Do you have a TRUE CCCV power supply or charger?

[SamTexas]

If you have one and have yourself actually verified its CCCV function, please post the brand, model and the place you bought it from. I would like to get one that supports 14 to 16s LiCo. Thanks.

 

[nicobie]

Every meanwell clone I've owned with the Fechter limiting board has been CCCV.

I'm not sure what you mean by TRUE.

 

[SamTexas]

I have never owned a Meanwell (or clone) power supply before.

A true CCCV charger is one that would actually supply the full stated current until the battery reaches its terminal voltage (under charge). Then it would maintain that terminal voltage until the battery is fully charged.

Example: An imaginary LiCo 10s, 2A CCCV charger charging an empty LiCo 10s, 50Ah battery: One should see a constant 2A current for at least 20 continuous hours, until the battery voltage reaches 42.0V. Then and only then should one observe a continuous gradual decrease in current for a few more hours until the battery is fully charged.

 

[liveforphysics]

That's what a meanwell with the CC board does.


I have about a dozen big CC/CV power supplies. Just picked up a 60v 250amp sorensen and a 32v 125amp sorensen last friday.

The 32v 125amp sorensen goes nicely on my stack of server supplies to make nice 125amp CC/CV charger that's good up to 135vdc. >15kw charging FTW. Charge your 30s20Ah Nano-tech pack from full empty to full charged in under 10minutes.

 

[NeilP]

How your are describing does not actually happen, no, not with a Meanwell with CC/Cv board or a BMS alloy shell charger.

They all give CC for a while till internal resistances etc start coming in to play and current starts dropping.

In order for a perfect CC/CV charge to occur, it would need a charger that started off at a voltage low enough to keep the current low..or a current limited supply. as the CC/CV board does with a meanwell.

As the pack becomes charged, its voltage rises, and since we have usually set the max output of our charger to max required voltage, the the PD between the charger and pack reduces, so therefore does current, tis continues til the pack reaches the same voltage as charger and current flow stops

in order for full CC to continue to the point where pack voltage reaches required voltage you would need to raise charger voltage to a figure above what you want the final pack voltage to be, but since the pack is drawing current it would keep the voltage down to below max voltage.

then a point would come when the pack reached its max charge voltage and the charger voltage will then need to be ramped down to keep pack within max

How wise this would be ..to keep forcing max charge current in to the pack, when it is getting near full charge, and plateauing out...not sure.

I suspect this is how the Fast charge no balance cycle works on many hobby chargers.

I asked this same question in this thread

http://www.endless-sphere.com/forums/viewtopic.php?f=14&t=39485


because this ramping up of charge voltage to keep current flowing in to the pack is what I do in the workshop if I ant a quick charge form my string of PC supplies + meanwell . I start off at whatever the string can put out..20 amps or so, then as the current starts reducing, I start winding up the output voltage of the Meanwell to keep the charge current up at 20 amps.
I do have cellLogs with alarms set to go off at any cell above 4.12volts, and I only leave it liek this while I am at my bench..

Someone else asked a similar thing a while back, someone looking for an intelligent bulk charge solution and wondering about creating software to run it, but when I asked about this thread, in my thread above, no one had heard of it

 

[SamTexas]

NeilP: I am sure true CCCV chargers exist, they are probably more expensise, thus rare. I have one lead acid battery charger that is claimed to be CCCV, but it's not. It can only hold the rated CC until the battery reaches about 85% to 90% of the final voltage.

How wise this would be ..to keep forcing max charge current in to the pack, when it is getting near full charge, and plateauing out...not sure.

I certainly don't see any harm in it. After all it is the method recommended by all Lithium manufacturers I know of. It does not have to be max charge current, it could be any constant current up to max as specified by the battery manufacturer. The advantage of true CCCV is that one can predict quite accurately the time it takes to charge a battery.

How your are describing does not actually happen, no, not with a Meanwell with CC/Cv board or a BMS alloy shell charger.

So you have already tried the Meanwell with the CCCV board and it did NOT work as advertised, correct?

 

[NeilP]

Yes, i have been using a Meanwell with a CC CV board and it does work successfully and as advertised, but that is different to what we seem to be talking about here.

The CC/CV board is designed to be a clip on addition to limit the current on a meanwell supply. This is because a Meanwell , although it does produces a constant current, it gives a constant current at about 125% of it maximum rated continuos rating. So it burn out very quickly if not modified. This is what the Fechter cc/cv board does, it limits the maximum current to prevent the Meanwell from toasting itself.
It does not ramp the voltage up once the current starts dropping to keep current flowing at the higher level, As the PD between pack and charger decreases, so current decreased. The CC board only keeps current down to a constant level.

I have been on the forum for about 18 months, and until I asked about this in my thread iI linked to earlier, I do not recall it being discussed before. The method so far has always been to get a PSU, set the maximum voltage to that which you want the pack to be fully charged at, and limit the current to whatever you need, either for pack or charger or both well being. there has not been as far as I am aware any talk of keeping the constant current going till the last minute, we have always allowed it to taper down as pack voltage comes up

 

[SamTexas]

Yes, i have been using a Meanwell with a CC CV board and it does work successfully and as advertised, but that is different to what we seem to be talking about here.

The CC/CV board is designed to be a clip on addition to limit the current on a meanwell supply. This is because a Meanwell , although it does produces a constant current, it gives a constant current at about 125% of it maximum rated continuos rating. So it burn out very quickly if not modified. This is what the Fechter cc/cv board does, it limits the maximum current to prevent the Meanwell from toasting itself.
It does not ramp the voltage up once the current starts dropping to keep current flowing at the higher level, As the PD between pack and charger decreases, so current decreased. The CC board only keeps current down to a constant level.

Yes, it's different from what I am talking about. If I read you right, the Meanwell/CC/CV board combo is definitely NOT TRUE CCCV by definition.

 

[ZOMGVTEK]

The Meanwell PSU's that don't have 'Hickup' style current limiting are CCCV. I use SP-500-24 units to bulk charge. They just need the jumper on the SVR2 pad replaced with a POT, and you can adjust the CC limiting from near 0 to about 115% of the rated current.

 

[NeilP]

The Meanwell PSU's that don't have 'Hickup' style current limiting are CCCV. I use SP-500-24 units to bulk charge. They just need the jumper on the SVR2 pad replaced with a POT, and you can adjust the CC limiting from near 0 to about 115% of the rated current.

No they are not. Or, maybe be they are, and what I am talking about is not what is meant by CC CV

Read the thread again, and also the one I link to earlier about setting the charger to above 4.2 by per cell

For whatever reason, as a Meanwell reaches ... ummmm not sure... 70 % charge? current starts tailing off as pack voltage rises and gets close to charger voltage.
The whole system has resistance, so when voltage between pack and charger reduces, current flow also reduces. This happens BEFORE pack reaches your end point voltage as set by SVR1

The only way to practically keep the current constant till pack voltage reaches your required end point voltage is to increase SVR1 to an open circuit voltage greater than you require. You need to keep raising this voltage till current increases back up to your required Constant Current charge rate
You then need to carefully monitor overall system voltage and reduce it (via SVR2 in this case) to keep pack voltage from exceeding required per cell voltage

How advisable this is, charging to full charge, all the way to full capacity I do not know



Edit .... Oh hang on. Both my 2x Meanwell 84 volt charger, and my single Meanwell 50 v charger BOTH use Fetcher CCCV boards for end of charge. I can't remember the last time I charged just using the current limit pot SVR2 Both my units are fitted with SVR2 mods. Maybe, just maybe doing it with that mod keeps voltage and current higher longer than the board? Will try tonight

 

[ZOMGVTEK]

The Meanwell PSU's that don't have 'Hickup' style current limiting are CCCV. I use SP-500-24 units to bulk charge. They just need the jumper on the SVR2 pad replaced with a POT, and you can adjust the CC limiting from near 0 to about 115% of the rated current.

No they are not. Or, maybe be they are, and what I am talking about is not what is meant by CC CV
[/b]

My bulk charger maintains a constant voltage, so long as the output current is equal to or less than the preset current. If the current must rise to force the preset voltage, the current drops to whatever voltage is required to output the set current. My charger runs the fans at full blast until the cells hit about 4.1V, then current slowly starts to drop and you can tell the current starts dropping when the fans slow down or turn off. However, it's wired with 10 AWG wire, and uses the inbuilt current limiting. I have not used a Fetcher board on a Meanwell.

The only reason why a supply should drop current AND voltage noticeably early, is if there is substantial enough resistance for whatever is measuring the voltage to see the preset voltage, and drop current to compensate. As the current decreases, the voltage drop would decrease as well, making the charge termination substantially longer than required. This is not normal behavior, but can occur. It does not indicate the charger is not CCCV.

Really, the only difference between a Meanwell supply in CC mode and a 'true' CC bench supply, is the Meanwell has a finite voltage range. Most bench supplies tend to go from 0V up to, or beyond the full rated voltage. For battery charging this is entirely irrelevent unless you want to charge packs of dramatically different voltage.

 

[NeilP]

My bulk charger maintains a constant voltage, so long as the output current is equal to or less than the preset current. .

Ah interesting, what do you have? must be somehing pretty beefy. I charge every day with a BMS Alloy shell 2kW charger, originaly set at 142 volts, but turned down to 84 at the moment. That shows an voltage just above that of the pack while putting out the 20 amps it is limited to. it stays at 20 amps and voltage slowly rises as pack voltage rises, then as it nears 4 volt per cell, current statrts to drop off.
Same happens with the twin meanwell set up at 8 amps and the single meanwell for the 50 volt pack

If the current must rise to force the preset voltage, the current drops to whatever voltage is required to output the set current. .

Do not get what you are saying here, typo maybe ?

What we need is the Voltage to rise to force the preset current, and then drop again as pack voltage reaches end of charge final voltage

The only reason why a supply should drop current AND voltage noticeably early.....

No one has said that Voltage is dropping, the measured voltage is increasing as current decreases, and this decrease in current occurs because of resistance and the reducing difference in voltage between the set voltage of the charger and the increasing voltage of the pack.

 

[ZOMGVTEK]

Something must be wrong with your charger. What you claim is occurring is not normal, unless you have substantial resistance somewhere thats making the charger see much higher than pack voltage, or you are misunderstanding the chargers intended operation.

Are you pushing more current through the shunt on the Fetcher board than reasonable? Do you have extremely thin wires, paralleled supplies, excessive connectors?

 

[Njay]

Yes, i have been using a Meanwell with a CC CV board and it does work successfully and as advertised, but that is different to what we seem to be talking about here.
It does not ramp the voltage up once the current starts dropping to keep current flowing at the higher level, As the PD between pack and charger decreases, so current decreased. The CC board only keeps current down to a constant level.

Yes, it's different from what I am talking about. If I read you right, the Meanwell/CC/CV board combo is definitely NOT TRUE CCCV by definition.

I don't see why the combination isn't a CCCV (I haven't looked into Fetcher's board details, but from descriptions I is just that: a current limiter). I have no hands-on experience so what I'm going to say is theory-based.

In the charging phase, the voltage output by the charger is controlled in order to keep the current constant - this implies that the charger voltage is just a little bit above the battery voltage (that is, the "ideal" voltage source inside the battery), and that the charger voltage raises with battery voltage so that the current is kept constant -> constant current phase.

Then there's a point where the charger's voltage reaches the maximum pre-set voltage and raises no more. Current will, of course, start decreasing since battery voltage will continue to increase as it charges -> constant voltage phase.

The MW will set the maximum voltage. Fetcher's board will limit the maximum current, by reducing the voltage presented to the battery (that's the only way we can reduce the current flowing into the battery). How isn't the combination a CCCV? Any voltage supply followed by a current limiter forms a CCCV system.

As I see it, the CV part is the reason why you can charge to 80% very fast and then the last mile takes much longer. You can't raise the voltage more than the max bat voltage to keep the current high (and the charging time low).

 

[NeilP]

Something must be wrong with your charger. ?

Three different chargers..no make that 4 with the PC string and Meanwell. and 4 different battery packs, so no it is not that. It is just how this works.
If you have a set voltage on your charger, so 83 volts for example, and the pack is at 74 volts that is 9 volts difference, and you get full current. as the pack builds up its charge, and pack voltage come up to say 81 volts, you now only have 2 volts difference between pack and charger. Lower PD, current gets less, just basic Ohm law.

What you claim is occurring is not normal, unless you have substantial resistance somewhere thats making the charger see much higher than pack voltage,

or you are misunderstanding the chargers intended operation.

Well I do not think there is a mis understanding. I have always seen this mode of operation, current reduces near end of charge, it does not stay at a Constant Current all the way to the end when pack is at final voltage.

Are you pushing more current through the shunt on the Fetcher board than reasonable?

8 amps so no, not xs current, and that is both Meanwells with CC/CV boards

Do you have extremely thin wires, paralleled supplies, excessive connectors?

Not so thin that it would cause massive voltage drop. The 2kW Alloy shell still has its original crappy chinese cable, but it is big enough. The other two Meanwell chargers are wired up with 12 or 10 gauge. Packs are 8 gauge on the parallel section and 10 where it spilts ff to each pack ( big back is 20s4p with 4mm bullets)

 

[ZOMGVTEK]

It looks like I'm not getting anywhere here.

Ohms law does not apply to a CCCV charger in the traditional sense. A CCCV charger should force voltage at the load, unless it reaches its CC limit. In that case, it will drop the voltage to whatever is required to maintain its configured current. As the battery charges, the voltage will rise to maintain that same current. Only when the battery reaches termination voltage should the current ever drop.

My Meanwell bulk charger acts exactly like this. The cells hit 4.1V, and the current starts to drop. The cell voltage does not rise from this point, since the charger is not rising voltage. I'm not sure why you would see things any differently.

 

[SamTexas]

ZOMGVTEK: Can you tell me if one of your charger is actually a TRUE CCCV as defined below. Thanks.

A true CCCV charger is one that would actually supply the full stated current until the battery reaches its terminal voltage (under charge). Then it would maintain that terminal voltage until the battery is fully charged.

Example: An imaginary LiCo 10s, 2A CCCV charger charging an empty LiCo 10s, 50Ah battery: One should see a constant 2A current for at least 20 continuous hours, until the battery voltage reaches 42.0V. Then and only then should one observe a continuous gradual decrease in current for a few more hours until the battery is fully charged.

 

[NeilP]

It looks like I'm not getting anywhere here.

.

I was thinking exactly the same

Ohms law does not apply to a CCCV charger in the traditional sense. .

Realise that, but that is he easiest way to expalin it, as that is what happens, volrage difference reduces and current reduces.

A CCCV charger should force voltage at the load, unless it reaches its CC limit. In that case, it will drop the voltage to whatever is required to maintain its configured current. .

Correct that is what the CC CV board does, via the OVP point, it brings the voltage down, that is not the point I am making, and Sam is asking about

As the battery charges, the voltage will rise to maintain that same current. .

Exactly but in the case of a Meanwell or a an alloy shell charger, or any charge system where the charger is set at a maximum voltage as pack voltage, this does not happen, current drops off earlier before the voltage reaches the open circuit voltage of the charger. Which (as current thiking goes) , is the voltage you want you pack to be at, at termination.

Only when the battery reaches termination voltage should the current ever drop..

But it does not, it drops earlier, how much earlier does vary, but it definetly drops earlier, which ever charger you use, on which ever batter pack.

What I suggested on the other thread, is, as current drops but before the measured termination voltage is reached, (as measured across the pack at the time of charging), the voltage of the charger is increased to above the termination setting, to keep full current charge going n to the pack. Only the measured voltage across the pack reaches termination voltage, do you start reducing the charger voltage, so as not to over volt the pack.

You have already stated this happens

As the battery charges, the voltage will rise to maintain that same current. .

All I am suggesting is to keep the voltage setting going up, above final termination point. As pack is still takng current, it will not go over voltage, and then reduce again as pack voltage is reached

My Meanwell bulk charger acts exactly like this. .

Maybe what I m seeing and what you are seeing is different, becaue i have a CC?CV board connected, o both my Meanwell rigs. I can by pass one easily enough, and jsut rely on the R33/SVR2 current limit to keep from toasting th eMenawell. I ill try it and see. Maybe Alloy shell charger works in a similar way to the CC/CV board and thererore acts the same. I'll try when I get a chance

I'm not sure why you would see things any differently.

Well I seee it different because that is what I am seeing happen in front of my eyes as I charge.

ZOMGVTEK: Can you tell me if one of your charger is actually a TRUE CCCV as defined below. Thanks.

A true CCCV charger is one that would actually supply the full stated current until the battery reaches its terminal voltage (under charge). Then it would maintain that terminal voltage until the battery is fully charged.

Sam, I think the answer to that is that ZOMGVTEK will say yes his is TRUE CCCV as you define, and myself with a Meanwell charge also would say no.

 

[ZOMGVTEK]

ZOMGVTEK: Can you tell me if one of your charger is actually a TRUE CCCV as defined below. Thanks.

A true CCCV charger is one that would actually supply the full stated current until the battery reaches its terminal voltage (under charge). Then it would maintain that terminal voltage until the battery is fully charged.

Example: An imaginary LiCo 10s, 2A CCCV charger charging an empty LiCo 10s, 50Ah battery: One should see a constant 2A current for at least 20 continuous hours, until the battery voltage reaches 42.0V. Then and only then should one observe a continuous gradual decrease in current for a few more hours until the battery is fully charged.

Yes.

I have never used the Fetcher board, so I can not speak for that. The SP-500 units I have do exactly that. Anything other than that is not CCCV.

If your meanwell clones are not doing this, they are poorly designed. The absolute BEST way to ensure you are forcing max current right up until the voltage hits OCV, is to move the voltage feedback right to the connector on the end of the charger. For higher power charging this can often be a good idea, especially if you are running the equipment at or above its rated output, or if its poorly designed. IIRC, Doc did this on his big 2kW Meanwell to make sure the charger won't slow down at the end of the charge. If it does, it does not necessarily indicate that it is not CCCV, but possibly that its current or voltage measurement is not accurate, linear, or poorly designed/placed such that it is not compensating for internal losses as the voltage of the supply changes.

 

[nieles]

with true cccv supply, you can make a short circuit beteween positive and negative and still only get 10A(or whatever the limit is set to) but with the meanwells this is not possible (99% sure)


about the current dropping before the terminal voltage is reached, two things are possible:

1, there is a voltage drop between the point the voltage is measured by the power supply and the battery terminals. this can be fixed by running some small signal wires from the battery connectors to the voltage measuring point in the supply (some supplies have Vsense terminals next to the power terminals)

2. the internal resistance of the battery pack is limiting the current (highly unlikely)

 

[deVries]

What I suggested on the other thread, is, as current drops but before the measured termination voltage is reached, (as measured across the pack at the time of charging), the voltage of the charger is increased to above the termination setting, to keep full current charge going n to the pack. Only the measured voltage across the pack reaches termination voltage, do you start reducing the charger voltage, so as not to over volt the pack.

Hi Neil,

With these types of chargers I think you wrote somewhere that you manually turn-up the voltage when the current begins to drop nearing the end of charge. About how far off volt-wise is that from your nominal pack voltage, when you begin to do this? I guess there is no way to do this automatically; you must change the voltage and monitor when the pack-side hits the right pack voltage to turn back down the volts on the charger to match the pack v.

Did you do a thread that talks about doing this, how to do it, or is this info in another thread?

Thanks.

 

[NeilP]

[Doc did this on his big 2kW Meanwell to make sure the charger won't slow down at the end of the charge. .

I asked him about that, and he eventually put it back to as it was as he coudl nto get it to work correctly like that. I was planning to do al his mods and asked him about that one

 

[ZOMGVTEK]

with true cccv supply, you can make a short circuit and still only get 10A(or whatever the limit is set to) but with the meanwells this is not possible (99% sure)

1, there is a voltage drop between the point the voltage is measured by the power supply and the battery terminals. this can be fixed by running some small signal wires from the battery connectors to the voltage measuring point in the supply (some supplies have Vsense terminals next to the power terminals)

Thats something that does not apply to a Meanwell, since they are not designed to operate as a standalone CCCV supply. In that sense, they are not a 'true' CCCV supply, but rather a CCCV charger with a finite voltage range. They have a rated output voltage they attempt to maintain, some just happen to have current limiting. This does not change the fact that they will not go outside of the rated voltage range to limit current, like would be required in a short circuit event. They will most likely just shut down.

However, for charging batteries, this does not tend to matter. You tend to have marginal 'compliance' required for the supply to dip down to pack voltage, unless you run more than one supply in series, and only one is current limited. In that case, the sole limited supply needs to have enough swing to sufficiently drop the chargers total output voltage to be able to effectively charge a dead pack.

It's very likely the voltage drop thats causing the charger to appear to 'slow down' near EOC is internal to the power supply itself. I would agree with you there. Moving the sense outboard should solve this, assuming the power supply is accurately reading the voltage... With a cheap power supply this is not always the case.

Neil: What Meanwell supplies are you using?

 

[ZOMGVTEK]

I would think that if the power supply does not give you an external voltage sense connection, it will not act like you want.

http://www.meanwell.com/search/sp-500/sp-500-spec.pdf

This model does have an external sense, and it works perfectly fine for me. Even if you don't connect an external wire to the sense, it only has to compensate for the wire and connection losses. If the supply does not give you this connection, it can be referenced internally in a location that is something less than desirable, causing the issues previously described.

If it's that important to you, buy a supply with an external voltage sense. If you have several supplies in series, you need to series the voltage sense leads, and run them with some thin wire as close to the load as possible.

 

[NeilP]

A pair of S-350-48s in series, both with SVR2 added and SVR 1 mod, CC/CV board switchable in out

Also a secone s-350-48 with cc/cv board for the Gf's bike

http://endless-sphere.com/forums/viewtopic.php?f=14&t=32344