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you are correct in that this is low wattage. My thought is the cells generally stay reasonably close so this small unit would handle my needs.
 

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you are correct in that this is low wattage. My thought is the cells generally stay reasonably close so this small unit would handle my needs.
Oh I think I understand more of what you are trying to do now. At first I thought you were trying to go from dead to safe full which for every 12 cell block would be around 33 hours with that.

I take it you are just using it on your lowest block to bring it inline with the other blocks? Basically using the CV portion that's 30V max (2.5V per cell) to make each block 30V thus back in balance. That would work for each of the blocks but on your slightly lower block is it still balance at the cell level? It will balance the blocks but not the cells so I'd verify that it's not actually one cell within the block that is the culprit first.

On the power supply make sure to get the non dimmable version which is CCCV. The 3 in 1 dimmable is just CC.
 

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Discussion Starter #23
Okay anyway so I'm not trying to balance cells or anything. I'm not worried about rebound. Just want to get the volts higher w/o waiting a whole day on my current 1/3 Amp grid charger.

Unless anyone thinks I'm choosing the wrong supply I'll probably buy the HLG-320H-C1750A for $69, which does 91 to 183V at 1.75A later today.
 

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I think there is a good shot that it will do what you want, but watch it carefully first time you use it to see what it does at the upper voltage termination.:)
 

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I'm not so sure you want a cc unit. That's what I used and it raised all 12-cell units about the same but 'bad' individual cells got worse. Have you considered a CV or a CVCC unit? Also what happened to me when I ran w/o the Interceptor, the car charged the whole pack, and very quickly.
 

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Okay anyway so I'm not trying to balance cells or anything. I'm not worried about rebound. Just want to get the volts higher w/o waiting a whole day on my current 1/3 Amp grid charger.

Unless anyone thinks I'm choosing the wrong supply I'll probably buy the HLG-320H-C1750A for $69, which does 91 to 183V at 1.75A later today.
It should but the datasheet doesn't specify what it does for termination at the upper end of it's voltage range. Definitely watch it the first time to me there are 3 possibilities.

1. (most likely) It terminates when the current drops below 1.75 amps. The datasheet says the CC region ends at 183V for an open circuit of 187V (4V difference). Under this scenario the battery will likely rebound a bit and be somewhere around 180V the next day since it was 183V when the charge terminated.

2 (somewhat likely). It continues to charge but at a slower rate than 1.75 amps and keeps the voltage at it's open circuit max of 187V and the current would slowly lower to basically zero. If you observe this happening on your clamp meter you have a 187V CC + CV charger that switches from CC to CV at 183V. Since it did CC + CV the battery will have no rebound and will be 187V the next day. The cells will be at 2.6V/cell so you do have a bit a breathing room still but less than before so likely you'll have to manually balance the cells a bit more often or just keep a closer eye on the voltage levels.

3. (not likely but definitely watch it the first time just in case otherwise bad things happen). The power supply does nothing to terminate and even though it's max open circuit rating is 187V you see it doing 188, 189, etc. This would obviously be bad as the power supply will likely fail but also because you don't want the batteries to get into the 190V range without a balancing BMS. If this occurs the charger should be returned and can't be used for your purposes.

That power supply has a dial as well for the output voltage/current to dial things in (I believe for 50%-100% of rated current so from .8875A to 1.75A). For the likeliest outcome of #1 above if you want it to stop at 180V on the dot you could likely adjust down a few mA of charging speed for stopping at the voltage level you want. If you adjust it down I'd expect the CC region to slightly grow and the termination voltage after rebound to go up slightly.

As @jime said definitely watch it the first time just in case it's number 3 or bad things might happen.
 

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I'm not so sure you want a cc unit. That's what I used and it raised all 12-cell units about the same but 'bad' individual cells got worse. Have you considered a CV or a CVCC unit? Also what happened to me when I ran w/o the Interceptor, the car charged the whole pack, and very quickly.
If a cell is going bad regardless of charger type it's going to diverge from the rest of the pack and will go either low or high since no balancing is being done on the charges or discharges. 1.75A is still less than .1C which is quite low, way lower than what would have been done in the Fit EV originally (obviously it has balancing as a backup though). Higher charge rate will slightly raise divergence especially if you go to higher C rates (3C, 5C, 10C) but .1C (C/10) is quite low. For healthy cells I'd expect there be to no increased divergence from it's peers. After all at that rate it'll likely still take around 10 hours to charge.

As far as divergence goes I'd expect there to be no difference between a CC and CCCV at the 2.0V -2.5V range because it's only the CC portion that increases the C rate of charging. Also, last I checked the max voltage of CC+CV chargers that Mean Well offers is 54V. I'm sure there is a brand that does make one that high (180V) but I have a feeling it'd be quite expensive.
 

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I'm not so sure you want a cc unit. That's what I used and it raised all 12-cell units about the same but 'bad' individual cells got worse.
CC in itself isn't a bad way to charge so long as one stays well short of ALL the cell maximums. At her pack target of 180V the cells should all be in the linear region of the charge curve. Even the balancing PL8 charger uses CC until it reaches the final few minutes of charging BUT the charger is detecting balance. I've used it to charge all the way to 2.7/cell safely, since it detects and corrects imbalance, and it is always CC most of the way up, because the cells are inherently well balanced.

Only with a very high SOC cell would one at some voltage get into the upper nonlinear part of the charging curve, FOR THAT CELL. If so, and rare in my view, operating in that region might make matters worse, since the high SOC cell could go nonlinear and rise more rapidly in voltage. When at 2.5V/cell target, it is very unlikely that a cell will get high enough to get into the nonlinear part of the charge curve.

IF one wanted to be ultra safe, then the course would be to remove all covers, or better drill them just over the tap screws, and quickly run manual measurements as one approached the 180V target. Of course, Peter's OBDII C&C tool would make it simple to closely watch this phase of the charge.
 

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Just a quick heads-up, touching on something that was mentioned up there somewhere: If the FIT cells (larger, high energy) are anything like the smaller, high power SCiBs, then there's very little difference between the state of charge achieved at XXX voltage at relatively high current versus XXX voltage at low current, i.e. the difference in charge added going from CC to CV is small. For example, there's certainly no need to have a CC-CV charge if your base CC current is only 1.75 amps - you'll add almost nothing having the current taper down from 1.75 amps to zero while holding the voltage constant.
 

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I have also looked at the spec sheet and I can't decipher how the power supply is going to terminate. As you said, it doesn't seem likely that it would self limit in a CV like behavior and taper to zero, since that would be a CC/CV supply. Thinking it through, I think there is some chance that it contains a resetting breaker which will trip at 180. Hopefull it is smart enough to only reset on removing the primary power. That would be ideal.
 

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I'm not so sure you want a cc unit. That's what I used and it raised all 12-cell units about the same but 'bad' individual cells got worse. Have you considered a CV or a CVCC unit? Also what happened to me when I ran w/o the Interceptor, the car charged the whole pack, and very quickly.
You should never use a constant-voltage power supply to charge batteries. The power supply will always try to output its rated voltage and will supply as much current as necessary to stay at that voltage. If you connect a constant-voltage power supply with no current-limiting to a lower-voltage battery, you're essentially shorting out the power supply and dumping tons of current into the battery (if the psu can sustain it). A current-limited power supply is required.

I have also looked at the spec sheet and I can't decipher how the power supply is going to terminate. As you said, it doesn't seem likely that it would self limit in a CV like behavior and taper to zero, since that would be a CC/CV supply. Thinking it through, I think there is some chance that it contains a resetting breaker which will trip at 180. Hopefull it is smart enough to only reset on removing the primary power. That would be ideal.
The only clues I see are that the max open-circuit voltage is 187V, and the constant-current region is from 91V-183V.
The shape of the graph on the third page implies the current will taper off to zero as it reaches the maximum voltage. I imagine this would occur from 183V-187V for this unit. It's just not advertised as a CC/CV power supply because it's only CV when it's outputting zero current. :)
Looks like a fine unit to use for charging a battery to me.
 

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^ I see a model that explicitly says "CC + CV," same part number but with a "B" at the end instead of an "A". I think I'd opt for that one instead of the potential vagaries you might encounter with the CC-only model. Seems like "A" might not do what you want it to do at the 'end of charge', like it might constantly trip ON and then OFF as the battery voltage peaks and relaxes at whatever output voltage you set... Here's a link to the "B" model:

 

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^ I see a model that explicitly says "CC + CV," same part number but with a "B" at the end instead of an "A". I think I'd opt for that one instead of the potential vagaries you might encounter with the CC-only model. Seems like "A" might not do what you want it to do at the 'end of charge', like it might constantly trip ON and then OFF as the battery voltage peaks and relaxes at whatever output voltage you set... Here's a link to the "B" model:

Likely depends on where you buy from and what their return policy is. I would think that a 183V charger with rebound down likely fits better than a 187V charge with no rebound. With monitoring the first charge if it doesn't behave you can manually stop and return at some places.
 

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^ Not sure I understand: '183V rebound down', '187V no rebound'? What are we talking about here?

Basically, if I'm understanding the difference between the "A" and "B" model correctly, the CC + CV model is closer to what you'd want in a charger, you'd just get that one and not worry about return policies.

You want to be able to set an upper voltage threshold suitable for the pack (or particular circumstances - maybe sometimes you want 180V, another time you want 172.8V) and be assured the power supply won't breach that - and do it in a controlled way, a way that it's designed for. That's the CC + CV "B" model. I don't know exactly how the other one handles the transition at max user-set output voltage - but it's not what the CC+CV model is, otherwise, there wouldn't be a CC+CV model. My guess is that it's not a very 'elegant' affair...
 

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^ I see a model that explicitly says "CC + CV," same part number but with a "B" at the end instead of an "A". I think I'd opt for that one instead of the potential vagaries you might encounter with the CC-only model. Seems like "A" might not do what you want it to do at the 'end of charge', like it might constantly trip ON and then OFF as the battery voltage peaks and relaxes at whatever output voltage you set... Here's a link to the "B" model:

According to the datasheet, the A or B only denotes the current adjustment method and the ingress protection rating. It makes no mention of there being any sort of CC or CV difference between the two.
86248


That third-party site probably isn't 100% accurate, especially considering the list of specs for the two otherwise-identical models are pretty different.

Get the A version, it lets you adjust the output current with a built-in potentiometer rather than having to hook up additional circuitry. The output voltage is not adjustable for either one.
 

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Look like a good choice. It will likely leave the battery at 183V instead of some approximation of 180V or so. That is only .04V above target. As before, the terminating cell levels should be checked as it gets to180V.
 

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That third-party site probably isn't 100% accurate, especially considering the list of specs for the two otherwise-identical models are pretty different... Get the A version, it lets you adjust the output current with a built-in potentiometer rather than having to hook up additional circuitry. The output voltage is not adjustable for either one.
If that's the case then, yeah, fooey. If I had more time I'd be looking for one with an adjustable output voltage -- and a real CC + CV. Seems like there's gotta be something like that...
 

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<edited>

Well, I don't know. I'm getting confuse so forget anything I said about the power supply:unsure:
 

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Look like a good choice. It will likely leave the battery at 183V instead of some approximation of 180V or so. That is only .04V above target. As before, the terminating cell levels should be checked as it gets to180V.
No, it will get up to 187V at most.
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But even 187V is 2.60V per cell for a 72-cell setup, which is within the acceptable range. That's about 98% SoC. I wouldn't charge it up that far every day though, you want to keep the min and max SoCs further from the extremes for longer cell life.
 

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Well, I don't know. I'm getting confuse so forget anything I said :unsure:
Yeah, sorry Jime, it's my fault -- or I could blame it on the sloppy specs at Sager - they list it as CC + CV model. But then, I also assumed either of these have adjustable output voltage when apparently they don't...

Mario's on top of it all, though. I still think adjustable output voltage is worth looking for, as well as CC + CV... Not being able to adjust and hit the exact target voltage seems pretty kludgey, especially when the termination voltage is probably a bit on the high side for the cells, on a regular basis...

edit: I did scan around Sager a bit for adjustable output voltage - not seeing anything for LED power supplies. Maybe that's not as common a feature as I was thinking, probably confusing LED with boiler-plate AC-DC power supplies, and I scanned those a bit but didn't see the high voltages needed...
 
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