Battery behavior

[voiceguy]

I read Rich Harman's "Unofficial Segway Battery FAQs" which I found quite helpful (http://www.spinfoot.com/SegwayBatteryFAQ.html) and saw a brief mention about a phenomenon I might have observed today ("There is some early indication that random shutdowns may be a possible symptom of a bad battery") and wanted to possibly add more to the above mentioned point:

[u]THE STORY</u>

I just purchased a pair of fairly used pre-owned batteries (for under $150 so no big investment) for "emergency" spares. I am satisfied with the deal as they lasted longer than I required or expected -- they got me maybe 3-4 miles (that with a lot of stopping to talk to folks around town etc).

I found that when I got down to the 3rd bar -- on acceleration -- the sad/red face came up, slowed me down + eventually, stick shake etc...

I gracefully restarted and gently continued riding to see what would happen. As long as I didn't accelerate quickly, I was able to go maybe 2-3 X as far as when I might attempt a restart on my current (newer) batteries.

As soon as I did anything indelicate, boom, El Red Nino....

This may help clarify the "...some early indication" and "that random shutdowns may be a possible symptom..." contained in the above FAQ statement.

After a 2 hour 15 min recharge, I made my way home....

I tested the Random theory out and found that even with a lot of hard accelerations the unit did 100%..not even a hint of shutdown ....until I was 2.5 or so bars down -- not too far from 3 -- and had started up a very steep sidewalk. It was precisely when I accelerated going UP that hill that the batteries went "ouch" and my Seg said "beep ..uh, um, duude....beep!" and the rest is almost history...

I shut down, then power assisted up to the top of the steep sidewalk. When I got to the top, I gently glided down the only slightly uphill sidewalk for awhile and then fairly normal sidewalk conditions for maybe 3/4 mile to a mile. When I got down to the good ol' three bars and accelerated at that point ......:-(

[u]Other's Experiences?</u>

A long post, I realize...but with all of the above, I'm interested hear if others have had
similar or almost identical stories/situations.

I am now doing the UBFaqs recondition steps (leaning unit in balance mode until shutdown ... and once again -- till shutdown -- and then (now) charging for 12 or more hrs (with a second 2-3 hour top-off (doing that 2nd tp off just for this reconditioning) to see if performance improves.

[u]My Technical Guess</u>

If I am perceiving this correctly, my battery (or batteries) have/has one or more weak cells.

So the Seg, gleaning that the battery will only give the unit X amount of power for the Y amount of ergs of energy being called for right now says "Ok, Redman, your on stage....now don't let the crowd heckle you much!"

As to that pesky "shutdown after 3 bars" situation; it seems to me that the level meter should be able to compute the drain from the battery during the various aspects of the glide and give a better indication of true potential power left at any given time. Same with the "partial charge looking like fullcharge"
phenomenon (right now with an i167's 12.0 software in any event, a full set of bars after a one-hour charge is of course not nearly the same as a full set after a 6 or even 3 hour fill-up).

Does anyone know if a smarter,
more sophisticated level meter has been incorporated into the i180 or XT?

In any event, I'd welcome other's bar stories ...yeah, I mean I guess I'll listen to those kind of bar stories too
if absolutly neccesary....


Voiceguy
"A journey of 1000 feet...begins with but a single lean foreward"

[austin@SOH]

We had bought a used i167 for a demo machine a couple months ago and was getting the same symptoms. The machine was used in tours and had a few hours on it. When I would try to really push it, I would get the red face. I talked to a few people and they suggested trying the battery conditioning, the only thing is instead of only once or twice, complete 5-6 full discharges. That is what a lot of tour companies use from what I hear and a lot of times it will restore some of the worst batteries.

Austin Colby (Austin@SOH)
Segway of Hagerstown
339 West Antietam Street
Hagerstown, MD 21740
Phone: (301) 766-0488 Mon-Fri 10am-6pm EST
Fax: (301) 766-0215

[W9GFO]

I have a set of batteries that showed no improvement until the eighth full charge/discharge cycle. When leaned against a wall it would go down to three bars in just a few hours. The next time I would check the machine would have already shut off. After that eighth charge it stayed in balance mode for 26.5 hrs. A sudden, significant improvement.

Rich H

The Un-Official Segway Battery FAQ
http://www.spinfoot.com/SegwayBatteryFAQ.html

[Ground Loop]

voiceguy, I think we will have a growing club as the number of aging 1st gen HTs grows.

You probably have the same problem as I, one or two weak cells that give up the ghost long before the others. I get the red face with four bars remaining, sometimes more. The gauge doesn't predict bad cells, and expects them all to hold full capacity.

As soon as one of your four battery blocks drops below 36ish volts, we get the sad face. The other three might still be perfectly fine, but we get to push it home.

I have to say I'm not impressed with the SAFT cells. Mine have around 50 charge cycles on them, mostly shallow discharges, and I was very meticulous about caring for them as instructed. I expected longer life.

It's clear batteries will be the highest recurring cost of Segway ownership. Much more per mile than any of my cars. :(

[Ground Loop]

quote:Originally posted by W9GFO
After that eighth charge it stayed in balance mode for 26.5 hrs. A sudden, significant improvement.


I'm curious to know how many rider miles you get out of it. I wouldn't be too surprised if the bottom drops out of that cell again after putting some load on it.

[panderso]

Put me on your list as well. I have already done the reconditioning and swapping the batteries. I still get the red face with the wrench symbol on the middle right side. I am being told by my dealer that it probably is the powerbase. Hopefully, it is just the batteries(less expensive solution)

[panderso]

Question? When you all are getting the red face and power shutdown do you try to start it up again? If so, does it power right up after the first try or numerous attempts? Also, has anyone had it never start up again.
So far my experiences are that sometimes it starts right up and sometimes it takes a few tries. So far(knock on wood) I have not gotten stranded away from home.

[voiceguy]

Panderso,

Well, I seem to always get a restart where I can glide some distance before shutdown again. I try not to do it more than once so as to leave some charge in the batteries (as I understand it, it's not good to fully discharge NIMH batteries all the way down to 0 -- maybe someone with more battery knowledge can explain why, or if that's true)

In my original post above, when I say I restarted, it was basically right away (or after a minute of "rest" time).

Voiceguy

"All I need is a full battery ... and a star to steer her by"

[Mr. Protocol]

The shutdown you're seeing when you accelerate quickly with three bars showing may not be indicative of a few bad cells. I think there's a strong possibility that it's due to increased internal resistance across all of the cells. This is something that happens when batteries reach the end of their useful life. As the packs continue to age, this sensitivity to high load will happen sooner and sooner in the discharge cycle.

[W9GFO]

quote:Originally posted by Ground Loop


I'm curious to know how many rider miles you get out of it.


Me too...

Rich H

The Un-Official Segway Battery FAQ
http://www.spinfoot.com/SegwayBatteryFAQ.html