Roomba exchange Lithium Ion battery for scooba

tum · Joined: 26 Apr 2008 Posts: 41

Does anyone know how long these last and what the capacity (mAh) is?

The battery in my new 5800 is absolutely useless.

Thanks :-)

debugger · Joined: 20 Jan 2007 Posts: 715 Location: UK - Glasgow

tum wrote: The battery in my new 5800 is absolutely useless.

Please define "absolutely useless" - does it complete 1 mission on a charge, does it complete 2, does it fail within 5 to 10 mins etc. ?

There are 2 battery types and typically one can do one and a bit runs and the other can do two and a bit runs. Is your battery blue or grey?

If you're getting less than 1 run then there's a problem and you should get iRobot to address it. I don't think anyone should have to consider replacing a battery on a brand new unit.

alik911 · Joined: 27 Aug 2007 Posts: 15 Location: Ukraine

I have received "new generation" Scooba 5800 last week.
It was made January, 2008 (as far as I can see in the serial number).

You can see the external differences with brush and battery.
(I don't know about and internal differences).
It's white low-capacity battery (3000mAh).
Old batteries (blue) were 4100mAh.

I have tested this battery with my old Scooba.
It works only 25 minutes, instead of 90 minutes.

RoombaExchange · Joined: 21 Aug 2006 Posts: 1187 Location: Florida USA

The Scooba Li-ion batteries are stated on the site as 3400mAh but when the batteries are built here and tested for capacity they are rated at 3800mAh before they pass our final testing, this is 3.8 Amp hours based on a 1A load. Scooba runs a bit above ~2.5A which translates into an average of 2 tank runs before needing a recharge. If charged in a PRE OSMO unit the li-ion will charge to full capacity inside the Scooba, If used in an OSMOed unit a CODE 9 charging error will sound once the Li-ion switches to trickle charge at 75-80% capacity and can be ran at this level but at a slightly reduced runtime.
For best results, in an OSMOed unit, it is recommended to use the Li-ion in conjunction with a scooba External charger so that the battery will charge completely to 100% capacity.

OSMO Dates: If build date is before 061122 (yymmdd) on 5900 or 060922 on 5800 then the scooba is "PRE OSMO" unless an update was installed by the owner with an update firmware module available from iRobot.

The benefits of Li-ion vs NiMH are that the Li-ion have a higher energy density (Wh/kg) and operate at a higher voltage 3.6v per cell, requiring fewer cells to maintain the voltage needed to operate a Roomba or a Scooba. The heat buildup is far lower than NiMH and the shelf life on a stored Li-ion pack is a 1-2% "self discharge" per month as opposed to 1-5% "self discharge" per day with NiMH.

In a nutshell, Li-ion cells have a higher maintained voltage curve under a load, lower operating heat, considered to have twice the charging cycle lifespan of NiMH and exhibits no memory effect.

alik911, The lower capacity NiMH battery that you have that is only running for 25 minutes may need to be ran "cycled" several times before the capacity is up to its potential. The brush obviously reduces the drag and thus reduces battery consumption. I would assume that this also reduces the cleaning ability as well with less then 1/4 of the brush surface.