense the absorbtion and cut back charging?????

Possibly a bit that has been missed here?

Possibly, Yes, No, Possibly!

 

As you are using a diode splitter, it is likely the batteries ar enot getting up to full charge from the alternator. The battery charger should be cutting back and not overcharging, but it depends on how much yor taking out and how much your putting back from each source.

With an inverter system you ideally need a mechanism to put back as much as possible as soon as possible!

[Chris Pink]

You get an isolated return starter motor

Probably not an option for small modern diesels, should be for your JP though!

 

Listers used to fit two external solenoids, so that the system was only 'earthed' while the starter was actually running, to some of their marine engines but the JP was usually fitted with a BS5 starter which is inherently isolated.

 

Tim

 

Wooden bearers? Elastic mounts?

 

My engine, if it is electrically connected to the hull is only connected through the stern gland and one would hope there's no metal to metal contact there.

[by'eck]

Wooden bearers? Elastic mounts?

 

My engine, if it is electrically connected to the hull is only connected through the stern gland and one would hope there's no metal to metal contact there.

 

Get a meter & find out. I'll bet there is zero resistance between engine block & hull. Many sea going vessels had brushes or similar to provide a ground to propshaft anyway.

 

Why mess with the vagaries of battery negative isolation. Strap battery negative to the hull & have done with it. There is just too much potential (pun?) for unintended negative returns to avoid it.

Edited May 17, 2011 by richardhula

[Gibbo]

There is just too much potential (pun?) for unintended negative returns to avoid it.

 

This is actually one of the main reasons. On intended "isolated systems" I've seen the results of a few unintended hull connections such as burnt engine control cables, melted engine wiring looms, inadvertent positive grounded systems (very nasty for hull corrosion)... the list goes on. It simply isn't worth the risk in my mind.

 

Knowing that Chalky knows his stuff, I suspect that he was confusing using the hull as a return path with bonding neg to the hull.

 

Possibly. I actually hope so!

[Chalky]

Oooo fight time.

 

You're wrong

 

Agreed. Rapid typing. The hull should be bonded, but not used as a conductor.It's impossible to avoid on my boat since the alternators fitted by the engine mariniser / painter are earthed through their cases. Comes of working in an industry where we use the body as the earth return.

 

The electrical engineers view of the car. The body is used to provide an earth return and an attractive bracket to hang the electrics off. The engine is to provide electrical power for the system and to heat/cool the occupant whilst they admire the electrical system. It also allows the electrics to be moved around so others can admire it. The seats provide a comfortable place to sit whilst you admire the electrics.

Many other departments don't see the world in the same way...

Edited May 17, 2011 by Chalky

[Andt The Fiddler]

Right lots to digest here,

 

And thanks to all for looking at the schematic.

 

Other Notes: -

 

I tend to keep the inverter switched off unless I need 240V without the generator.

 

The negatives go back to a negative block and the hull is not used as a return path.

 

I am watching lots at present and last night noticed that the (12V) Freezer is not cutting in and out - so this could be a 15A drain on the batteries permanentaly and possibly be a major part of the problem?

 

I checked out the old system with an AMT Gold IBT when I first noticed the problem, last calibrated April 2011 so I was confident those batteries had seen better (much better) days. I have to give this back soon!

 

Other than a correct technical solution I am now looking at getting the best life span form the new batteries, reliability & ease of use on the boat generally - these I would hope are indeed the same thing.

 

Once more thanks again and please keep it coming I will be reviewing my next move today. I am currently sitting here with the Generator running to keep things topped up if I am using 15A per hour on the freezer this is less than 10 hours per battery? The domestic battery bank is currently 4 x 110 Ah I have one more 110 Ah battery to add to this. The starter is 1 x 110 Ah.

 

Andy

[deletedaccount]

I'd imagine running a freezer off batteries would be a little bit of a problem! As in, it'll eat up the juice.

[mayalld]

The 12V system should float with respect to the hull - it should not be connected. Connecting it can lead to problems such as hull corrosion. Only the 240V earth / ground should be connected to the hull either via a galvanic isolator or as part of an isolating transformer circuit. The BSS does not allow/recommend that the hull is used as an earth return for any circuit.

 

Indeed it does not recommend that the hull is used as a return.

 

That doesn't mean that it should float.

 

There should be a negative bond to the hull.

[bottle]

I am watching lots at present and last night noticed that the (12V) Freezer is not cutting in and out - so this could be a 15A drain on the batteries permanentaly and possibly be a major part of the problem?

 

Yes it will be a major drain, depending on model/type I would expect a thermostat, if it is not cutting in and out then that is broke. (Stating the bl****ng obvious).