Konion 5s4p pack two in series 37V, 6Ah

[jerrysimon]

Hi all,

Ok you battery experts

I am looking for another lightweight pack and have managed to get hold of these. See first picture below.

My current DIY pack that I use for work is made up 6s1p packs of A123 LiFepo4 cynical cells which I connect in series to give me a 12s1p (39.6, 2.3Ah) pack weighing only 1kg. My setup is low power I average about 5A and rarely pull more than 10A. This pack does my 5.25 mile commute (I only use 1.4Ah) and then I recharge before returning home. I have used this pack for 3 years, 4500 miles and 850+ charge cycles.

This new pack would be for longer runs and keep the weight (and physical size) down (1.8kg) which I want as its used on my portable Brompton bike and goes in the back pocket of my Brompton C bag on the front.

Basically they come as 5s2p 18.5v 3Ah packs. I have joined two together for a 10s2p 37v, 3Ah pack to test them and they work great with my setup with little voltage drop under load. Now for 6Ah I could just get four and use parallel/series cables to put them together in a total 10s4p configuration. However I wondered if it is better to maybe join them like this (see second pic below) so I can then have two 5s4p packs that I connect in series. I know many say you don't need to balance them but I would like initially to check them out to see how they work. In this two 5s4p config I would only then need one balance and power lead to balance them with my RC charger like I do now with the A123 6s1p pack every few months.



See the second picture, not a great image but you get the idea. Basically just extending the parallel connection across both 5s2p packs top and bottom. As I said I would then only need one balance and power lead rather than two if they were split down into their supplied 5s2p configs.

Regards

Jerry

 

[jerrysimon]

I commuted back without charging this Konion 10s2p so took a total of 2.0Ah out of it. I have to admit it does not have the grunt of the A123s though still good as the 2.4Ah A123s would be almost empty and its not good to take them to zero every ride. Maybe this is because its only 2p and in a 4p config it would be better. I can see why maybe some use a 12s string. Doing that would make the pack too big for me though.

Testing the cell voltage afterwards they were well balanced and down from 4.1v at charge to 3.6v after taking 2.0Ah out of them when I got home. I would like to take them down to zero to see if they do in fact have 3.0Ah in them.

Hopefully doing this just once will be ok, my LVC is set at 31.5v so 3.15v per cell ?

Sorry if this has all been covered before but moving from one technology to another requires a bit of a learning curve.

Regards

Jerry

 

[999zip999]

Wish I could down load my pic's. But the konion cell have little past 3.3v and 3.2v is very flat at this point the weakest cell will start do fall off fast and then may chain react. Oh are these new or old tool pack stock ?

 

[docnjoj]

Please don't murder those Konions by bringing them to 0 volts under load. They might recover if the load is just 100ma but any large load like 1-2 amps will kill them for sure. I have 6 Fatpacks that I run as 36 volts 6p which is actually 12p since each Fatpack has 10S 2P and once accidently left them on to the controller at idle. They went to 0 volts but all recovered after recharge. I doubt they would recover if 0 volts under heavy load were to be achieved.
otherdoc

 

[999zip999]

I was always running 63v. or 74v. at 30amps so I was taking a good load. If killed slowly that's different.

 

[jerrysimon]

Thanks for the responses guys.

These are brand new cells. So the question I really want answered is, is it worth physically soldering the packs together as shown or just making up parallel and series leads to connect the four 5s2p packs up to give me a 10s4p pack.

Reading the FAQ sticky on this forum it seems one advantage is to avoid the rats nest of wires but it also appears that paralleling at cell level has advantages over and above that.

PS When I said "I would like to take them down to zero to see if they do in fact have 3.0Ah in them" I did not mean taking them down to 0v but rather to take them down capacity wise until they hit 31.6V (i.e. 3.1v/cell) upon which the LVC of my controller would kick in.

Regards

Jerry

 

[jerrysimon]

So anyone got advice on paralleling at the cell level as shown or should I just use leads to connect the 4*5s2p packs ?

Jerry

 

[jerrysimon]

Bump

Jerry

 

[999zip999]

I alway's hooked up my cells like on the right side of your pic with the pos. end as a long runnimg snake and never connected inbetween the cell in sereies when making a parrelle. Or make a parelle first then make a series connection. I way I did it. But my cells are used and over a 1-1/2 yr's old and have been dieing string by string just sitting. I quess I start looking at these low string and try to find the one dead cell in my parelle string of 10p3s 12v blocks and series up for 63v to 74v. if I can find some good ones. Out of 48 used drill packs or 480 cells If they drop I throw them out. So what do I know. Look at Drbass konion bulit in the used section for pic's. I just follow his build.
I like your minny packs.
But have move on to A123-20ah pouches but are limited with the big size and weight. For 84v.

 

[jerrysimon]

Thanks for answering 999zip999

So are you saying that I don't need to link the middle two rows horizontally just connect the two packs across their 5 parallel sets ?

I just can't seem to get my head round this

PS Ah I think I have it!

NOT like this which is ALL wrong connecting both parallel and series :?



But LIKE this ?



NOPE thats still wrong

Regards

Jerry

 

[999zip999]

I don't see why you would have the bar on bottom left 1 frist roll. And the connection on rolls 3 to4 bar the connection does a snake on bottom and a snake the top. Start at the neg. to parelle last cell on pos. end bar for series then parelle to end then on last cell neg. Parelle to end then series from end cell end. Check the used for sale thread Drbass with pic's Konion drill packs. Bottom of his frist post.

 

[999zip999]

Oh its makita pack's in the thread and not konion.

 

[999zip999]

Each side gets 2 U-shapes and a strait.

 

[jerrysimon]

Each side gets 2 U-shapes and a strait.

Thanks. Yes that is correct but having thought about it I now realise that you can put additional horizontals if you want to or not and it helps hold the pack together. You are simply connecting the +ve and-ve of each parallel strip. I guess this also helps if you are drawing a lot of current which of course I am not.

Regards

Jerry

 

[Spicerack]

Ok. Couple of things.

Firstly, don't take these cells down past 3.3-3.5V if possible and charge up to 4.15- you'll get much better life out of them.

You can parallell them any way you want. I hard parallelled mine as 3S8P blocks using zinc strips. Look in the modified photo below- put two packs side by side and connect A to A, B to B etc on the two packs. You can use reasonably decent size wire- say 14-16g but doesn't matter that much. You also need to attach your balance leads at these points. Easy enough to find 6 pin jst plugs with leads on ebay.

That's what I'd do anyway.

 

[jerrysimon]

Thanks very much andynogo. I think I finally got it when I woke up this morning and took another look lol

Re charge and discharge that is pretty much what I am doing.

Regards

Jerry

 

[999zip999]

Oh yes I was just following DrBass build. The 2p5s makita packs have all 4 ends connected with a square 2 pos. and 2 neg. I was just thinking it was just a snake. What's the pro's and con's. Thanks

 

[jerrysimon]

The only pros I can think of is it helps hold the packs together and distributes the current draw across more of the connecting bars ?

Jerry

 

[jerrysimon]

Ok just ordered another two of these packs. These appear to be genuine cells and the seller is very helpful replying to emails.

I will then build a 10s4p 36v 6Ah for around £100. This is good value (£2.5/$4 per cell delivered) given that you know all cells are new and don't have to to split Makita packs up test cells and solder up.

I will report back.

Regards

Jerry

 

[ecycler]

2 Years later... how did it go?

 

[jerrysimon]

Just seen this thread again. I am over three years on these commuting on my Brompton 10 miles round trip to work. Its pretty flat no hills and driving a low power Tongxin motor. They are still running and balanced perfectly. I dont think I have even balanced these since I first built the 2p and 4p packs!

I am looking at some later Samsung/Panny cells 2.5-30Ah high drain cells though as per my other thread I am not sure if these newer cells would survie as well as the Konions which have no BMS ?

PS Given the Konions have performed so well maybe I should just get a later version 2.2Ah

https://www.akkuteile.de/sony-konion-us18650vtc4-2100mah-3-6v-ungeschuetzt/a-100650/

Jerry

 

[cwah]

You can even take the vtc5:
http://www.nkon.nl/sony-us18650vtc5-flat-top.html

How many wh do you need and what is your discharge rate?

 

[999zip999]

The konions are of high quality. There are a lot of high quality cells now. High quality cells keep balance if used with your demands. 4 p you use your responsibly, I monitor my pack and monitor. Never leave anything pulled in.

 

[cwah]

jerry, just get these ones:
http://eu.nkon.nl/rechargeable/18650-size/panasonic-ncr18650b-made-in-japan.html

I realised that you are using 5-10A.... which is about 1C max so you can use high capacity cells.

At 4p you should have a 3.4 * 4 = 13.6ah. (12AH expected). So about double what you have...

For max lifecycle, just charge them to 4V/cell (that's what I do)... which would give you about 2/3% capacity so about 8AH.... :wink:

And as a bonus with your adjustable charger, you can charge higher voltage for the unexpected time where you need to travel further...

 

[jerrysimon]

Thanks cwah and 999zip999. Not in a hurry to get them yet so will have a think about it. As you say for the same 4p pack I can effectively double the capacity of my existing lightweight packs

I doubt I draw more than 6-8Ah max mostly its around 3Ah so could probably get away with cheaper low rated cells. The real issue is I don't want to have start messing around with a BMS.

I never charge them more than 4.1 volts each cell as I read that was a good way to extend their life and keeps them balanced as you say. I have a little charger that I use to charge the single cells for my lights and that charges them to 4.25 which is way too much and they get very hot.

So those ones you recommend did you use a BMS with them ?

Not sure if to get them with tabs or see if I can get them made up into 5s4p packs for me. Alternatively that 12V spot welder being sold here looks the business

Regards

Jerry