SOLVED: iCharger X6 + 24V 750W Meanwell for 100AH LFP cells, only get 21-22A continuous, not 30A

[vangogh]

UPDATE: Solved. The cells had already reached the constant voltage phase of charging, so the current was dropping as it should.

Anyone have experience with an iCharger X6 and a Meanwell 24V 750W power supply? Mine seems to work fine but I can't get it to go past 26A when charging just a 2p set of 100AH LFP cells. The power supply isn't even vaguely warm, so I'm fairly sure it's not the issue. I've just never seen anything beyond 26A, and it seems to go up to 25-26 briefly then settle down at 21-22A for the duration.

I tried upping my psu's voltage to its max at 27.66 but it makes no difference.

Here's a screenshot. I don't have temp or balance info, just directly wired to 2p 100AH cells, so I just set capacity at 200AH, and iCharger thinks it's a 1s, which it effectively is.

Cheers.

 

[john61ct]

It is usually a good idea to avoid approaching the maximum specification for reliability & longevity especially with cheap chinese gear.

Do you know the maximum **current input** spec?

The 4010-Duo's is 65A

which IIRC is why 34V is the minimum input in order to get its maximum output.

 

[vangogh]

It is usually a good idea to avoid approaching the maximum specification for reliability & longevity especially with cheap chinese gear.

Do you know the maximum **current input** spec?

The 4010-Duo's is 65A

which IIRC is why 34V is the minimum input in order to get its maximum output.

Thanks John. I always appreciate that you take a minute to offer guidance. I'm okay with running the device at max (with fans on it as I currently have) if it'll last hopefully even just a few weeks while I do some testing. It's owner's manual, and I confirmed in the settings shows an input current limit of 35A. It's output power max is 800W. But so far it never seems to go beyond 80-97W output. I updated the post above with a photo. It's even worse than I thought, and seems to go to 23-26A for a few seconds after starting, then settle down to 21-22A for the duration. I set my PSU to max voltage at 27.66, no change. iCharger fan is barely on, heat is low around 39C, and its overheat power reduce setting shouldn't kick in until 70C.

I thought I read a post the other day where a person said you could even hit the full 30A with a 12V power supply as long as your output was only a few hundred watts, but I'm pretty sure I also saw other posts saying 24V was needed. I ordered a little $4 jumper so I can try using my spare 500W 12V PSU. I figure it can't hurt to try that.

Cheers.

 

[john61ct]

Well of course your output Watts are only relevant within the context of high voltage packs, at lower voltages the Amps limitation rules.

Calculate that out first, maybe you don't need full possible power input?

 

[vangogh]

Well of course your output Watts are only relevant within the context of high voltage packs, at lower voltages the Amps limitation rules.

Calculate that out first, maybe you don't need full possible power input?

Indeed, I'm nowhere near the output limit, just mentioning where the setting is at because it could technically be set much lower and could cause the issue. But good news! I figured it out. I was already at the constant voltage stage of charging, so of course the current was less than 30A. I briefly upped the charge target to 3.65 and right away it went up to 27 and change, so I set it back.

I'm trying to run a full cycle on these cells so I can get a sense of whether the claimed 100AH capacity is legitimate. They feel "heavy" (subjective, need to weigh them), look a lot like CATL cells (good), and the laser weld of the busbars look like two parallel lines, and appear very robust. I tugged on one hard and got no noticeable cracking sound or unusual movement. I'm hoping to charge first to 3.6 then discharge to 3, then try again with 3.65 to 2.5v, and measure the AH during the discharge periods.

I tried to search around on these numbers or the qr code but can't find anything:

Cheers.

 

[john61ct]

Maybe for cap testing OK

but in actual usage I'd stop at 3.45-3.50 for good longevity.

Same with 2.5V that's going to drop lots of potential life cycles, 3.0V would be better.

What is the context, purpose to wanting such stressful tests?

Only bother measuring Ah from the discharge side, and pushing that function to the amps limit with that charger will likely burn it out, but then you said NP.

Link to the cells' source?

 

[vangogh]

Maybe for cap testing OK

but in actual usage I'd stop at 3.45-3.50 for good longevity.

Same with 2.5V that's going to drop lots of potential life cycles, 3.0V would be better.

What is the context, purpose to wanting such stressful tests?

Only bother measuring Ah from the discharge side, and pushing that function to the amps limit with that charger will likely burn it out, but then you said NP.

Link to the cells' source?

I'm definitely just doing cap testing right now, and these cells are indeed only for stress testing. I do understand that for the final battery banks the actual usage range should be lower. I plan to charge to 95% SOC and discharge to 15% since I only have a 5 year usage horizon, so I don't mind a shorter life. I estimate that's 3.6V and 3.15V, but I may be off on that, and welcome input.

Context and source of cells here: https://endless-sphere.com/forums/viewtopic.php?f=14&t=108254&p=1583113#p1583113

Thanks for info about only using discharge side Ah as a capacity measure. Good to know. For discharge, the unit self-limits to prevent damage and can only safely do about 30W (can be upped to 50W but I won't), so a little under 0.1C/10A for a single cell. But it allows you to add an expanded discharge bank to increase that, and it can measure the total power discharged.

I have 4 x 100W 0.3 ohm resistors I plan to solder up in parallel to provide 0.075 ohm resistance. If I've done my math correctly, with fully charged cells at 3.6V, I should see 3.6/0.075=48A discharge, or ~0.5C, plus the ~0.1C/10A from the iCharger = ~0.6C (really more like 0.57C), which is good enough to estimate my high-end discharge rate for a planned 20kWh 24V 800Ah bank with an 8s2p configuration.

Cheers.

 

[john61ct]

Aha I remember now.

I was not able to find a link to that Chinese vendor?

Or is that proprietary info between you and ECPC Carl?

At only a 5 year lifespan, under 2000 cycles they'll barely be broken in, you'll likely get what you paid for them selling secondhand

Very difficult to get precise SoC% levels, just define setpoints via voltage + current (C-rate) throughout.

Going past 3.5V, especially if holding CV for any time, you really are not adding much if any useful stored energy, just creating heat against resistance.

When testing that statement, remove excess "surface charge" voltage with a tiny load, then allow a few hours' isolation - resting voltage at 3.33-3.35V really is basically the best definition of SoC 100% Full.

By comparative cap testing between that and the result of say

hold 3.6V until current tapers down to 0.05C (or maybe 0.02C)

I'd be very surprised if you found more than 5% difference.

Does your use case need every mAh of cap utilization?

CC-only charging, "stop at X volts" is very easy to implement, and will give a precisely repeatable result if current is always the same.

3.15V as a LVC setpoint would be great, even at very low discharge C-rate.

I have 4 x 100W 0.3 ohm resistors I plan to solder up in parallel to provide 0.075 ohm resistance. If I've done my math correctly, with fully charged cells at 3.6V, I should see 3.6/0.075=48A discharge, or ~0.5C, plus the ~0.1C/10A from the iCharger = ~0.6C (really more like 0.57C), which is good enough to estimate my high-end discharge rate for a planned 20kWh 24V 800Ah bank with an 8s2p configuration.

Ahead of me there, please keep posting with details and results.

Don't bother doing pack level testing unless your gear is limited, one cell at a time is better.

Look for **consistency ** in test results, especially between different production runs, that's a more important measure of quality if you're buying batches over time.

Obviously lots of variation within one delivery is a Big Red Flag.

 

[vangogh]

I'm going to move my response over to that first thread since it's more on-topic. Thank you again John! You're a wealth of information and generous to offer your time on here.

Cheers.

 

[john61ct]

Thank **you** for the kind words.

And please know I am just a relative noob myself, and try to learn new stuff every day, what keeps me young at heart

so I welcome not just questions but also criticisms and corrections when I get stuff wrong!