iRobot Roomba Battery pack rebuild

by | Jul 11, 2018 | diy-irobot-roomba | 0 comments

Roomba Battery mod

Rebuilding iRobot Roomba NiMH battery pack

How did I mod (modify) and rebuild iRobot Roomba battery pack?

This page is about rebuilding Roomba’s battery pack.
After about 90.5-2 years of regular use and charge, Roomba will gradually start decreasing its working time till a point it will stop working in a middle of its cleaning cycle. This is the point where you should start consider replacing the battery pack.

You may purchase a new genuine iRobot 3000mAh battery pack for ~US$70 (July 2014), a 3rd party pack for a little less, OR you can rebuild your own pack for half the price and get better capacity.

Note Note:
This page describes Roomba 560 but it is the same for all 5xx 6xx 7xx 8xx series models that uses the shown type of battery pack

DISCLAIMER - Important!

A. Preparing for the rebuild:

Suggested tools and materials:

Hand tools such as pliers, screwdrivers, x-acto knife etc.

  • Solder iron and related soldering tools and materials / Spot welder
    Note Note: Since this article was first published, I improved the batteries tab soldering and instead of soldering, I now use “Spot-Welder“. There are many DIY guides on how to build a cheap mini spot welder for this job using a super-capacitor. The results are cleaner, flatter and faster to perform than those made by soldering.
  • Hot-air gun.
  • Hot-glue gun
  • A multimeter / multitester / VOM.
  • 12x Sub-C NiMH batteries with/without tabs. 3400mAh or higher
  • Metal tabs in case the batteries are without tabs.
  • 70mm diameter heat shrinkable tubeNote it is 110mm width when flat!
    You’ll need 180mm (7″) in length for 1x pack.
  • Some kind of thin adhesive tape in case you don’t have a Hot-glue gun.
How to rebuild Roomba’s battery pack?

Roomba’s battery pack is made of 12x Sub-C 1.2V batteries connected in-series to produce 14.4V.
Batteries are packed in a shrinkable sleeve and includes a special connection part that incorporates a thermistor which protects from excessive heat.
Rebuilding a new pack make use of new batteries and the connection part taken from the fault pack.

You may build a whole new pack using 12x new batteries OR repair a damaged pack by replacing defective batteries.

Note Note: In case of a repair, make sure the replacement batteries has the exact same capacity of the damaged ones.
1. Schematic of the battery pack showing front and rear battery rows.
2. Batteries soldering points
3. Top view of genuine battery pack and rebuild pack.
(Image shows soldered batteries before packing and w/o connection part)
4. Bottom view of genuine battery pack and rebuild pack
(Image shows soldered batteries before packing and w/o connection part)
B. Disassembly of the battery and rebuilding the new battery pack.
Note Note: It is advised to use hand screwdriver for fine torque control.
1. Place the Roomba top down on a solid work surface. Remove the screw from the rotating side brush and gently pull it out
2. Remove the four screws holding the bottom plate and remove the bottom plate
3. Take out the battery, lift it using the 2 tape tabs.
4. Arrange batteries according the above A1 schematics image. Mark each battery with + and – signs on its side to avoid mistakes.

Note: Image shows 3400mAH NiMH batteries, any mAh may be used based on how much you want to increase working time/battery cost, however, all batteries should be identical.

5. Remove (-) tab from each battery.
(-) side has a larger area that makes it easy for the soldering.
Remove contact’s sticker and scratch the metal surface a bit to help the soldering. See note about soldering/spot welding
6. Solder batteries in-series according to above A1 schematics. See note about soldering/spot welding
When done, check voltage on center + and – contacts to verify ~14.4-15.5DCV
7. Remove the 2 green tape tabs from the fault pack and store it for later use.
Remove shrink sleeve of the fault battery.
* Clue: If cut horizontally in the middle, it can be served for the new pack.
8. To disassemble the connection part,
first remove the protective cover on both parts around center batterie
9. Bend the pack to reach connection part.
10. Carefully remove adhesive fill that holds the connection part to the batteries.

11. Take out the connection part
Measure its resistance. It should read ~8.5-10.0kOhm (mine was taken from a 3000mAh NiMH battery and was 8.5kOhm)

12. Wrap adhesive tape around the batteries to hold its structure.
Loosen it a bit in the gap of the center front batteries to make room for the connection part.
If you have a hot-glue gun. use it instead to get a cleaner look and a stable structure prior of soldering/welding.

13. Place the connection part in the middle of the pack above the 2 unsoldered batteries.
14. Cut 180mm in length of the 70mm diameter shrinkable tube.

In case you use the previously removed shrink from the fault pack, place it over the new pack and wrap with a tape.

15. Insert new batteries pack inside the shrinkable tube. Position it symmetrically.
Use hot air gun to shrink the tube around the batteries pack.
When done shrinking, cut excessive tube from sides of pack.
16. Use sharp knife to cut around the top rib of the connection part.
* You may want to mark it prior of cutting to achieve clean line.
17. Place the 2x previously removed tape tabs on new pack sides.
You have now completed the rebuild of a Roomba battery pack.
C. Assembly – assemble the new battery pack in reverse order to what is listed above (B1-3). Upon inserting the battery pack you should hear the famous restart melody.
D. Voila – you now have a working iRobot Roomba with a new battery pack.

Have fun and enjoy your Roomba, Avi Clap

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iRobot Roomba DIY Guides by Avi

9-beep fix | power-supply conversion | speaker fix | CHM cleaning
Red CHM mod | Gray CHM mod | battery rebuild

Copyright © Schneor Design. All rights reserved. Do not copy without written consent from the author.

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Disclaimer

1. iRobot Roomba contains electronics, some works on high voltage.

Any modification made to your Roomba robot may cause damage to your equipment and harm to yourself or to others. 
Any modification made to your Roomba robot will void manufacturer warranty.
None of the following steps is recommended by me nor by the manufacturer, iRobot. 
This post show only my personal experience and know-how.
If you follow any of the steps, you do it on your own risk and responsibility.

2. Copyright © 2011 Avi. All rights reserved. 

Content including all text and images in part or in whole may not be reproduced, retransmitted, stored, distributed, disseminated, sold, published, broadcast or circulated in any medium
without written consent of the author

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