I don't understand that logic. Please explain.

Well, let’s say there’s nothing wrong with the batteries themselves, but the charging circuit has a problem.

If I run them down all the way - to the point beyond being able to power up my Segway - we’ve got a problem. At that point, I’ve got two dead batteries that may or may not come back AND a faulty power base.

But if I leave “some” charge in the battery, at least the seller can swap these batteries into another power base and figure out if the problem follows or not. If the problem is the batteries, fine, they’ll swap it out. Same for the powerbase.

So I’m playing with it overnight - leaving the batteries out altogether to hopefully “force” the Segway to reset itself. I don’t believe there are any storage capacitors onboard so this “should” do a full reset, in theory.

Again, the initial thought was around temperature, but the garage heater has been on 24x7 all week (I do not want to see that electric bill!). It’s averaging about 64 degrees in there, which I’m assuming should be sufficient to charge, yes?

Well, I assumed (bad I know) that we all know what happens to a dead Seg battery when you leave it sit long enough without recharging it

If I'm going to run them dead on purpose, I sure would want to be able to recharge them ASAP

If they won't charge when they have a 30% SOC, they're probably not going to charge when they're down near 0% either

Don

And if the problem is with the "calibration" (i.e., the Infokey is incorrectly showing the state of charge)? - that is, neither the batteries nor the powerbase?

Note that the calibration procedure (in the instruction manual) does not discharge the battery to zero. The Segway (if operating properly) will turn off at the point where the batteries can be recharged. That's the same point that it would, if gliding, do the "stick shake warning" and shut down.

Please keep us informed as things develop.

My guess (and yes, just a guess!) is that the calibration isn’t really the issue since the battery depletion has been about as I would expect. So it’s not as if the gauge is “stuck” per se - it’s going down as I use the battery.

I also suspect it’s not a calibration issue since the charging lights go green and stay solid green - even after a full day, no blinking at all. If the batteries were really “topped off” and just the gauge was out of whack, the lights would blink, right? I’d rather leave a little charge in the battery if I can, rather than bring it down to stick-shaker level. If nothing else, that’ll make it easier for me to move it around if I have to pack it up.

Unfortunately I don’t have the gear to check the battery capacity. I could put a multimeter on it, but that wouldn’t tell us anything but the voltage - no real bearing on the level of charge.

Ugh - if I had a second unit here, it’d be easier to diagnose. Did the overnight battery-out hard reset, with the batteries in the house at 72 degrees. Plugged it in about 9am this morning; will check again at 9pm tonight and if it’s still showing 2 bars ... methinks we have a charger problem.

Just assuming until we speak with Segway Inc but for now - it’s all I got. :-)

Here is how I would proceed with this repair in our shop. Based on what you are describing there are 3 components that I would focus on with the SE model, in the following order:
Power Board- likely the issue
Radio Board- possible
AC Input Filter- very rare

Verify charging- remove the batteries and take the voltage reading on both batteries for the baseline initial voltage reading. Reinstall the batteries and place the unit on charge for approximately 30 minutes. Remove the batteries and take the voltage reading again. There should be an increase from your initial voltage reading. If the voltage is the same, or lower, then the Power Board is the likely component that has failed.

If there is an increase in voltage during this initial test, I would then place the unit on charge for 8-12 hours. Retake the voltage reading afterwards and if you have a reading in the 78 range then the batteries are fully charged. Even though you are getting solid green lights and only 2 bars, the radio board may be failing which is not giving you the correct infokey information. The are other obvious signs that appear first, like trouble powering the unit on and off. This is likely not the issue, but it’s a possibility.

This is a start...

Power Boards run about $280 and take about .5 hours to swap out.

Excellent diagnosis! I just pulled and checked. Batt A is 75.3 volts; Batt B is 75.2. I’d say that’s fairly strong and well balanced between A-side and B-side.

I’m going to go for the gusto here and drain it in Wall-leaning mode. Let’s see what happens.

Thanks for the input - stay tuned!

This was not in my recommendation at all. If you have a faulty power board then you will have no way to charge them.

That was in the earlier recommendations - to try to recalibrate the gauge. If you think that’s a bad idea I’ll go shut it off and wait for Segway Inc’s response after the holiday. I agree; I don’t really want fully drained batteries but at 75+ volts, it sounds like they’re not near the 2 bars that’s showing on the Infokey ... but I fully admit I’m out of my depth here.

Do not drain the batteries down. I gave you a starting point. The voltage reading you are taking is the “resting” voltage of the battery. Once a load is placed on them the voltage will drop based on charge level and there is no way for you to monitor a battery like that unless you have the proper equipment that places a simulated load on the batteries while it is OFF the unit.

Disclosure- I am Level III trained in Segway PT repairs, and I repair 200+ units per year. Some repairs are straight forward, but yours will take a bit of time to R/O what component may be the root cause.