Off road Segway battery rebuild


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matchless

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Apr 17, 2022
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I bought two off road Segway X2's at auction, managed to recover the batteries but they failed again, I had one pair recelled using A123 ANR26650M1-B LiFEPO4 CELLS but the cost was painful, the original cells are Valence Proven 3.2v IFR 18650 EPi, 92 per battery x2 batteries per segway! thumbnail (12).jpg
I have obtained a couple of thousand 18650 Lion cells, can I use these instead? what would the BMS think of the increased voltage? would they charge ok from the internal charger? am I stupid? thumbnail (3).jpg thumbnail (86).jpgthumbnail (1).jpg
 

OffGridInTheCity

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Dec 15, 2018
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LifeP04 has a different voltage range than Lithium-ion - but for 24v, 48v (and 36v) there's a good match.
24v = 8s LifePo4 (A123 cells) = 7s Lithium-ion (18650 cells)
48v = 16s LifePo4 (A123 cells) = 14s Lithium-ion (18650 cells)

So yes if the original A123 based battery is 24v or 48v you can do a direct lithium-ion replacement in terms of voltage range. If the original A123 was 36v - then it can be approximated.

I'd suggest figuring out the original battery's nominal voltage / and voltage range specs.

If you're stupid for wanting to build a DIY battery from second hand cells... then you've found where they put the rest of us. :)
 

matchless

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Apr 17, 2022
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The original battery is 72v nominal using 96 cells, arranged in two blocks of 46 cells each, my first picture in my first post above shows two batteries taken out of their housings, the BM board sits on top, the charger is external to the twin batteries, but internal to the segway, here are close up pictures of one battery half and the original cells, what can you guys work out from that?
batt 1.jpgbatt 2.jpgthumbnail.jpg
 

floydR

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Aug 23, 2017
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23s LiFePO4 battery 73.6V nominal can be replaced with a 20s LiCo/NMC battery 74V nominal. if motor will work with slightly higher voltage
23s 73.6V-83.95V vs 20s 3.7V LICo/NMC 74V-84V
later floyd
 

matchless

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Apr 17, 2022
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Slight voltage difference does not seem to be an issue but will the BMS be happy with a different number of different chemistry cells?
Remenber I am well out of my confort zone here!
What will the change of cell type likely mean for range or performance?
 

matchless

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Apr 17, 2022
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Won't the BMS and charger be thinking it still has 3.2v LiFEPo4 cells and charge to that level?
 

floydR

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Aug 23, 2017
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Depending on the new cells capacity it may increase range and speed. just from the little research i did on the segway x2, there are companies that will rebuild your segway battery with 3.7V cells and they advertise increased range, speed.
Later floyd
 

matchless

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Apr 17, 2022
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Plan B is to try to sort out the existing cells and see how many, if any are good enough to reuse, then see if I have enough spares to make up the losses.
 

OffGridInTheCity

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Dec 15, 2018
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I think that will rule out changing cell types, there is an immobiliser fob linked to the BMS........
Interesting....

Plan B is to try to sort out the existing cells and see how many, if any are good enough to reuse, then see if I have enough spares to make up the losses.
You can also buy A123 second hand cells - here's 3 US sources that I trust and 2 of them have stock....
Battery Clearing House - https://www.batteryclearinghouse.com/search?type=product&q=NOT+tag:__gift+AND+A123*
Jag35.com - https://jag35.com/products/12v-a123-nec-alm12v7-ups-battery-modules
Battery Hookup - https://batteryhookup.com/products/emc-12v-module-with-8x-a123- (out of stock at the moment)
 

Redpacket

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Feb 28, 2018
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Have you figured out why the original packs failed? Is it bad cells or bad BMS?
 
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