48V Li-ion battery cell-replacement repair
Creator’s own settings as stated in the video (timestamps link to the moment). Not official values — test on scrap first.
Bill of materials
Welder, accessories, consumables and parts used in this build; quantities and specs are editable Download BOMDescription
A no-name e-bike's 48V Li-ion pack only goes one or two km: case not small but hollow inside, 18650 3P13S low-capacity cells, tester says 'battery condition extremely poor', not worth repairing; all replaced with EVE 2.5Ah in 4P13S = 48V 10Ah, honest capacity with no inflation, 30-odd km on an ordinary small bike; nickel-strip spot welding, BMS fitted, charge/discharge test
A 48V Li-ion battery; the customer says it only goes one or two km. No need to check the capacity: pick it up and you can tell the case isn't small but the cell capacity certainly is; no-name e-bikes off the internet all come with this kind; open it up and one section inside is empty; 18650 cells in 3P13S, ordinary low-capacity cells that won't last long even with light home use; test cell by cell with the resistance tester: readings 3.5–3.6V, resistance 16–24, screen says 'battery condition extremely poor, please service', no repair value at all. Replace everything: EVE 2.5 cells in 4P13S = 48V 10Ah, honest capacity with no inflation, an ordinary small bike will do 30-odd km no problem; spot-weld the cells in parallel and series with nickel strip; fit the BMS, charge/discharge test, battery done. 25 comments: many asking price (48V 10A / 30A / 5P13S, how much); 21700 5000mAh in 4P makes 48V 20Ah; lots of fake EVE cells, ¥2-odd each, zero volts after three months in storage; BAK 2900 without holders in 6P rides 60 km; a designated-driver bike's 48V 8Ah drops out as soon as the throttle turns, fixable?; Wuyang buyers got scammed with fake capacity.
Outcome
| Goal | Re-cell a no-name 48V battery to 4P13S 10Ah |
| Build | EVE 18650 2.5Ah ×52 + 13S BMS |
| Result | Assembled, finished after the charge/discharge test · not verified on camera |
Steps4 steps · click a frame to jump
1. Diagnosis: only one or two km; big case, small cells, no-name e-bike stock48V Li-ion only goes one or two km; no need to check capacity, case not small but cell capacity is; stock battery of a no-name e-bike; one section inside is empty.
00:08 – 00:42
2. Opened up: 18650 3P13S low-capacity cells; tester says 'extremely poor', worthless18650, 3P13S; ordinary low-capacity cells that won't last long even at home; tester cell by cell 3.5–3.6V, resistance 16–24, says battery condition extremely poor, please service; no repair value at all.
00:42 – 01:09
3. EVE 2.5Ah 4P13S = 48V 10Ah, no inflation; nickel-strip spot weldingReplace all with EVE 2.5 cells, 4P13S 48V 10Ah, honest capacity with no inflation, an ordinary small bike does 30-odd km; nickel-strip spot welding for the parallel and series connections.
01:09 – 01:31
4. Fit the BMS, charge/discharge testFit the BMS; charge/discharge test; battery done.
01:35 – 01:44
Bill of materials
| No-name 48V battery ×1 | 18650 3P13S · Being re-celled |
| EVE 18650 ×52 | 2.5Ah · 4P13S |
| Internal-resistance tester (cell by cell) ×1 | Assessment |
| Nickel strip + spot welder (UF20B) | Welding |
| 13S BMS ×1 | Protection |
Measured on camera
| Old cell voltage / resistance (tester) | 3.56–3.64V / 16–24mΩ, condition extremely poor 00:56 |
Creator’s tips
- A big case doesn't mean big capacity; no-name e-bike stock packs often use low-capacity cells 00:22
- When the tester says 'extremely poor' you can call it not worth repairing and re-cell straight away 00:56
- 4P13S of 2.5Ah = an honest 10Ah, 30-odd km on a small bike 01:09
Pitfalls
- Comment: lots of fake EVE cells, ¥2-odd each, zero volts after three months in storage
Li-ion safety
Quotes
Comment insightsanswered 0 · open 4 · corrections 4
Open questions
Corrections from viewers
I've built loads of packs like this over the past year, without holders you can fit 6P of 18650, built with BAK 2900 it does 60 km, tested myself at 140 jin, this bike isn't fast either, 21 tops, 7P is doable but it's a hassle, you have to make turns
Reply @小李哥:
I've built loads of packs like this over the past year, without holders you can fit 6P of 18650, built with BAK 2900 it does 60 km, tested myself at 140 jin, this bike isn't fast either, 21 tops, 7P is doable but it's a hassle, you have to make turns
Reply @小李哥:
I've built loads of packs like this over the past year, without holders you can fit 6P of 18650, built with BAK 2900 it does 60 km, tested myself at 140 jin, this bike isn't fast either, 21 tops, 7P is doable but it's a hassle, you have to make turns
Reply @小李哥: