Tuesday, 25 August 2015

36V 11.6Ah Super Tube Battery Real Life Review

UPDATE 31 Aug 2015: BMS board fixed, my old battery is now up and running again! Simply clean the salt bridge due to moisture penetration. All those riding in the wet did take its toll!


For lithium batteries, people always discuss how many charge-discharge cycles their battery last, but very few data regarding the electronics (i.e. the BMS, or Battery Management System).

My beloved 36V 11.6Ah tube battery (with original Panasonic cells) just died on the weekend :(. To my surprise, the cells themselves are still good. It's the electronics inside the battery system that is the culprit, i.e.:

  • the charging port is no longer be able to charge, and
  • the 4-pin output port also gives no output voltage (but can charge from this port).

This particular battery electronics have MOSFET driven switch for ON/OFF switch and the charging port ideal diode circuit (on top of the BMS).

I initially thought the PCB must have corroded since I always ride regardless weather (and it's been very wet lately). However, when I opened the BMS, it was dry-as, no sign of moisture what-so-ever (kudos for the battery design and build).

Since I have no time (yet) to further dissect the electronics, I already purchased the same battery for replacement. Again, to my surprise, the new battery did not perform any better compared to the old one. This, basically saying, the old battery has NOT lost ANY performance compared to new.

I get to work in 45 - 47 minutes (27km one way distance), which was same time compared to old one. When fresh, my cycle analyst shows peak power close to 800 Watts (old battery did the same). So, WOW! However, I haven't had the guts to test the capacity loss though. My guess the old battery probably have lost some of its capacity.

So, for documentation sake, my old battery has gone through (according to cycle analyst):

  • 497 cycles
  • 3701 Ah total

Based on the above, average 7.45Ah usage (65% Depth of Discharge) for its lifetime. And no noticable performance degradation. Impressive indeed.

Now, somehow I need to fix the electronics...