Neato lithium ion battery revisited

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Re: Neato lithium ion battery revisited

Postby TimTaler » November 25th, 2013, 5:22 am

jin7 wrote:" Re: Neato lithium ion upgrade
-4x Samsung 18650 http://www.amazon.de/Samsung-ICR18650-2 ... sung+18650

-4x Balancer http://www.elv.de/lithium-polymer-lipo- ... usatz.html

The temperature sensor from the old battery pack is accepted, as the lead. Then the two batteries (for each subject) in series parallel to each of the battery balancer and ready. follows photo, mine is still shrink-wrapped and wired not nice, I do not want to hurt you. "



Im the developer of the Lithium Upgrade-Kit, which is posted above.

It runs now since 4 month without any problems. I can provide with a upgrade inside of europe.Requires your old NIMH for reuse of connectors.

Why it works? "My" Lion battery and the high end balancer works with the same battery-voltages as the original NIMH. Plug and play without any modification on neato.
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Re: Neato lithium ion battery revisited

Postby vic7767 » November 25th, 2013, 11:16 am

What would be helpful is a few pictures of your modification as well as a wiring diagram.
Also did you use an additional load resistor ? How hot does the LBA 1 get ?
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Re: Neato lithium ion battery revisited

Postby TimTaler » November 26th, 2013, 2:25 am

here is a schematic of the "Taler-Lion-Kit"

http://abload.de/image.php?img=lionqgssd.jpg

With my recommended balancers the balancer current is limited to 300mA. Thats enough and nothing will get hot, because its the end of the chargecycle.

The 2x balancer Mosfets "fire" at 4.2V (+-0.5%). 2x4.2V =8.4V
The typically NIMH Charge Voltage is 1.4V. 6x1.4=8.4V

Conclusion: At 8.4V Neato stops charging and the balancers keep cool.

I think its possibly to send the preconfigured balancers worldwide, but without Lithium batteries.
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Re: Neato lithium ion battery revisited

Postby glnc222 » November 26th, 2013, 2:21 pm

Did you put LiPo or LiOn batteries in the Neato?

[edit] lithium phosphate? U.S. http://www.onlybatteries.com/showitem.asp?ItemID=15826.11&cat1=88&uid=2052
Lithium Ion? U.S. http://www.onlybatteries.com/showitem.asp?ItemID=17790.11&cat1=27&uid=1107
-- only 2200/2600 mah -- can they be paralleled?

[edit] LifePo -- Lithium Iron Phosphate the new-new thing, preferred where applicable:
http://www.environmentalgraffiti.com/energy/news-environmentally-rechargeable-lithium-iron-battery-better-lithium-ion-battery
Last edited by glnc222 on November 26th, 2013, 8:07 pm, edited 1 time in total.
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Re: Neato lithium ion battery revisited

Postby vic7767 » November 26th, 2013, 4:14 pm

I would like to order 4 of the PCBs to test with but cannot complete the order process using the URL. Also evidently there is no similar PCB with balancing for sale anywhere else.
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Re: Neato lithium ion battery revisited

Postby glnc222 » November 26th, 2013, 10:00 pm

Lithium sizes
U.S. Amazon listing for Timtaler's batteries at Amazon.de:
http://www.amazon.com/Samsung-Li-Ion-2600mAh-ICR18650-26F-Rechargeable-Battery-Flat/dp/B004TSKXO2/ref=sr_1_fkmr0_1?ie=UTF8&qid=1385516589&sr=8-1-fkmr0&keywords=Samsung+SDI+ICR18650-26F_X2+Li-Ion
Samsung Li-Ion 18650 3.7V 2600mAh-ICR18650-26F Rechargeable Battery-Flat Top


So 2600mah smaller than factory 3200 Nimh, but Neato uses only about 2ah. Bit deeper discharge, but Lithium.
Great discovery the balancer circuits used for assembling all sorts of Lithium packs prevent disrupting Neato software for Nickel batteries.
This could become the must-have accessory given battery replacements costing twice the cheapest vacuum cost over several years with the short lived Nickel batteries. The factory should sell discount versions without batteries, but impractical with warranties. Even if the factory cannot supply Lithium in the product liability environment, small aftermarket vendors should be able to. They need to test all the cells, though, with fire extinguisher handy. "It's 10 pm; do you know who your supplier is?"
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Re: Neato lithium ion battery revisited

Postby vic7767 » November 26th, 2013, 10:13 pm

What Tim did was to install 4 cells into each side of the Neato pack cavity. Two cells in series to provide 7.4 vdc that are then connected in parallel with two more cells. Each series group have 2600 mAH and when in parallel with a second pair the capacity is doubled to 5200 mAH.
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Re: Neato lithium ion battery revisited

Postby Gordon » November 26th, 2013, 10:42 pm

vic7767 wrote:What would be helpful is a few pictures of your modification as well as a wiring diagram.
Also did you use an additional load resistor ? How hot does the LBA 1 get ?
I rarely post to this forum, but today the Roomba Scooba Chat forum was showing no action at all, thus as I was leaving the site I scanned the Board index and noticed this thread as active. I can't talk about the Neato, but I like lithium cells and their control circuits so I began studying TimTaler's offering.

I thought his response to your wiring diagram question was laughable. This one:
laughableTalerDiagram.jpg
Although it is mis-marked, I later decided that its wiring does represent a shunt-style balancing scheme. My other problem was, I was fixated on "protective circuits" (for Li cells), not charge balancing! I was unhappy with the brevity of TimTaler's reply so I searched for additional information about his LBA-1 module. I came across the following images, made available in a Deutsch magazine.

The PCB foil patterns:
LBA-1_PCBfoils.jpg


A view of the PCA's component side:
LBA-1_PCA_comptsSide.jpg
LBA-1_PCA_comptsSide.jpg (32.61 KiB) Viewed 12015 times


And a view of the LBA-1 wired to two cells:
2eaLBA-1with2cells.jpg


By using the last three images, some visual reverse engineering can be done to reveal:
    1) The three 33 ohms resistors are // connected to make an 11 ohms resistance.
    2) The top side of the 11 ohms resistance connects to a cell's (+) terminal.
    3) The other end of the 11 ohms resistance connects to the source terminal of a power MOSFET.
    4) The FET's drain pin connects to the cell's (-) terminal.
Connections from (2), (3), & (4) support other component ops in the circuit, but don't need to be known to deduce operation of this balancer.

Wiring illustrated in the last image support the hand drawn sketch given by TimTaler. What was not stated is that his two little boxes contain the 11 ohms resistor in series with a P-chan power FET that becomes switched into conduction when its cell voltage exceeds 4.2V. The shunt load takes charge out of the first filled cell, turns that charge into heat, and diverts some of the charging PSU's current into the lagging, partner cell. At some point, the lagging cell will catch up with its SoC and it will be shunted by its balancer circuit. Probably, there will be a short period of oscillation back & forth, until the external charging controller takes action to terminate charging. Both cells should then exhibit a SoC voltage of 4.2V.

If these cells do not have internal Protection ICs, then the charging system is responsible for charge termination.

Similarly, the balancer is not built to interrupt normal discharge current, so a separate circuit is required to open the load path when a lithium cell's low voltage limit is reached.
Last edited by Gordon on November 29th, 2013, 3:15 am, edited 1 time in total.
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Re: Neato lithium ion battery revisited

Postby TimTaler » November 27th, 2013, 3:11 am

I made several tests with several circuits. A charge interrupt circuit resumes with a battery failure message from neato.

Why should i use a additional charge circuit, if neato has is out of the box?

The balancer works with 2 mosfets and one LM3420 (Lion Balancer IC) it´s not only a stupid OP. The second small mosfet turns the Balancer IC off, until the Voltage exceeds over 3.6V to minimize the quiescient currents.

I use it now since 4 month and checked the neato cut off voltages (end of charge to) it allways stops at 8.2-8.4V.

The balancer never goes warm or hot.

The runtime is with 2600mAh around 50-60min. (The voltage discharge curve is flatter as NIMH)
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Re: Neato lithium ion battery revisited

Postby glnc222 » November 27th, 2013, 3:48 am

I made several tests with several circuits. A charge interrupt circuit resumes with a battery failure message from neato.
Why should i use a additional charge circuit, if neato has is out of the box?


Not clear: Were you referring to the development history, or does your present pack with balancer cause a Neato error message preventing cleaning?

Commercial LiOn Packs
Some LiOn packs with "IC protection" are commercially available, e.g. http://www.megabatteries.com/item_details2.asp?id=14911&cat_id=206&uid=1396
Whether "IC protection" is equivalent to the balancer circuit unknown.
Li-Ion Size: 2 x 18650 (cylindrical) Capacity: 2200 mAh (2600 also available higher price)
Working Voltage: 7.2V
Peak Voltage: 8.4V
Cut off voltage: 5.5 V
Max Charging Current: 1 Amp( recommended ) - 2 Amp max.
Max Discharging Current: 2 Amp limited by polyswitch
Installed IC chip will prevent the battery pack from over charge and over discharge. It helps protect battery chemistry integrity and prolongs battery life.
Installed polyswitch will cut off power if battery discharging current more than 2 Amp.

Wonder if the IC mentioned has all the functions of the balancer; two needed in parallel for Neato capacity. Could be wrong configuration -- two IC's instead of one for parallel pairs. For experts to opine.
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Re: Neato lithium ion battery revisited

Postby TimTaler » November 27th, 2013, 5:43 am

The present pack never produce Neato error messages.

Neato errors only with low/High Voltage cut off, like 18650cells with internal IC protection.
If you charge a 18650 with internal circuit above 8.4V it turns off (cell goes to high impedance) the same at low Cut off voltage --> Neato Message Battery error/Fail ...
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Re: Neato lithium ion battery revisited

Postby glnc222 » November 27th, 2013, 1:45 pm

It would be interesting if LifePo (Lithium Iron Phosphate) batteries could be used, 3.2v per cell instead 3.7, 5 in series instead of 4. 3x2 on one side of Neato, 2x2 the other side. Proper length cells needed to fit the Neato compartment. Reports are these are the newest advances in Lithium batteries.
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Re: Neato lithium ion battery revisited

Postby glnc222 » November 27th, 2013, 6:29 pm

More "balancer" versions and background info on charging LiOn at http://www.flyelectric.ukgateway.net/lithium-balancer.htm
Balancers seem normally built into chargers, specified with this feature, instead of into packs, saving duplication in every pack and that cost. The Neato charger, though, needs supplementing, so add to the pack, with a compact version. Balancing is also referred to as an "equilibrium" function. Some commercial PCB's exist.
Ought to be of interest to Roomba users as well. Their NiMh batteries are no longer lived than Neato's.
The LiOn cells referenced by TimTaler are pretty cheap compared to the larger NiMh cells.

[edit] curious warning in above:
Do not leave balancers connected for long periods of time as they can flatten and kill small packs. Larger capacity packs naturally take longer than smaller packs.

Wonder if that has any implications for Neato usage. Does Mr. Taler's circuit overcome this with particular features?

[edit] more mystery:
A lithium charger needs to take the cells voltage up to 4.2v per cell at a charge current of about 1C (ie: 1 x the cell's capacity). Once the voltage reaches this maximum the current needs to keep declining until the cell is fully charged. These characteristics of the charger are called 'constant current constant voltage' (CC CV). Voltage peak is not an indicater of 'fullness' like with Nicads and NiMHs. This means they have to have a special charger.

So can Neato's NiMh charger do a proper job on Lithium, even when the cut-off triggered error-msg is avoided?

some balancers work by discharging over-voltage cells -- can't be left on

NiMh Charging background http://www.talkingelectronics.com/projects/ChargingNiMH/ChargingNiMH.html
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Re: Neato lithium ion battery revisited

Postby glnc222 » November 28th, 2013, 12:18 am

Nickel chargers on LiOn
These [LiOn] batteries need a special charger, as they will only charge up to about 50% capacity if placed in a regular charging unit.
[url](http://www.buyabattery.com/facts.asp[/url])
Is this how TimTaler's pack is working? 5000mah pack for Neato's 2ah use? Could promote lifetime.
Supposedly full takes "CV CC constant voltage and current" procedure.
But I thought the switch to high impedance Neato doesn't like is at full charge...

Suppressing Neato's error msg is just a byproduct of the balancer function. Does it help with charging?
The point about not leaving balancers permanently connected must be addressed. Maybe only good if left on charger?
Need a description of the different states: charging, charging ended, off charger, running. What is it doing to the expensive battery? "The Good, the Bad, and the Ugly".

[edit]simplify?
Why not just a 1ooma or whatnot load across the battery switched on by a transistor at charging voltage and off when not charging? Find the simplest circuit, without IC power supply regulators etc. if possible.
It may be possible to read over USB the minimal charging current on NiMh at full charge. With 100ma load heat sinks are needed, and maybe metal compartment covers? Not ventilated.
[edit] apparently Lithium has more severe needs for balancing due to sharp cut off when charged: if in series, one cutting off early prevents the other from charging. A switched parallel charging scheme for all the cells is a necessity. NiMh may be more flexible in series.
Last edited by glnc222 on November 29th, 2013, 2:34 pm, edited 1 time in total.
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Re: Neato lithium ion battery revisited

Postby TimTaler » November 28th, 2013, 2:23 am

"Wonder if that has any implications for Neato usage. Does Mr. Taler's circuit overcome this with particular features?"

i wrote it above:
The second small mosfet turns the Balancer IC off, until the Voltage exceeds over 3.6V to minimize the quiescient currents.

"These [LiOn] batteries need a special charger, as they will only charge up to about 50% capacity if placed in a regular charging unit."

crazy, this would mean, my neato works with 1300mAh (50%of2600mAh) 55-60minutes ...

You can everything discuss dead...
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Re: Neato lithium ion battery revisited

Postby glnc222 » November 28th, 2013, 4:48 am

"4X" was misinterpreted as 4 on each side -- actually 4 total, 2 each side. Four boards per Neato, one each cell.
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Re: Neato lithium ion battery revisited

Postby TimTaler » November 28th, 2013, 5:34 am

Yes, thats right 4 total.
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Re: Neato lithium ion battery revisited

Postby glnc222 » November 28th, 2013, 6:20 pm

It wil be a lot cheaper to maintain the Neato when these are packaged in a way only the cells need to be replaced when used up, instead of $60 worth of circuitry every time. Panasonic/Seiko cells come with high protection IC's for under-over current, voltage, and temperature, as well, and Japanese made. More expensive than the Samsung and plain Japanese, but nothing wrong with some backup on fire-hazard Lithium, and dubious Neato central processors. Chargers for these come with warnings not to charge unattended. Maybe the dog can attend it...
[edit] position the dock in the fireplace.
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Re: Neato lithium ion battery revisited

Postby TimTaler » November 29th, 2013, 3:05 am

fire-hazard Lithium:


Ruggedness data from Samsung cells
9.1 Overcharge Test
Test method: To charge the standard charged cell with 12V and 2.8A at 25℃
for 2.5 hours.
Criteria: No fire, and no explosion.
9.2 External Short-circuit Test
Test method: To short-circuit the standard charged cell by connecting positive and
negative terminal by less than 50mΩwire for 3hours.
Criteria: No fire, and no explosion.
9.3 Reverse Charge Test
Test method: To charge the standard charged cell with charge current 2.8A
By –12V for 2.5 hours.
Criteria: No fire, and no explosion.
9.4 Heating Test
Test method: To heat up the standard charged cell at heating rate 5℃ per minute up to
130℃ and keep the cell in oven for 60 minutes.
Criteria: No fire, and no explosion.

pls keep as in the loop about your experience with cells with integrated circuit.
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Re: Neato lithium ion battery revisited

Postby glnc222 » November 29th, 2013, 4:10 am

Excellent lab work on hazards.

Roomba LiOn Batteries
Only now recall seeing LiOn batteries for Roomba's in the aftermarket years ago. New versions now available here from our familiar parts specialist: http://www.robotreviews.com/chat/viewtopic.php?f=11&t=17491 or contact Robot-Doc.com, Vic7767.com.

Where Roomba's go can Neato's be far behind? Stay tuned.

[edit] this thread added to list of all Neato mods for utility http://www.robotreviews.com/chat/viewtopic.php?f=20&t=16475
Last edited by glnc222 on December 7th, 2013, 7:43 pm, edited 1 time in total.
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