Rolling my own 18650 pack?

[macribs]

So due to financial strains I have faced the ugly truth and the only way to get a 18650 pack this year is to do one myself. This leads to all kinds of questions flying around in my head. I had an initial plan to use an 18650 pack from Okasira welded and wired so to work with the Adaptto BMS. But looking at various threads and doing a BMS all them tiny wires going all over makes my head hurt. I have no prior soldering experience except doing small DIY soldering around the house. I am a noobie to this kind of work.

So here we go.

1: I picture using cell holders and ghetto style spot welder for nickel strips. Do I risk damaging cells due to too much heat?

2: When ordering cells and for the matching part, how much overhead in cells, 10% likely to be enough?

3: So without using a BMS, can I monitor the cells cut off from the adaptto controller? Like set cut off a 20% charge, or is that part of the BMS and must be monitored manually without the BMS? (I guess I am asking if the low volt setting is part of the controller firmware)

4: What kind of bulk charger would be a good match? I would need one that cut power when 80-85% is reached..

5: There are so many 18650 vendors and so much fake cells and rejected cells floating around so I need tips for trusted vendors. I am not set on a manufacturer - price is important too as well as quality, mAh, discharge rate and availability. Shipping within EU would be a plus.

6: Related to previous Q. C rate how important is that for max acceleration? Will higher C rate mean that peak A is higher then battery A?

7: When I use the battery calculator (epowerbikes.ru) there seems to be huge difference in battery A. Are the variations as big between different brands and models as the calculator indicates? Same pack 20s16p varies from 64A to 320A. The variations seems so big am I to assume they are wrong? Or do I read it incorrect?

 

[alexis57]

Hi,
One question : For which use ? ... tell us your motor, controller (voltage and power of your controller/motor)

 

[Ohbse]

If you're willing to take on building the battery from scratch then you can definitely get your head around running the 4s connectors. It is not hard, much less difficult than all of the rest of the work.

Can't build a battery until you can define the requirements.

Physical dimensions it needs to fit in
Maximum current required
Motor
Total bike weight
Expected type of riding onroad/offroad, type of terrain etc
Desired range
Actual budget

Regarding the charging, you don't need to buy a bulk charger - the Adaptto does the charging using virtually any power supply and is configurable for any final charge voltage. You can set it to stop at the equivalent of any cell voltage. You would however be quite mad to not use the BMS, it gives substantially more peace of mind.

 

[macribs]

Yeah it will be a 20s16p pack, feeding an adaptto maxi to a qs 205 v3 pack will need to fit into a vector frame. 125mm x 370mm x 200mm. I will either make "half a pack" 20s8p if total costs exceeds my budget and make a duplicate whenever money allow. And this might also be adding to the complexity of wiring up the BMS.

Choosing between all the different brands and models of cells seems a little bit daunting, as there seems to be so much variations in capacity, c-rate and price.

 

[ozman]

16p?
Are you mounting your controller on the outside of the frame.

 

[Ohbse]

Personally i would go with LG-HG2 cells. 3000mah 20amp continuous discharge. Would be a very high energy pack that can deliver huge peaks.

Are you sure you need a battery that big? You didn't answer my questions about what you're actually going to use this bike for, that would really help. If you're going to be using this as your primary transportation on a daily basis for years to come then what you buy is going to be dramatically different if you're building a toy. For something that gets occasional use that can afford to be a bit fiddly I probably wouldn't recommend 18650's at all to be honest. While better in almost every respect, they're more money as a result when compared to something like HK Multistar.

Given that you've been talking about building a bike for a very long time now with no apparent progress I assume it's not solving a critical transportation requirement...

 

[macribs]

The bike will be first and foremost for fun. Hard accelerations. Big grins. But I set out to be a little green too. So it will also be the daily driver around the city, pick up groceries etc. For now street riding. Later also trials, dirt roads and back country. But for it to be a daily driver the fun factor must be there too. I have custom sider covers made to allow for extra width of the the battery box - I did order frame spacers but those spacers looked ridiculous in real life. No this bike will not solve a critical transportation issue, but nevertheless I set out to use it daily. To do my part. The lack of progress is due to health issues, been in and out of the hospital the past 6 months. Finally feeling better and will do my best to complete. But two major tasks at hand. Wheel build and battery so I have no time line for completion. I put in the hours when I feel up to it.

Either controller or charger outside frame.

Truth be told due to the delay in build process and my current "half of a man" status I was counting pennies considering to get a ready made bike just to get max riding done for what is left of the summer. I even got a really good deal on a well-build-ready-to-race Phasor but had to let it go due to cash flow issues. So as I faced the harsh reality I decided I might as well do the build properly no matter how long it takes to complete.

 

[litespeed]

I know you have a way more powerful set up (I plan to get a 205 V3 as soon as Vito or Cherry gets back to me) I have a 22.5 amp pack and have gone up to 36 miles at an average of 20 mph peaking at about 40 many times and only used 11 amps max. This is a Lyen 18Fet MXUS V1 6T combo in a 17" rim, I only peak at about 75 amps though. I think you would be surprised how far you can go on a 30 amp or 12p 25R pack. I'm all about plenty and really don't get range anxiety which is nice. Hard to ride 40 miles on a bike seat at any age, or at least it is for me.

Tom

 

[Kimhus]

Macribs: I have been lurking on this forum for quite some time, and have recently built a bike with Vector frame, Max-e and LG HE2 batteries i got from Queen battery (or something) on AliExpress. I have also bought the JP spot welder, witch works great btw.
I seems now that I have some dud cells in my battery pack, and will have to disassemble at least one of my two packs. I use 20S10P, and considering to convert the massive "bricks" into smaller units.

I see that you live in Norway, and if you live in Oslo area I could probably help you out

 

[macribs]

I know you have a way more powerful set up (I plan to get a 205 V3 as soon as Vito or Cherry gets back to me) I have a 22.5 amp pack and have gone up to 36 miles at an average of 20 mph peaking at about 40 many times and only used 11 amps max. This is a Lyen 18Fet MXUS V1 6T combo in a 17" rim, I only peak at about 75 amps though. I think you would be surprised how far you can go on a 30 amp or 12p 25R pack. I'm all about plenty and really don't get range anxiety which is nice. Hard to ride 40 miles on a bike seat at any age, or at least it is for me.

Tom

Yeah I know for mundane street riding battery is overkill. But WOT riding, full acceleration from each intersection has a massive impact to the mileage. And when doing back country riding later on I would hate to be limited by the battery. Miles and miles of gravel roads, steep climbs and rear wheel spinning in the gravel on each turr, timber lanes and trials begging for hi speed WTO riding. Will be a bummer to have to pedal back home because of an empty pack

 

[macribs]

@Kimhus good to know, I might just take you upon on that if the battery build becomes too much to handle.

 

[TheBeastie]

I remember you getting help on building a lipo pack. what ever happened with that?

 

[macribs]

I remember you getting help on building a lipo pack. what ever happened with that?

Yeah that didn't end as I hoped.

 

[macribs]

If you're willing to take on building the battery from scratch then you can definitely get your head around running the 4s connectors. It is not hard, much less difficult than all of the rest of the work.

Can't build a battery until you can define the requirements.


Regarding the charging, you don't need to buy a bulk charger - the Adaptto does the charging using virtually any power supply and is configurable for any final charge voltage. You can set it to stop at the equivalent of any cell voltage. You would however be quite mad to not use the BMS, it gives substantially more peace of mind.

Will I need to solder wires to each cell? That would require some mad ass soldering. Guess I have to figure out how to do this then, to get the most out of controller and BMS. The lazy bum in me think of all the soldering as an unbearable task weighing med down. But I guess if I bite the bullet and don't rush task will be completed some day. Remember I spoke with a dude that done a 5K km hike, he said the only way to complete was to put one foot in front of the other and accept it would be hell

 

[Kimhus]

@Kimhus good to know, I might just take you upon on that if the battery build becomes too much to handle.

Just pm me if it comes to that

And you will not have to solder balance wire to every cell, but only to every "pack" of parallell cells

 

[Ohbse]

Will I need to solder wires to each cell? That would require some mad ass soldering. Guess I have to figure out how to do this then, to get the most out of controller and BMS. The lazy bum in me think of all the soldering as an unbearable task weighing med down.

As Kimhus mentioned, no - only one little wire to each set of parallel cells, so 20 total. Adding the balance connectors to my pack took me perhaps 10 minutes, vs probably 5 hours of spot welding. You have potentially got 60% more cells than I did, but will require the same amount of balance wires - it really is probably the smallest task required. 320 cells will require a bare minimum of 4000 spot welds FYI

Are you really sure you're in a position to take on building this pack? If the balance connectors are psyching you out then you're probably going to have a bad time with the actual hard work part! 20s16p is a pretty large pack, 16kg. It's probably too big to build as two bricks, you'll need to split it into 4 probably at minimum.