Scooba battery exposed!

[czunit]

Ok, well I got a dead Scooba from a friend the other day to see if I could "fix" it. Long story short, his battery was bad.

So after recommending a new battery pack I decided it was time to "evaluate" this battery. Scooba batteries are not like Roomba ones; there are no screws for example. So I used a razor blade and screwdrivers to pry the case open.

Big pain in neck; either iRobot does not want people swapping batteries or they are paranoid about water getting in. Due to the latch thing on Scooba batteries I can believe both. Regardless, I've attached a few pictures of the pack.

The pack uses 4200ma/hr batteries. They look to be the extra long AA types, somewhat thicker as well. This is what is on the battery:

Uniross 1.2.v 4100mah
AAB04895/05331-PO110051

Standard assembly; two wires for + and -, the other two are for the temp sensor embedded in the pack. When taking the pack apart note that there *are* four little embedded latches in there, but with the glue it's possible you could break them. See my pictures for where they are.

And the battery inside is glued to the case. This battery is not as easy to service as it could otherwise be.

[vic7767]

Great detective work czunit ! So they are definitely not sub C cells like in the Roomba battery packs. Can you get in there and measure which cell or cells are defective ? Hopefully we can find a seller of this type battery like we did for Roomba packs.

[czunit]

Great detective work czunit ! So they are definitely not sub C cells like in the Roomba battery packs. Can you get in there and measure which cell or cells are defective ? Hopefully we can find a seller of this type battery like we did for Roomba packs.

I looked up the battery type; it's 4/3rd A size. Here's a link:

http://www.batteryspace.com/index.aspPa ... ProdID=155

Looks like they cost about $5.00 each, or $60 for a pack of 12. I'm beginning to see why the Scooba battery costs so much. My guess is it was a form-factor issue in fitting it in there coupled with a need for more power for the pumps.

Given this, I'm pretty positive that the battery packs on the 5800 and 5900 are identical. Which makes sense; the model numbers are the same and iRobot only sells one type of pack.

I'll order a pair of cells and take a look at this pack over the week. It's going to look ugly when I'm done with it, but at least it should tell me if the pack "can" be fixed.

One of the things I have in my shed from the "blow up Prismatic" days is a hand build NiCD/NiMH charger built around the BQ2004 series of charging chips. It can watch a battery pack for delta voltage, delta temperature, max charge rate and charge time. I can also set it to charge, discharge, charge over and over to see if a pack is any good. I'll have to give this test Scooba pack a shot once I weed out the bad battery.

Chris

[Gordon]

Thanks for hacking that S-batt open, czunit, as well as reporting findings. You have confirmed my guestimation done 11 mos. ago in the battery-page at Scooba Techincal!
I will update the page to include your exact cell detail.
As discussed in the referent page, Roger C. had partially pried open his Scooba-batt to study re-build potential. Thorough bonding of parts thwarted total separation of the case halves.
I therefore asked myself what might be done to make opening the case a more reasonable task. {I decided to delete the marked-up sawing photo, because I eventually cracked open a Scooba-case and could see that the saw-blade would have cut right through the internal solder-lugs to which the red & black wires are soldered. Sawing is not a good process when battery re-building is intended.}

[czunit]

Thanks for hacking that S-batt open, czunit, as well as reporting findings. You have confirmed my guestimation done 11 mos. ago in the battery-page at Scooba Techincal!
I will update the page to include your exact cell detail.

No problem; I like taking things apart. In a way I was sad that was it; I was ready to take the whole Scooba apart. But now it works, drat.

As discussed in the referent page, Roger C. had partially pried open his S-batt to study re-build potential. Thorough bonding of parts thwarted total separation of the case halves.

He probably ran into the issue I did which is they glued the heck out of this thing. However they glued the case to the plastic liner surrounding the batteries. If you slit that liner, it opens up like a clam. Then use your tool of choice to remove the now shot liner.

I therefore asked myself what might be done to make opening the case a more reasonable task. I came up with the following:

Hard soultion. Just use a box-cutter and a pair of screwdrivers. If I had known the path I could have opened the battery pack without damaging those four little latchettes, and made it so I could open/close the pack at will.

I also think you need to have the case closed. This *is* running in a wet environment, and I remember that NiCD/NiMH batteries emit potassium hydroxide. This stuff wrecks *havoc* with anything that is not nickel or stainless steel, especially when hydrated.

I did a check of the batteries and sure enough one of them is stone dead. As in zero volts dead. Rest are 1.3 volts or so, which makes a whole lot of sense actually. So one way to tell if your pack is toast is to measure the voltage after a charge and sitting for an hour. If it's 15.6 or so it's a good pack. If it's 14.3 volts (you would think that's right) it has at least 1 dud cell. Which would act as a resistor and drop the voltage under load like a rock.

I'll cut out and replace the one dead cell, then see what happens. They might have these at battery warehouse; I'll check. Ultimately though I see why the new pack is $60 bucks.

Chris

[Gordon]

...{Roger}... probably ran into the issue I did which is they glued the heck out of this thing. However they glued the case to the plastic liner surrounding the batteries. If you slit that liner, it opens up like a clam. Then use your tool of choice to remove the now shot liner.

Chris, with that prompting, I reviewed your pix and can see that I had misinterpreted your 1648 image -- it is the liner that is all kachingered, not the lid! Sorry about that.

Hard soultion. Just use a box-cutter and a pair of screwdrivers. If I had known the path I could have opened the battery pack without damaging those four little latchettes, and made it so I could open/close the pack at will.

I see your point, so whenever I get to that stage, I think I will try breaking the bondline with hammer and putty knife, similar to opening APS cases. Then use your open-case image to guide depressing the casing to unlatch it.

I also think you need to have the case closed. This *is* running in a wet environment, and I remember that NiCD/NiMH batteries emit potassium hydroxide. This stuff wrecks *havoc* with anything that is not nickel or stainless steel, especially when hydrated.

I don't think anyone should be alarmed about leaking KOH. cells are designed to leak gas, not solids or liquids. When they finally DO leak liquid, the cell is really dead, and would have been detected by loss of performance long before that stage is reached.
In addition, note that these battery cases are not liquid-tight, they have vias on the bottom through which liquid could go either way, in or out.

[davem]

Good to see someone else go all the way and report back.

FWIW: previous useful threads on Scooba battery rebuilds:

http://www.robotreviews.com/chat/viewtopic.php?t=3355

http://www.robotreviews.com/chat/viewtopic.php?t=3213

Dave.

[czunit]

I don't think anyone should be alarmed about leaking KOH. cells are designed to leak gas, not solids or liquids. When they finally DO leak liquid, the cell is really dead, and would have been detected by loss of performance long before that stage is reached.

*nod* Might be true, I am pretty used to 30ah flooded NiCDs these days. Really nice but they vent a KaOH gas that can just melt copper into sulfate.

In addition, note that these battery cases are not liquid-tight, they have vias on the bottom through which liquid could go either way, in or out. :)

True, however the good people at iRobot actually put rubber glue-in gaskets inside the battery box around the clip. So the rest of the battery is still pretty water repellent overall.

Chris

[bhyde]

More pictures: http://pics.cozy.org/main.php?g2_view=c ... emId=22529

[freemab]

The "batteryspace" link czunit posted a while ago seems dead now.

I think this is the proper battery, but am not 100% certain:
http://parts.digikey.com/1/parts/1701-b ... 4-5ah.html