Joinrun S4 Smart Charger on Amazon. $14.94 free shipping.

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toddcshoe
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Joinrun S4 Smart Charger on Amazon. $14.94 free shipping.

Found this giveaway for this charger on Amazon. Looks amazingly similar to the MiBoxer C4. Specs look good on it. 4th slot even used for discharge and determining battery capacity. Anyway. This is the link for the giveaway. Of course I clicked on it and didn’t win, but, when it tells you you haven’t won it takes 50% off the $29.98 retail price if you add it to your cart. Figured for $15 through Amazon I can always send it back if it’s junk.

https://www.amazon.com/ga/p/b689fc68f288c4f5?nav=amz&fsrc=glp&return_to=...

pennzy
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Thanks for the heads up . Just ordered one. Do you know the charge current max. per slot?

edit: just found it , 800 and 350 mA

Lux-Perpetua
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Offer is valid only for US residents. Sad

pennzy
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Received my Joinrun charger yesterday. I have been topping off cells with it to get a feel for how it operates. Not as intuitive as the Miboxer C2-6000 I have been using. It’s default charge current is 800 ma. If charging 14500 , 350 ma must be selected manually. What struck me is that all the internal resistance readings ( 4th slot only ) are in the ballpark they should be in considering all my cells are new high quality cells. The Miboxer always measured resistance as being much higher. That made me feel better. For instance , the 30Qs all measured around 50 mohms with the Joinrun opposed to about 150-200 mohms on the Miboxer. The sliders don’t feel as smooth or strong on the Joinrun but they seem to do the job. The CV stage is shorter also. (Miboxer went on forever) For $14.94 it is a keeper, for $29.88 I would probably pass. 800 ma max charge rate is a little on the low side. Have not checked out the capacity test (again 4th slot only)yet.

pennzy
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One more thing I noticed. It early terminates @ 4.12 volts . The current was approximately 170ma at that point. This explains why it doesn’t take as long as the Miboxer maybe?

toddcshoe
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Just got mine in the mail today. Running a few suspect MJ1 cells through the capacity test to see what it says so I can compare it to a known good cell. This is my first “smart” charger. I just had a Nitecore I4 for normal charging. Never knew if my cells were as advertised unless I took them over to a friends house. Will be nice to know what to expect out of some of my late night 14500 finds on amazon. Hard to beat it I for a bit less than $15. Time will tell I reckon.

pennzy
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What voltages are you getting coming off the charger?

toddcshoe
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The charger is showing 4.18 but looking at it with my DMM is showing 4.21 So I will go with 4.195 Smile

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I haven’t run a battery to full charge yet. Still testing capacity. As soon as the tested cell is done I will throw it on a full charge and see what my terminating voltage is.

pennzy
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I ran one capacity test last night . I’m a little confused whether it is measuring discharge or charge capacity . It looks to me to measures mah as it charges for the second time.

All 4 slots on mine terminate at 4.10 volts . I don’t think the CV stage goes on long enough to fully charge the cells. Let me know how yours work.

toddcshoe
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I watched the one capacity test that I have run so far. I watched the mah run up as the cell was discharging, I fell asleep before it got to the end of that and I woke up in the morning with a fully charged cell and a reading of 2773mah on a claimed 2800mah cell. So I didn’t get to see if the mah reading continues to change on the recharge cycle. Cell measured 4.19 volts with my DMM afterwards. The screen on the charger displayed 4.20 volt with the “full” text underneath it. I also didn’t get a chance to see how long the CV stage is. I will pop in some slightly used cells today and see what voltage the cells are charging to and keep a better eye on it.

pennzy
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Did it record the discharge capacity? I only saw the last charge reading. Tried fiddling with the mode switch but nothing else came up. They can’t really expect you to catch it just right before it starts recharging. It would not be very useful that way or am I missing something . Never had a smart charger either.

toddcshoe
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I don’t know if it stays recorded or how you can go back to those records. I am not sure yet. I know when I woke up in the morning the tested mah was still on the screen until I took the battery out. Don’t know where it went after that. I have another cell in now that is just about done with it’s discharge cycle. I will see if I can find my last few records. I believe the directions says it saves past test. Still trying to keep an eye on it and see what voltage it uses as a cutoff for it’s test. Down to 2.92 volts as of right now. Seeing if it cuts off at 2.9

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2.8 volts was the cutoff on the test. Finally got to see it with my own eyes. VTC6 with about 10 charge cycles on it tested to 3060mah. Can’t really complain about that. I did some other test today on some junk 14500 cells and a Sofirn cell from last night. I will see if I can find those test and how to get to the saved test………….Ten minutes later………… Okay, after re-reading the directions. It does remember the completed test but only until you take the battery out of the slot. Once you take the battery out it goes away. It doesn’t get stored anywhere.

pennzy
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Ok , how do you find the stored capacity reading. Yours sounds like it is working fine.

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It’s stored as long as the battery is still in the slot. It goes bye bye as soon as you take the cell out. It doesn’t keep the test in memory after the cell is removed. After reading the directions again I noticed they probably shouldn’t have used the word “stored” and used the word “displayed”.

Everything on mine is working like a champ. Ran test on 4 known good cells and they were all withing 5% of what my buddies fancy tester said. I also ran test on 2 known junk cells with the same results. Even ran test on some ultrafire and trustfire cells just to see what they really will do. It’s quite pathetic really. The voltage drops like a rock on those junk cells anywhere below 3.8 volts with only 400ma of draw. Those cells are damn scary.

pennzy
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Isn’t the charge capacity the value that will be displayed on the screen while the cell is still in the charger?

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The charging current is showed at the lower left of the screen during the recharge but the capacity test results are displayed right underneath slot 4. So when you start a capacity test it keeps a running measurement of mah and the discharge rate. After the discharge is done the mah capacity stays where it is and the battery starts recharging and where the discharge current was displayed is now where the charging current is displayed. When the recharge is complete the mah capacity stays and Full will be displayed where the charging current was. It measures the batteries capacity in the discharge cycle not the charge cycle.

pennzy
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That is not what mine does. The mah reading was rising on the second charge cycle and that is what was displayed when full. Never saw any discharge number. May have been there at the end of discharge cycle but didn’t catch it. I will try again to verify this but that is what I saw I think. Problem is it takes like 2/3 of a day to complete and I don’t like to sleep with it charging.

Update : ok, it charged up cell ( arrow down on display ?) It started discharge ( arrow up ) and it is registering mahs.Voltage is dropping . Everything going as should except the arrow direction seems to be reversed.
toddcshoe
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I see. I better understand now. Mine doesn’t do any counting up from the end of the discharge cycle through the recharge cycle. When I put a cell in slot 4 I push the mode button until mah blinks then long press till the 3 little arrow boxes show up on the right of the slot 4 battery meter thing. Then it tops off the battery to full, discharges, and recharges.

Yes it does take some time. I know other chargers have higher discharge and recharge rates so they would be quicker. I think when my discharge/capacity test is over I will pull it and recharge it in a different charger that I have that charges with 1.5amps. For the money I am happy with it so far.

pennzy
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I’ll watch it closer this time. I could have been imagining things the first time . Wouldn’t be the first time. Big Smile

pennzy
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Started the capacity test but lost it about 2 hours in when the power cord pulled out as I picked it up to see the screen. Going to start it over again today. The mah reading was ticking upward and the voltage was decreasing . On a side note, I emailed the company on Amazon yesterday and told them my charger was only charging to 4.10 volts . They got back today and said to keep it and they provided a coupon code for 99 % off on a replacement . So kudos for their CS department.

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That’s awesome. Hopefully you just got a dud. Nice to see their CS is on top. Makes me feel a little safer now. At least now you will be able to do two capacity test at the same time and get them almost charged back up. Big Smile Have you checked it with NIMH batteries yet. If it’s up to snuff you may have a dedicated charger for them.

pennzy
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Well , my second S4 came today . This one charges to 4.15 volts . Same short CV stage . I guess my cells will last longer at least.