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Looking for an affordable 137.6A single prismatic LFP cell constant current charging solution

cj0

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May 29, 2024
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For some cell experiments I am looking for an acceptable priced constant power charger for a single LiFePO4 cell.

Cell datasheet states: 0.5P 502.4W @3.65V
Thus around 3V the charger should be able to supply 502.4/3=167.46 amps (I rounded this up to 170A).
I can live with CC 502.4W/3.65V=137.6A.
  1. A bench/desktop power supply was my first though. Those lack a "CW" (constant power) mode, or when they have a CW-mode, these programmable power supplies are so expensive that the suppliers don't even dare to mention the price.
  2. An industrial power supply was my second though. Most (f.e. TDK SWS1000L-3) have a configurable voltage, but no constant power mode. This PSU is expected to touch OCP within seconds.
  3. Then I stumbled upon a programmable AC-DC power supply, that can be put in parallel, like a TDK HWS3000G-24 or XP Power HPF3K0PS24. Those power supplies are still € 2000 for 2 pcs.

Any suggestions for a reasonable priced high current single LFP cell charging solution supplying 137.6A or modbus/serial programmable to mimic a CW-mode and 3.66V OVP?
 
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I'd like to see what suggestions you get.

A 3.65 volt and 170 amp draw will have a bit of voltage drop on a 2/0 cable with a 2' run. 2%, or around 30 watts, so I'd expect the wire would have some heating. My favorite ampacity chart for 60C says not to use wire less than 2/0, but with a different insulation, perhaps 200 C, the thickness goes down as the temp rating goes up.
 
A 3.65 volt and 170 amp draw will have a bit of voltage drop on a 2/0 cable with a 2' run. 2%, or around 30 watts, so I'd expect the wire would have some heating. My favorite ampacity chart for 60C says not to use wire less than 2/0, but with a different insulation, perhaps 200 C, the thickness goes down as the temp rating goes up.
These high current power supplies have a screw connection without insulation. Maybe I will bend a solid busbar for the connection. For 2 supplies in parallel maximum current is 85 amps per cable.
 
CC and CV are easy and prolific.

CW are rare and expensive.

High current of any type is expensive.

The linked unit does not do CW, only CC and CV.

Either you need to compromise your testing, become an electronics whiz and build your own, or you need to compromise your goals, so they are attainable on cheaper equipment.
 
...The linked unit does not do CW, only CC and CV.

Either you need to compromise your testing, become an electronics whiz and build your own, or you need to compromise your goals, so they are attainable on cheaper equipment.
I can live with CC and OVP. Though I must be able to modify the current. The goal stays to have 502.4/3.65=137.6 amps at OVP point.

How (un)likely is it that a constant 100A industrial power supply can be place in parallel with f.e. a 0-60A bench/lab power supply?
 
How important is it that you charge at maximum power? Looks like 280AH cell? I mean something like:
Is on the order of a buck a watt, and you want 1/2 a kilowatt, so nothing's going to be cheap...

Maybe you could ask the vendor above for the 500W (or 150A?) version? They can be remarkably helpful if you want something a little unusual.
 
What about Meanwell?

You can use 3x the MS-360-3B in parallel

Each one provides 60A. 3.3V nominal, but can be adjusted to 2.6-4V, and has constant current limiting (usefull when using as charger)

And they are rather affordable, around $80/piece


Or the HRP-600-3.3, which provides 120A at approx $150

Some of the Meanwells also provide voltage sensing options.


I have a Wemaxpower bench power supply. Mine 'only' provides 60A but for me thats sufficient (I opted for 60A and 0-30V since that also allows me to charge 12V or 24V sets). They do have more beefy models and have full adjustable current limiting. So if you need to be able to adjust the current, that might be an option to look for. (However they are much pricier than just a simple Meanwell power supply)

But getting eg the 0-15V / 2000W version might be an option, that provides 125A. Expect to pay 500-1000 euro incl shipping and all taxes.
Keep in mind that, just as with most bench power supplies, its not recommended to run >80% of the rating for continous long times. But with a
125A unit you can run it at 100A just fine.
 
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At that current the supply would need remote cell voltage sensing to compensate for cabling and connectors voltage drop.

There will be a lot of cell overpotential voltage bump (+80 to +120 mV) at that current.

High risk setup for inducing cell damage.
 
MS-360-3B
When attaching a lithium battery as sink to such a source, I accept that the sink will accept more current then the supply is able to supply. Thus supply OCP will kick in rapidly. I think I need a power supply that limits the current by itself to a maximum, without activating an OCP, or don't I?
 
When attaching a lithium battery as sink to such a source, I accept that the sink will accept more current then the supply is able to supply. Thus supply OCP will kick in rapidly. I think I need a power supply that limits the current by itself to a maximum, without activating an OCP, or don't I?
You can use 3x the MS-360-3B in parallel

Each one provides 60A. 3.3V nominal, but can be adjusted to 2.6-4V, and has constant current limiting (usefull when using as charger)

And they are rather affordable, around $80/piece
^^^^ That.
 
This reply is too cryptic for me. What do you mean?
You asked for power supply options with current limited outputs.

@DJSmiley responded with the MS-360-3B which has all those features (and remote sensing, as recommended by @RCinFLA) and can be paralleled for your desired output power.

Not clear on how you might adjust the current limiting, but we'll leave that as an exercise for the student.
 
@DJSmiley responded with the MS-360-3B which has all those features
I am having doubt if the MS-360-3B is suitable.

Without "simple constant current control" (TDK has only 2 models with that feature, 12 VDC and up), whether a power supply with OCP can charge a battery, depends on the type of overcurrent protection, according to TDK.

Only a power supply that has constant current voltage drooping type characteristics, can be used to charge a battery with constant current out of the box. Not the fold-back drooping type, neither the intermittent type.

Neither terms can I find in the MS-360-3B datasheet, the MS-360-3B manual contains in section "3.4 Short Circuit Protection & Over Current Protection (O.C.P.)":
MS-75/150/210/300/360 are constant current type while MD-100 is shut-off type
Is this the confirmation that an MS-360-3B can charge a battery out of the box?

PS The MS-360-3B is a module, that needs to be used in combination with a PFC-450/600/1000, adding at least USD 220 to the costs.
 
I've used multiple Meanwell power supplies as charger for topbalancing or fastcharging a battery bank.

As long as they have constant current limiting it works fine.
They do run hot since they are continous at max load but if you don't mind the noise (fans run on full power) you're good.

Based on the images of the MS-360-B I don't think any chassis is essential. They do seem to have screw terminals. When in a chasiss, Meanwell has also suitable busbars to parallel them, but I don't see any reason why they wouldn't work without having the chassis.

Apart from not beeing able to adjust the current limit (it's just the fixed value of approx 60A) I don't see any problem in using one. Only if you need the current to be adjustable you should look into other options.
 
Based on the images of the MS-360-B I don't think any chassis is essential. They do seem to have screw terminals. When in a chasiss, Meanwell has also suitable busbars to parallel them, but I don't see any reason why they wouldn't work without having the chassis.
A quote from the MP450,650,1K0 instruction manual:
the line input is rectified into high DC voltage (around 390VDC) by the front-end PFC stage, and then the DC output modules will transfer the operating voltage into all kinds of DC output voltages.
Unless you are able to supply 390VDC, you need the chassis. The modules run on 390VDC input, have no fans, etcetera.
Though I'd like the idea to mix and match modules: with 1 MS-210 and 2 MS-300 I expect an output of 138.5 Amps. That is close to the target charging current.
 
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Deja Vu All Over Again:
Says it'll do up to 200A by running all four outputs in parallel.
 
The Mean Well MP/MS is too difficult to source in The Netherlands. I think I am going to try to charge a single CB75 LiFePo4 cell with a Mean Well HRP-600-3.3. The voltage is adjustable between 2.8 and 3.8 volts. It has a remote sensing option. However the current is limited to 120 amps max.
 
I can confirm that the Mean Well HRP-600-3.3 power supply is able to charge a single cell from approximately (factory) of 40% SoC (3.2875V) with up to 120 apms.

At 120 amps and 3 times 10 mm2 copper, the ripple is much lower then expected: max. 4,3 mV rms, and max. 51 mV peak-to-peak according to the LMG95.

The CB75 1,00 second DC voltage increase from 3.28749 to 3.31669 is 29.2 mV.
The CB75 2,00 second DC voltage increase from 3.28749 to 3.35809 is 70.6 mV.
The CB75 1,00 second DC voltage decrease from 3.44783 to 3.44200 is 58.3 mV.
The CB75 2,00 second DC voltage decrease from 3.44783 to 3.37858 is 69.25 mV.
7 minute resting voltage is 3.32550V
10 minute resting voltage is 3.32142V
15 minute resting voltage is 3.31801V

This voltage decrease is too much. My PeakTech 4350 clamp meter in mA mode measures a reverse current of 0.45 Amps when the power to the supply is disconnected. That is not handy. There is a path of 4.7 ohms between V- and V+ when the power supply has no AC.
 
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