Victron ArgoFET

zoidberg

zoidberg

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.... charge controllers/splitters.

They've been around a while. Would someone kindly advise in some detail what they do - and perhaps more important, what they don't?

I've peered at the spartan download, and asked the makers. Not much wiser for that exercise.....

Argo-Fet-Battery-Isolators
 
"Reports that say that something hasn't happened are always interesting to me, because as we know, there are known knowns; there are things we know we know. We also know there are known unknowns; that is to say we know there are some things we do not know. But there are also unknown unknowns – the ones we don't know we don't know."

Donald Rumsfeld.
 
zoidberg said:
.... charge controllers/splitters.

They've been around a while. Would someone kindly advise in some detail what they do - and perhaps more important, what they don't?

I've peered at the spartan download, and asked the makers. Not much wiser for that exercise.....

Argo-Fet-Battery-Isolators
Click to expand...

What Paul Rainbow and the data sheet say!

Similar to a diode splitters, allowing 2 or 3 batteries ( or battery banks) to be simultaneously charged from the same charging source, without them being connected to each other.

The snag with ordinary diode splitters is that there is a significant voltage drop across them which slows the charging rate and more importantly, perhaps, prevents the batteries becoming fully charged.

A battery sensed alternator, or advanced regulator, will compensate for this but your bog standard alternator/ regulator does not do this.

The FET isolator has a very low voltage drop, so low that it can be ignored. No alternator modificationss or fancy charging devices are required

They have no snags that might be associated with VSRs
 
VicS said:
What Paul Rainbow and the data sheet say!

Similar to a diode splitters, allowing 2 or 3 batteries ( or battery banks) to be simultaneously charged from the same charging source, without them being connected to each other.

The snag with ordinary diode splitters is that there is a significant voltage drop across them which slows the charging rate and more importantly, perhaps, prevents the batteries becoming fully charged.

A battery sensed alternator, or advanced regulator, will compensate for this but your bog standard alternator/ regulator does not do this.

The FET isolator has a very low voltage drop, so low that it can be ignored. No alternator modificationss or fancy charging devices are required

They have no snags that might be associated with VSRs
Click to expand...

I'm confused a bit by their circuit diagram.

Suppose we have a 3 battery version, with one battery dedicated to starting, and two house batteries, how is the house load served by both house batteries?

I googled installation drawings and they show separate loads on each battery.
 
chewi said:
I'm confused a bit by their circuit diagram.

Suppose we have a 3 battery version, with one battery dedicated to starting, and two house batteries, how is the house load served by both house batteries?

I googled installation drawings and they show separate loads on each battery.
Click to expand...

They are charge splitting devices. They allow 3 separate batteries or battery banks to be charged simultaneously. Multiple domestic batteries would be wired together as one bank. The third battery might be a dedicated bow thruster or anchor winch battery.
 
chewi said:
I'm confused a bit by their circuit diagram.

Suppose we have a 3 battery version, with one battery dedicated to starting, and two house batteries, how is the house load served by both house batteries?

I googled installation drawings and they show separate loads on each battery.
Click to expand...

Your two domestic batteries would be connected in parallel and you'd use a 2 output isolator, one output to the engine battery and the other to the domestic bank.

The outputs connect to banks of batteries, not individual batteries. If the domestic bank consists of multiple batteries it still only needs to be connected to one output. A single battery (such as your engine start battery) is still classed as a bank in this respect.
 
This 'bear of little brain' is still puzzled.

Given that the installation of 4-5 AGM batteries I'm putting in would cost me >£1000 to replace if I fried them, or cut their lives in half by a dumb, inadequate charging regime, it matters that I understand what's going on and get it right first time. It would be further dismaying if I spent ~£100 on this Victron FET thingy ( or 3 times that with Sterling ) and still bugrdemup. That's why I'm consulting.

I asked the manufacturer. They didn't explain HOW their device splits the alternator output - they simply reiterated that it did.

Here's their simple diagram, annotated with the capacities of the battery-groups I intend. The small-capacity/high-CCA Start unit ( 50Ah ) is very close to the engine-alternator. So also is the Primary Services ( 112Ah ) group, which could 'support' the Start unit if needed, by link/switchery. I have good reason for specifying a Secondary Services group ( 132Ah ) just as someone fitting a 'thruster' or 'anchor winch'. The specialist I buy my batteries from ( 20+ years in the trade and a blue-water sailor ) encourages me to keep those two Services groups separated, use them alternately, and to charge them separately.

There will be some modest PV 'controlled' input providing trickle charge when the boat is unattended. That's endorsed.


42100072262_99ab76176a.jpg



As I understand it, this Victron FET device accepts all the charging voltage and charging current delivered from the alternator. Let's assume that's 14.4V and 60 amps, at 2500rpm ( motoring downriver after slipping lines ). The 'controlled' output voltage doesn't change so that's fed to each of the 3 batteries - continuously. There's no suggestion that the current supplied to each battery is other than 60/3 amps each, for there's no 'battery sensing' that I can see. That's 20 amps each.... continuous.

After a few minutes, one or other of the batteries is close to fully charged - probably the 50Ah Start unit. The others most likely are still some way from fully charged. All three continue to be presented with 14.4V/20 amps each.....

After a while, the 50Ah battery becomes over-charged, with a consequent reduction in service life. Continue longer, it gets overheated and 'fried', and fails. This could occur during a long period of motoring e.g. across Biscay or back from Ireland. Several published authorities, including Don Casey, warn against this.

Is this the reality? Am I missing something fundamental ( not unknown ) and if so, what is it? How do I resolve it.....?
 
zoidberg said:
Is this the reality? Am I missing something fundamental ( not unknown ) and if so, what is it? How do I resolve it.....?
Click to expand...

Just because the alternator is capable of a particular charging output does not mean the batteries are subjected to it, they only take what they need. My batteries, for instance, have been connected to 260w of solar power for the past two years, the engine battery gets very little use, it has not gone up in smoke yet. A big mobo with two hefty alternators will be charging all the time the boat is at sea, they don't fry batteries every time they go out.

Just fit the Victron device as per the diagram (you should be able to omit the energise wire) and it will work fine. Just about everyone on this forum (and elsewhere) has a split charge system where the engine battery "sees" the alternator output even when it's charged.
 
The start battery will see the charging volts whenever the engine is running. It won't take 20A, it will take what it takes at 14.4V.
Probably about 100mA when it's fully charged?
If you do a normal number of engine hours per year, the battery will die of age before it dies of overcharging.
For this kind of thing to be an issue, it generally needs almost constant charging, like shore power at night, solar most of the day and high engine hours.
 
zoidberg said:
This 'bear of little brain' is still puzzled.

Given that the installation of 4-5 AGM batteries I'm putting in would cost me >£1000 to replace if I fried them, or cut their lives in half by a dumb, inadequate charging regime, it matters that I understand what's going on and get it right first time. It would be further dismaying if I spent ~£100 on this Victron FET thingy ( or 3 times that with Sterling ) and still bugrdemup. That's why I'm consulting.

I asked the manufacturer. They didn't explain HOW their device splits the alternator output - they simply reiterated that it did.

Here's their simple diagram, annotated with the capacities of the battery-groups I intend. The small-capacity/high-CCA Start unit ( 50Ah ) is very close to the engine-alternator. So also is the Primary Services ( 112Ah ) group, which could 'support' the Start unit if needed, by link/switchery. I have good reason for specifying a Secondary Services group ( 132Ah ) just as someone fitting a 'thruster' or 'anchor winch'. The specialist I buy my batteries from ( 20+ years in the trade and a blue-water sailor ) encourages me to keep those two Services groups separated, use them alternately, and to charge them separately.

There will be some modest PV 'controlled' input providing trickle charge when the boat is unattended. That's endorsed.



As I understand it, this Victron FET device accepts all the charging voltage and charging current delivered from the alternator. Let's assume that's 14.4V and 60 amps, at 2500rpm ( motoring downriver after slipping lines ). The 'controlled' output voltage doesn't change so that's fed to each of the 3 batteries - continuously. There's no suggestion that the current supplied to each battery is other than 60/3 amps each, for there's no 'battery sensing' that I can see. That's 20 amps each.... continuous.

After a few minutes, one or other of the batteries is close to fully charged - probably the 50Ah Start unit. The others most likely are still some way from fully charged. All three continue to be presented with 14.4V/20 amps each.....

After a while, the 50Ah battery becomes over-charged, with a consequent reduction in service life. Continue longer, it gets overheated and 'fried', and fails. This could occur during a long period of motoring e.g. across Biscay or back from Ireland. Several published authorities, including Don Casey, warn against this.

Is this the reality? Am I missing something fundamental ( not unknown ) and if so, what is it? How do I resolve it.....?
Click to expand...
No this is not the reality

Highlighted is where your thinking is wrong.

Each battery will only draw the current its capacity and state of charge dictates. A large battery with a low state of charge will draw more current than a smaller battery , or one at a higher state of charge . A small battery that is almost fully charged will draw only a very small current. They will in effect tend towards balancing each other in terms of % state of charge.
 
Thanks, PD, lw395 and VicS.... and others.

I'll do what I'm told. In fact, I've just ordered one of them thingys.


As an aside, the best price was offered by Battery Megastore. I phoned them to confirm 'stock available', and the fellah confirmed. He also advised of a £7:50 carriage charge. I demurred, knowing that MyHermes were about half that. He advised he had no authority to change or waive the carriage charge, which made them not the cheapest.

I went back to eBay. The cheapest there was B'Megastore again, but with FREE POSTAGE. Go figure....

'Can't get the staff'.....
 
Last edited:
zoidberg said:
Thanks, PD and VicS.... and others.

I'll do what I'm told. In fact, I've just ordered one of them thingys.
Click to expand...

Good choice, they're pretty well "fit and forget". However, I can't help thinking that your 115Ah Primary Services battery is woefully undersized in these modern times.
 
pvb said:
However, I can't help thinking that your 115Ah Primary Services battery is woefully undersized in these modern times.
Click to expand...

Thanks.

I've always been rather frugal with on-board kit and 'lecky usage. The boat is very much 'so last century' and so am I. Money I save on not having hot and cold running prosecco can be earmarked for a new 'bling anchor'..... and I do have a couple of paraffin pressure lamps somewhere! ;)

One thing I will have, in addition to 'normal' all-LED lighting, will be a humungous supplementary stern light which I can hang up/switch on in conditions of night and poor viz, which will push out very much more than the silly minimum 2 nautical miles' worth of lumens. In today's poor watchkeeping environment, I want to be seen at rather more than 2 miles, which is just 5-6 minutes for a fast reefer/150,000 tons of Maersk..... not enough 'in these modern times'!
 
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