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[Richard230]

I don't believe that the BMS will permit you to damage the battery pack.  As the pack nears its final few amp hours, the BMS will cut the power to a walking pace and if you finally hit the bottom of the pack it will cut off all power and you will end up pushing.  Matt told me that he ran his 2012 Zero S out of juice and barely made it to a 120V wall outlet at a restaurant, moving at only 25 mph for the last few miles.  Apparently, this did no damage to his batteries and after a few hours charging he was able to return home at normal speeds.

[BSDThw]

The Sevcon reduce power from 58V to 54V (cutoff).

54V / 18 = 3V per Cell.

This should still be a save voltage.

[trikester]

It's the same with Li battery powered power tools. The cut-off protection is built into the battery pack so that it is never discharged below the point where damage would occur.

However, the reason Zero doesn't want us to leave our bikes unplugged for weeks at a time is because there is a constant drain on the battery by those protection and management circuits. This drain can eventually take the battery below the damage point in voltage. However, with the 2013 batteries that situation is much improved by the "at rest" discharge being greatly reduced from previous years. The 2013's can sit for long periods of time without being plugged in, without causing damage.

The most critical were the 2010's which needed to not be left more than a week without being plugged in, to avoid damage.

Trikester

[protomech]

I believe the change to the lower power BMS was made for the 2012 bikes.

Per Zero:
New battery management system with enhanced 24/7 cell monitoring and a 92% reduction in power consumption

I left saturday morning for a canoeing trip with the bike at approximately a 50% SOC, unplugged.

I returned wednesday evening with the bike at approximately the same SOC.

The Sevcon reduce power from 58V to 54V (cutoff).

54V / 18 = 3V per Cell.

This should still be a save voltage.

EIG (2012 Zeros) lists the lower cutoff voltage at 2.5V per cell.

[trikester]

I believe the change to the lower power BMS was made for the 2012 bikes.

You may be correct but I was going by what I was told, that it was in 2013 models. Maybe they reduced it for 2012 and then reduced it some more for 2013.

Trikester

[w34p0n2m4n]

Haha, yeah I took the MSF's experienced rider course the other day and one of the instructors was scolding the class for leaving the ignition on when they dismounted the school's bikes. An hour or two later they noticed that I happened to leave my ignition on so the headlight was still shining. They said something like "that poor battery" and I was like 'I don't think you have to worry about THAT battery."

Believe it or not it took them a few hours to notice that my bike wasn't making any noise.

[BrianTRice@gmail.com]

Haha, yeah I took the MSF's experienced rider course the other day and one of the instructors was scolding the class for leaving the ignition on when they dismounted the school's bikes. An hour or two later they noticed that I happened to leave my ignition on so the headlight was still shining. They said something like "that poor battery" and I was like 'I don't think you have to worry about THAT battery."

Believe it or not it took them a few hours to notice that my bike wasn't making any noise.

Nice. The MSF ERC class must be super-easy with the Zero. I struggled the whole time with the class-provided BMW G650's incredibly over-stretched and under-adjusted clutch cable. Ow! Clunking between first and second gear makes the routines hard to focus on.

Parking lot slow speed practice on the Zero DS has been very easy by comparison.

[w34p0n2m4n]

Yeah, there were several parts of the exercises that just didn't apply to me since I didn't have any gears to shift and didn't have a friction zone to manage. By the end of the afternoon the instructors and there boss were all talking about getting their own Zero.

[trikester]

The local rider safety course, of MSF, in my area, has considered getting Zero XU's to teach bike handling before teaching the shifting and clutch etc. Since the parking lot where they teach doesn't have AC power, the XU would work out well because they can remove the batteries and take them to their office for charging overnight.

Trikester

[blippincott]

Congrats on the new Zero S!! I got mine in mid June from AF1 Racing here in Austin Tx.

   I have long been a proponent of alternative energies and wanted to build or convert an electric vehicle since I was in middle school in the late seventies. As an enthusiastic kid with no experience in EVs or a driver's license, I got told to shut up a lot. Now I am older, have many years experience in machine shop, electronics, & driving, and the world has changed a bit. It seemed it was time to make this real. I just joined the forum and am glad to see more useful information exchanged on these and other electric motorcycles that are on the roads now. I hope I am not hijacking this thread by being too far off subject. Be safe. 

[trikester]

It sounds like you will be interested in following my thread (in this forum) as I convert my home built gas powered (Yamaha) trike to Zero's 2013 FX power components. Yesterday I completed the base support for the batteries and today I'll take a photo and post it on my thread tonight. My task now is to figure out how I will secure the batteries in place.

Trikester