Cheap power supply for top balancing (tested and works well).

Just John

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First, a link to the cheapest 30 volt, 10 amp supply I could find on Amazon. There are others on occasion that go on special for a dollar or two less, but this one is pretty consistently the cheapest I could find.


An alternative that is not as cheap, but since it has a fine voltage and amp adjustment, is easier to use (plus has a 4 digit display).


Opening them both up and checking the boards and components used, the first (cheapest) does not have 5 volt at 2 amp section for the USB charge port, otherwise they are very close to identical. Same parts in the same locations, same cutouts on the PCB for isolation, just no USB charging, and less digits on the display (also of course more touchy to set).

Lots of power supplies in this class all seem to be identical in design, for instance the Kaiweets reviewed here is identical internally to the second (more expensive) I listed above.


I will also inform you that the one Will Prowse recommends is identical internally as well (the Dr. meter here). Long Wei, Nice Power, Wanptek, and many others all appear to be manufactured with identical components, just different cases.

Anyway, recently there was a lot of discussion about the ability of these supplies to put out their full rated current and voltage without having them die. Certainly as a general rule, don't run Chinese power supplies at more than 80%. I can tell you, I've tested the top two linked above, and you can be sure they actually will put out 0-30 volts and 0-10 amps indefinitely. I used 10 gauge wire with nice crimp ring terminals to test, but even so, there is drop/loss due to the cable. First I set the power supply to the desired voltage using a meter (no load), then hooked up to my electronic load and told it to draw 10 amps current for the maximum time (it has a limit of 60,000 seconds for a timed test, that's 16 and 2/3 hours each test). I also placed a temperature probe on the exhaust fan outlet and monitored any temperature rise (you can see the exhaust temperature in the Riden display).

For 3.65 volts:

365v_10a_power.jpg
365v_10a_et5410.jpg

For 14.6 volts:

14v_10a_power.jpg
14v_10a_et5410.jpg

For 30 volts at 10 amps:

30v_10a_power.jpg
30v_10a_et5410.jpg
 

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Just John

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I should probably add, these are great for charging individual cells, and packs up to 24 volts, but they are terribly noisy supplies and are not really a "lab power supply" even if they are advertised as such. Lots of switching noise, but batteries don't care.
 

Just John

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I should probably add, these are great for charging individual cells, and packs up to 24 volts, but they are terribly noisy supplies and are not really a "lab power supply" even if they are advertised as such. Lots of switching noise, but batteries don't care.
If anyone is interested, I've found a guy who shows how to modify the supply a bit to eliminate quite a bit of the switching noise.

 

KauaiMolokai

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Thanks John, this is super helpful - you buying these and taking them apart and testing them. I was just looking for a power supply exactly like these and pretty overwhelmed by the choices. In the end, without someone doing what you did, it's just a gamble. Much appreciate you doing what you did and posting

Aloha
 

Just John

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Thanks John, this is super helpful - you buying these and taking them apart and testing them. I was just looking for a power supply exactly like these and pretty overwhelmed by the choices. In the end, without someone doing what you did, it's just a gamble. Much appreciate you doing what you did and posting

Aloha
Thanks, I appreciate the response. If anyone is interested, I'm going to sell the (now used) supply for what I paid for it, and throw in some 10 gauge wire with crimped ring terminals (just tell me what size). Most will want the 1/4 inch (works great for M6 sized Eve or Lishen). Anyway, although used now, it is a well tested supply, and I would use priority mail to ship.
 

KauaiMolokai

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Hi John,
Which one are you selling?
This is a brilliant idea! Otherwise you end up, like me, with tons of extra stuff you don't use!

Aloha
 

MrNatural22

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I’ve been using the cheaper Longwei as a charger on my 24v A123 batteries since June last year.
The fan is quite noticeable but my tinnitus blends well with it. 🤫
It takes about 9hrs to recharge from 20% DOD back up when it drops the current down to 1.2a 👍 Thats where I want them full. I start out set at 28.6v 10a. It has done its job well, never been a problem since I’ve owned it.
I did do the 10g wire upgrade on the leads did away with those banana plugs, but I still use the alligator clips to attach to the batteries. Small acceptable loss.
I’m pleased with it for what a paid and so far it’s been trouble free.
 

Just John

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Hi John,
Which one are you selling?
This is a brilliant idea! Otherwise you end up, like me, with tons of extra stuff you don't use!

Aloha
The cheap one, cost me $52 plus tax from Amazon. I will sell it for $50, throw in a quality cable and ship it via priority mail for that price. That means it costs me about $15 to $20 to test it.
 

Just John

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I’ve been using the cheaper Longwei as a charger on my 24v A123 batteries since June last year.
The fan is quite noticeable but my tinnitus blends well with it. 🤫
It takes about 9hrs to recharge from 20% DOD back up when it drops the current down to 1.2a 👍 Thats where I want them full. I start out set at 28.6v 10a. It has done its job well, never been a problem since I’ve owned it.
I did do the 10g wire upgrade on the leads did away with those banana plugs, but I still use the alligator clips to attach to the batteries. Small acceptable loss.
I’m pleased with it for what a paid and so far it’s been trouble free.
Yes, the fan is smaller and noisier than the more expensive Longwei. My wife made me move everything to the garage when I got a 1200 watt supply for my Riden that has a 24v fan with no speed control.
 

Gaze

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Question: While attempting to charge a 48v NMC battery pack, I get a large spark when connecting a power supply similar to those you've tested above. 60v / 10a. The PS instructions say to set CV and CC prior to connection to device, then turn the PS off, then connect to device (battery in my case), then turn on the PS. This results in the spark while the PS is still 'off'. Two solutions have been suggested:
1) use a resistor to pre-charge the power supply before battery connection. Would this be while the power supply is still 'off'?
2) set the power supply to the same voltage as the SOC of the battery and connect while the PS is 'on'

Would you have any suggestions/opinions about this? That spark is not my favorite thing.
 

Just John

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Question: While attempting to charge a 48v NMC battery pack, I get a large spark when connecting a power supply similar to those you've tested above. 60v / 10a. The PS instructions say to set CV and CC prior to connection to device, then turn the PS off, then connect to device (battery in my case), then turn on the PS. This results in the spark while the PS is still 'off'. Two solutions have been suggested:
1) use a resistor to pre-charge the power supply before battery connection. Would this be while the power supply is still 'off'?
2) set the power supply to the same voltage as the SOC of the battery and connect while the PS is 'on'

Would you have any suggestions/opinions about this? That spark is not my favorite thing.
It's likely the capacitors in the power supply causing the spark, just like an inverter does. You can try the same precharge trick for an inverter (use a power resistor and connect before the capacitors discharge fully). I have never had that problem so far, but I am also dealing with half the voltage.
 

Gaze

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Thanks. Any opinion on option 2, which is to turn the PS on, set is to a matching voltage, then connect. I've been reluctant to try this since it doesn't follow the PS manufacturer's instructions to first turn off the PS before connecting to a device.

Anyone else out there encounter this spark while charging a 48v battery?
 

Just John

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Thanks. Any opinion on option 2, which is to turn the PS on, set is to a matching voltage, then connect. I've been reluctant to try this since it doesn't follow the PS manufacturer's instructions to first turn off the PS before connecting to a device.

Anyone else out there encounter this spark while charging a 48v battery?
That option should work fine, I connect and disconnect all the time while the supply is running and it hasn't killed one yet. Which power supply do you have?
 

Gaze

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That option should work fine, I connect and disconnect all the time while the supply is running and it hasn't killed one yet. Which power supply do you have?
I've owned 2 different ones off Amazon, lemme check...
Kungber 60v
Tuffion 30v
 

Just John

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I've owned 2 different ones off Amazon, lemme check...
Kungber 60v
Tuffion 30v
Yes, both of those are the same basic design, no problem, you won't kill them. Just make sure of the polarity first.
 

Gaze

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Yes, both of those are the same basic design, no problem, you won't kill them. Just make sure of the polarity first.
lol I'm more concerned with killing me

Ok...I'm going to give it a try (option 2). I'm surprised there's been only rare reports of big spark when charging a battery. I have eye protection, gloves, long sleeve shirt, take wedding ring off, etc., then POP! I'm thinking...this can't be right
 

Just John

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lol I'm more concerned with killing me

Ok...I'm going to give it a try (option 2). I'm surprised there's been only rare reports of big spark when charging a battery. I have eye protection, gloves, long sleeve shirt, take wedding ring off, etc., then POP! I'm thinking...this can't be right

My Riden 18 amp supply makes a pretty significant snap and arc when cranked up to 60 volts, but it has an output enable and disable button.
 

Gaze

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I've been considering the unit shown here (the one on the right), based on the guy's recommendations:
 

Just John

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I've been considering the unit shown here (the one on the right), based on the guy's recommendations:
You need a Riden supply if you want a programmable supply. Well worth the money.
The supply on the left is the same internally as this cheap supply.
Interesting that he calls it control voltage and control current, never heard that. Constant current and constant voltage is the term. Maybe it's a British thing.
 
Last edited:

dgd4040

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Great information John. Is there a supply you would recommend that is a little better quality and more then 10amps?
 
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