Battery Chat Questions Thread

[jgrohol]

If you would like to have certain questions answered in tomorrow night's chat but are going to be unable to make it, ask them here and hopefully someone can ask them on your behalf! We hope you can make it at 7:00pm ET Wednesday evening for the chat.

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All views expressed here are my own, not necessarily those of my employer or others. Check out http://grohol.com/.

[W9GFO]

The I series is advertised as 72 volts, yet each battery has two 36 volt outputs. Are the 36v outputs combined inside the base to make 72v, or was it just easier to call it 72v because each battery has 60 cells?

Rich H

[W9GFO]

When discharging the HT by leaning against a wall, how does the Seg determine when the voltage is too low to continue? Is the cutoff voltage determined by measuring each group of 30 cells or each block of ten cells?

Rich H

[W9GFO]

I have gathered quite a number of "bad" batteries. Batteries that give no light when charging, those that give a red light when charging and of course those that will show a green light, yet not charge. I have tested litterally hundreds of cells and have not yet found even one cell that failed to take a charge. On batteries that were capable of taking a charge I have successfully brought them back to life and they continue to perform well. Those that will not take a charge (on the HT), I have tested and found the cells to be ok but they will not work on the HT. Is it a circuitry or software failure?

Can you comment on the different failure modes of these batteries?

Rich H

[sholloway]

Theoretically, what would be the range when the new LIon batteries come out?

[W9GFO]

It is my opinion that the HT would benefit from a discharge cycle that discharges each block of ten cells equally and fully. For example, when leaned against a wall with no rider detects depressed, the HT would independently discharge each block to .9v/cell or whatever is the lowest aceptable voltage. Discharging this low would mean that if a rider detect was pressed after passing the cutoff threshold, the HT would go into a safety shutdown.

Was this considered? If so, why not implemented?

Rich H

[W9GFO]

During regenerative charging, are the cells charged through the same circuitry as when plugged in? In other words, is each block of ten charged independently or are the cells charged through the outputs (30 cells), bypassing the charger contained within the battery pack?

Rich H

[W9GFO]

When new batteries are available, will they work on machines running version 10 and 11 software?

Rich H

[W9GFO]

Consider a Seg that cannot be left plugged in more than 12 hours. It also cannot be run down. If it has not been used, which is better;

a. plug it in everyday for the twelve hours

b. plug it in once a week

c. something else?

Rich H

[dzdk6s]

Originally posted by Solarseg - Very Interesting
Looking for Partners - Applications
Has Segway looked in to these?

Twice the power of lithium ion and four times that of NiMH!
http://www.zmp.com/

[SegwayUtah]

quote:Originally posted by W9GFO

It is my opinion that the HT would benefit from a discharge cycle that discharges each block of ten cells equally and fully. For example, when leaned against a wall with no rider detects depressed, the HT would independently discharge each block to .9v/cell or whatever is the lowest aceptable voltage. Discharging this low would mean that if a rider detect was pressed after passing the cutoff threshold, the HT would go into a safety shutdown.

Was this considered? If so, why not implemented?

Rich, wow, great questions! I'm not sure what the official answers are, but I do know that the HT would need a _third_ mode (power assist, balance mode, and discharge mode) to do this. Since balance mode by definition needs to be able to carry a person instantly when they land on the rider detects, maybe a "orange pulsing" discharge mode could be implemented. Of course, it takes away from the "simpleness" of the HT, but it would be cool.

And of course my question:

Which power technologies look most promising for the Segway HT? We now have Lithium batteries which don't react with oxygen (won't explode) and we have some pretty cool exotic technologies. Superconductors have a few major problems to be worked out, etc. Which ones have been tested, and which of them looks to be the most promising?

Also, I think at SegwayFesT! 2003 last year, the engineering team was hoping to give us more information on batteries at this year's SegwayFest! 2004. Is this a replacement for that discussion and, if not, will anything be ready for October? [We of course want 'standard' Segway quality rather too, :)]

Chris

[W9GFO]

quote:Originally posted by SegwayUtah

but I do know that the HT would need a _third_ mode (power assist, balance mode, and discharge mode) to do this.


I think they could set it up so that the HT only went into this "discharge" mode after remaining motionless for say 30 minutes. After that time, if past the threshold, any movement would cause it to instantly power off.

Rich H

[legpain]

I would like to run the HT from an outside power source. I’ve connected the HT to an inverter and then an external wheelchair battery that’s being charged with a solar panel. Currently when I connect the inverter I’ll get a reduced performance mode and can only travel at about 2-3 mph. Can this be a programming change to have the HT run normal? With this configuration all I can do is charge the HT batteries while I sit and have a cup of coffee…

Thank you,
John

[Sunday]

I recall that the Xootr ex3 used NiMh batteries, and encountered serious issues with them due to the jarring effect of the harsh ride. Does LLC plan on incorporating any type of shock mounting into future battery packs to prevent solder connections from being damaged during harsh and bumpy riding conditions? Has this even been an issue with any battery failures?

Mark

[SegwayUtah]

quote:Originally posted by W9GFO

I think they could set it up so that the HT only went into this "discharge" mode after remaining motionless for say 30 minutes. After that time, if past the threshold, any movement would cause it to instantly power off.

I think the problem is trust in the machine. If the machine doesn't turn "off" in balance mode, it should always be ready to take a rider. Think of President Bush -- he had ultimate trust in the machine (but unfortunately didn't understand that it needed to be turned on). This would happen to many of us if "balance mode" timed out.

Either that, or we would be constantly checking to see if we were really still in balance mode or not when getting on and off quickly (or semi-quickly).

Chris

[Florida Ever-Glides]

Can a DC plug-in ever be available to accomodate a variety of options?...

Tom Jacobson
http://www.floridaever-glides.com

[W9GFO]

quote:Originally posted by SegwayUtah


I think the problem is trust in the machine. If the machine doesn't turn "off" in balance mode, it should always be ready to take a rider. Think of President Bush -- he had ultimate trust in the machine (but unfortunately didn't understand that it needed to be turned on). This would happen to many of us if "balance mode" timed out.

Either that, or we would be constantly checking to see if we were really still in balance mode or not when getting on and off quickly (or semi-quickly).


You would only need to be checking if you left it more than 30 minutes with almost no power left...

I suppose if someone left the Seg against the wall with one blinking bar, and walked away from it for more than 30 minutes, then, upon returning, without touching it, and without looking to see if it was on, jumped up onto it - then they might be surprised to find it non-functional.

I wouldn't have much sympathy for them. I think people have to take a little personal responsibility for their own well being.

Rich H

[Neelix]

quote:Originally posted by W9GFO

Consider a Seg that cannot be left plugged in more than 12 hours. It also cannot be run down. If it has not been used, which is better;

a. plug it in everyday for the twelve hours

b. plug it in once a week

c. something else?

Rich H


Are the hours cumulative? i.e if the batteries are full from a 12 hour charge and it is unplugged, would plugging it back in again immeadiately without running down the battery at all cause it to explode or whatever the consequences are?

How is "run down" determined? Surely the batteries will never become 100% depleted.

*loves logic puzzles*

-------------------------
Fear not, for even though I come from the Forbidden City, I surely do not agree with the rules.
Chris Knight

[Stewbonz]

Re; regenerative braking.
How long of a hill would it be necessary to ride down to re-charge the batteries?

JEFF JARVIS
http://www.thailandsegwaytours.com/

[SegwayUtah]

Rich,

I'm not sure it's even something I want to know, but how much power do you think the HT batteries have left in them when they're "empty"? Is it healthy for them to deplete them further via some other mechanism before recharge?

Chris

[W9GFO]

It is safe to discharge a single cell completely. However, when assembled in packs not all cells will discharge equally. If you try to discharge completely you risk cell reversal which will cause damage.

As it is now, the Seg shuts off at a certain voltage. That cutoff point must have enough energy left to power the seg through a safety shutdown. I also suspect that the lowest block of ten cells will trigger the cutoff.

That means that the block that could benefit most from a deep discharge will not go below that cutoff level and the rest of the cells in the pack are discharged even less.

Rich H

[luckie]

I'm still curious about these two.

1. (Just thinking theoretically)
If my commute back and forth to work each day only consumes 40% of the Segway's full charge, to maximize the longevity of the batteries I should:
a. Charge every other night allowing the discharge to get to 80% before recharging.
b. Charge every night even though it's only used 40% of the charge.


2. (Still thinking theoretically)
Given the Toyota Prius uses NiMH batteries just like the Segway (likely good for 300-500 charges?), and it's charge-recharge cycling must be even more erratic (ie shallow discharge for 15 minutes, followed by brief charge 5 minutes, then discharge in town for 45 minutes, then charge on highway for 30 minutes etc), why would Toyota predict the batteries have a 8-10 year life?


----
Douglas B. Luckie, Ph.D.
Cystic Fibrosis Research Lab
Department of Physiology and Lyman Briggs School of Science
Michigan State University
http://surf.to/msucf
http://35.9.122.184/blinky.gif

[SegwayUtah]

luckie,

The info I've read on batteries (esp. LIon) seems to indicate that a bunch of shallow discharges is much, much better than deeper discharges. If I remember right, I've seen documentation showing full magnitudes (i.e. 2x, 3x, 5x, 10x) of actual battery life when discharges were only 10% followed by a recharge.

Chris

[W9GFO]

I think that is true if your goal is maximum lifetime. However, if you want your batteries to last as long as possible while providing maximum range, I believe deep discharging is necessary. That's for NiMH, don't know much about LiIons. Yet.

Rich H

[ftropea]

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