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LiFepo4 top balancing equipment recommendations

I am not familiar with how bench power supplies are "supposed to work". Trying to learn something here.
Is this the expected behavior that the amperage drops to zero when battery reaches that voltage?

And, is this how ALL bench power supplies work (looking at the cheapies on Alibaba here) or is it something that one SHOULD verify before leaving it on and walking away?
Any Constant voltage supply will drop to zero amps as the cells charge and almost any bench-top supply will be a constant voltage supply or have a constant voltage mode. (I can imagine a constant-current only bench-top supply but it would be a rare beast)

When considering a supply for working with LiFePO4, I like supplies that are Constant Voltage - Constant Current (CV-CC). With these supplies you can set the max current and max voltage they will supply. A supply of this type will drop to a lower voltage than the set voltage to keep the current at the set value. However, as long as the current is at or below the set value it will regulate the voltage to the set value.

For the cells we typically use on this forum the low cost 10A supplies from AliX will almost never exceed the current the cells can take. In fact, even a 20A supply is only .2C of a 100Ah cell and .07C of a 270Ah cell. Consequently, one could correctly argue the CC mode is unnecessary.....but I like to have it anyway.
 
I have a concern about the bench top power supply. Since its not a charger, will it automatically stop charging when the batteries balance at 3.6v or will you need to stay and watch to make shore the batteries don't over charge?
I have top balanced a couple of 8 cell 280Ah battery banks now. I notice it IS a big time saver to use my 12v 50 amp charger option to get my then sets of 4 cells up near full charge, then go for the 8 (or more) cell Top Balancing. Note on using one of those 30V 10 A bench power supplies: (in my set up): When I turn the bottom knob fully clockwise, that is for max amps. ... & then to get the max 10 amp charging, I then twist the upper voltage knob fully clockwise, then slowly back counter clock wise till I see the amp figure drop slightly (the volt figure then drops some too). I figure that back off provides some little protection from way overcharging your battery if you go to a sleeping at the wheel cycle. The higher your battery voltage gets, the less amp show signifying what amps are cranking into battery.

I am top charging one cell right now. ... To get near the max 10 amp charge, the voltage on my bench power supply is set at 4.40v. If I dial it down to 3.65 v, the amps in to battery reduces to just 3.6 amps (with my DMM measuring 3.28v at battery). Those charging amps will keep reducing as the battery voltage gets higher. While others may have different ways, ... I have taken to only doing this when I am around to check the battery with my digital multimeter (might even set an alarm on my phone to remind me as voltage get closer to what I want at battery). When my battery volts is above 3.4 volts, I watch closer. Then at 3.5v.; ... I might then set the volts on bench power to 3.65v, and watch the amps in charge will then go way down. HEADS UP when the battery gets above 3.4 volts, the rest of the cell charging to 3.65 v can happen way more quickly than one might expect (when using the previous part of the charging cycle as your reference)!!! ... I have found that to be the case with one cell, and/or when top balance charging 8 cells. The one exception I saw on one cycle of a top balance charge of 8 cells taking forever; was; ... I had once had one defective cell in a set of 8, that would just not charge up beyond 3.37 volts, and that held back my full set from reaching 3.65v).

One other note: When I am using my 50 amp LiFePO4 cell charger without a BMS; to keep any one of my 4 cells from going over 3.65v, I will put a DDM on each cell as they are charging to get the picture of how closely they are balanced as they charge. Again, I watch much closer when batteries get above 3.4v.

... Hope that is some kind of useful references :+)
 
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Don't know if it's been said but a reminder. When parallel top balancing cells make sure to set the voltage of the power supply to 3.65 volts before connecting to the cells. Failure to do so will result in the cells being overcharged. Also it's a good idea to measure the output voltage of the power supply with a DMM to make sure the voltage of the power supply and the DMM are the same. :)
 
That works, too. Just should use a BMS while charging as a series pack, in case one of the cells gets to far out of spec from the rest. But it shouldn't take 24 hours to finish them off in Parallel to 3.65V. From 3.5V to 3.65V should only take a few hours. Maybe take them to 3.65V, let them rest a bit and see where they settle down to and top them off again. I just went ahead and built my battery after they hit 3.65V once. But I was impatient by then.
Yes, to BMS idea as much safer, ...as I just recently got one overcharged cell using the method mentioned method. My 4 cell battery charger does stops charging at top voltage for full set, but one cell got too high. ... I put a 20 amp draw on that cell to bring it's voltage down asp, and crossing my fingers in hoping I did not hurt it too much.
 
Amperage dropping to zero is not the same as terminating the charge.
Even though no current flows the cells are still exposed to unnecessary voltage stress.
I didn't say to leave them sitting at Zero Amps for a long time. Just you don't have to be sitting in front of the B/PS waiting for the instant it does.
 
make sure to set the voltage of the power supply to 3.65 volts before connecting to the cells.
So set voltage 1st, leave power button on, then hook up to battery? ... Mine does not show voltage sometimes until I hook it to battery; but it did today. Might be some fluke I have. ... Also question: When setting voltage 1st to then get am amp charge going; and then using the method of turning up the voltage until one gets a 10 amp charge (instead of just 3.5amps) ... Do you think setting the voltage 1st then has an advantage? Whatever way one goes, I do think 3.4v or more deserves close attention, and that might be when to dial back to 3.65v to not be look at a cell that just reached 4.0v or 4.4 v; which is not good.
 
So set voltage 1st, leave power button on, then hook up to battery? ... Mine does not show voltage sometimes until I hook it to battery; but it did today. Might be some fluke I have. ... Also question: When setting voltage 1st to then get am amp charge going; and then using the method of turning up the voltage until one gets a 10 amp charge (instead of just 3.5amps) ... Do you think setting the voltage 1st then has an advantage? Whatever way one goes, I do think 3.4v or more deserves close attention, and that might be when to dial back to 3.65v to not be look at a cell that just reached 4.0v or 4.4 v; which is not good.
With the Amps set to minimum, you may need to turn the amps up a little bit for the volts to read. Then you can turn it off and connect the battery. It should return to the preset voltage when you turn it back on. If your R/PS is set to 3.65V and you turn the amps to maximum, it should output to the maximum amperage limit of your R/PS. When your Cells/battery fill up, the amps should start dropping and the R/PS should switch from CC mode to CV mode. That is the way a normal R/PS works.
 
That's how I use my power supply .... set the amps to maximum ..... adjust the voltage to what I want .... and then connect to the battery.
 
With the Amps set to minimum, you may need to turn the amps up a little bit for the volts to read. Then you can turn it off and connect the battery. It should return to the preset voltage when you turn it back on. If your R/PS is set to 3.65V and you turn the amps to maximum, it should output to the maximum amperage limit of your R/PS. When your Cells/battery fill up, the amps should start dropping and the R/PS should switch from CC mode to CV mode. That is the way a normal R/PS works.
Thanks for: "With the Amps set to minimum, you may need to turn the amps up a little bit for the volts to read. Then you can turn it off and connect the battery." I think that is a good specifics for me to update with. I try it. I never registered those specific before (which I have l looked for) in directions or manuals or video clips. Thanks Sgt Raven :+) from Capt Bill
 
I am top charging one cell right now. ... To get near the max 10 amp charge, the voltage on my bench power supply is set at 4.40v. If I dial it down to 3.65 v, the amps in to battery reduces to just 3.6 amps (with my DMM measuring 3.28v at battery). Those charging amps will keep reducing as the battery voltage gets higher. While others may have different ways, ... I have taken to only doing this when I am around to check the battery with my digital multimeter (might even set an alarm on my phone to remind me as voltage get closer to what I want at battery). When my battery volts is above 3.4 volts, I watch closer. Then at 3.5v.; ... I might then set the volts on bench power to 3.65v, and watch the amps in charge will then go way down. HEADS UP when the battery gets above 3.4 volts, the rest of the cell charging to 3.65 v can happen way more quickly than one might expect (when using the previous part of the charging cycle as your reference)!!! ... I

Just wanted to share that I found this very helpful and confirming my experience on the slow amp charging when set to 3.65V max voltage, If only I had the balls to go to 4.40v to charge faster because this is slow as fudge!
 
Warning: If you hook it up backwards you can blow out a diode in it. The symptom is that it shows it is pumping current but there is no voltage.
(don't ask how I know ☹). The good news is that the fix is relatively easy if you have a soldering iron.

I have debated putting a schotky diode in series with the output to protect the supply from my dumb stunts, but then the voltage displayed would be off by a few tenths of a volt.
I made the same mistake. If you rush it’s easy to mix up due to the batteries having a black positive post. I bought a uf5408 diode to replace. Hope it works.
 
... I’ll probablly charge at 30 amps. (link) TekPower TP1540E DC Adjustable Switching Power Supply 15V 40A Digital Display
Here's some links that work yours did not work for me): ... I intend to try on a LiFePO4 280Ah Cell Recovery method (mentioned in a recent ... " ... cell deviation at float?" thread ... for a set of 8x 280Ah LiFePO4 cells I have that briefly hit 1.4v (got caught off guard overnight via my equipment idle draw; ... w BMS low cell volt trigger wired to cut inverter draw only, ... instead of my full 24v battery bank. Those 8 cells are now a below par mix of runners (volt peakers at top end of bulk charge) and/ or Low Ah cells showing voltage drop (noticeable drops beyond the better cells)... at low voltage.

I am Considering this TekPower 15 Volt DC 40.0 Amp Switch Mode Power Supply for $198.37
... https://www.circuitspecialists.com/csi1540sw.html or https://www.ebay.com/itm/164972289976 $190
or possibly a ... TekPower TP1830SB DC Adjustable DC Power Supply 1.5-15V 30A with Digital Display ... $160
... Leaning towards the 40Amp model) ... If anyone has additional comment / or a better deal to consider;
All eyes and ears over here. ... for furthering my hands on type lessons :+) Bill
 
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Here's some links that work yours did not work for me): ... I intend to try on a LiFePO4 280Ah Cell Recovery method (mentioned in a recent ... " ... cell deviation at float?" thread ... for a set of 8x 280Ah LiFePO4 cells I have that briefly hit 1.4v (got caught off guard overnight via my equipment idle draw; ... w BMS low cell volt trigger wired to cut inverter draw only, ... instead of my full 24v battery bank. Those 8 cells are now a below par mix of runners (volt peakers at top end of bulk charge) and/ or Low Ah cells showing voltage drop (noticeable drops beyond the better cells)... at low voltage.

I am Considering this TekPower 15 Volt DC 40.0 Amp Switch Mode Power Supply for $198.37
... https://www.circuitspecialists.com/csi1540sw.html or https://www.ebay.com/itm/164972289976 $190
or possibly a ... TekPower TP1830SB DC Adjustable DC Power Supply 1.5-15V 30A with Digital Display ... $160
... Leaning towards the 40Amp model) ... If anyone has additional comment / or a better deal to consider;
All eyes and ears over here. ... for furthering my hands on type lessons :+) Bill
Another option is this 0-15V 60A power supply. I just received mine a couple hours ago and will test it:
HUIOU KXN-1560D Adjustable Switching DC Power Supply 0-15V 0-60A https://www.amazon.com/dp/B0856ZP4M...l_i_HNTTD1AA5M5Z4GVDNTVX?_encoding=UTF8&psc=1
57C41153-9A0D-4E65-BE8A-4F1DF854EFCC.jpeg
I imagine it’ll have the same issues as others have described (mostly just coarse settings only).
One thing I’ve wonder is, is there any consideration on top of the normal ones (3.65V max measured at the leads, stay within the c-rate of the cells) top-balancing cells using high amperage such as 50A or 60A?
Also, people say they use the power supplies at lower amperage for longevity, but wouldn’t longevity be linked to wattage instead of just amps? I’m assuming this power supply I got can spit out 900W (15V at 60A) but I’ll probably be using it at 3.65V most of the time. Even at 60A, that’s just 219W, or less than 25% of the power this supply is rated for. Is it really necessary to use lower amperage?

Quick update: it’s a little tough to get 3.65V precisely (measured at the end of the leads) with this unit. As a matter of fact, the first time I tried, the voltage kept changing between 3.4V and 3.9V but I think it’s because I had the amperage knob too low (more testing needed).
I then brought it up to 14.4V (to charge another LiFePO4 setup already top-balanced) and that seemed to hold just fine.
Any reason I should NOT use this to charge a battery pack that’s already top-balanced and that has a BMS?
When I lowered it again to around 3.6V and it seemed to be more steady. I wonder if it has something to do with how you approach a voltage value and the current knob position. I’ll give the instructions another read.
 
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Another option is this 0-15V 60A power supply. I just received mine a couple hours ago and will test it:
HUIOU KXN-1560D Adjustable Switching DC Power Supply 0-15V 0-60A https://www.amazon.com/dp/B0856ZP4M...l_i_HNTTD1AA5M5Z4GVDNTVX?_encoding=UTF8&psc=1
View attachment 93924
I imagine it’ll have the same issues as others have described (mostly just coarse settings only).
One thing I’ve wonder is, is there any consideration on top of the normal ones (3.65V max measured at the leads, stay within the c-rate of the cells) top-balancing cells using high amperage such as 50A or 60A?
Also, people say they use the power supplies at lower amperage for longevity, but wouldn’t longevity be linked to wattage instead of just amps? I’m assuming this power supply I got can spit out 900W (15V at 60A) but I’ll probably be using it at 3.65V most of the time. Even at 60A, that’s just 219W, or less than 25% of the power this supply is rated for. Is it really necessary to use lower amperage?

Quick update: it’s very hard to get 3.65V precisely (measured at the end of the leads) with this unit. As a matter of fact, the first time I tried, the voltage kept changing between 3.4V and 3.9V!
I then brought it up to 14.4V (to charge another LiFePO4 setup already top-balanced) and that seemed to hold just fine.
Any reason I should NOT use this to charge a battery pack that’s already top-balanced and that has a BMS?
Then I lowered it again to around 3.6V and it seemed to be more steady. I wonder if it has something to do with how you approach a voltage value and the current knob position. I’ll give the instructions another read.
Good to see options. I like the TekPower 15 Volt DC 40.0 Amp I picked for having more of a track record, plus it has big amp cable connectors in back of the unit for the higher amp range. I notice Amazon has no reviews yet for the unit you picked, ... so hope your testing turns out good. IMO: It is certainly nice to have a 60 amp charger option over that common 10 amp limits on the less expensive Bench Power Supplies, ... for a Top Balance, or even a 12v battery bank charge. IMO: The front terminals on that unit look a bit iffy (smallish) for 60 Amps. I will also remind you that many folks on this forum say use larger gauge wire with more solid terminals (than one supplied) between your power supply and the battery terminals to get the higher amps flowing properly. I have been confirming my dc amp flows when using these type of unit with clamp meter, just to confirm what's going on.

One recent fine tuning lesson for me has been: ... to set the top voltage I want, ... I now put a digital volt meter/ multimeter on my Bench Power Supply power/charge terminals, ... turn it on, and then dial in that voltage target I want using my DMM to confirm it. ... One likely has to turn up the current a small bit to start registering some voltage if your started out like I do with both voltage and current knobs both spun left. After Setting your Voltage Target; ... then turn the unit OFF, ... and then connect it to your battery, ... making sure of proper polarity. Then turn your Bench (Switching) Power Supply back ON, and dial up the Amps current you what you want ... to get your charge cycle started. I like confirming my amp flows when using these type of units with clamp meter, just to know what's going on. The Amps showing on Power Supply will drop as you get near or at your Target Voltage. I personally like writing down voltages of the battery terminal a few times as I charge, to confirm all is working properly. Hope that is not too redundant to what you have already figured out. Good Luck. Will be interested in your later report.
 
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Good to see options. I like the TekPower 15 Volt DC 40.0 Amp I picked for having more of a track record, plus it has big amp cable connectors in back of the unit for the higher amp range. I notice Amazon has no reviews yet for the unit you picked, ... so hope your testing turns out good. IMO: It is certainly nice to have a 60 amp charger option over that common 10 amp limits on the less expensive Bench Power Supplies, ... for a Top Balance, or even a 12v battery bank charge. IMO: The front terminals on that unit look a bit iffy (smallish) for 60 Amps. I will also remind you that many folks on this forum say use larger gauge wire with more solid terminals (than one supplied) between your power supply and the battery terminals to get the higher amps flowing properly. I have been confirming my dc amp flows when using these type of unit with clamp meter, just to confirm what's going on.

One recent fine tuning lesson for me has been: ... to set the top voltage I want, ... I now put a digital volt meter/ multimeter on my Bench Power Supply power/charge terminals, ... turn it on, and then dial in that voltage target I want using my DMM to confirm it. ... One likely has to turn up the current a small bit to start registering some voltage if your started out like I do with both voltage and current knobs both spun left. After Setting your Voltage Target; ... then turn the unit OFF, ... and then connect it to your battery, ... making sure of proper polarity. Then turn your Bench (Switching) Power Supply back ON, and dial up the Amps current you what you want ... to get your charge cycle started. I like confirming my amp flows when using these type of units with clamp meter, just to know what's going on. The Amps showing on Power Supply will drop as you get near or at your Target Voltage. I personally like writing down voltages of the battery terminal a few times as I charge, to confirm all is working properly. Hope that is not too redundant to what you have already figured out. Good Luck. Will be interested in your later report.
Oh yeah, thanks for the reminders on all of it :)
The power supply didn’t even come with leads and the high amperage terminals are definitely in the rear (the front is 10A max). I had already made 6AWG cables with proper hydraulically crimper terminals for it.
I also tinkered with it more and now I feel more confident about hitting the lower voltages right. The knob is still too coarse but it takes several full rotations to get from 0V to 15V (about 5 full turns). That knob is nicely dampened too, it’s just tough to hit 3.650V exactly.
I had it setup to charge a partially built and top-balanced 300Ah pack with a BMS and it gave it 50A for 3hrs without an issue. I didn’t notice the fan coming on, but I have a separate fan hitting the back of the unit anyway (it’s about 64°f in that room).
I also have my other 10A power supply top-balancing another pack in this photo. I’ll leave it like that overnight (it’s set to 3.64V) and maybe tomorrow I’ll see how it does on the 60A power supply.
8D0969E3-1FF3-44A5-9BC1-1AA0D5E63072.jpeg

I did another test this morning. Brought the power supply to 3.641V (measured at the end of the leads with the current knob cranked all the way up), turned the current down, turn the PS off and plug it into the battery. Turned everything back on and cranked the current up, the battery was happily sipping over 60A of top-balancing current.
94B6C6E6-22CE-4726-93E8-D1A90EDB5921.jpeg

The internal fan turned on after a few minutes so I switched my own fan on and lowered the amperage to 50A. It only sat like that for 5min or so.
Then I wanted to see how the current would act if the PS voltage was closer to the cell voltage (which is currently at 3.340V right now). I turned everything off, disconnected the leads and connected my voltmeter to the end of the leads to lower the PS from 3.641V to 3.400V. That’s when I saw my meter was measuring 3.681V at the end of the leads!!
C67DF0A2-269C-42F9-BC4A-952B2B961B71.jpeg

I had not touched the voltage knob at all during this test. If I did it accidentally, I didn’t notice, but I doubt that’s the case. I’m not too sure what happened here but I don’t think I’ll use this supply for top-balancing if I can’t rely on the PS keeping its set 3.641V value… I guess you get what you pay for.
 
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Here's another update. I ended up using the 60A power supply to do some top-balancing after all. What I did was set the power supply to around 3.500V and let it do its thing. I checked it every now and then with the voltmeter to make sure things were working right. When the amperage dropped (didn't take long from 3.350V at 50A), I checked the voltage again at the power supply and it had climbed a little, maybe 3.520V if I remember correctly. I noticed the display on the PS was pretty decent at letting me know when it thought the voltage changed from 3.5V to 3.6V (its threshold measured at the end of the leads seemed to be around 3.580V on my voltmeter). So I set the power supply to about 3.585V and let it do its thing again, checking often. When the display on the PS indicated 3.6V, I would stop, disconnect and measure the battery and the PS setting. The power supply would usually be around 3.61V and I'd have to lower it a little.
But basically, this little dance worked pretty great to get a bulk charge on the cells at a high amperage in a pretty quick way! I started top-balancing these 304Ah cells Sunday evening on a 10A PS and, as everyone knows, it takes forever. I didn't think it would be done until this coming weekend. Now, the cells are at 3.61V and I'm finishing them off on the more precise 10A power supply. When I set that one to 3.650V at 10A and connected them, the cells only took around 2A of current. That's when I started writing this update. Right now, about 5min later, the cells are taking less than 1A.
The process is a bit messy, but being conservative with voltage settings, this 60A PS does get these cells top-balanced MUCH MUCH faster! That, and it also makes capacity testing much faster!

Another update: 1hr after writing this post and the cells are at 3.647V taking 0.140A from the 10A power supply.
 
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