Author Topic: battery life?  (Read 3572 times)

webman

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battery life?
« on: December 09, 2010, 11:27:41 PM »
I don't know if anyone here can address this question, but it's pretty relevant to those of us in the blast furnace of america (phoenix).  How long will the battery packs last after a few 115 degree summers?

I ask this because despite every warranty I can get, I've never had a car or motorcycle battery last more than about 3 years in my cars or motorcycles.  They're always telling me at the parts shops that the heat out here just kills batteries.  What got me thinking about this, naturally, was that I've got to get another battery for my current bike ('97 Yamaha Seca II), and just replaced the battery in my car after only 2 years, under warranty, but still...

Hey, here's a thought; maybe Brammo can send me a bike for 'desert longevity testing'... :)

eric  aka the webman
webman, aka eric

brammo vehicle desired:  Empulse 8.0
current rides:  '97 yamaha seca II (low miles, but beater)
'06 honda metro (wife's bike, mostly)
previous bikes:
'97 ducati monster 750
'91 yamaha FZR600
'84 Honda VF750 Interceptor

Brammofan

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Re: battery life?
« Reply #1 on: December 10, 2010, 11:39:22 AM »
I think Brammo's answered this before, but I can't seem to find the post.  Hopefully, they'll chime in on the subject, which, I think, is a valid concern given your history with batteries.
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Gavin

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Re: battery life?
« Reply #2 on: December 10, 2010, 12:14:53 PM »
While this is a good, great price for these batteries, I would say that unless you need them now or within 6 months, I would wait. Especially if you might not need new batteries for a couple of years or more.

This tech is growing FAST. In two years you will get these same batteries or better batteries for even less than this great deal. And you won't have to worry about how to store the batteries, whether they need charging etc etc...and will have a warranty....(with these batteries the warranty is already running...will likely be over by the time you start using them.)

Just IMHO....That said, if anybody has a current EV project in the works or planned, jumping on this great deal would be a very good idea.

Gavin

HighlanderMWC

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Re: battery life?
« Reply #3 on: December 10, 2010, 03:06:03 PM »
While this is a good, great price for these batteries, I would say that unless you need them now or within 6 months, I would wait. Especially if you might not need new batteries for a couple of years or more.

This tech is growing FAST. In two years you will get these same batteries or better batteries for even less than this great deal. And you won't have to worry about how to store the batteries, whether they need charging etc etc...and will have a warranty....(with these batteries the warranty is already running...will likely be over by the time you start using them.)

Just IMHO....That said, if anybody has a current EV project in the works or planned, jumping on this great deal would be a very good idea.

Gavin

Perhaps you meant this for the thread where they were selling batteries?

Phantom

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Re: battery life?
« Reply #4 on: December 10, 2010, 03:23:54 PM »

Here is an operating temperature range reference I found online about LiFePo batteries in general:

Temperature Range (-20C to 70C) (-4F to 158F)

Source: http://www.iloveebikes.com/batteries.html

protomech

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Re: battery life?
« Reply #5 on: December 10, 2010, 04:43:05 PM »
Short answer, you don't know until you try. 115F is on the upper-end of the operating range for most batteries, and higher temperatures do tend to wear the battery more quickly.

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Leyden Energy hasn't published any real datasheets for their Lithium Ion batteries (Enertia+ and Empulse), but they list these specs:
Discharge: -30C to 60C
Charge: -20C to 60C

Valence has published a datasheet (pdf) for their U-Charge XP batteries used in the Enertia. They list these specs:
Discharge: -10C to 50C (122F)
Charge: 0C to 45C (113F)
Storage: -40C to 50C

See below a pair of performances charts for the Valence batteries. First, the lifecycle graph.

At the max temp, a C/2 charge/discharge cycle allows for 1500 cycles before the battery drops to 80% capacity. Brammo charges the batteries slower than C/2 (800w charger, about C/4), but you're likely to discharge closer to 1.5-2.5C while riding. I don't know what impact a lighter charge or heavier discharge rate will have on the battery life.

After 1500 full cycles (or 3000 half cycles), you're looking at around 5-7 years and 45k miles on the bike. The battery has fallen to 80% capacity (typical range 24-26 miles), and barring catastrophic failure should still be useful as long as you're happy with the range.

Second, the temperature graph. Cold temperatures (below freezing) take a heavy toll on useful capacity, and this is at a C/5 discharge rate. The battery looks like it responds better to warmer temperatures, including up to 45 C.
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webman

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Re: battery life?
« Reply #6 on: December 10, 2010, 07:46:29 PM »
Wow, thanks for the detailed responses, guys!  I'll have to look this data over closely this weekend, but right now, I've gotta catch a plane back home.  Have a good weekend!

eric aka webman
webman, aka eric

brammo vehicle desired:  Empulse 8.0
current rides:  '97 yamaha seca II (low miles, but beater)
'06 honda metro (wife's bike, mostly)
previous bikes:
'97 ducati monster 750
'91 yamaha FZR600
'84 Honda VF750 Interceptor