building my first battery

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la8rat

1 W
Joined
Mar 12, 2019
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59
hi
ive done some reading and watched some youtube vids. ive been planning my perfect battery .
its to be used on a mid drive motor (tsdz2) so does not need huge amps but does need lots of kwh.

ive gone for a 14s5p 52v style using samsung 18650 35e cells

this will fit nicely in the frame bag i have
2v2farp.gif


apologise for the roughness of the plan but hopefully the idea will be apparent.

mainly looking for any thoughs on improvments or things to change or be aware of.

mods.. if there is already a topic for this kind of thing please could you put this in its correct place.

thanks all
 
Make sure that you have enough strips going from each parallel group being serialized. Lots of first time builders do not have enough interconnects between the series connections.

Also, watch this video. He details a good amount of areas that you can mess up on. I think it's a good video for instilling confidence for a first-timer.

[youtube]vFqJBzyRHa0[/youtube]
 
cheers for the reply, i want to try and use single trapezoid shapes cut out of wide nickle strip for the parallel 5 packs if i can find wide enough nickle strip and then do the series connections with multiple braided copper link wires.you can see that some parallels dont sit side by side with the next one. would that be a good way of doing it for maximum current flow and least pack resistance?

great vid cheers for putting that up cal3thousand :bigthumb:
 
Yes, the wide strips can carry more current. How are you planning to connect the cells? Spot welder?
 
dont use 35E's, they dont last long on ebikes.
dont go beyond 29E and just use more to compensate for more capacity.
 
Cal3thousand yes spot welding. Im in the process of makeing one. Updates will be posted here.

Flippy. Why dont they last long on ebikes? What sort of bikes have you experience of trying them on? What is it about ebikes in particular that make these a bad cell choice?

Im looking for maximum amp hours for minimum weight. "Just adding more" is missing the point. The max draw from the pack will be 15amps peak. So 3 amps per cell. On a cell rated at 8 amps.

Thanks for the replys.
 
My other choice was the lg mj1 as favoured by luna batteries. But it gets bad reviews. The e35 did ok in this test but has low max charge current.
Sanyo was best but a fair bit more expensive.

[youtube]https://youtu.be/fJDuKyXfrQY[/youtube]
 
la8rat said:
Cal3thousand yes spot welding. Im in the process of makeing one. Updates will be posted here.

Flippy. Why dont they last long on ebikes? What sort of bikes have you experience of trying them on? What is it about ebikes in particular that make these a bad cell choice?
Im looking for maximum amp hours for minimum weight. "Just adding more" is missing the point. The max draw from the pack will be 15amps peak. So 3 amps per cell. On a cell rated at 8 amps.
Thanks for the replys.
Click to expand...
the 35E's have poor cycles, especially on high loads.
if you keep under 1C its fine but you need to cap your charging to 4.1V max per cell and dont go below 3V.
otherwise you are going to kill your pack a lot faster then your care for.

i have a couple grand worth of testing equipment and i have tested a lot of cells already. some of that data is already shared on this forum.
 
:thumb: Ok cheers for that flippy. Looking at the data sheet it seems to agree with what you are saying. The bike is purley a leisure bike, no big daily commutes so i could probably live with a poor duty life but i would need a charger that i have more control over.
Given my needs could you recommend a battery that you think fits the bill, or a charger that has some programmable features to get the most out of the e35.

Thanks
 
just grab a cheap aliexpress charger if you are on a budget and turn the pot inside down to the desired voltage.
if you have a bit more money i would recommmend getting a mean well, a HLG-320H-54A would fit the bill.
 
thanks i didnt realise the chargers had pots inside them DOH.. will there be a current pot as well so i can dorm the amps down from 2 to 1?

ill have a look at that hlg charger as well.

i appreciate the the help :bigthumb:
 
la8rat said:
thanks i didnt realise the chargers had pots inside them DOH.. will there be a current pot as well so i can dorm the amps down from 2 to 1?

ill have a look at that hlg charger as well.

i appreciate the the help :bigthumb:
Click to expand...

To answer for him, yes, most will have 2-5 pots inside. If not pots, they will have some type of resistor where you can either pot or augment with other resistors in series or parallel.

I think the likeliness of a pot to be there are in this order: voltage adjust, current adjust, end of charge current, then other voltage and current trims that I am not too familiar with.
 
some of them are a bit finniky to get changed if you dont know how.

personall i would opt for a HLG from meanwell, they have 2 pots, one for current and one for volts. hard to mess up and very high quality for the same price as a POS luna style charger.
 
About the HLG

The thing i found was a power source for led lighting fixed at 5.something amps and said nothing about possible adjustments.

I did see the luna charger and a post somewhere from a guy complaining they were hard to get hold of. The reply was to use a 60v 5amp lab power supply. Which do look good.

Couldn't look into it to much. Was having a bit of a nightmare at work.
 
I love the HLG and CLG lines from Meanwell. They are adjustable and mostly water-resistant depending on model. You can also put them in serial AND parallel. Super robust.
 
la8rat said:
About the HLG

The thing i found was a power source for led lighting fixed at 5.something amps and said nothing about possible adjustments.

I did see the luna charger and a post somewhere from a guy complaining they were hard to get hold of. The reply was to use a 60v 5amp lab power supply. Which do look good.

Couldn't look into it to much. Was having a bit of a nightmare at work.
Click to expand...

watch the model number. the HLG is the series, the number is the wattage and the next number is the voltage, the last letter is the version. the A version have the 2 potsunder the rubber caps, the other versions have either nothing at all or work with a external wire input for external pots. so you want the A version always.

just watch the datasheets for the correct voltage ranges, not all wattage models have the same voltage range. the difference might not be huge but it can be enough to just -not- reach the proper range you want.

if you have space issues or no ventilation (HLG and ELG need a LOT of free air) you need to use the HRP series. they have active cooling. they are medical grade so virturally indistructable but more expensive. but they pack a lot more power in a small space. expecially the HRP-300 series is great for tight spaces as it is 1U tall and has a back fan so you can stack them. onyl drawback (if it is one) is that it can only run at full current, it only has voltage control.
 
Thanks. Ill look again.

No space or ventilation issues. I have a sort of workshop come garage :) id only need it to be waterproof if someone nicked my roof .

You rack stack chargers? Is this linked to all the testing you do?
 
trapezoidal sheets of nickel should work well. It's vitally important in that kind of build to have good insulation between the cell groups. Something that won't melt when it gets hot and vibration resistant. Nomex paper works well, as does fiberglass tape.
You also nee to be sure all the positive ends of the cells have paper insulator rings (some cells come with this from the factory, some don't).

I did something similar with this pack build. Nickel sheets save lots of time over individual strips but won't work well with interlocking cell holders.

Img_1098.jpg
 
la8rat said:
You rack stack chargers? Is this linked to all the testing you do?
Click to expand...
i have a company that builds custom batteries and mobile off grid power systems.
i also work a lot with upgrading electric mopeds and stuff.
basically anything bigger then a ebike. or a ebike with more then 2kW, otherwise i am not interested, too much work for too little money and there is no fun in recelling a granny bike.

but yes, because i build big packs (like in dozens of kWh) i need data to support my warranty and to show companies that buy my products that my products can deliver the power and lifespan they expect.
 
Fechter
I love the simplicity of your build p+s out of single nickle sheet. Would the fiberglass tape not stop my pack from fitting together neatly given that its not going to be in straight lines as yours is but rather the hexagonal pattern?
Point taken about the paper positive end insulator, i shall get myself some of those.
How thick was the nickel sheet in that build?

Flippy
Ahh that would explain it all then, getting into this has really opened my eyes to the staggering amount of 18650 and other cells that must get used, manufactured and scrapped on a daily basis.
As your signature hints... truly the new fuel of our time. All very interesting stuff.

Thanks all :thumb:
 
When it comes to the actual matching up of the 5p packs. Ive been dreading having to fully charge all 70 cells 2 at a time on my nightcore 18650 charger.
Just a thought i had this morning.
Ill already have a 14s bms, can i make a 14 cell battery holder and create a temporary 1p14s pack to utilize the bms and my 52v charger to make the job a lot quicker or am i missing some obvious problem?

5 lots of 14 cells on charge at once sounds a lot better than 35 lots of 2.
 
a 1P pack will take ages to fill because you need dozens of amps to fill it in a reasonable time.
 
I used .15mm nickel sheet on my pack. It welds very easily and should be good for the amount of current I'm running.

The fiberglass tape or Nomex paper can be wrapped so it follows the cell contour and you can still do hexagonal packing but there will be the thickness of the insulation between. I would not skip this step as the plastic wrappers on the cells can easily melt or chafe, causing a catastrophic short.

flippy said:
a 1P pack will take ages to fill because you need dozens of amps to fill it in a reasonable time.
Click to expand...

I think he means a 1s pack. Your idea to use a 14s, 1p setup might work but the balancing of the BMS will be super slow. If the cells all come up to the same voltage then it might not take so long. I find pre-balancing the cells before a pack build is slow and a PITA, but necessary.
 
Ok my cells and nickel should be here in a few days. Also waiting on my ssr relay to arrive then i can finish my welder

20190420_125744_zps7lpr8hv4.jpg


20190420_115647_zps0quqri57.jpg

I know people have had varied amounts of success with this style of welder so im aiming to iron out some inconsistencies. Will add a spring to the arm to keep an even pressure on every weld .got the timer. And have the electrodes on a swivel so they can self level.

Needs a bit of a tidy up then im all set for some test welds.

Thoughts?
 
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