Asked — Edited

A Low Cost Li-Ion Battery Solution

I use LI-ion cell phone batteries in the Roomba robot, the EZ-B, and the Wifi board. All of the batteries have built in Power control boards that monitor charge and discharge and will open each batteries electrical path if exceeded. That way I get to use the standard NiMH, NiCD power supplies. You can buy bulk cell phone batteries for about $1 each and a lot of them have 1200 to 1600 mAH capacity. Then it's just a matter of series/parallel arrangements to obtain the voltage and current needed for your projects.

The cell phone batteries installed in the Roomba are a 4(S) 2(P) 1250 mAH cells that provide 14.8 volts @ 2500 mAH. I leave the stock Roomba battery connected all the time unless actually using the Roomba. I have two 7.4vdc 2600 mAH LI-ion packs from a Cannon camera in parallel to provide the EZ-B with 7.4 vdc @ 5200 mAH and 2 3.7vdc 1600 mAH cell phone batteries in parallel for 3200 mAH current for the WiFi board. All battery packs have 2.5mm jacks so that the standard 22.5 vdc .75 amp Roomba power supply can be used to charge them all. Actually all packs have their own Roomba power supplies.


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Great idea! thanks Robot-Doc...."power to the people"......and their robots:) )


Boeing is going to pull all of the li-ion batteries out of the Dreamliners. Maybe they will end up on Ebay.


Those are not cell phone LI-ion batteries and do not have the built in Power Control Boards. There are several million cell phone batteries in use everyday with no fires.


I hope that you did not interpret my comment to be sarcastic. If so, I apologize. It was simply a joke aimed more at Boing, than your comment. Your suggestion is a good one, and I imagine that it might benefit many here looking for dependable power source for their robots.


No problem, I just want the potential hackers of robots to not be concerned with cell phone LI-ion battery packs. The less informed may avoid LI-ion anything due to national news reports that have nothing to do with the cell type of this thread.



Do you have any pictures or descriptions of how you put the cell phone packs together with a charging port/chargers? Also, do all Cell Phone batteries have power control boards, or do you need to explicitly search for that when looking for batteries to purchase (any links to where you buy them would be great...).

I am currently powering my small test bot with AA's, but I would like to have an in-place rechargeable solution.




@thetechguru - All cellphone batteries have the PCB built into them. There are no links available since I use ebay and batteries and sellers are always changing. I'll post some pictures soon.



Thanks. That is good to know. I always thought the "smarts" were in the phone or the charger. Knowing it is in the battery makes it a lot easier.



I work for a cell company and I tear those things apart , there's no charging controller in the battery packs of cell phones , the charging circuit is in the phone itself. If you Notice there are always two sets of contacts , two are for charge monitoring and two are the pos and neg output. If you can get them cheap enough making your own batteries would be great. Remember each battery is a single lipo Cell 3.7 volts min charge 4.2 max. Remember this when arranging them.


I agree with jstame1 about the charging smarts but there is also a charge/dis-charge Power Control Board that is built into the cell phone LI-ion packs that I use. I get them them for $1 each if 100 are purchased. They are rated @ 1600 mAH and 3.7vdc LI-ion packs. I use a standard Roomba power supply to charge these packs when they are wired in series to obtain 14.4vdc. I also double up two series groups to obtain 3200 mAH capacity for longer run times.

And I've also worked for several cell phone providers like AT&T, Lucent, Rochester Tel, US West, QWEST, Bell South, and LEACO.

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