HOW TO – iRobot dead cell battery fix

Robotics Technology
HOW TO – iRobot dead cell battery fix

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Mikey’s HOW TO – iRobot dead cell battery fix

I have three iRobots which help clean our house. I bought them about two years ago. As the one year warranty was coming up I called iRobot and asked them to help with various issues. They basically replaced all three of them. Now that I am at the one year point with the replacements I’m running out of options as things break. I can either fix it myself, or buy more shit. Obviously, I don’t want to pay for anything. This morning I took apart the battery pack in the Dirt Dog vacuum cleaner. After about 30 minutes of cutting, sawing, and taping I had a battery pack that was performing like a new one. Now instead of getting 10 minutes of lousy vacuuming I get over a hour of powerful cleaning. This saved about $60 which is the cost of buying a new replacement pack from iRobot.

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Photos & Instructable on fixing the batteries…

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6 thoughts on “HOW TO – iRobot dead cell battery fix

  1. Rich says:

    While this works for the short-term, in any situation where a battery pack is configured in a series, cell types should ALWAYS be the same. Cells have different discharge rates, resistances, and other tolerances. The voltages match, but current flows through the pack as a unit.

    A cell with different characteristics can cause the other cells to discharge into it, or can discharge into the other cells. This creates a fire risk, and can cause overheating/leakage.

    An entirely NEW battery pack constructed of new or used cells with similar characteristics would be a MUCH better long-term solution. These cells are sold for hobby purposes and are fairly cheap unless you buy the real high-end cells rated for super-high discharge rates etc.

    1. Bob Amelio says:

      please help me out here i believe i got my robot back in 2002 when it first came out in the p.c. richards stores, but the battery seem to have a very shore life, i brought it for my mom, who has pass away, and was just getting mad at ne because it kept gettig stuck everywhere. , The problem is that i can’t soilder the wires, and the cheappers, battery pact i seen is about $31, $32 dollars and high, does anyone know the cheappers way i can get a battery pack so i may get the roomba working again ? THANK YOU EVERYONE.

  2. David says:

    I’ve replaced a Roomba pack a few times. I bought one batch of just the cells off ebay and transplanted them into a battery case. The second battery I transplanted newer cells from the 1st dead battery to fix the dead cells. Seems to me like it was always cells 2 & 3 on one side next to the positive lead. The Roomba must have a voltage regulator here, and I think it (very) slowly cooks those two cells.

    Rich is right tho, mismatched cells will discharge differently, and the AA cell can’t match the sub-c cells for the amount of current it can handle before the voltage sags.
    You might get away with it for a while, especially if you use a slow charger every now and then to “form” up the pack (bring all the cells up to peak. The Roomba isn’t supper aggressive in discharge, so that helps.


  3. Michael says:

    I agree with David and Rich.

    I bought a pre-wired replacement pack (I had to insert it into the old case) off ebay. I replaced the 3300 mAh NiMH pack with a 2400 mAh NiCd pack and it runs just as good as new (NiCd have slower self-discharge rates and are more robust than NiMH, just have to watch out for the memory effect).

    I don’t charge the battery in the robot any more due to the heating of the first couple of batteries. The roomba charging algorithm is terrible…it doesn’t reduce to a low enough trickle, it just cooks the battery.

  4. Spokehedz says:

    As with Michael, David and Rich, I really must stress how BAD of an idea this is.

    While this will ‘work’ I strongly recommend against it.

    Replacement batteries are easily enough found and it is a lot cheaper to buy enough for two packs and then have one ready for when the one goes.

  5. enyduke says:

    Please share illustration on replacing batteries in Roomba 4210 Batterypack rebuilding!

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