10s 18650 BMS Battery Build

Hi guys,

I am currently using a 6s setup (two zippy 5000mah 3s in series) and I am looking to add a bit of power and also improve the ease of charging and maintaining the packs. I have read what feels like 100s of posts about building a pack but nobody has really done a step by step newbie guide! After sort of grasping all the do’s and donts of building a reliable pack this is what I have come up with.

I want to use 18650 cells, not sure if these are actually samsung cells but look pretty good for the price. (Oh I’m a student so don’t have that much disposable income haha) http://www.aliexpress.com/item/2015-10PCS-Samsung-Original-18650-ICR18650-26F-2600mAh-Li-ion-3-7V-Rechargeable-Battery-Rechargeable-flashlight/32505862751.html

So if i order 2 lots of those for 20 cells i can make a 10s pack with slightly increased mah ratings. Also gonna need a BMS to keep all these cells balanced. Would this be good? http://r.ebay.com/lNASwp

So the question is how to connect the pieces of the puzzle. Illustrator is my friend so I’ve drawn a pretty simple diagram of the parts and how i think I’m supposed to connect everything. Does this look correct?

Thanks for the help!


Thank god. I am in the exact situation looking to do the same thing. Hopefully some good info pops up in here.

Yeah I’ve found the info really lacking for building small packs for skateboard use. There is some good info on endless sphere but those e-bike packs are huge and expensive!

Once I have this figured out I’m planning on doing a complete build post and also a step by step on building a reliable pack for e-board use. The SPACE cell looks awesome but I have a Loaded Tan Tien thats suuuuper flexy which won’t play nice with the hard case of the battery.

I’m pretty much trying to build a DIY space cell that I can configure to fit my board, I don’t want to rip off any of enertions awesome designs but it would be really handy for a diagram of the SPACE cell haha :smiley:

Oh also is anyone else on here from the UK?



Yea there are local battery shops around here that will spot weld and heat shrink battery packs for pennies on the dollar but I don’t quite understand how to choose the right BMS and wire it in. Also it looks like everyone is using the same laptop charher socket so I would like to get specs on that. For example. Bubblegum boards used the same exact charger port than enertion did on his packs.

Im pretty sure it doesn’t really matter what socket is used for charging. As long as it is rated for the amps your charging the pack. I was planning on using a standard jack like this to charge. Just connect 36v to the terminals.

1 Like

Guys check this build up for some good info


You’re going want to put some cells in parallele


Thanks for the link. Its weird I read through that thread awesome build by whitepony and it gave me lots of info but he’s not using a bms, and I sort of think thats essential based on what I’ve read.


Im also interested in this was thinking about using 18650 battery holders and soilder the connection to brackets then pop in the batteries then shrink them i was hoping this diagram works i need a simplified answer like this one to the confusing science of lithium batteries seem like no ones chiming in i kn9w someone has to know something about this post to futher promiseing results come on people lo l:) ???

1 Like

G’day Jack

I brought my cells ( http://www.batterysupports.com/lg-lgdbhe21865-high-drain-2500mah-36v-20a-lithium-ion-lion-p-345.html ) and BMS ( http://www.batterysupports.com/36v-60a-12s-12x-32v-lifepo4-battery-bms-lfp-pcm-smt-pcb-system-p-251.html ) from SuPower

I brought 30 cells arranged in 10 x 3P packs (good for a maximum of 60A continuous) and soldered the packs together in series. The BMS I brought is rated at 60A continuous but apparently can supply up to 80A peak. The total cost was around $280 delivered to Oz. The cells arrived in good condition and each had a charge of very close to 3.6V, It was fairly easy dealing with Lillian from SuPower and the delivery time wasn’t too bad given that the cells come from China.

I haven’t had my board running all that long but so far I am impressed with the battery pack and BMS. I managed to do about 18Kms the other day and still had 34V of charge (I usually charge the pack to about 41.0V). The BMS does a very good job of keeping the cells in balance, so far my checks have indicated that the cells have been kept close to the stated balance tolerance (a measured maximum difference of 0.054V across all cells).

I soldered my packs together using nickel plated strips. Ideally I wouldn’t recommend soldering the battery packs as its not really that easy and isn’t good for the batteries. Next time I build a pack I will make a capacitive discharge spot welder and weld the packs. But sometimes you just have to do what you need to do. I use an XT60 connector to charge the pack in the board mounted enclosure, however I do like the DC jacks that you have suggested and will probably use something similar when I re-design my battery enclosure.

A couple of key points I that I would pass on are to make sure you insulate every thing really well, especially the balance wires and anywhere a positive could come into contact with a negative. You do not want to short these cells its dangerous and very bad for the cells. Also try really hard to minimize the heat you put into the cells and make sure you have really strong low resistance joints between cell packs (easier said than done).

Here is how it all turned out.

I would be happy to provide any further insights into my experiences during the build of the battery pack if you need.



Also I forgot to mention that my battery back is wired exactly as per your drawing. The only difference I have is that I have a soft switch between the VESC and the battery.

I am going to follow this thread. How many cells do you think you are going to put im parallel. Also check out whitepony’s diagram on connecting cells because he did a design that folded out so it was flat, may help a bit.

PS: Love your website! The designs are quite cool IMO

@scoobiext Your pack looks amazing, I’m loving the CF case also!

I’m thinking of using 2 cells parallel and using the same wiring diagram as I posted for 10s2P Am I right in thinking that will give me just over 5000mah as the cells are 2600mah. How would the discharge current handling capability be with 10 less cells than you? I don’t really do long journeys so there isn’t much point carrying around the extra bulk and cost.

Are you pleased with the BMS? I think the one your using looks better than the link I posted. Does it get very hot during heavy use? I wanted to put it on top of the cells as I don’t have much space but would that damage the cells in the long term?

Oh also whats that black heat shrink wrapped thing in the bottom right in the middle photo? Looks like a DC jack :smiley:

@lox897 Im looking at using 20 cells total so hopefully 2 parallel will work for me. Im trying to keep the cost and space down as I don’t really travel far on one charge.

Thanks for the kind words about my website, as part of my university course I’m looking for internship opportunities next year so its a good way to make a good first impression with my work! Cheers


1 Like

Yeah, it will give you 5.2amps/5200mah. According to chaka if your going 30 mph (depends on weight, gearing, hill/no hill etc) you will be drawing 20 amps 740 watts. Your batteries should have a 20 amp constant rating and your BMS at 40 amps should be fine. If anyone can explain this in more detail or more correct that would be good.

I’d use a watt meter on your board now and see how many watts you are pulling then you can tell us that and then people can tell you what you need.

Yeah there is a lot of conflicting info here. Thats why I’m trying to get to a point where theres some solid data and easy to build pack for e-boards. Unfortunately my board is down as my ESC went into meltdown. I’m waiting for 10 VESC PCBs from china which should be here in the next few days.

I’m sure you’ve seen this thread I put up, but I’d be happy to give you any more detailed pics if you’re looking for something specific.

Here’s the thread though for anyone interested

Where can I buy these from? Do you have a link? (I’m talking about the charge plugs) Thanks!

Edit! I found some

Where did you find them?

On Amazon. Bought 10 for under 4 bucks with frees shipping

Thanks for your comments Jack.

Sorry for confusing the issue, the cells, BMS and wiring diagram in your original post would all work. Also given that the original space cells are 40A rated I would assume that 40A is enough to power a e-board and you should be right to go with your intended setup.

You are right with regards to the battery capacity. The battery capacity will be the total of the single cell capacity times the number of parallel cells. The discharge current is also the total of the single cell discharge times the number of cells in parallel (e.g. for 2P @ 20A = 40A and 3P @ 20A = 60A). I think LG make a high discharge 3000 mAh cell so if you wanted a little more range you could go down that track, although as you say you you don’t need to go too far on one charge

The range of a battery pack depends on the energy stored in the battery pack and the amount of load on the battery. The stored energy in the battery can be worked out by multiplying the battery capacity with the battery voltage. For example a 10S2P pack with a single cell capacity of 2500mAh ( a total of 5 Ah) would give you 180 Wh, To work out how long this battery back would last you need to divide the amount of available energy by the load. So for a continuous 740w load, this battery pack would last about 15 minutes. Note that it would be unusual to have a continuous load in a e-board application and real world figures would suggest that you would get more like double this run time.

The main reason I went to a 3P pack was to achieve a higher maximum discharge current to allow for the extra load when I go up hills, and so I could run two motors. Having said this I think it would be very rare that I would even get close to 60A’s. You can decrease the amount of current drawn from a battery by placing more cells in series. To explain this, P(power) =V(volts) x I(amps), so in lox897 example if you use 10S (36V) you would draw a nominal current of 20A, if you stepped up to 12S (43.6V) you would only draw about 17A (sorry if this is teaching you to suck eggs). I guess the important thing with current draw is to give yourself a bit of a buffer between your expected current draw (load) and the battery maximum continuous discharge for instances when you use more current such as going up hills and starting.

I am happy with my BMS and I haven’t noticed any signs of over heating (its hard to check when you are using the board). The BMS you have linked to actually looks very similar in design to mine, just a little smaller which can probably be attributed to the lower current rating. Basically you need to match your BMS cutoff current with the maximum continuous discharge of the batteries, which you have in your example. I would be a little reluctant to put the BMS on top of the batteries as you will get some heat from the BMS (mostly through the transistors/FETs, but also a little from the discharge resistors). If you shield the batteries enough from the heat from the FETs you will probably be okay though.

The shrink wrapped thing in my pictures is a capacitor which is wired to the battery terminals of the speed controller. I have since swapped this style of cap to the cap board used by others such as Vedder, Enertion and Chaka.

You mentioned your board is very flexible, I would be careful with this with any battery pack that is assembled using solid links. For your application you might be better of wiring each set of cells together with flexible wiring to ensure there are no torsional loads placed on the links between packs. This is partially the reason I have my battery back sitting in a CF tray.

Sorry for the long winded reply but hopefully this helps.