Moped Battery Build

knightgreider

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Joined
Nov 28, 2017
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21
Hey everyone, I am building my first pack and was curious about how to solve this.

I am running a 10s8p build with low-cost SamsungINR18650-13Q cells running a 36v 10.3ah pack. I was following the way this guystutorial with using this busbar method.Youtube link

When I was designing the packs I assumed I could just run one side to be positiveand one to be negative. Now that I am doing this that is not the case. Do I just run 2 more bus bars? I did not solder the bus bars yet, and was hoping one of you could tell me how to fix it or what to do before I move forward. I attached a pic to show what I am doing.


image_npdbgq.jpg
 
Your current pack layout would allow for Pos/Neg to be on the same side. With the way you have it laid out in the pic, they would be on the other side.
Had you done 10s16p, then you'd have a bit of different layout/configuration/pack-size.

Before putting the bars on the pack, I would recommend heating the bars up with a heat gun or on a stove or such and then hit each of those solder points again with the iron. By heating the whole bar up, the iron won't have to work as hard to heat up the one spot. You joints look a little to "balled" and not fused enough with the bar.
 
Oh, so if I had a heat gun and heated up the bus bar then re-soldered each joint with the fuse wires? Is that what I should have done from the beginning when I first lay the solder down?

I still don't understandhow I can fix this so that the negative is on one side and the positive is on the other? (both on the left or right) Is that what you meant? From the video, the guy had the positive and negative bus bars on opposite sides and opposite ends? Is my project salvageable by just moving some batteries around?

Thanks, Korishan!
 
His pack is a 7s, that's why his Pos/Neg are on opposite sides. Even number in series will end up with them on the same side, odd number in series is on opposite sides.

The heat gun trick is just so the whole bar is hot so when the iron is being used, it's heat isn't being sucked away faster than what it can apply. Honestly, that trick just came to me when I saw what you had and needed to be done :p maybe I saw it somewhere else before
Also with the guy in the video, his iron looks to be about 100W, it's a got large barrel and a pretty good sized tip.

If you want the Pos/Neg terminals on different sides, you either need to change you series to an odd count (9 or 11), or play with different designs to see what gives you that with the 10s. I'm not sure how you would get them on opposite sides. I doubt it's really critical. Having them both on the same side actually would make working with it slightly easier as you don't have a lead on the "bottom" of the pack
 
I gotcha, I just didn't know where to put the positive vs. the negative if they are both on either side. Are you saying you can only do it with an odd number of parallelcells?
I would like to have the terminals on both sides.
 
As your pack design, you Pos/Neg will be on the same side. In the picture as the pack sits, will be between the back and the table. I drew in the last bar on the pack, and put labels where your connectors would be at.


image_mbowek.jpg



On the other side of the pack, the bus bars would be off set from the ones shown. So you wouldn't connect a bus bar at the same location, otherwise you'll blow fuses. So, you currently have bus between 1 & 2, 3 & 4, 5 & 6, 7 & 8, 9 & 10. The other side would be 2 & 3, 4 & 5, 6 & 7, 8 & 9
 
Thanks, Man. That makes sense now. You are awesome! What does everyone wrap the batteries in? I was looking at this?Amazon lInk

Soldering today or tomorrow.
 
Usually most of us don't wrap the cells since they won't be exposed to weather conditions. However, being a moped pack, you'd be similar to the eBike groups. I've seen them use the larger shrink wrap like that. I've also seen those who just make a small box then wrap that in duct tape or something similar. I guess depends on permanent you want it or ease of accessibility.
 
Oh gotcha, I ordered that shrink wrap. I was wondering what gauge of wire that my batteries would be using if I'm running 2- 36v packs in Series? Is there a standard guide as to which size wires will go from each battery to the controller? I am getting ready to finish one of the batteries and am looking to charge it soon. The controller says it can draw up to 192 Amps. I don't think I'll program it to do that. Any recommendations? I found some guides online, but nothing definitive.
 
The wire size totally depends on the amp draw. 192Amps is MASSIVE.... You need HUGE cables.

http://www.solar-wind.co.uk/cable-sizing-DC-cables.html

Thats like 35mm2 wires from the pack to the motor if its max 1 meter and up to 5% loss.
Between cells for no large loss then you need decent thick fuse wire that easy can do 20A to lower the losses as much as possible.

Personally i would only fuse the pack and not individual cells if they are new. Its a Ebike pack :)
 
Wow I love that website. Thanks man.
Igot the motor andcontroller yesterday and was looking at the power chart and the length of cable it I will most likely only draw around96 amps. I can limit it with the software the controller comes with. The data table is linked here.72v motor PDFif I can use 10 gauge high tempwire I think Ill do that.
Would this wire work?Amazon link

Thank you!
 
Hey everyone, what charger would you suggest for my 2 batteries that I built with 36v-10ah battery packs with an Anderson connector? I am not running a BMS.
 
knightgreider said:
Hey everyone, what charger would you suggest for my 2 batteries that I built with 36v-10ah battery packs with an Anderson connector? I am not running a BMS.

TheiCharger 1010B+ is capable of charging up to 10s. There are clones out there that may be a little cheaper. But if you shop around you should be able to get the iCharger at a reasonable price. I bought a Charsoon Antimatter charger, because it was almost half the price of the iCharger. I have no complaints so far.

My chargers are only 6s, but I have 3 of them. If I need to charge more than 6s, I just use two chargers.

Most larger chargers require an external power supply. I prefer to go this way, as secondhand server power supplies are often cheap. However, if you want to charge at the full 300w you will need more than the 12v most server supplies have. You will be limited to about 250w. This would not matter if you were charging at 0.5c, as 5a @ 36v is only 180w.


knightgreider said:
Wow I love that website. Thanks man.
Igot the motor andcontroller yesterday and was looking at the power chart and the length of cable it I will most likely only draw around96 amps. I can limit it with the software the controller comes with. The data table is linked here.72v motor PDFif I can use 10 gauge high tempwire I think Ill do that.
Would this wire work?Amazon link

Thank you!

Amazon link is broken.
 
Thanks I am looking at that charger when I build my new pack.

So... I am starting from scratch with another pack, I just bought 80 of these https://www.imrbatteries.com/samsung-33g-18650-3500mah-6-5a-flat-top-battery/ for a 72v - 25.2ah battery pack. I am a bit scared because I might be drawing too many amps per cell. When I bought them last Friday (they didn't ship yet) I thought 6.5a draw would be ok for each cell because I thought the amps were drawn from each battery. So little more 1amp per cell max. But now I think (I could be wrong). Would I be drawing from amps each of the series of batteries in the pack of my 8s10p pack, which would be 11.75amps a piece. Is this right?

According to this data sheet from my motor and controller (also the same as 48v vs 72v motor), it's drawing around 94 amps max (I hope) linked below.
https://www.goldenmotor.com/hubmotors/hubmotor-imgs/HPM3000-48V3KW Data.pdf

Thanks!
 
knightgreider said:
Thanks I am looking at that charger when I build my new pack.

So... I am starting from scratch with another pack, I just bought 80 of these https://www.imrbatteries.com/samsung-33g-18650-3500mah-6-5a-flat-top-battery/ for a 72v - 25.2ah battery pack. I am a bit scared because I might be drawing too many amps per cell. When I bought them last Friday (they didn't ship yet) I thought 6.5a draw would be ok for each cell because I thought the amps were drawn from each battery. So little more 1amp per cell max. But now I think (I could be wrong). Would I be drawing from amps each of the series of batteries in the pack of my 8s10p pack, which would be 11.75amps a piece. Is this right?

According to this data sheet from my motor and controller (also the same as 48v vs 72v motor), it's drawing around 94 amps max (I hope) linked below.
https://www.goldenmotor.com/hubmotors/hubmotor-imgs/HPM3000-48V3KW Data.pdf

Thanks!

This is from Your link :

image_kkanbj.jpg

6,5 A Max per cell.
 
What math should I do for max discharge?


Yeah, but what would be the max discharge on a 8s10p pack of 94a? I always thought the max discharge was evenly divided by the total number of cells... Now I am wondering if it is 11.75a or 9.4a?
 
knightgreider said:
What math should I do for max discharge?


Yeah, but what would be the max discharge on a 8s10p pack of 94a? I always thought the max discharge was evenly divided by the total number of cells... Now I am wondering if it is 11.75a or 9.4a?



Just think of the number of cells in parallel. (not the (total) number of cells)
6p -> 6 times 6.5 Amps ...
10 P -> 10 times 6.5 Amps, so it is 65 Amps max per specification.
 
I'm not saying I know what I'm talking about, cause I've never built or used an e-bike. I think you're better off using high drain cells like the Samsung 30Q. Even though the ones you bought may be rated for 6.5A, the performance suffers. So you wouldn't want to max out your therotical amps. Without the high drain capabilities, the voltage drop during high loads may be significant causing premature cut-offs. I can see if you try to go full throttle you will find that the bms will cut off due to a low battery condition, then come back on again when the cell voltage recovers. The only way around it is to add more cells in parallel.

I wonder if there's options for dual chemistries, like a supercap or high charge/discharge chemistries where the supercaps are used during bursts of high speed throttles.
 
not2bme said:
I'm not saying I know what I'm talking about, cause I've never built or used an e-bike. I think you're better off using high drain cells like the Samsung 30Q. Even though the ones you bought may be rated for 6.5A, the performance suffers. So you wouldn't want to max out your therotical amps. Without the high drain capabilities, the voltage drop during high loads may be significant causing premature cut-offs. I can see if you try to go full throttle you will find that the bms will cut off due to a low battery condition, then come back on again when the cell voltage recovers. The only way around it is to add more cells in parallel.

I wonder if there's options for dual chemistries, like a supercap or high charge/discharge chemistries where the supercaps are used during bursts of high speed throttles.

All what you say may happen.
You mention a BMS Undervoltage Cutout - as far as i have understood the OP said he doesnt want to use a BMS. Very bad idea, given the case that cells might get temporarily undervoltage just by to high drains, as you describe. This board here has several people doing a powerwall running without BMS - and loosing a bank to under- (over-)voltage (lucky guys, if they only lost a bank).

For my personal taste, the battery is just to small for the task - its weight is (my guessing) even less what the fuel (i assume is a bike project) might have had in comparison.
But, thats not a go-nogo criteria, its just what disadvantages of cell overloading the OP is willing to take.
 
I will be using a BMS for this new pack actually. I bought the wrong batteries, and they are not returnable. So I will be needing to sell them so I can purchase the 15a max draw now battery now. I also figured out why my pack shorted. I was running 80 of these.https://secondlifestorage.com/t-LG-LGABB41865-Cell-Specifications

Before now I didn't understand thoroughly what continuous draw actually matters for the motor. Since I have the moped put together, I rode it twice and probably blew the fuses because I was drawing too much power. That's why out why it was bogging down. I thought it was my brakes rubbing... :( Now I'll order these batteries for the 9.4max draw so I won't be bogged down and fully accelerate.

The link aboveis the 30Q batteries that not2bme suggested. Does anyone have an activeBMS suggestion for an 8s10p pack? I haven't done a BMS yet, I know there are a bunch of videos out there which I will be going through. But I'm interested to see what everyone suggests.

So now I just need to sell the 80 of these that I bought. Does anyone want them for less than I paid for them? My loss.https://www.imrbatteries.com/samsung-33g-18650-3500mah-6-5a-flat-top-battery/

Thanks for your help everyone!
 
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