Battery charging BEST practice

[asifjahmed]

I know that most of us (myself included) plug in our glides whenever we are not using them.

I myself have done this ever since i got my first i167.

However, lately I have been hearing people mention that they do not charge their units until the battery is low.

Can someone corroborate one of these methodologies?

I would like to get to the bottom of this and have an official BEST PRACTICE.

I know that Segway says to always keep it plugged in, but i'm hoping someone has more technical evidence to support this.

Thanks

Asif

[Tarkus]

Leave it plugged in.
I've done both and without scientific, specific gravity of what cells gobbledegoop, the ones left plugged in have better range than the one I let run lower.

Be Big,
Alan

[polo_pro]

I know that most of us (myself included) plug in our glides whenever we are not using them.

I myself have done this ever since i got my first i167.

However, lately I have been hearing people mention that they do not charge their units until the battery is low.

Can someone corroborate one of these methodologies?

I would like to get to the bottom of this and have an official BEST PRACTICE.

I know that Segway says to always keep it plugged in, but i'm hoping someone has more technical evidence to support this.

Thanks

Asif

I can summarize things very succinctly. People who wait to charge Li-Ion batteries till they get "low" enjoy annoying their dealer and begging Segway INC to make up for their mistakes. Yes I know that's harsh. But it's the realities.

Very simply when a Li-Ion battery drops below a certain voltage, it won't charge. So that means that when someone let's their Li-Ion battery get low, and then waits a day or two, they're hoping the passive current drawn by the segway when it's off won't cause the Li-Ion battery to drop too low. What's the reward in this situation...what's their motivation? Well, these folks think they MIGHT get one more charge out of the batteries a couple years from now.

When in reality, they find out they've lost hundreds and hundreds of charges and made their segway inop for a month or two while they get new batteries.

So....keep your Li-Ion batteries plugged in. It's simple. It's easy. Don't whine about it. 8^) 8^) 8^)

ps - None of what I've said applies to NiMH. That's a different type of battery that needs conditioning OCCASIONALLY. Oddly enough this means that you're suppose to draw down the battery to a very low energy state. But this is OK, because NiMH will still take a charge...there's no cut off point where the voltage in the battery got too low.

I think this is the source of the confusion for some people when charging their Li-Ions.

[KSagal]

I spoke to Doug Field, the Technology Manager at Segway Inc. for what he does with his own segways...

He leaves them plugged in.

While I don't know his exact title, I do know that I do not know another person with more complete knowledge of segways and their batteries...

Asked and answered. Best Practice = leave plugged in when not in use.

[byped]

The battery is truely the thorn of a Segway. Most other things are nominal and quite industrial strength; however, the notion of absence on charging is a real liability.

IMO, it's the last of the really big technical shortcomings from an "appliance" perspective.

[Eric Payne]

...IMO, it's the last of the really big technical shortcomings from an "appliance" perspective.

I agree.

You know, when I was a kid, on our bikes we had those generators that used the rotation of the wheel to twirl a dynamo which would generate current to light our headlights... and the faster we went, the brighter the beam of the headligh. With technology being what it is today, isn't there some variant of that which might, possibly, delay the discharge of batteries, giving longer range?

No, I'm not talking some type of perpetual motion... but it just seems to me, having a very rudimentary "passing interest" sort of knowledge, there appears to be a bit of energy being wasted simply by the high-speed rotation of the tires which could, possibly, be funneled back into the unit.

Eric Payne
Glendale, AZ

[asifjahmed]

It's definitely an idea to toy around with, but I do know that the Segway uses regenerative braking, thus doing exactly what you are talking about, just not the entire time the unit is running.

Also, I would think that the nominal amount of current being produced by such a generator would be mostly, if not all canceled out by the additional resistance applied to the wheels.

Just my $.02

Best Regards

Asif

I agree.

You know, when I was a kid, on our bikes we had those generators that used the rotation of the wheel to twirl a dynamo which would generate current to light our headlights... and the faster we went, the brighter the beam of the headligh. With technology being what it is today, isn't there some variant of that which might, possibly, delay the discharge of batteries, giving longer range?

No, I'm not talking some type of perpetual motion... but it just seems to me, having a very rudimentary "passing interest" sort of knowledge, there appears to be a bit of energy being wasted simply by the high-speed rotation of the tires which could, possibly, be funneled back into the unit.

Eric Payne
Glendale, AZ

[hellphish]

Also, I would think that the nominal amount of current being produced by such a generator would be mostly, if not all canceled out by the additional resistance applied to the wheels.

Thermodynamics agrees with you. The only things you can harvest from a segway in motion would be heat or moving air.

[quade]

No, I'm not talking some type of perpetual motion... but it just seems to me, having a very rudimentary "passing interest" sort of knowledge, there appears to be a bit of energy being wasted simply by the high-speed rotation of the tires which could, possibly, be funneled back into the unit.

The First Law of Thermodynamics (http://en.wikipedia.org/wiki/First_law_of_thermodynamics) would prevent such a device from putting into the system any more energy than would be taken out of the system by the friction and heat losses of creating it.

In other words, trying to do this would only make the device less efficient than it already is.

[jgbackes]

But... If you could harness the wasted heat energy from the top of the batteries and motors you'd have something. There are a few people right now working on heat to electricity panels. Basically taking the infra-red energy (heat) and using that to drive a solar cell like device.

If only hoping made it so!

[Segdoc]

Polo,

My first Segway was a new i167 that was a year old and had been ridden about 2 hours in that year and the owner kept it plugged in all the time. When I bought it the first thing I had to do was to buy 2 new li-ion batteries. Since then I have had 7 (Segway years- Segways owned x years of ownership) using my method of charging when the battery is pooped, not before with no battery failures. My last battery failed after 14 months and less than 20 recharges. My i170 is nearing 3 years old with the original batteries that are charged only when on the last bar and they are doing fine.The last one failed me on a new XT. This XT had sat with fully charged batteries for one week when I found the defective pack. This was well within the factory recommendations. My new battery came with the following factory instructions:

"In order to maintain the best performance from your Segway PT battery packs, fully charge your battery packs for at least 12 hours, once a month or once every 12 hours of operation, whichever comes first." "Do not store your Segway PT or battery packs for more than one month without fully charging the battery packs at least once every 30 days. Allowing the packs to fully discharge over time could cause permanent damage." "Even if you will not be using your Segway PT for an extended period of time, you should leave it plugged in to AC power".

This certainly sounds like an option to the way you want to keep your battery packs charged.

Marsh

[Segdoc]

Li-ion battery exposed:

http://img.photobucket.com/albums/v24/TheMetalDoctor/DSC02301.jpg
http://img.photobucket.com/albums/v24/TheMetalDoctor/DSC02302.jpg

There seems to be significant circuitry in the battery to control charging and cell balancing. Guess this is where the replacement charge is....

Marsh

[polo_pro]

My new battery came with the following factory instructions:

"In order to maintain the best performance from your Segway PT battery packs, fully charge your battery packs for at least 12 hours, once a month or once every 12 hours of operation, whichever comes first." "Do not store your Segway PT or battery packs for more than one month without fully charging the battery packs at least once every 30 days. Allow the packs to fully discharge over time could cause permanent damage." "Even if you will not be using your Segway PT for an extended period of time, you should leave it plugged in to AC power".

This certainly sounds like an option to the way you want to keep your battery packs charged.

That's sound advice from the factory. They seem to want owners to use their segways at least once a month in a manner which draws down the battery almost completely and then immediately charge it for 12 hours. And if "monthly" isn't clear enough, I'll interpret their next option as "every tenth time".

Clearly they don't want someone to draw down the batteries only half way every single time again and again and again for months on end. I'm going to hazard to guess that's because the weakest cells in the pack are being put under the most strain in that situation (without a chance for "balancing" to occur). But now I'm starting to interpret their advice...and I should leave that to the more technically capable SC members (bystander...that's your cue).

Any way you look at it, leaving Li-Ions unplugged for extended periods of time is a bad idea. You're playing Russian roulettes with your batteries. I'll also readily agree that leaving them plugged in isn't a "cure all". But if you're not going to ride your segway regularly and hard (say in polo...you knew that was coming, eh?), well, I think it's the best course of action to leave them plugged in (vs not).

ps - While I wrote up my original response, I did remember a time when desert_seg said that he'd had a Li-Ion go bad that HAD been plugged in for an extended time. So I'm not trying to claim that it'll never happen...just that you're improving your odds of having working batteries if you take the stance of keeping it plugged in all the time.

In a sense it's a shame that the CSB doesn't have a timing mechanism built into it that drains the batteries and charges them back up fully every month. But that'd add alot of complexity, and I'm sure users would be pissed if every so often they reached down to use their segway and found it in the middle of this "extended discharge/recharge" that'd likely take a day and a half to do.

[bentbiker]

Clearly they don't want someone to draw down the batteries only half way every single time again and again and again for months on end.


I have read and re-read INC's instructions and I don't see how you can conclude that they want a total discharge once a month. They merely say that in the worst case, you need to put them on a charger for at least 12 hours every 30 days. When they say to fully charge the batteries, they don't say "from a fully discharged state."

[PeteInLongBeach]

I have read and re-read INC's instructions and I don't see how you can conclude that they want a total discharge once a month. They merely say that in the worst case, you need to put them on a charger for at least 12 hours every 30 days. When they say to fully charge the batteries, they don't say "from a fully discharged state."

Right. And I followed the advisory in the i180 manual when I decided to keep it in the RV. Inferring from the instructions, it appeared OK to leave the machine for 2 or 3 weeks without plugging in, and indeed there was very little charging necessary after such periods. And I only did this on a couple of occasions before others advised that there might be an issue with the early Li Ions, and keeping them disconnected while in storage was the safer thing to do. But, INC's documentation did not say anything about battery problems if the machines are off charge for less than a month.

[bentbiker]

Right. And I followed the advisory in the i180 manual when I decided to keep it in the RV. Inferring from the instructions, it appeared OK to leave the machine for 2 or 3 weeks without plugging in, and indeed there was very little charging necessary after such periods. And I only did this on a couple of occasions before others advised that there might be an issue with the early Li Ions, and keeping them disconnected while in storage was the safer thing to do. But, INC's documentation did not say anything about battery problems if the machines are off charge for less than a month.
Pete,

Just from the postings on here, my conclusion is that there are way more failed batteries (including NEW units) than is acceptable. Having now seen the complexity of the circuitry (in SegDoc's pictures), I'm not surprised. That being the case, I'd think some kind longer warranty is going to be necessary once the word gets out -- maybe even a prorated warranty extension would be worthwhile. If, during the first year of warranty, an owner purchased a six year extension for perhaps $100, the warranty would cover you totally for another 2 years and then drop linearly over the next 4 years. The thought of paying $800 to $1600 after as little as 13 months of use, is really unpleasant. The automotive industry is struggling with this very thing as they try to figure out what to do about the battery packs in the "expected" plug-in hybrids which will cost many thousands of dollars.

Bottom line, I don't think anything you did or didn't do caused the problem; I think you just have one more of the numerous failing batteries.

[glen_d]

My comment is a side note about following Segway's charging advice.

I have an i180 and an i2, both running lithium ion batteries since new. They are used for distances much less than 24 miles, then plugged in for charging. I keep them on a charger all winter (power filtered through a surge protector) when they get very little use at all. The i180 is over 2 years old with about 750 miles.

After a year of short runs immediately followed by 16 hours of charging, the battery meter on my i180 was very inaccurate. It would show an 80 - 90% discharge after 3 miles. So I leaned my i180 up against a wall to fully discharge it. The Segway shut itself off some time in the middle of the night. Next morning, I plugged it in and let it charge for about 18 hours. Now the battery meter is accurate again. I had to do this last year too.

So at least on my routine, I'll need to fully discharge the battery once a year to reset the battery meter. Otherwise . . . I can't discern any benefit to fully discharging a li-ion, nor any detriment to leaving the unit plugged in.

Glen

[dynk]

When I purchased my first Segway (an i2) last month, the salesperson told me to keep it plugged in whenever not in use.

My only question now, is: What about in our New England Winters? Do I keep it plugged in when not in use for 2-3 months?

[polo_pro]

When I purchased my first Segway (an i2) last month, the salesperson told me to keep it plugged in whenever not in use.

My only question now, is: What about in our New England Winters? Do I keep it plugged in when not in use for 2-3 months?

I'd say "yes". And I'd even recommend one more step. Mid winter, unplug it, turn it on, let it gently fall against the wall and leave it like that until the battery runs out. It'll take a day or two of pushing gently against that wall for this to happen. Shortly after this happens (not more than a day), charge it up fully for at least 12 hours. Then go back to leaving it plugged in all the time.

While this exercise causes you to lose one of your Li-Ion battery's 500 charges, I believe it'll also minimize the chances of finding you've lost all the rest of the charges in your battery at the end of the winter (with a big ugly red LED glaring at you). However, I'll also point out that I'm not employed by Segway INC (nor do I own an i2). In other words, how much did you pay me for my advice? $0? Ah well, you get what you paid for! 8^) 8^) 8^)

ps - I'm assuming you keep your i2 indoors throught the winter. I'm not talking about the garage. I'm thinking nice cozy warm living spaces.

[bystander]

When I purchased my first Segway (an i2) last month, the salesperson told me to keep it plugged in whenever not in use.

My only question now, is: What about in our New England Winters? Do I keep it plugged in when not in use for 2-3 months?Answer:

Yes, what the salesperson told you was correct.

Comments:

By the way, although the PT "eats" 120-140 watts when charging, it will not be using up that much energy continuously during it's 2-3 month "Winter vacation".

When both green LEDs are on, it's consuming 120-140 watts, but when the LEDs are blinking often, it's a fraction of that (approx 1/6, or 20-24 watts). And when the green LEDs are occasionally blinking, it's less than that. I don't know exactly how little it will draw during a 2-3 month duration, I don't have any empirical data on that. Perhaps we could get a follow up to the whitepaper concerning economy (http://www.segway.com/downloads/pdfs/energy_efficient_segway_whitepaper.pdf) that would shed some light on this aspect of PT ownership.

If (and that may be a pretty big "if") the PT averages 5 watts for the 2 -3 months of idle storage, and if you pay $0.10 per kilowatt hour, that could come out to about $0.72 to $1.08 for the entire period, or 1.2 cents per day.

If the PT averages 10 watts on idle then the figures would be double, or 2.4 cents per day.

If the PT averages 2.5 watts on idle then the figures would be half, or 0.6 cents per day.

Since my PT is still slightly warm to the touch after 24 hours of charging (it's definitely in the "occasional blink" stage by then), I suspect it may be drawing at least 10 watts.

The current measuring equipment I use to monitor the wattage draw is not accurate when used on the pulsing method employed by the PT charger, once it gets to the "occasional blink" stage. So I can't tell the precise amount with the tools at hand.

P.S. I would definitely take Steve's (polo's) advice about storing in non-frigid regions over the winter, but would hesitate to follow his advice about the one-time discharge.

What I would do is wait until Spring, and see if the blinky gauge is still accurate before taking such action. If blinky is still indicating accurately, there's no need to take corrective action.

And on Saphion, you don't need to rest the PT against the wall the whole time (may take up to 30 hours?). On Saphion you can ride it down to the last bar, and _then_ lean it against the wall in balance mode. You're just recalibrating the gauge, not reconditioning the packs.

And "500" lifetime charges may be conservative. Could be 1000, could be more (http://forums.segwaychat.com/showpost.php?p=150318&postcount=36).

[glen_d]

While this exercise causes you to lose one of your Li-Ion battery's 500 charges, I believe it'll also minimize the chances of finding you've lost all the rest of the charges in your battery at the end of the winter (with a big ugly red LED glaring at you).

Why?

Glen

[shep]

If the PT averages 10 watts on idle then the figures would be double, or 2.4 cents per day.


My measurements indicate it draws about 11watts in the idle state. This measured in watt hours over a 24 hour period. YMMV.

What might be interesting to some, I've hooked mine (i180+lithium) up to a solar panel->charge controller->battery(12v AGM)->inverter. Watching the DC current out of the 12v battery (with solar panels disconnected just for purposes of measurement) I notice the i180 draws 10.0A with the battery at 12.65v while charging. While idling, as each LED blinks on, it draws 5A and on the odd occasion where both LEDs blink on simultaneously, the draw goes, as expected, to 10A. While the LEDs are off, the current is only slightly more than the quiescent current drawn by the inverter (about 0.125A).

[polo_pro]

Why?

Weak cells that lose charge more rapidly under slow charge are brought back to full capacity. This essentially is "balancing" and seems prudent if you plan to leave a set of batteries for months on a charger. But like I said above...I'm not a segway employee. I'm just a guy giving advice....or maybe I'm just starting rumors! 8^) 8^) 8^)

ps - I think what I'm suggesting is beyond the usual "keep it plugged in all the time". I'd think that'd be sufficient, but if you want to do a little more then you can try what I'm suggesting. I'm not trying to claim your batteries will be worthless after charging for a winter. I've heard of isolated cases of this, but no epidemic.

[bystander]

Weak cells that lose charge more rapidly under slow charge are brought back to full capacity. This essentially is "balancing" and seems prudent if you plan to leave a set of batteries for months on a charger.
This advice is sound for NiMH PT batteries, as they do not have any built-in cell balancing circuits.

But the Saphions for PT _do_ have built in cell balancers, and they work just fine, - when the user keeps the PT plugged in.

That's what your $2.38 over the Winter is paying for, a healthy, happy, well-balanced Saphion battery - LOL.

If you want to pick nits over NiMH, there are cases where a long-term unattended charge would be a bad idea. If there are a number of brown-outs or brief power-outs over the 2-3 months, the charger will cycle back to full-charge mode each and every time. If it only happens once or twice, the system can take it. But if it happens dozens of times over the 2-3 months the NiMH packs will become overcharged and damaged.

In such situations (unattended NiMH charging over months) a UPS is a wise precaution. Either that, or fully charging the NiMH batteries, then disconnecting them from the PT, once each month. But that's kinda high-maintenance at that point.

The Saphion charger, when reset by a brown-out or short power-out, will go to full charge at first as well. But only briefly, as it is intelligent enough to know to revert to trickle charge if it finds the batteries are already charged. At the 2006 Segfest, the Segway engineers mentioned that the more sophisticated Saphion charging cycle can go both forwards and backwards in charging sequence, as conditions permit. (think packs cooling down in a cool room after a hot day's use) The NiMH cycle is one way only, and does not adapt as well to changing conditions.

...8^) 8^) 8^)...
Now those are happy smilies? sarcastic smilies? "lazy"-rolled over smilies? big-grin, google-eyed similes? they don't look like "winking" smilies. I just don't want to miss-interpret and knock this thread even further off-topic. - LOL (in this case, I intended that to mean "Laughs Out Loud", which is what I'm doing (sometimes) while I'm typing this - just to be clear)

My measurements indicate it draws about 11watts in the idle state. This measured in watt hours over a 24 hour period. YMMV.

What might be interesting to some, I've hooked mine (i180+lithium) up to a solar panel->charge controller->battery(12v AGM)->inverter. Watching the DC current out of the 12v battery (with solar panels disconnected just for purposes of measurement) I notice the i180 draws 10.0A with the battery at 12.65v while charging. While idling, as each LED blinks on, it draws 5A and on the odd occasion where both LEDs blink on simultaneously, the draw goes, as expected, to 10A. While the LEDs are off, the current is only slightly more than the quiescent current drawn by the inverter (about 0.125A).
Re: 11 watts, thanks for that datum.

And yes, the two sides of the charging system, as indicated by the two green LEDs are independent, each "side" drawing about 60-70 watts while the corresponding green LED is lit. And the duty cycle of the blink determines the average draw.

If 11 watts are being drawn in idle mode on average, then the duty cycle is approx. 8.5%. So, (11 x 24) 264 watt-hours each day for 90 days, a total of $2.38 for the "Winter".

[ryan_walters]

Re: 11 watts, thanks for that datum.

If 11 watts are being drawn in idle mode on average, then the duty cycle is approx. 8.5%. So, (11 x 24) 264 watt-hours each day for 90 days, a total of $2.38 for the "Winter".


In my measurements, I got a 4 watt average. As per this post:

http://forums.segwaychat.com/showpost.php?p=139368&postcount=47

I calculated a month would be 2.88 kw/h. With the current price of electricity here, that would be $0.25 - $0.30 a month.

[bystander]

In my measurements, I got a 4 watt average. As per this post:

http://forums.segwaychat.com/showpost.php?p=139368&postcount=47

I calculated a month would be 2.88 kw/h. With the current price of electricity here, that would be $0.25 - $0.30 a month.It appears your device measures watt-hours for an extended period. I am curious what sampling method the device uses. If it's expecting an steady load, but the load changes quickly, there may be a discrepancy between actual power and indicated power.

Some types of power measuring equipment expects a steady flow of power and makes certain (incorrect) assumptions about the average power flow. These types of meters can be confused when the power is pulsating, as it is when the PT is charging in what we're calling "idle mode" (The part of the charging process long after the main charge is completed, when the LEDs are blinking occasionally).

Based on the warmth the PT chassis produces, I tend to think that the 11 watt figure is closer to the actual amount than a figure of 4 watts. I suspect that the 11 watt figure may be conservative.

I'm sure the "actual" amount varies from machine to machine. I'm not saying your metering equipment did not indicate a figure of 4 watts. It may well have, the problem is the meter may have been faked out by the pulsing.

What I am asking is, would a 4 watt heater with a couple of square feet of surface area (such as the PT chassis) be as warm to the touch as it is? Perhaps your PT doesn't get as warm as mine?

Of course, it would be better that the figure was 4 watts, for economy purposes. I wish I new a better way of determining the actual value with less uncertainty.

But we're looking at $2.40 vs. $0.90. Maybe it's not worth arguing about, eh?

P.S. Would you happen to have a link to the user manual of the "kill a watt"? I looked on the P3 website (http://www.p3international.com/products/special/P4400/P4400-CE.html), but there aren't any there right now.

[ryan_walters]

It appears your device measures watt-hours for an extended period. I am curious what sampling method the device uses.


P.S. Would you happen to have a link to the user manual of the "kill a watt"? I looked on the P3 website (http://www.p3international.com/products/special/P4400/P4400-CE.html), but there aren't any there right now.



Your right, I don't know the sampling rate it uses. It does show the pulses from 1 watt to 10-20 watts quite clearly though. These pulses (in current) are when you get a longer 'blink' (like it does in balance charge mode) instead of the quick flashes of maintainence mode. I don't have anything that will give me a real time data output of AC watts. My battery analizer gives me dc voltage readings 3 times per second, but can't measure anything ac, let alone correct for power factor.

I've never noticed my segway warm at all (above ambient) after being in maintainence mode charge for a while.

I don't have a manual for the kill-a-watt. I was actually only borrowing one from work for a while. The manual probably wouldn't have that kind of detailed information anyway. The company themselves might be able to tell you, as long as they understand what is being asked.