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Victron combi versus Separates


Dr Bob

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38 minutes ago, Sea Dog said:

I restored shore AC througout the boat by connecting the AC into the Combi to both of the Combi outputs - shore only circuits and short break (inverter maintained). The inverter side still worked, so I could reconnect the short break circuits and use the inverter whilst cruising, but it was a bit inconvenient. Fitting an easier means of  this changeover would have been a 'fix' of sorts, and a separate charger could have been added to replace the charger side, but would still mean I had a broken Combi and a 'work around'. 

Switch off and disconnect now, you have now created a potential 400v+ death trap.

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8 minutes ago, Robbo said:

Switch off and disconnect now, you have now created a potential 400v+ death trap.

I don't think so Robbo, but I'd be very glad (and keen!) to listen to an explanation of your point in case I'm wrong! 

(I should just add that the Combi is on the bench in my garage).

Edited by Sea Dog
Bit in brackets
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4 minutes ago, Sea Dog said:

I don't think so Robbo, but I'd be very glad (and keen!) to listen to an explanation of your point in case I'm wrong! 

Inverter and shore power plugged into the same circuit and very easily potentially at the same time.

Edited by Robbo
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37 minutes ago, Sea Dog said:

Ah, thanks. That wasn't the case - all of the cables were removed from the inverter first. :)

Phew! But of course if you wanted to leave the Combi in situ for some reason, eg making use of the terminals temporarily, it would be OK to connect all the cables to the Combi input - assuming the terminals were big enough.

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22 minutes ago, nicknorman said:

Phew! But of course if you wanted to leave the Combi in situ for some reason, eg making use of the terminals temporarily, it would be OK to connect all the cables to the Combi input - assuming the terminals were big enough.

Thanks Nick, you're quite right.  Actually, that's exactly what I did when it first went down and I needed to restore power quickly!  Once the unit was taken out, it was into temporary choc block connectors.  (I left stage one out back there to avoid further confusion, 'cos I got what Robbo was concerned about).

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1 hour ago, Robbo said:

Inverter and shore power plugged into the same circuit and very easily potentially at the same time.

It would have been much clearer if I'd have put: "I disconnected the inverter outputs and connected them directly to the AC input terminals, bypassing the inverter itself" in the first place!  Thanks for caring :)

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20 hours ago, WotEver said:

Well, that definitely wants upping :)  

If you raise it to about 13.6V it’ll be a much more useful float voltage. 

Getting back to when it switches, does the manual say anything about “when the charge current reduces to x Amps...”. If so, can x be changed?

Wotever, thanks for the input.

Ok, just spent some time looking at the manual. There are 3 choices for the 'charging characteristic' ie when it goes from Absorbtion to float. I am not sure what mine is set on till I take the front panel off and work out how to read the lights/dip switches - which looks rather complex. 1. is Fixed - and hence you just set a time that the charger holds the Absorption mode before switching. 2. Is adaptive - the charger changes to float when it thinks the current is a the right level to do this - but there doesnt seem to be a control to change that tail current. 3. is similar to 2 but changes the voltage down by another 0.8V  after 24hrs on float.

I have a feeling that mine is on 3 - as last night with the solar not contributing, I had a voltage of 12.8V and current of 0.5A.

Today, the shore power went off for an hour and on turning on, the voltage went up to 14.6v and the current dropped from 20A to 12 A over a 10 minute period then it went into float although the solar was working and feeding 5A. State of charge of the battery? I think it was full when we got back to the boat yesterday but have run the eberspacher for 3 hrs  (3 one hour periods)- so estimate 40-50Ahrs out but the charger has only been charging at less than 0.5A and at times -0.5A.

I have someone coming on Monday to fix the earth leakage problem I have (previous galvanic isolator thread, which just needs a better earth from the combi) and will have a look at the combi settings then.

I've attached the installation manual for the combi, but dont spend too long looking at it as I am 95% of the way to changing it all round and just using the combi as the inverter.

 

Set the DS 3-7

Set the charging characteristic

Example

DS-8

DS-7

DS-6

DS-5

DS-4

DS-3

off on

on on

off DS-2

DS-1

Determine the required charging characteristic:

  1. 1:  Fixed

  2. 2:  Adaptive

  3. 3:  Adaptive with BatterySafe

mode (default)

Press the pushbuttons until the required LED indication is displayed.

Required: charging characteristic is Fixed.
Setting number = 1.
LED indication =

00 00 00 01

01

Victron inverter charger install manual-rev08.pdf

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12 minutes ago, Dr Bob said:

 

I have someone coming on Monday to fix the earth leakage problem I have (previous galvanic isolator thread, which just needs a better earth from the combi) and will have a look at the combi settings then.

Before you get too carried away on raising float voltage arbitrarily, here's Victron's latest take on longer term float voltage (they now use 13.8v when first switching to 'float') for their newer range of chargers:

Storage Mode: less maintenance and aging when the battery is not in use 
The storage mode kicks in whenever the battery has not been subjected to discharge during 24 hours. In the storage mode float voltage is reduced to 2,2V/cell (13,2V for a 12V battery) to minimize gassing and corrosion of the positive 
plates. Once a week the voltage is raised back to the absorption level to ‘equalize’ the battery. This feature prevents stratification of the electrolyte and sulfation, a major cause of early battery failure.

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1 hour ago, Sea Dog said:

Before you get too carried away on raising float voltage arbitrarily, here's Victron's latest take on longer term float voltage (they now use 13.8v when first switching to 'float') for their newer range of chargers:

Storage Mode: less maintenance and aging when the battery is not in use 
The storage mode kicks in whenever the battery has not been subjected to discharge during 24 hours. In the storage mode float voltage is reduced to 2,2V/cell (13,2V for a 12V battery) to minimize gassing and corrosion of the positive 
plates. Once a week the voltage is raised back to the absorption level to ‘equalize’ the battery. This feature prevents stratification of the electrolyte and sulfation, a major cause of early battery failure.

I think that is what the manual for this box says. I've not really run on shore power for long enough to understand just how the Combi is charging, but it looks like the float voltage is 13.2 then dropping back to 12.8V if not subjected to discharge - but watching it today it has been down at 12.8V but there are loads on the batteries viz lights, pumps, eberspacher etc and also inputs via solar which has been up to 5A today (200W only).

What I really need is to be able to keep at a reasonable float voltage ie 13.8V for long enough to get the battery to 100% THEN drop it back to a tick over. If I go out over a 3 days trip (2 nights out), I know how much Ahrs I am using (say 200Ahrs) and I know how many hours the engine has run and have recorded the approx Ahrs back in (via the Ahr counter - pinch of salt, or integrating the Amps in), and the Victron is going into float at 13.2V or down to 12.8V far too early - when I have 50-70Ahrs unaccounted for (assuming a 20% effeciency loss on charging). I need to get that 50-70Ahrs back in but the victron seems to go into 'armchair mode'. It would be even better if it was in absorption mode at 14.4V (or 14.8V when cold) so I could watch the tail current but it always goes to float when the tail current is still dropping.

Edited by Dr Bob
speeling agian
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12 minutes ago, Dr Bob said:

I think that is what the manual for this box says. I've not really run on shore power for long enough to understand just how the Combi is charging, but it looks like the float voltage is 13.2 then dropping back to 12.8V if not subjected to discharge - but watching it today it has been down at 12.8V but there are loads on the batteries viz lights, pumps, eberspacher etc and also inputs via solar which has been up to 5A today (200W only).

What I really need is to be able to keep at a reasonable float voltage ie 13.8V for long enough to get the battery to 100% THEN drop it back to a tick over. If I go out over a 3 days trip (2 nights out), I know how much Ahrs I am using (say 200Ahrs) and I know how many hours the engine has run and have recorded the approx Ahrs back in (via the Ahr counter - pinch of salt, or integrating the Amps in), and the Victron is going into float at 13.2V or down to 12.8V far too early - when I have 50-70Ahrs unaccounted for (assuming a 20% effeciency loss on charging). I need to get that 50-70Ahrs back in but the victron seems to go into 'armchair mode'. It would be even better if it was in absorption mode at 14.4V (or 14.8V when cold) so I could watch the tail current but it always goes to float when the tail current is still dropping.

 Instead of amp counting, flip everything off when it's kicked into float mode and use a hydrometer to find your true state of SoC

Would be handy if you let us know what type absorption setting you have.   

Still don't understand why your looking at other chargers, when you have a very good one in your mits, and all it requires is looking at the settings.

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5 minutes ago, Robbo said:

Still don't understand why your looking at other chargers, when you have a very good one in your mits, and all it requires is looking at the settings.

I think you have a point there, Robbo, as that's a pretty good Combi he has there.  Certainly the relatively recent versions have a good range of settings, although Victron manuals aren't hugely impressive from what I've seen and what's doable by dip switches does seem to be a fair bit less than via their connect software.   He does refer to an issue in his first post where, despite being in charger only, it cut power to his 240V domestics leaving his heaters, etc, off until he was there to reset it though. Maybe it's a bit dicky?

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12 minutes ago, Sea Dog said:

I think you have a point there, Robbo, as that's a pretty good Combi he has there.  Certainly the relatively recent versions have a good range of settings, although Victron manuals aren't hugely impressive from what I've seen and what's doable by dip switches does seem to be a fair bit less than via their connect software.   He does refer to an issue in his first post where, despite being in charger only, it cut power to his 240V domestics leaving his heaters, etc, off until he was there to reset it though. Maybe it's a bit dicky?

But if it’s only cut out the once, it could have just been a blip?  The settings for the charger are quite vast and match modern combis by the looks of it, modern combis have more features but the charge settings look similar.  It certainly very customisable, just not as easy as plug into a PC as it’s all via dip switches.

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28 minutes ago, Robbo said:

 Instead of amp counting, flip everything off when it's kicked into float mode and use a hydrometer to find your true state of SoC

Would be handy if you let us know what type absorption setting you have.   

Still don't understand why your looking at other chargers, when you have a very good one in your mits, and all it requires is looking at the settings.

yes, I think I will try and measure the SG. I will have a go tomorrow when it should be fully charged to get a baseline on using the hydrometer - not used one for 30 years!

I know it is a decent bit of kit but:

-its likely 15 years old

- it failed to switch properly during the recent cold spell and left the boat without power so no oil filled radiators working (so maybe a foretaste of what is to come)

- I am not sure it is controllable enough to charge the batteries as it seems a pain to change the parameters. (The Sterling power chargers seems a lot more flexible but i need to do more research). I cant see a way to programme it to change to float at a set tail current - only by setting a set time.

Like many on here, I would prefer separate units so if it goes wrong, I havent lost both inverter and charger at the same time - although I can see how to get 240V back easily.

The cost of buying a new charger and re-wiring, using the combi as the inverter, isnt too bad.

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On 14/12/2017 at 18:53, nicknorman said:

That is only because you don’t understand how to use the device.:P

When you plug in shore power, you should always switch the Combi to charger only to avoid just this sort of problem.

Yup, that's what I do.

However, if I had specified the boat, I would have had seperates.

21 hours ago, WotEver said:

If the combi is switched to ‘Charger only’ does it still pass the AC? If so that sounds like the best setting when you’re away from the boat. 

Yes. It is how I leave my boat in cold weather, and the mains feeds the oil filled rads and dehumidifier. 

Edited by cuthound
Spillung
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17 minutes ago, WotEver said:

Which is why pilots use checklists even when it’s their thousandth flight. 

They do, but it doesn’t stop them making mistakes. Lines skipped on the checklist, items read out but not actioned etc.

If you are a nervous flyer and want to see just how incompetent professional pilots can be, have a read of this report just out (hint: they fly altitudes in metres in a few countries including China.)  AAIB report December

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24 minutes ago, nicknorman said:

They do, but it doesn’t stop them making mistakes. Lines skipped on the checklist, items read out but not actioned etc.

If you are a nervous flyer and want to see just how incompetent professional pilots can be, have a read of this report just out (hint: they fly altitudes in metres in a few countries including China.)  AAIB report December

My best mate was ex-RAF and then a captain with BA flying long haul 747-400’s. Sadly he passed away suddenly from a heart attack but over the years he and I had many long conversations about the state he would sometimes be in prior to flying; ridiculously tired or hungover (or, worse, sometimes both). He told me many scary stories that he had first hand experience of. 

Folk sometimes think they’re infallible. The truth is far from that. With the possible exception of ‘Sully’ Sullenberger. ;)

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