Neato Signature (battery ?) problem

[tchup]

Hi all,

First of all, thanks a lot for all the useful information on this forum. I've learned a lot concerning my Neato by reading some of the topics.

I have an issue with my Neato XV Signature that I don't understand: when I launch a cleaning cycle after charging on its dock, it stops after just a few seconds saying it has to recharge. The charge is curiously short (5mn or so), and then it goes cleaning for a while (I would say for a shorter time than normal, 20-30mn ).

Before ordering new batteries, I want to be sure that it's not another faulty component on the motherboard or the charging dock. I tried the recalibration with the "New batteries" option with no luck.
After a bit of analysis through USB, I suspect a problem with the Fuel Gauge. I tried a discharge of the NiMH batteries, as described on another topic:
- Full charge (almost 100%, around 16V)
- Discharge by running the fan (1.1A consumption, tension and fuel gauge goes slowly down)
- After maybe 15mn, the fuel gauge jumped suddenly from 80% to 15%, tension still at 13.5V. If I understood well, normally the tension could go as low as 12V (1V/cell) during a discharge. According to me, this 15% value on the fuel gauge seems wrong.
Then the bot showed the low battery message and turned off.

Do you have any idea what's wrong ? Is this only the gauge management ? Or is the battery defective ?
Thanks for any advice, I'm a bit lost here.

[PDWhite]

tchup,

It's not the batteries. I'm having exactly the same problem on an XV-21. Trying it with the new battery or the old one appears to make no difference. I tried setting the fuel gauge to 0, which allows a charge cycle to start, but the charge sequence is momentary as the battery is already charged. I have no idea what is making the unit think the battery is low. There are both analog and digital readings. Battery charge level must be an analog. My suspicion is that the OS isn't getting the message. There may be another digital/analog signal necessary for the OS logic to conclude the batter is charged and ready.

[glnc222]

Maybe set fuel gauge to 100 after charging -- which terminates merely on a full condition indicated by heating with NiMh chemistry (when full, charging current dissipated as heat, unlike lithium). In XV models the fuel gauge is computed by the cpu from sampling battery current with a built-in ammeter shunt somewhere. Current is reported over USB. In Botvac a separate Maxim IC computes the fuel gauge for the cpu which just reads the data from it; some of those IC's have needed replacement.
The cleaning load is around 3 amps so just running the fan will run maybe three times longer than cleaning. Software limits runs to about 2ah charge usage, preserving unused capacity margin against damaging deep discharge and returns to base.

[tchup]

OK, I think my bot is slowly dying, my LCD doesn't display anything now. Don't know if it's related or just bad luck.

Back to the batteries, even if I force the fuel gauge to 100 after charging, it goes back to the dock after a few seconds.

When you say the batteries heat up when full, how much ? I got 45°C earlier today, is it normal temperature ? I read more like 30°C on another thread.

About the current the cpu uses to compute the fuel gauge, what value should it display during charge and after ? I had negative values when I checked while charging. I can extract full charge info tomorrow if needed.

Thanks for you help!

[glnc222]

Batteries starting from room temperature around 20C won't go up much over 30C, unless a charger is left pumping it up. The software terminates charging when the temperature rises faster than 1C/minute -- not a level, but rate of increase, to get ahead of the curve. Open air single cell NiMh chargers use a slight drop in voltage when full instead of heat, but because of the heating enclosed packs are typically controlled by the temperature, to avoid over-heating. The Neato has some emergency heat shut down around 60C I think -- like on fire. There are also high temperature sensitive fuses in the battery pack.
If a recently charged battery still warm is recharged with a short cycle just to detect its full state, I suppose the battery could get hotter than usual.
It is common to need a new battery just to insure that is not the problem when diagnosing system problems.
When lithium replacements for NiMh are used in NiMh systems, an adapter synthesizes a temperature signal to look like NiMh. Bots with OEM lithium have a different charging procedure based on voltage only. XV models have software with both NiMH and Lithium procedures, selected by an unpublished SetConfig command in the software installation operation -- because Vorwerk's XV, VR100, had lithium batteries. Users can switch the configuration over USB to make replacement XV lithium batteries DIY. The commercial replacements all use the adapter method. The Botvac with different OS and software does not have this configuration command, with the difference built into the different software versions to install, and different system boards etc. in the different models.

[glnc222]

I can only assume the Fuel Gauge should be set near 100 by software when the battery fully charges. It is used by the software limiting discharge to about 2ah when cleaning (so larger batteries do not increase run time). A defective or worn out battery will discharge quickly when running. Defects in the power supply circuit components might also cause odd behavior, hard to diagnose -- except by trying a known good battery.
The fuel gauge right after stopping to return to base, before recharging, might be interesting.

[tchup]

OK, I'll try ordering new batteries and keep you up to date. Thanks !

[glnc222]

I assume you are aware of the "New Battery" option in the LCD menu. This is used when replacing batteries because the system has some sort of model of the battery capacity which it adjusts when prematurely running low, adjusting for aging, insuring return to base, limiting run time. "New Battery" resets this calculation. The system will do a charging cycle anytime the battery is disconnected to calibrate the charge level by starting out full, even if the battery is full -- short in that case.

[tchup]

Yes, this the first thing I tried when I had battery issues, but it didn't change anything.
Anyway, I ordered new batteries, I hope it will solve the problem. The only thing is: as my LCD isn't working anymore, I will have to go blind to the "New battery" menu when I have my new cells. Is it possible to do it by USB ?

[glnc222]

I do not see the New Battery command in the USB programming manual (top of forum). I have to wonder whethre it does this when the battery is disconnected, but has not been tested, fairly tedious. Besides replacing the LCD display component (instead of the entire assembly), some were fixed by adding more voltage to the power supply line:
Repairing the LCD by increasing the power supply voltage
http://www.robotreviews.com/chat/viewto ... 81#p148381
and later posts http://www.robotreviews.com/chat/viewto ... 15#p151615

[tchup]

I'll look into it, thanks!

[tchup]

Quick update on my problem:
I ordered Lithium replacement batteries, as discussed. Problem solved ! Run time is now close to 1h.
LCD is still not working, I think I will manage without it.