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[kensiko]

Directly heating the batteries with a DIY contact heater, you'd better be damned confident in your skills  It doesn't take much over 100ºC (cell temp) to start a runaway.  So I'm going to rank that as "crazy."

Just point a space heater at it on low, it doesn't take much Wattage to maintain a moderate temperature when it's continuous.  I did the same for my gas bike that got finicky about starting when cold, I actually put a space heater on one of those lamp timers and had it kick on a couple hours before I left in the morning.  No flammable cardboard box necessary.  More waste without direct contact but it allows the bike much more latitude to self regulate its temperature.

I thought about it and the plastic cardboard type would be best, not sure you know what I'm speaking about, it the plastic they use for big outdoor sign.

[Lipo423]

I would look to get an electric heating blanket/mat.
Anything that gets not in conflict with "safety" for both the bike batteries and the house.

If you plan in leaving the bike for a few days unused leave the batteries at 30-35% charge…try to avoid leaving the bike plugged "infinitely" (I know Zero recommends that in the owner's manual but the rational behind has nothing to do with Lithium battery life)

[nicktulloh]

If you plan in leaving the bike for a few days unused leave the batteries at 30-35% charge…try to avoid leaving the bike plugged "infinitely" (I know Zero recommends that in the owner's manual but the rational behind has nothing to do with Lithium battery life)

What does it have to do with? I'm open to learn but my current plan is to abide by the manual.

[kensiko]

I would look to get an electric heating blanket/mat.
Anything that gets not in conflict with "safety" for both the bike batteries and the house.

If you plan in leaving the bike for a few days unused leave the batteries at 30-35% charge…try to avoid leaving the bike plugged "infinitely" (I know Zero recommends that in the owner's manual but the rational behind has nothing to do with Lithium battery life)

You would put this under the bike ? http://www.ebay.ca/itm/Heated-Outdoor-Walkway-Mat-by-Heattrak-New-Residential-Heating-Walkway-Mat-/251290110082?pt=Motors_Automotive_Tools&hash=item3a820ec882&vxp=mtr

[LiveandLetDrive]

I think LiPo423 means directly on the outside of the battery module.  If you're going to do that, just be very sure that it can't ever for any reason exceed 80*C or so (whatever Zero has as the max storage air temp).  Heating with direct contact just allows less opportunity for excess heat to convect away and it doesn't take much power to reach runaway temps if the thing is insulated by the mat wrapped around it.

[zap mc]

Is it better to keep the battery plugged-in? I know Zero recommend to always let it plugged-in, but is it a necessity for extreme cold temperature?

ALWAYS keep it plugged in or else your warranty will be void. I assume Zero can now tell if you haven't from the datalogging and if there is a battery problem and they refuse to take care of it under warranty then you will have effectively written your bike off if it needs a new battery and it is not covered.

[kensiko]

Noted !

[Lipo423]

There has been a lot of discussion on this "leaving the battery plugged when not in use" well, I would disagree with that…Anyone just a little familiar with Lithium Polymer battery behavior would tell you not to do so…on the other hand I understand the warranty issue, but this has nothing to do with the chemistry behavior which is what it is (whatever Zero says)
Zero is just trying to avoid customers with low-battery issues and the potential warranty claims that this represents.

You may want to follow Zero's advice (warranty period), and then do the right thing after that

[WindRider]

Lipo, what would you suggest then as the best way to get the longest battery life from a Zero that lives somewhere with a 4-6 month winter season?

Zero must be quite confident in their current recommendation of keeping the bike plugged in now as they have 2 years of field data to stand on and they just increased the battery pack warranty to 5 years so I am curious why there is still a debate about this topic.  And no, I am not a battery or chemistry expert, just curious and want to get the best life from my battery pack. 

[nicktulloh]

You may want to follow Zero's advice (warranty period), and then do the right thing after that

If there was a consensus from the forum experts on what that 'right thing' is, I'd probably do it. Especially since I'm sure they'd help me out with any future warranty issues.

My bikes live in the unheated barn and will not have any aux heat applied. Period.

[NoiseBoy]

There has been a lot of discussion on this "leaving the battery plugged when not in use" well, I would disagree with that…Anyone just a little familiar with Lithium Polymer battery behavior would tell you not to do so…

Well its a good thing the batteries aren't lithium polymer then.  It doesn't matter anyway whether its right or wrong, i'd do what the warranty says when such an expensive component is concerned.

[Lipo423]

Yes, our batteries are Lithium Polymer, the Zero S 2012 model has a Lithium Polymer Manganese battery (I have not checked the specific cathode material on the 2013 model, but I would think they are also Lipo's base).

Long storing is never recommended for lithium at full charge, if having to leave the pack unused for long periods of time it is better to do it at 30-40% capacity, check the voltage level periodically and eventually do another partial charge. If you charge the battery pack partially you extend the life-span (if you do a 40 miles ride/day, you do not need to fully charge the pack every time). Cell balancing is needed, but not everyday.
A well treated battery pack with last more than 8 years at a reasonable capacity level (in the 70-80% level)

Let's remember that batteries have to be used (cycle), and aging will happen anyway, not matter if we charge them 10 times or 100...

The last non-military (commercial) developed Lithium chemistries have been in use since 96'-2000 with limited track-record/experience (in non laboratory applications)

[NoiseBoy]

I think maybe you mean to say Li-ion rather than lipo? The 2012 and 2013 bikes use Lithium Nickel Manganese Cobalt Oxide cells which are much more rugged than lipo and the theory is that leaving the bike fully charged and plugged in may result in a very slight reduction in capacity over a few years but this is preferable to having the owner charge periodically to maintain a lower SOC but forgetting about it and bricking the battery. Also it wouldn't take much of a fault in the bms or contactor for example to result in a continuous current drain. If that happened the charger may well save the day.

[Lipo423]

Mmm…not sure if the 2013 do not have electrolyte gel (having checked that). I was told they are Lipo chemistry by a Zero guy.
Yes, I know the LiNiMnCoO2  behavior (the good and the bad).
BMS or main contactor high current drain? That is unlikely to be happening (no impossible, but very unlikely)

In any case, whatever cathode or anode material they are made of, they are all Lithium based (when mixing the different chemistries you gain or loose longevity, capacity, safety C rate, etc…) and the behavior is the same when talking about fully charged stored batteries. Not very healthy.

[kensiko]

Would this be enough ? It's low power.

http://www.sunbeam.com/sunbeam/BRF9HQS-R622-13A44.html