"I NEED TO COOL DOWN MY BATTERIES"

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"I NEED TO COOL DOWN MY BATTERIES"

Postby ag43 » July 3rd, 2015, 10:57 am

i'm using lithiumpowerinc's batteries for a few months now without any problem. yesterday suddenly i've received "I NEED TO COOL DOWN MY BATTERIES" error. i've restarted the robot and since then i'm getting "battery error 0002 please restart". how do i fix this?
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Re: "I NEED TO COOL DOWN MY BATTERIES"

Postby vic7767 » July 3rd, 2015, 11:28 am

One of your battery packs is stuck in the high temp state. There is a condition that the Neato charging system responds to that stops high current charging. The signal that the Neato monitors for this condition is the thermistor output. Normally during charging of your LI-ion packs there is a signal sent from the Power Control Board that tells the Neato to stop the high current charging because the cells in the pack are now fully charged. Sometime this thermistor signal from the pack gets stuck on and the Neato will give you the temp error.

Try running your Neato to help discharge the pack and possibly reset the PCB circuit inside. You may have to use the USB connection with your PC and set the Fuel percentage to 100 and then send it on a cleaning run.
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Re: "I NEED TO COOL DOWN MY BATTERIES"

Postby robocleaner » July 3rd, 2015, 12:58 pm

It may just be that the batteries ARE too hot... which is worrying with Lithium cells (Boeings’ Dreamliner springs to mind). I’d first be checking the packs aren’t swelling or deformed.
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Re: "I NEED TO COOL DOWN MY BATTERIES"

Postby vic7767 » July 3rd, 2015, 1:32 pm

The LI-ion packs used in the Neato don't overheat. The power control board built into each pack has a circuit designed to mimic NiMH cells that do get hot. The Neato monitors the twin packs thermistor leads that are connected to a resistive reporting circuit in the LI-ion pack. In actuality there is no heat generated at all during the charging session internal to the LI-ion packs just a simulated resistance sent to the Neato.
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Re: "I NEED TO COOL DOWN MY BATTERIES"

Postby glnc222 » July 3rd, 2015, 2:20 pm

There could be a defect in the Neato system board instead of the battery pack board. Testing with a regular NiMh battery is needed.

The "cool the battery" message is generated at an unusually high temperature beyond the normal range of heating inherent in the NIMh chemistry when charging, and so beyond what the lithium battery adapter circuit would normally generate to control the Neato. There is a question whether the circuit inside the battery pack is failing to generate the proper signal or the Neato system board is not processing the signal properly.

The thermistor is a resistor connected in series inside the Neato with about a 21K ohm resistor to the 5v power supply. The cpu reads the voltage at the division between this resistor and the approximately 10K ohm resistance of the thermistor, whose resistance falls as the temperature rises. One end of the thermistor is grounded. The voltage ranges over about 1-2v, near 1.5v at room temperature. The lithium adapter circuit uses some sort of transistor circuit to present a variable resistance under control of the charging adapter. A short circuit of the variable resistance would indicate an extreme high temperature. At the highest temperature the Neato will shut down as well as issuing an error message, I think. There is an additional error message if Neato finds the thermistor disconnected.

The apparent temperature seen by the cpu can be displayed by the Neato Control Program or the GetAnalogSensors command over USB. The NiMh batteries seldom go over 30C at the end of charging (they heat when approaching the full state). Temperatures of 60C may trigger error messages. An external battery charger can have an automatic shutdown at 70C.

The "0002" error is not clear but means some further battery condition such as appearing to be disconnected. The lithium adapter board has sleep modes and protection modes disconnecting the battery.

Since the thermistor is on the 5v Neato power supply problems with that voltage supply could cause improper readings. Failures in that supply are observed in the "dim mode" failure of the Neato cpu, caused by defects in capacitor C10 on the system board. The higher temperature reading means a lower power supply, just what the dim mode problem involves.

The easiest way to identify which system is failing would seem to be testing whether the Neato errors occur with a plain NiMh pack without any adapter circuit involved.

[edit] Note only the high side pack thermistor (the pack with the 16v terminal) is used by the Neato charging circuit to control charging. The low side thermistor may be read just for emergency excess temperatures.
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Re: "I NEED TO COOL DOWN MY BATTERIES"

Postby robocleaner » July 3rd, 2015, 4:59 pm

vic7767 wrote:The LI-ion packs used in the Neato don't overheat... In actuality there is no heat generated at all during the charging session internal to the LI-ion packs...

Not intentionally no. But the operating parameters for Lithium are very narrow. Over/under voltage, too high current, too high/low temperature... all can contribute to internal chemical breakdown and early failure of the separators. With Lithium, swelling can be an early indication. When that chemical breakdown happens with NiMh chemistry, the cell most often simply stops working. With Lithium, you end up with overheating that rapidly develops into thermal runaway and fire or explosion result... as Toshiba, Apple, Dell, Sony and Boeing (among others) will tell you. No control board - whether a fault in that circuit contributed to the failure or not - is going to stop it. As you point out, unlike NiMh, heat shouldn't be generated during normal Lithium operation, so anything telling me a Lithium cell IS overheating is in my view cause for concern.
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Re: "I NEED TO COOL DOWN MY BATTERIES"

Postby vic7767 » July 3rd, 2015, 5:23 pm

robocleaner wrote:anything telling me a Lithium cell IS overheating is in my view cause for concern.


You are certainly welcome to have concern if you want. I'm just expressing what causes this error in these special LI-ion packs sold by the vendor in Taiwan. The fault shows up in both the Neato and Roomba packs. Sometimes the error will stop after a discharge and a new charging cycle is begun. If the error continues then the vendor will replace it. The warranty is a full year.
l
The LI-NMC chemistry is much more stable than the LIPO4 packs that are prevalent in the R/C market. I have been using LI-ion packs for 8 years now and have never had a battery overheat, blow up, swell up, etc. A lot of time I've used surplus cell phone batteries to rebuild NiMH Roomba and Scooba battery cases with these same cell phone batteries without any failures of overheating or bad power control boards. In the past before cell balancing became available a lot of the packs I built eventually would no longer perform due to no cell balancing but that was not a fault of the PCB.
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Re: "I NEED TO COOL DOWN MY BATTERIES"

Postby robocleaner » July 3rd, 2015, 7:30 pm

No, I'm not suggesting cell overheating/failure is an everyday occurrence. But Apple did recall 6 million Li-Ion batteries due to a higher than expected cell-failure rate, and even the current Apple iPhone 6 still features a warning message to warn that "iPhone needs to cool down before you can use it" when the cells are about to explode!
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Re: "I NEED TO COOL DOWN MY BATTERIES"

Postby glnc222 » July 3rd, 2015, 10:11 pm

The ANewPow/ Lithium Power Corp Neato batteries use LiNMC chemistry a more stable type than the lithium ion cells in phones. Also if they got hot you could actually feel them. The signal to the Neato may not respond to temperature at all, but just be used to control the charger. The Neato reading may not represent any actual heating. There is still a safety thermistor on the adapter I think, to disconnect, along with all the various protections used on lithium batteries, under-over voltage, excess drain, etc. etc. It is a complicated rigmarole. Ironically, the Neato firmware can be set over USB to operate as a lithium charger used in the Vorwerk models.

There can be a role of the environment with phones which might be in the sun or something as well. You don't want to charge in a hot environment. No Neato's in Death Valley;let the vultures clean it.
The LiNMC cells are more resistant to damage from heat and present less of a hazard. The company has also supplied products for medical equipment.
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Re: "I NEED TO COOL DOWN MY BATTERIES"

Postby ag43 » July 5th, 2015, 1:42 pm

I've unplugged the batteries for three days and now everything works fine. if the problem returns i'll update here. thanks for the help!
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Re: "I NEED TO COOL DOWN MY BATTERIES"

Postby shaileshmd » March 18th, 2017, 4:15 pm

I have tried using noncharged Li battery and a generic Ni MH 4000 battery. The message, battery needs to cool down keeps repeating. The LCD screen immediately shuts down. Unable to access the menu, not charging at all. I have called Neato. The CSR asked to try name brand battery. I am waiting for the delivery. The Li manufacturer commented not seeing this error. Help is appreciated.
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Re: "I NEED TO COOL DOWN MY BATTERIES"

Postby glnc222 » March 18th, 2017, 4:56 pm

Software has an emergency fire hazard shut down of the unit around 60C on the thermistors. Resistance falls with increased temperature, so a disconnected thermistor would read cold, besides a specific error msg for missing thermistor. So maybe there is a short circuit in the thermistor wiring, or a system board defect. You can measure the voltage on the thermistor yellow leads (one of which is system ground, the other through a 21K resistor to the 5v system logic power, so the cpu can read the divided voltage, around 1.5v I forget exactly, with 10K thermistor at 25C. The lithium replacements for NiMh synthesize the thermistor signal with a faux temperature rise simulating NiMh behavior at end of charging. I don't have specific Botvac data, presumed similar XV. The XV thermistors are identified in the Lithium Power Revisited thread.
Thermistor readings by the cpu are available over USB with Neato Control Program or terminal emulator.
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