4 stage multi-output chargers

[blackrose]

Let's use a typical situation where a 4 stage multi-output battery charger has 2 of its 3 outputs connected to the domestic battery bank and the third output is connected to the start battery. The charger runs through its bulk, absorption & float stages but the small start battery will probably be topped up long before the big domestic bank. I realise that to a certain extent a battery will only take what it needs but what is happening here exactly? I would imagine that ideally the start battery should be on float charge as soon as it becomes fully charged, so in this case is it receiving a bulk or absorption charge which it cannot accept and thus being slightly overcharged?

Edited October 24, 2007 by blackrose

[Gary Peacock]

Let's use a typical situation where a 4 stage multi-output battery charger has 2 of its 3 outputs connected to the domestic battery bank and the third output is connected to the start battery. The charger runs through its bulk, absorption & float stages but the small start battery will probably be topped up long before the big domestic bank. I realise that to a certain extent a battery will only take what it needs but what is happening here exactly? I would imagine that ideally the start battery should be on float charge as soon as it becomes fully charged, so in this case is it receiving a bulk or absorption charge which it cannot accept and thus being slightly overcharged?

 

On most charges the axillary charge lines only provide a trickle charge they are really intended to keep a starter battery topped up.

[blackrose]

On most charges the axillary charge lines only provide a trickle charge they are really intended to keep a starter battery topped up.

 

I'm not sure that's correct Gary. Even one output terminal can provide the full output of the charger if the battery bank connected to the other output terminals is fully charged.

[Gibbo]

You need to clarify in your own head what bulk, acceptance and float actually are.

 

Bulk stage is a charging stage that is current limited. This is the current limit of the charger. It might be limited because that is the most the charge source is physically capable of supplying (as in the case of an alternator or very simple transformer/rectifier charger) or it may be limited electronically as in the case of a "smart" charger.

 

Acceptance/absorption is voltage limited. The charger simply limits the voltage supplied to the batteries. They draw whatever current they will.

 

Float is exactly the same as acceptance but at a lower voltage.

 

It isn't possible to dictate the current and the voltage. Only one of them can be controlled. If the charger sets the current, then the batteries will dictate the voltage. And Vice versa.

 

So start with the bulk phase. The charger throws it maximum amps at the batteries. If the batteries are big and flat, they will hold the voltage low. If they are small (in relation to the charge current) or well charged then the voltage will instantly jump right up to the acceptance voltage. So in this case there will be no bulk stage. It will go right into acceptance.

 

During acceptance the charger sets the voltage. The batteries will draw a progressively lower current as they become charged.

 

So the idea of "bulk charging a battery that doesn't need it" is just daft. It can't happen. Bulk charge can only happen if the batteries do need it. If they don't need it then the voltage will go up to acceptance thus missing out the bulk stage.

 

Despite rumours to the contrary it is generally accepted that an acceptance cycle is safe up to about 48 hours.

 

People should stop worrying about overcharging batteries. Of course it is possible but that is very rarely the problem. I've only ever seen it on one installation. That was because the alternator reg was faulty and was charging at 20 volts.

 

I've seen undercharging on thousands of installations.

 

In the example you give of the starter battery being already full the answer is "so what?". It's full so it won't draw any current. The fact that the charger has wacked 14.6 volts across isn't a problem. In cars and trucks they get this voltage all day, everyday. And in this case they don't even get used apart form starting the engine.

 

Gibbo

 

Edited to add: In actual fact 99% of multi ouput chargers are simply a single output charger with a diode splitter on the output.

Edited October 24, 2007 by Gibbo

[blackrose]

Thanks, I think I understand now!

[Gary Peacock]

I'm not sure that's correct Gary. Even one output terminal can provide the full output of the charger if the battery bank connected to the other output terminals is fully charged.

 

I think I get too used to Mastervolt and Victron and forget about the rest of the world!

[anhar]

I have a Victron inverter/charger and the start battery charge output is stated as 4 amp with no stage pattern, in contrast to the complex staged charge pattern of the domestic battery output. Incidentally the latter can be varied for different types of batteries etc. by attaching a computer with Victron software that can be downloaded from their website. Many other features such as shore line input levels can also be varied in this way.

 

regards

Steve

Edited October 25, 2007 by anhar

[Lesd]

do you have a remote panel on your Vitron Steve ? I believe you can adjust this shore line current limit on that very easily.

Les

[Gary Peacock]

I have a Victron inverter/charger and the start battery charge output is stated as 4 amp with no stage pattern, in contrast to the complex staged charge pattern of the domestic battery output. Incidentally the latter can be varied for different types of batteries etc. by attaching a computer with Victron software that can be downloaded from their website. Many other features such as shore line input levels can also be varied in this way.

 

regards

Steve

 

You do need their interface adapter to link the PC but I am playing with it now to setup a Multiplus and it is a lot less hassle than doing it by hand on the unit and it does seem quite a useful bit of software, the Mastervolt kit is easier without software using the MICC if you have one.

 

I still like Mastervolt but we have changed back to Victron for 2008 mainly because of a change to using the ESP system from Energy Solutions that is based around it.

 

I have been hearing good things about the Kipoint equipment too from builders that are using it from the various sources now importing it. I doubt we will be using them without a customer requests it but that is more about trying to stick with a good one stop solution with a name customers are familliar with.

[Sir Nibble]

Computers? Software? We're charging a battery here aren't we?

OK Gibbo, you're the expert. In terms of money saved in less frequent battery replacement, how long would it take in your opinion to make back the cost of one of these things compared with just relying on the alternator like I do. 20-30 years?

[anhar]

do you have a remote panel on your Vitron Steve ? I believe you can adjust this shore line current limit on that very easily.

Les

Hello Les

 

No I don't have the remote panel. Haven't needed it so far.

 

You are right that this enables alteration of the input current limit. It also has more warning lights on it than the main unit. But that's all it does as far as I know. The software version has that and a great deal of additional potential adjustments that can be made to the unit, and it's free, though it does require that one has a computer to attach to it.

 

I've had some email discussions with Victron on this, to which incidentally they responded each time within hours, because I may wish to use a small portable Honda EU "suitcase" style generator for charging whilst moored if I go longer term cruising and am therefore off the shore line for extended periods. It wouldn't in that case be adequate to have the remote input control panel because although that will reduce the maximum input current correctly, some other adjustments have to be made to the operation of the unit to do with the way the Honda responds to it. "Dynamic Current Limiter" is the Victron term for the internal adjustment that needs to be made for use with the Honda so that it works optimally. This adjustment can I understand be made only by the software route.

 

Therefore if I am going to have to use a computer and the software, which they call VE Configure, in any case to adjust the Victron to work with a Honda generator, I may as well use it also for the input shore current limiter and avoid the cost of the remote panel which won't then be needed.

 

The software contains a virtual version of the remote panel which can be seen on page seven of the guide:

 

http://www.victronenergy.com/upload/docume...re-20060612.pdf

 

regards

Steve

[blackrose]

Computers? Software? We're charging a battery here aren't we?OK Gibbo, you're the expert. In terms of money saved in less frequent battery replacement, how long would it take in your opinion to make back the cost of one of these things compared with just relying on the alternator like I do. 20-30 years?

One of these new-fangled 30amp things cost me £223. That's not a lot of batteries.

 

I think I get too used to Mastervolt and Victron and forget about the rest of the world!

I was probably thinking of a less prestigious manufacturer in my original example. Edited October 25, 2007 by blackrose

[Sir Nibble]

One of these new-fangled 30amp things cost me £223. That's not a lot of batteries.

 

No but you have to SAVE that money before the unit pays for itself. So if a set of batteries costs £200 and you change them every 3 years, but with this new unit they go 4 years, then in 12 years you will have saved one set of batteries and still be £23 out of pocket.

Just off the top of the head figures and I cannot back them up. The point is I am not representing this as fact, I am asking what the facts are.

[smileypete]

No but you have to SAVE that money before the unit pays for itself. So if a set of batteries costs £200 and you change them every 3 years, but with this new unit they go 4 years, then in 12 years you will have saved one set of batteries and still be £23 out of pocket.

Just off the top of the head figures and I cannot back them up. The point is I am not representing this as fact, I am asking what the facts are.

Hi,

 

Are we talking about chargers or alternator controllers here?

 

If chargers then the saving is against alternative charging; for engines its diesel costs and engine hours.

 

That said I run my 12v pumps and lights off a 12A mains power supply, so no battery wear and tear.

 

cheers,

Pete.

Edited October 25, 2007 by smileypete

[Nobber]

I jus' lifts up my trunk an' trumpets, then I charge.

Edited October 25, 2007 by Nobber

[John Orentas]

How many of us really do have a burning need for one of the 4 stage thingies, then why not a 6 or 8 stage surely they must be even better and I keep hearing this 2 or 3 year battery life, I said a few weeks ago, I have never had a battery that has lasted less than 5 years. I have just taken one off that is just short of 20 years old.

 

I think some peoples commercial ambitions are overcoming their common sense.

[Gibbo]

OK Gibbo, you're the expert. In terms of money saved in less frequent battery replacement, how long would it take in your opinion to make back the cost of one of these things compared with just relying on the alternator like I do. 20-30 years?

 

An alternator at say 14.2 to 14.6 volts will do a decent job because it's not on all the time.

 

If you charged at that voltage from shorepower then after a few days it would start to use lots of water in the batteries. So it needs a float voltage too. In order for the charger to have a clearly defined acceptance voltage it also needs a clearly defined bulk current. The easiest way to get all this is with a computer. It could be done with a purely an analogue circuit but would be more complicated and cost more.

 

If you charged from shorepower with a basic transformer/rectifer charger then you would either get not fully charged batteries or overcharged batteries. Both would wreck them.

 

Using that type of charger could result in new batteries every 6 months. So you can work out how long for yourself.

 

How many of us really do have a burning need for one of the 4 stage thingies, then why not a 6 or 8 stage surely they must be even better and I keep hearing this 2 or 3 year battery life, I said a few weeks ago, I have never had a battery that has lasted less than 5 years. I have just taken one off that is just short of 20 years old.I think some peoples commercial ambitions are overcoming their common sense.

 

Do you still use a wind up gramaphone and watch a rotating disc Logie Baird style TV?

 

Gibbo

Edited October 25, 2007 by Gibbo

[Denis R]

I said a few weeks ago, I have never had a battery that has lasted less than 5 years. I have just taken one off that is just short of 20 years old.

Wish I had your good fortune John! I've just had one battery go down in a big way after only 18months - and that was with it spending its first 6 months on pretty much continuous float courtesy of the Victron unit when I was shore-line connected. I now categorise batteries, as advised by Gibbo some time back, as consumable items!

[RobinJ]

No but you have to SAVE that money before the unit pays for itself. So if a set of batteries costs £200 and you change them every 3 years, but with this new unit they go 4 years, then in 12 years you will have saved one set of batteries and still be £23 out of pocket.

You also have to look at the other benefits too. If you don't need a lot of power to run everything then don't bother, if you do then it nice to be able to get the maximum power out of what you have when you want it!

How much is that worth?

[anhar]

You also have to look at the other benefits too. If you don't need a lot of power to run everything then don't bother, if you do then it nice to be able to get the maximum power out of what you have when you want it!

How much is that worth?

This is exactly the point I was going to make. This discussion isn't about money at all as I see it, it's about ensuring that batteries are sufficiently charged to supply demand when off charge for as long as possible for comfort and convenience purposes. Obviously one wants them to last as long as possible before replacement but as I understand it, that comes automatically with the territory of ensuring they are properly charged anyway.

 

Fitting only the best charging/inverter equipment is one essential thing, whatever it costs. I can't understand people who fit anything other than Victron or Mastervolt just to save a small amount which is probably peanuts in comparison with the cost of the boat. Far more important than cost is quality.

 

Coincidentally, I've noticed that Gary in his blog on this site has written a piece saying just that, comparing the false economy of many stingy narrowboaters trying to save pennies with those who buy his company's Euro boats and specify seagoing quality equipment rather than the second rate canal kit that many readers of this forum install.

 

regards

Steve

Edited October 25, 2007 by anhar

[John Orentas]

"Wind up gramophone and watch a rotating disk Logie Baird style TV"

 

Interesting to see these two engineering devices mentioned together, one of those text book type of examples in physics. It is often said that the principals involved with a gramophone have been known for a couple of thousand years, had it been translated into a practical device it is possible that we could hear the word of Christ today.

 

It has only become known for the past decade or two that Baird was the number one expert and probably the instigator of what became Radar during the last war.. I saw an interview in which he said that the somewhat silly mechanical TV system was a sort of front for genuine electronic systems and research.. He and someone else described how they demonstrated a colour television image in the very early 1940's, had it been made public it would have put the UK team years ahead of all their competitors.

 

Like many other British inventors Baird was totally under-rated in his lifetime others took all the credit for his work and was later sold down the river by the British government.

[blackrose]

No but you have to SAVE that money before the unit pays for itself. So if a set of batteries costs £200 and you change them every 3 years, but with this new unit they go 4 years, then in 12 years you will have saved one set of batteries and still be £23 out of pocket.

Just off the top of the head figures and I cannot back them up. The point is I am not representing this as fact, I am asking what the facts are.

 

But you're not only paying for the amount of batteries saved, you're also paying for the convenience of just being able to leave the charger on for months on end when on shore power, to know that the correct charge is going into that batteries and they're neither being over nor undercharged, and for the convenience of the powerpack mode in which the charger automatically & instantaneously puts exactly the same charge back into the batteries as is being drawn, in effect using shorepower to bypass the batteries. (Ok, it's not actually bypassing the batteries but you know what I mean - it's like your DC system is running off mains.)

 

If you don't have shorepower perhaps the arguments against paying for an intelligent charger stack up, but I don't know anyone on shorepower who has invested in one of these things and regretted it. It's one of the best bits of kit on my boat.

 

Edited to say: Of course you still have to check the fluid levels of your wet lead/acid batteries every couple of months & top up if necessary. Many boat owners with smart chargers neglect to do this because the powerpack mode lulls them into thinking that their batteries are ok. It's only when they disconnect the shorepower cable and go for a cruise that they realise their batteries are knackered .

Edited October 25, 2007 by blackrose

[John Orentas]

Wish I had your good fortune John! I've just had one battery go down in a big way after only 18months - and that was with it spending its first 6 months on pretty much continuous float courtesy of the Victron unit when I was shore-line connected. I now categorise batteries, as advised by Gibbo some time back, as consumable items!

 

 

Nothing to do with good fortune Denis.. There might just be a moral to that tale, alternators in the form they are fitted to engines have been developed for charging batteries in a sort of way that gives a reasonable life expectancy to all the components.

 

Of course the output can be boosted, you can get 500 horsepower out of a small family car, thats great if you don't mind that it blows up now and then.

[blackrose]

Computers? Software? We're charging a battery here aren't we?

 

Anyway, Snibble, you're the alternator whizz. Isn't there a fair bit of technology in modern alternators and their internal regulators these days?

Edited October 25, 2007 by blackrose

[ChrisPy]

Interesting to see these two engineering devices mentioned together, one of those text book type of examples in physics. It is often said that the principals involved with a gramophone have been known for a couple of thousand years, had it been translated into a practical device it is possible that we could hear the word of Christ today.

... and the Victorians knew the principles of the fax machine even though they didn't have the electronic wizardry to translate 'mark-space' into an electronic pulse.