IRobot Dead Battery Cell Fix

152,140

51

45

Posted in TechnologyRobots

Introduction: IRobot Dead Battery Cell Fix

About: I design and sell two different electronic devices. The first devices desulfates old dying batteries. The second assists people with the fermentation of foods. When I am not working on electronics I like to ...

A step-by-step tutorial showing how I repaired my $60 Dirt Dog battery with just a AA battery and some tape. We start off with a Dirt Dog battery that has a voltage of 15.87V which is indicative of a bad cell. When we complete the repair we are at 17.12V and that is without even charging the pack.

Step 1: Remove Triangle Screws

The iRobot battery has a bunch of annoying triangle shapped screws. I've read that some people can easily unscrew them with a appropriately sized flat had screwdriver. I used another technique which works for most "secure" screws types.

Step 2: Dremmel the Screws

I used my dremmel to cut flat lines across the screws. Later I cut a second set (not shown) so that a phillips head can be used to unscrew and rescrew these. This is a cute trick to use for all sorts of stuff you are not supposed to service yourself.

Step 3: Get That Case Open

There are claims that you can just pop the battery lid after removing clips and doing some prying on the irobot batteries. I think there is a little more to this. The Dirt Dog in particular seemed to have a well glued on battery lid. It was no match for a dremmel. Be careful to not cut deep. Good ventilation is useful here as the plastic smells terrible when you are cutting/burning it off with the dremmel.

Step 4: The Battery Cells

Here are the cells. These are 12 sub-c sized / 1.2V / 2600mAh / NiMH batteries. These vary between different models so yours might be a little different. The dirt dog seems to have a cheap ass NiMH (low amp hour) versus the higher end models.

Step 5: Make a Mess

Yeah, now this is a good time. Go ahead and rip off that glue on paper stuff. It's cool. We need access on both sides to the batteries so we can find our dead cell.

Step 6: Bust Out Your Meter

Betcha your dead cell is the second one in from the positive lead. Lots of reports on this one cell dying first. I have found that the cells near the postive leads seem to always go first. I had to replace a battery in the golf cart today and you guessed it...the first one on the positive side had pretty much died.

Step 7: Bye Bye Dead Guy

Get the the dead cell out of the pack. This will take a little prying and some cutting of tabs. Try to leave yourself as much tab from the remaining batteries so you can easily get a replacement battery in there.

Step 8: Cheat the System

There is a lot of info on the web about replacing your dying roomba battery with 12 new cells. This is wasteful. Just drop in a standard AA NiMH. I had a 2300mAh one on hand. A 2600mAh would have been more appropriate to match the other cells, but I didn't want to give up my good new cells. This one is about five years old and still doing great. No need to buy new fancy batteries or replace them all. I bet you have lots of NiMH AA's cells handy. Putting the AA in at angle will ensure a good fit, notice I didn't get that part right.

Step 9: ReVolt

Our voltage has jumped from 15.87 to a ass kicking 17.10. Nice, this is how we do it. My usage of the orange tape was more about making a dynamite looking tight pack. This was actually a bad idea as the tape made it difficult to get the battery case closed. I ended up cutting most of the horizontal tape off.

Step 10: Pack It In

Now that you have your batteries giving you a good voltage just pack them back into the plastic case and get it back in your iRobot.

Step 11: Test Drive

I let my irobot charge for 30 minutes then watched it clean my floors for over a hour. Imagine what it can do on a full charge. I'm pretty thrilled that I revived my year old dirt dog with basically a AA battery and some tape. No need to order replacement cells or pay shipping and handeling. Next, I'm going to deal with a old iRobot scooba battery.

Share

Recommendations

  • Spotless Contest

    Spotless Contest
  • Microcontroller Contest

    Microcontroller Contest
  • Space Challenge

    Space Challenge
user

We have a be nice policy.
Please be positive and constructive.

Tips

Questions

45 Comments

When replacing a new batter cell do you have to solder it to the other batteries or is there another way around this? Would I be able to just use the metal connector bridge and apply tape and firm pressure to make sure there is contact between the battery and the bridge, or maybe even foil?

2 replies

Hello Alden,

I'm not Mr Safety at all, but I strongly advising you never to try to solder any battery, no mather how skilled you are, consummer grade welder/tools aren't safe to do such a job. I once looked into doing that, but reading about it made me realised that was a bad idea..

The thing I'd suggest you to do is secure the "connector tab" to the battery and hot glue it. You might have to do it in two step per side, note that if you put hot glue next to the first place, it will probably melt again, so make sure you have something to keep the tab tight againt the battery (an unfolded big trombone might help to keep pressure while avoiding that your tool get glued). Another solution could be strong tape, like aluminum, but this is a conductive and may loosen over (short) time..

Good luck ;)

sorry, but you can safely soldier the ends of batteries... How? 1# First get your soldinng iron as hot as you can. 2# put flux on both pieces to be solded. #3 with the tab place on the battery, lay your solder on the place you’re solding, take your hot iron and quickly place it on the solder jount and press down for three to five seconds and remove. It’s done and the battery didn’t get hot

This really works. I've made it before by myself using a good Low Self-Discharge Ni-MH battery. I strongly recommend using good batteries to replace NiCd or NiMH cells. It may be best to use 2 batteries in parallel if it fits the cell volume, because mAh is important, but the battery must support the mA while in use. Another thing... Do this at your own risk! Batteries may explode if short-circuited or overcharged!

I gotta try this hack....I have had my iRobot vacuum for 3 years and never actually got a new battery...now maybe I won't have to buy one :)

I gotta try this hack....I have had my iRobot vacuum for 3 years and never actually got a new battery...now maybe I won't have to buy one :)

In the UK screwfix do a security bit set for £5 which copes with most of the common 'tamper proof' screws

When replacing a new battery cell do you have to solder it to the other batteries or is there another way around this? Would I be able to just use the metal connector bridge and apply tape and firm pressure to make sure there is contact between the battery and the bridge, or maybe even foil?

I am having difficulty with this method. I have 3 Rombas that test good using the one new 14.4 volt battery that I purchased. When charged it reads 15.4 volts.
The other two read 18.2 and 16.5 but will not run a Romba.
I opened the 16.5 one using the chisel method (I have a triangle screwdriver). I used the dremel tool to grind a hole in the insulation and measured the voltage of each cell.
1.38 1.39 1.39 1.39 1.39 1.30 1.38 1.39 1.36 1.39 1.38 1.36 1.34
This addes up to 16.5 . This battery will not run a romba so how do I know which is the bad cell and why wont it run? (since this voltage is higher than the new one)
All suggestions will be appricated.

DSCF6217.JPGDSCF6218.JPG
1 reply

I'm having the same problem, voltage measures OK but will not run a Roomba. So how did you end up identifying the bad cells?

Thanks for the advice. I opened up my battery and found 4 dead cells. I replaced them with some spare cells I had laying around from a craftsman cordless drill. Now, instead of running for 20 sec it just ran a 40 min cycle.

5 replies

Please read and reply to my post just after yours. My question is: How can I identify the cell or cells that are dead? You assistance will be appreciated.

I opened the 16.5 volt battery using the chisel method (I have a triangle screwdriver). I used the dremel tool to grind a hole in the insulation and measured the voltage of each cell.
1.38 1.39 1.39 1.39 1.39 1.30 1.38 1.39 1.36 1.39 1.38 1.36 1.34
although it is 16.5 volts is won't charge up enough to run a romba.

I solved my own problem. Once I used a battery tester and not a voltmeter I located 4 dead cells. The battery tester checks voltage under a load. They sell them at Radio Shack. You could probably do the same thing by loading the cell with a resistor while checking the voltage (or flashlight bulb.)

Sorry to tell you, but from those battery readings, it is not not the battery. The four that I found dead had readings of 0.2 and such. and then once I replaced them my battery reading was back up to a total of 16 volts where as before it was 10 volts. it might be the actual roomba that has a charging issue. Sorry dude.

How can I identify the dead cell(s). All my cells have close to the same voltage but will not charge.

Dead cells read 0V.

If it is not charging there is probably too much built up resistance (sulfation). In that case it is typically the charger shutting off. I've made some chargers that just rev up the voltage so that weak cells can be recovered. However, they are not for commercial sale at this time.

How can you test the cells without disconnecting them 1st???
Thanks, great idea!

OK, a regular Torx T7 bit will work, but:

1. you have to keep firm downward pressure to keep it from walking out
2. you may damage one of the wings of the bit
3. the screws that have cracking plastic around them are torqued the most

Thanks for the irobot battery fix. Now how about that scooba battery.
If I can get in it I can fix it. Where should I make the cut?
dcr1942@GMAIL.COM

This is so awesome - thank you for this! I'm going to try this tonight and check the cells and drop in a few of the extra AA's I have. Is it possible, if needed, to replace ALL the cells with rechargeable AA's over time?