Hi Greg, my gen 1 specialised battery will not turn on. Last time I rode the battery turned itself off a couple of times but turned straight back on with the switch. I recharged it to about 80%. Several weeks later I tried to top it up but it wouldn’t start up when plugging in the charger or pushing the start button. I have opened the battery and found moisture in the case and oxidation around the control switches and LEDs. I have cleaned the oxidation off with isopropyl alcohol. The battery is showing 40v on a multimeter and each bank of 4 cells is 4.07v except one bank that is only 3.63v.
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Specialised Levo gen 1 battery won’t turn on
- Thread starter Junor
- Start date
@Junor - good detective work getting in there with the multimeter. You've actually diagnosed this pretty accurately already, so let me lay out what's happening and what your options are.
The diagnosis: one weak cell group and a locked BMS Your pack has 10 cell groups in series. Nine of them are sitting at 4.07V - perfectly healthy. That one group at 3.63V is the problem.
The BMS cuts out the power supply to the motor and locks it when it finds any battery group drops below a certain voltage threshold.
That voltage discrepancy - combined with the moisture and the oxidation - is almost certainly why the BMS has locked out entirely.
Lithium cells self-discharge slowly, and if the battery was already partially depleted when you stored it, weeks of sitting could have dragged that cell group below the BMS's low-voltage cutoff. At that point the BMS locks out charging as a safety measure.
The moisture and switch oxidation you found is a separate but related problem - water entering the battery and affecting the LED/switch board is a known issue on these; cleaning with isopropyl alcohol is the right first step.
What are your options? 1. Bring the weak group up manually
One user opened the battery case, found cells in a low-voltage condition, hooked them up individually to a smart charger made for RC batteries and brought each cell in the pack to 4.2V, then ran it through 3 cycles from full to dead - and it recovered.
Critical safety note: avoid charging more than one group at a time, and do NOT use one multi-cell charger across two groups simultaneously - it will short circuit your Levo BMS and destroy it. Use two completely independent chargers if you must do two groups at once.
2. The BMS may still be in "Permanent Failure" state even after balancing the cells If the BMS has entered a "Permanent Failure" state, it needs to be unlocked - and that's not something dealer diagnostic tools can do.
Specialized batteries can be repaired though - most of these with the BMS locked have good cells inside, it's just the management system that's thrown a padlock on things.
3. Check the SFC fuses on the BMS board Check the SFC fuses for continuity. If they're blown, the BMS has likely entered protection mode - and even if you replace the fuses, the battery won't recover without unlocking the BMS.
My honest read of your situation: You've done the hard bit by opening it and finding the fault. The weak cell group (3.63V vs 4.07V) is recoverable - that's not a dead cell, just an undercharged/unbalanced one. Bring it up carefully with an independent charger to match the others, then see if the BMS will accept a charge again.
If it stays locked after that, you're into specialist BMS-unlock territory rather than dealer territory -
there are people who've reverse-engineered these Specialized BMS systems and can separate the BMS from the cells, reset it, and reconnect - including resetting cycle count and battery health metrics.
Worth a search for Specialized eBike battery repair specialists in your area - it's a better bet than a new battery at current prices.
