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[trikester]

I now own a 2012 DS but I will be keeping my 2010 DS for at least another 1 1/2 years so that I don't have to return my CA $1500 rebate (required to keep 3 years). A good use for the old bike would be to keep it in the basement of my mountain cabin, for riding when I'm up there. I can keep it plugged in to an outlet in the basement.

Here's my question: It can get down into the teens (*F) occasionally during the winter, but maybe not quite that cold in the basement. Can there be a problem with the battery when storing the bike in those low temperatures? I realize it won't store as much energy, when cold, but I'm only concerned about damage from freezing temps.

Any info on this would be appreciated. 

[protomech]

Here's what the 2010 owner's manual says:

High or Low Temperature
Action: If the BMS senses that the power pack is too hot, above 71°C (160°F), or too cold, below - 6°C (20°F), it sends a signal to disable the motor controller and the motorcycle will not run until the temperature returns to an acceptable level. The charger will also be disabled in this condition.

The power pack should be kept away from excessive heat. The lithium ion cells should not get above 71°C (160°F). Do not store in a hot car or trailer, or leave the power pack in direct sunlight.

To prolong the life of your power pack you should store your motorcycle in a cool area. Storing your motorcycle in a hot area will cause your power pack’s life to be shortened.

Typically the acceptable storage conditions are wider than the acceptable charge or discharge conditions.

Check with Zero to be sure, but storage down into the teens should be no problem. Certainly, if the temperature in the basement stays above 20 then you should be fine.

[frodus]

Its a bit of a double edged sword though.... if its cold, and your batteries have any self-discharge, and its in the teens, the charger will be disabled and your Zero will be unable to keep the batteries charged until the temperature raises above 20F.

[oobflyer]

I would plug it into a timer and let it charge for a few minutes each day (or night) to keep the batteries topped-off.

I found out with my Vectrix (Li-ion) that when it just sits in the garage the batteries discharge at a rate of about 5 AH/week. So I top off the batteries every week or so to prevent the "bricking" that Tesla is dealing with right now.

[trikester]

I remember reading in my 2010 owner's manual that once the battery is charged the charger then looks at the charge level once every 72 hours and will turn itself on to recharge if needed. So it looks like the timer is already built into the ZERO's charger.

Thanks everyone, it sounds like I won't have a problem at the temps I expect to encounter. I also have a desert cabin, where the summer temps could be a problem, but I don't intend to leave a DS out there in the summer. The mountain cabin basement is always very cool in the summer (it's at 7000 feet elevation).

[Lipo423]

Lithium batteries are a bit sensitive to temperature -especially high temperatures. In order to preserve battery life I would suggest you a couple of things:

- Do not leave the battery fully charged when planning to storage the bike for a while (the battery capacity drops more when fully charged than when partially - 30-40% of full charge is a good number for storaging). This is something well known for the RC Electric cars aficionados, it is called storage charge.
- Cold weather is actually better than hot weather for Lithium (at 0 celsius you may loose 2% of capacity in a year when partially charged, this number climbs to 6% when fully charged)
- Every time you plug your charger you are "consuming" a battery charging cicle...do not charge for the sake of charging.
- Lithium do not like to be charged at 100% and not being de-charged right away, actually from the numbers that Zero supplies, the BMS would not let charging the battery pack at 100%...if it would the packs would last 500 cycles, not more than 2000

[protomech]

Lipo423,

I've heard some of those tips before (re: putting the bike in a storage mode).

Brammo recommends fully charging the Enertia prior to storage. This may actually be more harmful than charging more frequently at a lower SOC, but probably less harmful than allowing the battery to self-discharge below its lower voltage limit.

2010 Enertia Manual p.69:

Preparation for Storage
1. Wash and dry your Enertia. Wax all painted surfaces (except matte surfaces).
2. Lubricate the drive chain (page 65).
3. Inflate the tires to their recommended pressures (page 60).
4. Fully charge the bike (page 39).
5. Store your Enertia in an unheated area, free of dampness, away from sunlight, with a minimum of daily temperature
variation.
6. Place your Enertia on blocks to lift both tires off the floor.
7. Cover your Enertia with a porous material. Avoid using plastic or similar non-breathing materials that restrict air flow and
allow heat and moisture to accumulate.
If possible, fully charge the bike at least once every (3) three months during storage.

Zero doesn't explicitly say to fully charge before storage, but they do recommend that you keep the bike plugged in at all times and mention a maximum duration for storing the bike unplugged and fully charged.

2012 Zero S/DS Owner's Manual p. 4-8:

Keep you power pack connected to the charger when your motorcycle is sitting in storage or if it will be sitting unused for more than 7 days. The power pack must be charged within 24 hours if fully discharged, and charged within 60 days if stored fully charged. Zero recommends you plug in your Zero motorcycle after 7 days, even if fully charged. Please leave your Zero motorcycle plugged in whenever possible.

p. 4-11

Note: Frequent top off charging is good for the power pack’s life span, so do not hesitate to charge frequently.

- Every time you plug your charger you are "consuming" a battery charging cicle...do not charge for the sake of charging.

I am not sure this is correct for Zero's batteries.

[Lipo423]

Thanks Protomech,

My experience with electric motorbikes is inexistent, which is luckily not the case with batteries, and electric bicycles 
Each manufacturer (we are talking about companies that have been selling electric bikes for not a long time)has its own view -which I respect - my view and advice with current Lithium chemistries is the one I posted.
Zero's battery packs have a few advantages/features/benefits which I can summarize:
- They use Lithium Manganese chemistry (not the highest Kw/h/kg, but safer and most important long life). they could use Li-Cobalt (around 30% more energy), but is not safe...and lasts less...
- As stated earlier they do not charge the packs at 100%, so when you charge the pack at 100% you might be actually charging it at 85%, which is not 30-40%, but is not 100%
- I have seen a few electric motocycle manufacturers claiming incredible range with 3-4 Kw packs...no way...Zero has understood that and today have probably the bigggest battery pack in the market.
- Charging cycles rules apply to any battery, including Zero ones, you can only increase the number of cycles by reducing the depth of decharging.

[protomech]

I believe Zero is using EIG C020 pouch cells for the 2012 bikes (3.65v 20Ah). The high energy chemistry is 175 Wh/kg if their specifications are accurate.
http://www.eigbattery.com/

EIG specifies -30C to +50C operating & storage, +0C to +50C charge.

In the summer here it can get up to 105-110F (40-43C).

In the winter it can drop into the 20s and 30s (F), but I really need better gear to ride much below 30. They don't publish available capacity curves per temperature, but I figure range at +0C will likely be 85-90% of 10-20C range. Possibly less.. will have to see how I do next winter.

[Lipo423]

Do you know if the 2012 battery pack has any cooling system or especial enclosure?
Lithium would perform very well at +20 or +25C...I find the -30C too low, actually they would have marginal functionality or stop working (unless they are build in a special enclosure).
As you pointed out it is a shame they do not publish available capacity curves per temperature, as the gap is too high (80 degrees)to get a clear picture...experience will tell us, but I suspect that at 0C the capacity may drops more.

[protomech]

The 2012 batteries are not actively cooled. There is a finned heatsink mounted on the underside of the seat tail, but I suspect this is for the controller.

I'm kind of tempted to open up the bike this weekend and see what that heatsink is connected to.

Toshiba's SCiB lithium-titanate chemistry claims 85% capacity available at -30C. SCiB is a much lower energy-density chemistry, but not all lithium is the same.
http://www.toshiba.com/ind/data/tag_files/SCiB_Brochure_5383.pdf

However, if EIG's batteries have any kind of useful capacity at -30C, they should be just fine at +0C.

[Lipo423]

Unfortunately I cannot help (I do not have the bike yet), will let you know in a couple of weeks...
The different chemistries do change the behaviour but not at a very high level, and all of them are affected by temperature, the tricky thing as we all know is that no manufacturer delivers full information, and they all talk about "ideal" scenarios, which is b... (I'm only aware of Dry Solid polymer batteries that need to work from 60-100C...)