14s10p non welding DIY battery

[lazy_mosquito]

Hi,

I am planning to make a battery for my bullitt. The weight is not that important because it is a cargobike and the battery will be placed low in the bike.
I have a bafang bbshd and my former battery died on me after 6 years of service. This was a 52V 14s8p of 21 AH. I would like to improve my range, that's why i would choose for a 14s10p. i would use quality batteries and I am in doubt between the Samsung 18650 35E, the Sanyo NCR18650GA 3350mAh or the Samsung INR21700-50E (14s8p)
My BBSHD is set at 25A in the controller.

I would make my own batterycase with a no-weld system. i will share the plans when they are finished.
My main question is, is it better to make 2 14s5p battery packs and put them in parallel instead of one monolithic pack, this for easier charging and heat production because of the size of the battery?
And any suggestions for the choice of batteries ? I drive mainly on flat road and with a maximum of 40km/h

 

[john61ct]

Not GA.

50E will of course yield higher capacity not only per cell count but also overall energy density.

35E, Sony VC7, LG M36/MJ1 all excellent, see testing results thread here

 

[john61ct]

I like the ability to use lower cost hobby gear 8S and below, so would split the pack 7S/7S rather than in parallel.

 

[john61ct]

Are you planning on using an existing no-weld system, or designing your own from scratch?

 

[lazy_mosquito]

Are you planning on using an existing no-weld system, or designing your own from scratch?

I am planning to make my own system, looking around here, to learn from the mistakes and the success stories from others. But for bigger packs i didn't find a good enough solution yet, that's why i am making my own design.

 

[lazy_mosquito]

Not GA.

50E will of course yield higher capacity not only per cell count but also overall energy density.

35E, Sony VC7, LG M36/MJ1 all excellent, see testing results thread here

i can't find the thread you are pointing to. Do you have a link?

 

[clockwork247]

Hi,

I am planning to make a battery for my bullitt. The weight is not that important because it is a cargobike and the battery will be placed low in the bike.
I have a bafang bbshd and my former battery died on me after 6 years of service. This was a 52V 14s8p of 21 AH. I would like to improve my range, that's why i would choose for a 14s10p. i would use quality batteries and I am in doubt between the Samsung 18650 35E, the Sanyo NCR18650GA 3350mAh or the Samsung INR21700-50E (14s8p)
My BBSHD is set at 25A in the controller.

I would make my own batterycase with a no-weld system. i will share the plans when they are finished.
My main question is, is it better to make 2 14s5p battery packs and put them in parallel instead of one monolithic pack, this for easier charging and heat production because of the size of the battery?
And any suggestions for the choice of batteries ? I drive mainly on flat road and with a maximum of 40km/h

if your previous battery last you 6 years, I would go get it again, and if you want to increase your range, buy 2X of it.

From personal experience, building DIY battery no-weld system is costly, and in the long run too much work to take care of.

May I ask what battery did you get from your old system?

I suggest if you build yours, do it in 1 pack, that way you only need 1 BMS instead of 2.

Heat isn't an issue if it's built properly. and especially with larger parallel packs like you are trying to do, you won't push much ampage over each cell, so heat is even less of an issue.

 

[john61ct]

Not GA.

50E will of course yield higher capacity not only per cell count but also overall energy density.

35E, Sony VC7, LG M36/MJ1 all excellent, see testing results thread here

i can't find the thread you are pointing to. Do you have a link?

eponysterical handle

https://bfy.tw/P3m8

 

[lazy_mosquito]

May I ask what battery did you get from your old system?

It was a battery from em3ev. it was a 14s8p battery 52V. They don't offer that type anymore. I am very happy with their service. Only it becomes so expensive to import them to Europe. If i want a similar battery (14s9p) it will cost me roughly 1000 euro with taxes. If i make it myself it will cost me aproximately half of it, and i can later just replace the batteries which cost me around 350 euros

 

[lazy_mosquito]

Not GA.

50E will of course yield higher capacity not only per cell count but also overall energy density.

35E, Sony VC7, LG M36/MJ1 all excellent, see testing results thread here

i can't find the thread you are pointing to. Do you have a link?

eponysterical handle

https://bfy.tw/P3m8

Thanks for this very instructive link, would have never thought about this one myself.
every day i learn something new

 

[lazy_mosquito]

I suggest if you build yours, do it in 1 pack, that way you only need 1 BMS instead of 2.

Heat isn't an issue if it's built properly. and especially with larger parallel packs like you are trying to do, you won't push much ampage over each cell, so heat is even less of an issue.

I am in doubt between the samsung 29E, 50E or lg m36.
They all have a great recharge cycle, if not charged and discharged too hard.

Because I would take a big pack 14s9p or 14s10p charging and discharging shouldn't be an issue.
Normally I have the habit of loading my battery pack for 90 percent when I come home and drive it until 20% is left. In general, I reload my batterie every week.
Sometimes my bike stays there for 3 or 4 days charged at 90 %. Is this really bad for the battery, or is one of the former mentioned batteries I would like to use less prone to damage from sitting there at 90 %? i couldn't realy find an answer on that in the thread about cycle ageing https://endless-sphere.com/forums/viewtopic.php?f=14&t=103092&start=425


Is there an advantage in using the 50E? I would use a 14s8p in that case. I would have fewer batteries in parallel but the 50E can have a little more charge and discharge. I would expect that should compensate?


About the BMS, 1 BMS seems indeed to be the best option. I would go for a smart bms with a progammable cutoff voltage for charging and discharging. Any ideas or suggestions. And yes i found already the 61 pages bluetooth bms forum, but i hope somebody could give me start in the right direction.

 

[lazy_mosquito]

i made some first 3d sketches for the battery pack
All this plates are lasercut from polycarbonate and connected with long screws to keep everything together

 

[Vbruun]

I have used 2 BMS's from this vendor

https://www.lithiumbatterypcb.com/smart-bms-software-download/

They work well and are common port types - more safer.

 

[Vbruun]

Your pack looks nice, but why not just spot-weld it?

It is not hard and you can probably rent a Kweld from someone in here for 100 euros - much cheaper than all the stuff you need to make the no-weld pack.

 

[lazy_mosquito]

i have a lasercutter so the plastic cutting is almost for free. the only cost is cutting the copper

 

[john61ct]

Sitting for a few hours or even a day or two at 90% SoC will not "damage" anything, in the immediate sense, just shorten lifespan off the back end

certainly better than closer to 99% full

but 80% would be better

none of those as good as 60% or lower.

The actual number of cycles lost is impossible to quantify, so many other inter-related factors.

If you abused your pack otherwise so capacity was down to 80% after 50 cycles, then that one factor might not be worth worrying about.

If you were truly coddling to try to get to 500 cycles, then it would make a difference.

 

[lazy_mosquito]

thanks for thre reply,

I suppose I will take it as a standard to load it till 80% SOC except when i need a longer drive. i can afford to load it less, it's big enough, but when i really need the distance i load it for 100%.

I would go for the LG M36, because of the good reviews they got in the tests performed here on this site
145 batteries will set me back 410 Euro's
the Samsung 35E will cost me 398 euro's for 145 pieces, but i have a light preference for the LG's. (just gut feeling )

Should 5 extra batteries be enough, or are there often more dud's in a lot off batteries?

For the bms i would take the SKU: SP15S001V1-14s-60A or the SP15S008C-14SL-100A both are smart BMS from www.lithiumbatterypcb.com. (I have a light preference for the 60 Amp version because of the dimensions, it would fit on the side of the pack) They both have Bluetooth and a pc connection. The only problem i have is that i can't find any information if they are able to balance at 80% charge. somebody knows or has an alternative that can balance at a programmable value?

I still have a charger from em3ev which can switch between 50%, 90% and 100% and charges at 5 amps. I am happy with it but it has no 80% switch.
Two alternatives i found are the Satiator at a whopping 300$ and the LUNA CHARGER 52V ADVANCED 300W EBIKE CHARGER for a 100$. somebody knows a better/cheaper alternative that can load at 80% and even can go higher than 5amps? (and preferably sells in Europe)

 

[Vbruun]

thanks for thre reply,

I suppose I will take it as a standard to load it till 80% SOC except when i need a longer drive. i can afford to load it less, it's big enough, but when i really need the distance i load it for 100%.

I would go for the LG M36, because of the good reviews they got in the tests performed here on this site
145 batteries will set me back 410 Euro's
the Samsung 35E will cost me 398 euro's for 145 pieces, but i have a light preference for the LG's. (just gut feeling )

Should 5 extra batteries be enough, or are there often more dud's in a lot off batteries?

For the bms i would take the SKU: SP15S001V1-14s-60A or the SP15S008C-14SL-100A both are smart BMS from www.lithiumbatterypcb.com. (I have a light preference for the 60 Amp version because of the dimensions, it would fit on the side of the pack) They both have Bluetooth and a pc connection. The only problem i have is that i can't find any information if they are able to balance at 80% charge. somebody knows or has an alternative that can balance at a programmable value?

I still have a charger from em3ev which can switch between 50%, 90% and 100% and charges at 5 amps. I am happy with it but it has no 80% switch.
Two alternatives i found are the Satiator at a whopping 300$ and the LUNA CHARGER 52V ADVANCED 300W EBIKE CHARGER for a 100$. somebody knows a better/cheaper alternative that can load at 80% and even can go higher than 5amps? (and preferably sells in Europe)

I think I can answer that

I agree with LG m36, there is a thread in here somewhere about cycle testing and those batteries do far more 2200 mah cycles (thats how the experiment was set up) than any other high capacity battery.
I can't remember the name but use the search funtion and you will find it.

I have bought around 250 cells from nkon and I have never had a dead cell yet. I have started to only buy 1 extra cell.

I use the 60 amp BMS in question and it does balance from 3,5v and up depending on how you adjust the settings. Don't get the PC dongle. Everything can be adjusted from the app and it has worked flawlessly for me on two different batteries now.
As far as SOC is concerned, this can also be adjusted in the app. The High voltage cutoff is adjustable so you don't need an adjustable charger. Just use the one you have.

As far as cycles go, I am pretty convinced you can get a lot more than 500 cycles out of this battery, provided your pack design doesn't corrode over time.
It seems that when babied a bit the cells you have will really do a lot of cycles and your use case seems to be babying the cells a lot.

 

[Balmorhea]

somebody knows a better/cheaper alternative that can load at 80% and even can go higher than 5amps? (and preferably sells in Europe)

MeanWell HLG-480H-54A would do it at 9A or more. It costs more than Luna’s charger (which is a crappy unit), but less than Cycle Satiator. It’s just a power supply, so it doesn’t offer any of Cycle Satiator’s amenities, but it’s adjustable for voltage and constant current.

MeanWell CC/CV power supplies are available in a wide range of power ratings, so you can use and pay for as much or as little as you want.

 

[lazy_mosquito]

I agree with LG m36, there is a thread in here somewhere about cycle testing and those batteries do far more 2200 mah cycles (thats how the experiment was set up) than any other high capacity battery.
I can't remember the name but use the search funtion and you will find it.

I have bought around 250 cells from nkon and I have never had a dead cell yet. I have started to only buy 1 extra cell.

I use the 60 amp BMS in question and it does balance from 3,5v and up depending on how you adjust the settings. Don't get the PC dongle. Everything can be adjusted from the app and it has worked flawlessly for me on two different batteries now.
As far as SOC is concerned, this can also be adjusted in the app. The High voltage cutoff is adjustable so you don't need an adjustable charger. Just use the one you have.

As far as cycles go, I am pretty convinced you can get a lot more than 500 cycles out of this battery, provided your pack design doesn't corrode over time.
It seems that when babied a bit the cells you have will really do a lot of cycles and your use case seems to be babying the cells a lot.

I found the thread already, somebody pointed it out to me https://endless-sphere.com/forums/viewtopic.php?f=14&t=103092&start=425

glad to hear nkon is trustworthy

Thanks for the extra info for the BMS, good to hear it has a programmable balance value and an adjustable High voltage cutoff.

MeanWell HLG-480H-54A would do it at 9A or more. It costs more than Luna’s charger (which is a crappy unit), but less than Cycle Satiator. It’s just a power supply, so it doesn’t offer any of Cycle Satiator’s amenities, but it’s adjustable for voltage and constant current.

Gone keep this one in mind, but will first try if my charger does well in combination with the BMS. If i can arrange it via the High Voltage cutoff, this would be a cheaper solution, although the 9A would be welcome.

 

[john61ct]

Nothing magical about 80% vs 90%

Best to use per-cell voltages, most have very screwy ideas about translating to SoC%.

4.05V is very close to 100% Full anyway for most chemistries,

4.10V (or even 4.15V) will give just a bit more range, especially if you hold Absorb / CV stage until you stop when amps are trailing down to 0.05C

no point ever going higher in normal cycling, just for benchmark tests

 

[lazy_mosquito]

Making the final drawings for the battery.

I have one question about the casing of the battery. There is always a risk of fire with li-ion batteries, this risk is already much less with a good BMS, but still, there will always be a risk.

Originally I was thinking of making a polycarbonate casing, but because of sturdiness and fire resistance, I am now considering using 4mm aluminum for the outer shell. Would this be enough to protect against fire, or should a steel or inox casing of 1.2 mm be better? I would prefer the aluminium case because of weight.

 

[john61ct]

Overkill.

The fire risk is 90% while charging,

presumably off the bike,

unless the owner is clueless about monitoring SoH as the pack wears.

In fact, what difference do you think the case material really makes? Melting metal is much greater hazard than a bit more plastic IMO.

Finally in a violent incident, a metal case is more likely to help short things out, just as dangerous if not more than the fire risk.

A strong sheet material that is dielectric and fire resistant would be better.

But still overthinking IMO.

All that said, polished aluminum would look dead sexy.

But then in an area with many thieves, that is a downside, not a plus.

 

[lazy_mosquito]

I agree with most of it, problem is i am loading the battery on my bike.

The reason i was asking, i was not sure if the casing would melt, in case of melting i agree completely this would create a bigger hazard. There exist a kind of paint that foams up in case of overheating and creates thus a fireproof barriere for a certain while, which would probably be enough for the time of the fire. But i agree i am probably overthinking the design because of all the horrorstories i read about li-ion batteries going up in flames.

I am also back on the drawing table because i anticipate a problem in my design. It will be very easy to put all the batteries in the plate at the bottom, but it will be almost impossible to get all the batteries aligned perfectly to put the plate on top over them. When one of the 140 batteries is misaligned the plate will not slide over the batteries. and i go for a close fit.
So i was thinking of 3d printing an extra layer with conical wholes which fits under the top plate which guides the batteries to their respectively whole.

About visibillity, the battery is concealed in my aluminium trunk of the bullit, so theft is not a direct problem, but the battery pack being sexy is also not an iminent pro