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Old 01-01-2011, 02:00 AM   #11
Ground Loop
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The DEKA batteries have an odd story. I found two i167 NiMH batteries on eBay back in 2006.
They arrived with none of the standard serial numbers or markings, just "DEKA" stickers. They were also mostly-shot, of course. I never got more than a mile out of them. The seller went mute, of course.

I don't think they were commercial Segway product, but some kind of DEKA pre-production battery. Who knows.

The standard batteries have ID stickers on each pack of 10 cells. These had none.


Does anyone know WTF that GLUE is that Segway uses in the battery packs?? It's insane.. I call it Demon Snot, but I'd love to know what it sells as. I haven't found any solvent that releases it easily. I'm just using a heat gun to soften it up in the extreme, so I can apply crazy amounts of force to lift the old NiMH packs out. With enough swearing, it works.

I have no intention of sealing these LiPo packs, since I don't ride the in the rain, and I have to take each of the packs out for charging and balancing anyway.
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Old 01-01-2011, 09:57 AM   #12
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Quote:
Originally Posted by Ground Loop View Post
...I have no intention of sealing these LiPo packs, since I don't ride the in the rain, and I have to take each of the packs out for charging and balancing anyway.

I wonder if you could incorporate a mechanical A-B switch kind of device, so that you could have one lead that comes out of a future iteration of this battery system. OF course, it would have to be an A-B-C-D-E switch, but you could plug in your charger, then just flip to another letter every couple hours.

It may not be too hard to incorporate a slide or rotary switch into the pack, and have just the knob (or a slot for a screwdriver) thru the case of the battery, which will allow you to put the covers back on.

This is not so much for gliding in the rain, but because this is a lot of power to have uncovered, since the road is full of all sorts of hazards, including puddles, and other potential hazards.
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Old 01-01-2011, 03:59 PM   #13
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It's true, Karl. I'd be better off with a sealed pack (or mostly sealed) even in dry weather.

I think team222badbrad was getting at a similar idea -- discharging in series, and then switching over to a parallel arrangement for one-tap charging.
If the four series "lobes" of the Segway power are discharged to the same level, I will look into doing that..

Charging as a 9S4P configuration, or even a 3S12P would be much easier to wire externally.

I checked the in-battery circuit board, and there are taps between each 12v module, and a whole lot of digital circuitry in there, so I don't think I can pull one over on the Segway by wiring more directly.

Still, ANY miles is better than zero miles and a BEEP BEEP BEEP "get off" going uphill.
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Old 01-09-2011, 01:32 AM   #14
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Another update -- I had to build TWO conversion packs in order to ride. (Alas, I have not a single viable NiMH pack to ride with.)

So far, so good! These cheap 3S battery packs are not a perfect fit to Segway riding -- there are complications.

First, the overall loaded voltage of 9S LiPo is slightly lower than what the Segway wants for NiMH. So right off the bat, with charged batteries, the Segway goes to 3 bars (half) charge indicator. After a couple miles, it's down to 2 bars.

The good news is that this seems to bother it not at all -- it stays on 2 bars for a long time. Without more detailed voltage monitoring, I'm not going to find the limit, but it's good enough to call the Segway serviceable once again.

The 2200mAh 20C packs are probably borderline for hillclimbing or demanding rides. I rode full-speed up some moderate hills, and the packs got just a little warm to the touch -- still below body temperature. I wouldn't try sustained extreme climbs in hot weather, since I effectively have no temperature monitoring on these, and no airflow.

Charging turns out to be easier than I thought.. I just bus all six of the packs in PARALLEL for charging, since they're all discharged the same amount. I bus all the balance taps as well. No problem. The charger treats it as a 3S 13.2 Amp-hour pack, charges at 25 Amps and has them fully done in 20 minutes, balanced.

I removed one of the circuit boards from a junk battery pack, and it's far more complicated than I thought. I was hoping to adjust its notion of "charged" to match the min/max of LiPo, but forget it.
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Old 01-09-2011, 07:28 PM   #15
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Default Lipo battery hack

Greetings fellow San Diegan,

You are to be complimented on your DIY flair, just watch those hobby cells so that they don't add flare to flair ;-)

Have you thought to order up a single 2200mAh cell to add to your 66.6V string? I think that this voltage will still be compatible with the 12.0 firmware, but I'd like to here from you on this.

How much range are you getting?

Keep us posted, please.

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Old 01-10-2011, 10:21 PM   #16
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Since the batteries attach to the BMS in 12V clusters he would have to add cells in multiples of six. Unbalanced battery clusters would result in reduced performance if a single cell were added. We have done the same thing with small SLA and LiFePO4 batteries. It can be done but the like always the OEM charger is not compatible.
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Old 01-10-2011, 10:53 PM   #17
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Hi Jason,

Good to hear from you.

These are 3.7V cells, so I am confused by your suggestion that they would go together in groups of 6 to form 12V clusters. Please clarify for me, if you would.

I believe he is not using the stock BMS board at all, but rather charging in parallel and balancing with a hobby charger.

Thanks,

Jim
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Old 01-12-2011, 05:31 AM   #18
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Correct. I dare not use the Magnetek external or the Segway internal chargers with these batteries -- I'm certainly it would blow them up with a NiMH charge profile.

I'm removing the battery cases from the Segway, and then removing the 3S Lipo's from the batteries to charge on a bench... that's 12 3S batteries, for anyone keeping track.


As you know, the Segway effectively has four strings of NiMH batteries, two in each battery pack. Each string is made up of three 10-cell strings.
So for one voltage rail the Segway has 10+10+10, four times.
It *does* monitor the voltage of each of those 10-cell strings, so I can't spoof it by replacing all three with one large battery pack.

Instead, I have 3S + 3S + 3S in LiPo, each one replacing a string of 10 NiMH.

I would very much like to try "3S + 4S + 3S" to see if the Segway complains about inequality, or abuses the 4S pack, or just corrects the battery gauge.

Given the discharge curve of LiPo, I'm not all that concerned with the low battery bars, since it will just park at "two bars" for most of the useable range.
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Old 01-12-2011, 05:35 AM   #19
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First, this is what the PCB inside the battery looks like:


It's quite a bit more than I was expecting, and dashed any hopes I had of a full roll-my-own battery pack. Wow.

Notice the steel battery tabs at the top, which are bent over the top of the PCB. For my second battery pack conversion, I thought I'd try to be cleaner and replace the battery tabs entirely, by soldering the 12ga wire to the PCB.

That wasn't an effort I'd like to repeat. It required drilling holes in the back of the battery just to get to the solder tabs:


The resulting battery looked fine, and had fewer sharp edges, but was a more strained fit with the large wires coming over the top:


And the Zippy/HobbyKing XT60 connectors are actually pretty awesome, especially since they come on the batteries already. HK sells the female connectors, with leads already soldered, so this is pure Win. I like them.

I think I'm going to make a third assembly, using XT60 connectors (again) and soldering to the cut-off battery tabs. Then I'll have all 12 batteries on the same connector, which would be nice for massively-parallel charging.

If I was doing this over again, and not so bent on using cheap $8 batteries, I think 4000mAh or even 5000mAh of the right dimensions would be the way to go.

I'd like to find a way to bring the required leads out of the Segway for charging without so much screwdriver time, too.
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Old 01-12-2011, 10:04 AM   #20
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Default Roll your own battery pack?

Quote:
Originally Posted by MTOBATTERY View Post
Since the batteries attach to the BMS in 12V clusters he would have to add cells in multiples of six. Unbalanced battery clusters would result in reduced performance if a single cell were added. We have done the same thing with small SLA and LiFePO4 batteries. It can be done but the like always the OEM charger is not compatible.
My confusion, here. Ground loop was talking about NiMH, and I had convinced myself that Safions were LiPo, when it seems they are LiFePO4. The hobby packs are made from stacks of prismatic cells. Adding another identical cell in series with those 1P packs should not unbalance anything. I'd try carefully to open up and remove a cell from one of the $8 packs (you did buy extras?)

Quote:
Originally Posted by Ground Loop View Post
Correct. I dare not use the Magnetek external or the Segway internal chargers with these batteries -- I'm certainly it would blow them up with a NiMH charge profile.

I'm removing the battery cases from the Segway, and then removing the 3S Lipo's from the batteries to charge on a bench... that's 12 3S batteries, for anyone keeping track.


As you know, the Segway effectively has four strings of NiMH batteries, two in each battery pack. Each string is made up of three 10-cell strings.
So for one voltage rail the Segway has 10+10+10, four times.
It *does* monitor the voltage of each of those 10-cell strings, so I can't spoof it by replacing all three with one large battery pack.


Instead, I have 3S + 3S + 3S in LiPo, each one replacing a string of 10 NiMH.

I would very much like to try "3S + 4S + 3S" to see if the Segway complains about inequality, or abuses the 4S pack, or just corrects the battery gauge.

Given the discharge curve of LiPo, I'm not all that concerned with the low battery bars, since it will just park at "two bars" for most of the useable range.

I have only taken apart the Lithium pack. Thanks for the details and the photos. You might spoof it effectively if you were to feed it N fake voltage signals, or copies of one rescaled voltage value for the whole pack. If the goal is to keep your lithiums from undervolting during a glide, the stock NIMH circuit may not be calibrated to save an 11.1v cluster if it expects a 12V cluster as I think Jason wrote.

If the Seg's undervolt threshold is 0.9v per cell, then it will stop you (presumable shake stick and shut down) at 7.2v per cluster. Lithium Polymer cells, I've read, have a cut off at 2.5v per cell or 7.5v per hobby pack. If the Seg's cutoff is 1v, then you are fine. May I suggest, if you haven't seen them, inexpensive audible alarm mini-boards for your packs. Some can be seen in the accessories section at Hobby shack.

Do you or anyone else know what info and in what format the Segway control board "must"get from the battery control board? Aside from battery power, I only saw four pins leaving the battery housing; anyone know what they have on them? If we have clusters of 12v, then these pins can't be sense pins for the 6 clusters. Please don't tell me there is a CAN channel here. I'd just as soon be rid of the batt control board if it isn't performing a charging function, and the main board can be convinced to do without it.



Quote:
Originally Posted by Ground Loop View Post
First, this is what the PCB inside the battery looks like:


It's quite a bit more than I was expecting, and dashed any hopes I had of a full roll-my-own battery pack. Wow.

Notice the steel battery tabs at the top, which are bent over the top of the PCB. For my second battery pack conversion, I thought I'd try to be cleaner and replace the battery tabs entirely, by soldering the 12ga wire to the PCB.

That wasn't an effort I'd like to repeat. It required drilling holes in the back of the battery just to get to the solder tabs:


The resulting battery looked fine, and had fewer sharp edges, but was a more strained fit with the large wires coming over the top:


And the Zippy/HobbyKing XT60 connectors are actually pretty awesome, especially since they come on the batteries already. HK sells the female connectors, with leads already soldered, so this is pure Win. I like them.

I think I'm going to make a third assembly, using XT60 connectors (again) and soldering to the cut-off battery tabs. Then I'll have all 12 batteries on the same connector, which would be nice for massively-parallel charging.

If I was doing this over again, and not so bent on using cheap $8 batteries, I think 4000mAh or even 5000mAh of the right dimensions would be the way to go.

I'd like to find a way to bring the required leads out of the Segway for charging without so much screwdriver time, too.
I think the right number of 3.7v cells in series for the 12.0 firmware is likely 19, not 18 and not 20. Prime numbers can be inconvenient ;-)

If you build a third assembly, let me offer you use of my Fein cutting tool and help you part the top at the original weld line. You should be able to get at the old charge board this way. I have been searching for hobby-priced cells that will fit in a larger Lithium Segway battery shell I recently opened. 10Ah per shell may be possible - 1.5kWh per Glide!

Either way, I have an electric bike project and want to buy some of the $8 packs, so, If you want to combine shipping, let's talk. I also have a battery test unit and some data logging capabilities in my shop in El Cajon, in case you are interested.
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