Best multiple cell charger/discharger?


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Alec_J

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Mar 16, 2017
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89
I apologize if this has been addressed here before. If so I have been unable to find the thread.

I am looking at the different 4 slot charger/discharges, and I can't decide which one to purchase. I have been reading reviews on the lygte-info.dk website and I just can't decide which to get. The Xtar VP4 Dragon looks to be one of the tops but I don't want to spend $100 on it at this point. I am still trying to decide if I will continue pursuing this build. I am having a bit of a difficult time sourcing batteries thus far. I hate to buy laptop batteries off fleabay, but may not have another choice if I continue. I'm in the Kansas City area if anyone has recommendations?

So in the sub $50 category which ones do you guys recommend? I see the Opus frequently is it a good charger/discharged? Are there others to consider? I have an iMax b6 AC v2 but 1 cell at a time is beyond slow. I have a few tp4056's but not a power supply yet. I was considering getting a computer power supply and converting it to supply a few tp4056's, but that doesn't help with discharge cycles.

I'm open to any and all suggestions.

Thanks!
Alec
 

Korishan

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Jan 7, 2017
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6,837
I think most of the guys here use the Opus. I personally don't have one of those or the other fancier chargers. I had ordered a Nitecore D4, but it never came and I got my money back for it. However, just noticed, I wanted the I4, anyways. I guess I=Intelligent, and D=Dummy :p

For standard testing, initial charging, most use the iMax or clones or the TP4056's. A few of us have, or are, building a TP4056 based charger that will also do a load test as well.

For starters, I'd recommend the Opus, as it's very well documented on this forum of it's pros/cons. Second up would be the iMax, and third Nitecore
 

APD

Member
Joined
Jan 29, 2017
Messages
89
Alec_J said:
I apologize if this has been addressed here before. If so I have been unable to find the thread.

I am looking at the different 4 slot charger/discharges, and I can't decide which one to purchase. I have been reading reviews on the lygte-info.dk website and I just can't decide which to get. The Xtar VP4 Dragon looks to be one of the tops but I don't want to spend $100 on it at this point. I am still trying to decide if I will continue pursuing this build. I am having a bit of a difficult time sourcing batteries thus far. I hate to buy laptop batteries off fleabay, but may not have another choice if I continue. I'm in the Kansas City area if anyone has recommendations?

So in the sub $50 category which ones do you guys recommend? I see the Opus frequently is it a good charger/discharged? Are there others to consider? I have an iMax b6 AC v2 but 1 cell at a time is beyond slow. I have a few tp4056's but not a power supply yet. I was considering getting a computer power supply and converting it to supply a few tp4056's, but that doesn't help with discharge cycles.

I'm open to any and all suggestions.

Thanks!
Alec
I have an Imax B6, a NiteCore D4, and 20 TP4056 for charging. Imax is good for charging as you can set it for 5 amps and load up a bunch of cells in parallel. Not good for discharging.
Opus does charge and discharge automatically, wish I had one, but I can build 8-10 of these for the price of an opus:
For discharging I use these ZB2L3 's with an 1157 auto bulb and single cell holder. Total cost is about $4 each if you order from china.

image_yutysw.jpg
 

Wattsup

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Joined
Feb 19, 2017
Messages
512
I have a nitecore i4 and a universalintelligent charger same as nokoser.
If I was to buy another would be the Opus, that would be my first choice
 

ozz93666

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Feb 22, 2017
Messages
341
Totally depends on what numbers of cells you are expecting to process ... if large numbers you need to build your own custom setup ...

I've had my opus for a few weeks now .... wish I had never bought it ... not suitable in my opinion.
 

Alec_J

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Mar 16, 2017
Messages
89
ozz93666 said:
Totally depends on what numbers of cells you are expecting to process ... if large numbers you need to build your own custom setup ...

I've had my Opus for a few weeks now .... wish I had never bought it ... not suitable in my opinion.


Oz would you mind expanding on why you feel it is not suitable?
 

daromer

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Oct 8, 2016
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image_iwsknn.jpg


Running opus. Got 10 of em and processed 3000 cells and they do what i want. They give me an approx number of the health of the cells.
 

Alec_J

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Mar 16, 2017
Messages
89
daromer said:
image_iwsknn.jpg


Running Opus. Got 10 of em and processed 3000 cells and they do what i want. They give me an approx number of the health of the cells.


Daromer I watched your build of that charging station. Good video! Thanks for posting it! I think I'm over thinking this.

Can you do a discharge function on the Opus and nothing else? So for example can I put 2 cells on to discharge an come back in a few hours and take them off discharged, or does it automatically go into charge mode and begin charging at the end of discharge mode?
 

tchipperfield

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Mar 15, 2017
Messages
11
The Opus will do almost anything you want...

Test capacity will charge to full capacity, then discharge, then charge back up again. You simply pop the cells in, then come back to fully charged cells with the display reading the capacity of each.

Obviously you can also use it to just charge or discharge the cells too.
 

Alec_J

Member
Joined
Mar 16, 2017
Messages
89
tchipperfield said:
The Opus will do almost anything you want...

Test capacity will charge to full capacity, then discharge, then charge back up again. You simply pop the cells in, then come back to fully charged cells with the display reading the capacity of each.

Obviously you can also use it to just charge or discharge the cells too.


Oh that's great! That's even better. Thanks all! I think I will try the Opus.
 

Rick Rose

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Mar 25, 2017
Messages
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The OPUS BT-C3100 v2.2 is the only 4 cell charger/discharge I've used that lets me measure the internal resistance of the battery. This is one measurement that lets you know the true lifespan of the cell. So not all 2500 mAh batteries are the same. If you have one that measures at 75 ohms and another that measures at 125 ohms, the 75 is the one that will last longer.

When you are putting used batteries together the internal resistance is a better way to match them. Try not to mix a 75 ohm and a 300 ohm. The higher rating will fail sooner and short out your pack. Of course if you're using new cells, this isn't important but as they age it will become more important.

I us the 18650 batteries interchangeably (think flashlight). I don't solder them into a brick and since I'm taking them all out after every discharge I don't need a BMS as they are all balanced when they are charged individually. Granted, I'm only using 50 at a time. This would never work with a Powerwall but for my ebike it's pretty sweet.
 

daromer

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Oct 8, 2016
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Note that measuring IR with Opus is not that accurate. You can get 75 one try and 150 another... Try just to press the battery slightly harder when doing it and you will see different values every time! I did a video and uploaded on FB some months back when i showed this. Its due to the contacts in the Opus.

Also note that you really dont know for how longer a 75mOhm will last compared to one at 300mOhm. Even though 300 is a bit high. Note that the 300 will be less used/pushed to its limits than a 75 will due to the actual resistance. It kind of balances it self out.

With that said if you got cells in an amount that you can divide alot then do it. But also note that if you wanna divide based on those numbers Opus might not be the best charger due to its inaccuracy :)

For high current purpose applications like EV stuff this is alot more important than a power wall that you have max current very very low :) Never the less. My limits of ir is set to 300 max and so far no problem due to this. As long as all packs have an avg ir of roughly the same and also same goes for capacity it will server you pretty well. On the other hand i have only been running that system for a year now so my numbers are still not anything that can be used as a base. I dont think anyone actually have enough numbers for the DIY regarding that yet.
 

ozz93666

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Feb 22, 2017
Messages
341
Alec_J said:
ozz93666 said:
Totally depends on what numbers of cells you are expecting to process ... if large numbers you need to build your own custom setup ...

I've had my http://amzn.to/2kH0vxfOpus for a few weeks now .... wish I had never bought it ... not suitable in my opinion.


Oz would you mind expanding on why you feel it is not suitable?

I finally decided on what I think the best way to process cells is ... I'm building a set-up which will process 20 at a time ..

21 individual cell holders (spring) I've cut the side wings off these to make loading easier .... price 5 english pounds
20 chargers tp2046...................................................................................................................5.50
20 step down 3A converters ..........................................................................................................11.20
10 three way switches ...................................................................................................................3.10
1 voltmeter ................................................................................................................................... 1.00
1 celldis charger /capacity measurer (three red buttons and display) ...............................................3.00

Total cost 24 english pounds... less than the cost of one opus

The step down converters feed the tp2046....thencan be run on a supply form 7 -28V can be wired directly to a solar panel, nothing in between .

So ... 20 cells are loaded ...red light indicates charging ...after a few hours green lights show all charged . Ten switches (one for two cell holders) are then switched from up position to down position .... this disconnects +ve end of cell holder(all -ve cell holder terminals are connected together)from charger and puts all cell holders connectedin parallel ... this is to even out any variation in voltage to which the cells have been charged to...onevoltmeter indicates voltage..
After five hours of thisthey should all be at the same voltage .... then the switches are put to center position which isolates each cell .... leave overnight ....

So in the morning we have 20 cells fully charged we have to check voltage ... any that are lower than 10mv than the rest show excessive self discharge , may want to be discarded ... check internal resistance .... and capacity ...

all three parameterscan be checked in 15 secs for each cell ....no need to fully discharge cells for this..

Discharger is set to discharge at 2A .... cell holder is different from the 20 charging ones ...not coil spring on -ve but the other type , this gives a firm contact necessary to measure internal resistance and discharge at 2A.

put a cell in .... display is open circuit voltage ... then press button to start 2 A discharge .... from the new voltage figure we can find internal resistance ... watch display for 15 secs ... by the voltage under 2A load experience has shown me a fairindication of capacity can be found ... with practice you will soon spot any cells which are under capacity ....

We don't need an accurate capacity measurement to the nearest mA .... there's wide disagreement on what is an acceptable cell ... even 0.5Ahr capacity can be used in pacs ... some only use above 1,5 Ahr ... depends if you have access to plenty of cells or not ....

The problems with opus I've found ...loading the cells is not as easy as spring holders ...stiff and jerky ...inaccurate int resistance measurement because of this insecureelectrical contact, the manual admits there maybe a 20% error due to "contact resistance"..
Trickle charging near the end of charging , I don't need this lengthy process ..... and to get capacity the cells have to be discharged completely , unnecessary , wasteful and time consuming
And lastly the frigin mainsplug !!! Does not fit securely in any outlet...
 

daromer

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Oct 8, 2016
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5,662
Agree on the ir but the capacity is still major thing for most of us. Thats what we build the pack around.

But everyone of us have different needs. :)
 
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