How fast is it possible to destroy a scooba battery?

Mastiff · Joined: 20 Sep 2007 Posts: 135

Close to two months ago my Scooba 5800 suddenly started to only give me five minutes or less before it stopped with a red battery light. I figured (with a lot of help from the forum) that the battery was destroyed by not having it OSMO'ed, so I got an OSMO upgrade and ran that. Then I tried again, and that didn't help, of course. The battery was fried. So I got another battery from eBay, and that worked well the first 2-3 runs. Suddenly, today, it stopped after five minutes again! Does this mean that there's a serious charging error in the Scooba, so I have killed another expensive battery? I got a charger along with the last battery, so I can get a third battery and use that (stopping the charge after three hours, or whatever). Is that what I'm looking at?

Fraggboy · Posted: June 19, 2008, 11:23 am Post subject:

I don't know. I just got my replacement battery and clear OSMO from iRobot. They are unclear as to what is being updated from the OSMO. It has been roughly 8 months I have owned my Scooba.

Do you know if the battery from ebay is brand new or used? Also, something to note is if it is brand new, how long has it been sitting..

I am unplugging the charger after the Scooba finishes charging. I think that might be the best way to protect the battery..

vic7767 · Joined: 14 Jan 2006 Posts: 3287 Location: Louisiana

You can check the Sticky "READ FIRST" to determine if your Scooba requires the OSMO charging firmware patch. If you have an external charger it should never charge your Scooba battery for more than 3 continuous hours. THe non OSMOed early model Scoobas have a charging system that is very agressive and can cook your battery in as little as 4 months.

Mastiff · Joined: 20 Sep 2007 Posts: 135

OK, I bought a triple set (charger, PSU & battery) slightly used. The first runs it had more juice than the original battery for this Scooba. I have measured the charing voltage on the battery after the very short run (5 minutes), and it started at around 16V (the same as the battery power) and moved up to 19 V in around five minutes. I'm guessing it'll keep klimbing slowly. But still, we're talking about a week or so on the charger, with almost daily runs. Should it even be possible to kill a battery that fast?

Btw I tried the previous battery in the charger for three hours, and that still only gave me 5 minutes of washing. I'm really depressed right now... These things clean out my wallet even more efficient than the floors! :cry:

bob_ninja · Joined: 17 Apr 2006 Posts: 174

There are many important details missnig for your posts.

When using Scooba, do you keep it running until battery is completely drained? What is your typical runtime for a single cleaning cycle?

"slightly used" battery from eBay is very vague.

There are couple of key point to understand to ensure maximum battery lifespan.

1) Scooba is very demanding energy user. It tends to drain battery quickly. Moreover, as a battery approaches its empty state then damage starts to take place. Therefore, you should always run a single cleaning cycle (single tank fillup) and recharge battery even when not empty.

Recharging battery that is half empty will at least double its lifespan.

On the other hand, using a battery to its limit, unitl completely empty, can kill it as quickly as say 50 cycles.

2) I didn't OSMO my machines. I simply use a timer and limit charging to about 4 hours per day. In general you don't want it on a charger for more than 1-2 days, even with OSMO.

In my case, I tried running 2 cleaning missions with 5800 and battery weakend a lot after about 50 cycles. I still use it and handles a single cleaning mission with ease.

Therefore, I got a spare battery and charger. Now after every single mission I swap batteries - bot battery onto charger and spare from charger into bot. That way no single battery ever runs more than one mission without some charge in between.

Finally, the new battery and new 350 I bought from iRobot have a larger capacity battery (I think 4Ah). These of course should last much longer as they are better equiped to handle the Scooba load. No issues for me so far.

P.S.: Actually the only issue is wife who doesn't like the noise and stops me all the time :(

bob_ninja · Joined: 17 Apr 2006 Posts: 174

Mastiff wrote: ....

Btw I tried the previous battery in the charger for three hours, and that still only gave me 5 minutes of washing. I'm really depressed right now... These things clean out my wallet even more efficient than the floors! :cry:

Sometimes it is cheaper to spend more money. Get a brand new battery from iRobot directly. If properly treated you should get likely over 200 cycles, probably more. So if you use it every single day then it should last a full year at least.

The key is to charge often and never drain fully.

Mastiff · Joined: 20 Sep 2007 Posts: 135

Well, to quote the seller: Quote: I used it for about a month before my unit broke. It all sat around for a couple months then till I got around to listing it on Ebay. There were no issues with the battery that I am aware of, my Scooba quit picking up the solution from the floor. The kids had fun chasing it though... :lol:

So it can't be anywhere near 50 cycles. And I don't usually run it more than one cycle, I did however do that one time on this battery, just to check that the battery wasn't bad. And it ran both cycles without any error messages, it simply used up the full tank. Then it suddenly stopped after five minutes. So all in all I would assume we're talking about max 30 cycles. And going from being able to run two cycles to stopping after five minutes really doesn't sound possible to me unless there's something very wrong with the charging on the Scooba. Am I right?

vic7767 · Joined: 14 Jan 2006 Posts: 3287 Location: Louisiana

You may also want to consider converting to a LI-ion Scooba battery. Then you don't have to worry about the charger and how long the battery remains on the charger. The LI-ion has built in components to control the charge and discharge power of each cell and will last about twice as long as the stock NiMH IRobot battery.

Mastiff · Joined: 20 Sep 2007 Posts: 135

Vic, I'm actively considering it. But if there's an ugly fault on the charging in the Scooba (maybe it gives out spikes with higher voltage?) that would probably kill this battery as well. On the other hand I could just charge it in the charger.

Mastiff · Joined: 20 Sep 2007 Posts: 135

Holy Captain Nemo, Batman! This is strange. I charged it for around three hours yesterday with my newest power supply (which I bought along with this battery) and left it overnight without any power connected. Today I put it on the floor, and it washed for all of 15 seconds!

I really think there's something seriously wrong somewhere, because when I think about it, this is exactly what happened with my previous battery. One day it had it's normal cleaning cycles, and the next day it said "da-da-da-daaaa" and stopped after five minutes. There was no slow decline or even fast decline, it just went straight from regular to five minutes and dead. Since that happens with this battery too, there has to be some power spikes rom the PSU or something, right?

But if I buy another battery (that one will get old very fast...) and only charge that the three hours in the external charger, that will ensure that neither a bad PSU nor a bad Scooba can kill that battery, right?

bob_ninja · Joined: 17 Apr 2006 Posts: 174

Yes, you are 100% correct.
NiMH batteries usually don't fail so abruptly. Normally you might have 1-2 weaker cells reducing runtime. I never heard anyone go from 30-60 min to 15 seconds.

Certainly look into your bots and chargers, power supply, etc.

For starters, I would obtain a higher quality noise supressor, surge protector power strip to ensure steady power. Also a timer would be useful to limit charge times, just in case.

Mastiff · Joined: 20 Sep 2007 Posts: 135

Yeah, thanks. I just spoke to the only Norwegian Scooba/Roomba company, and they had LiIon-batteries. So I'm gonna use that with the external charger. And this may be because of the 220-110 V converter I use as well, so I'm gonna replace that with one I have that is of professional qality (bought for an LCD projector). I'm guessing that may be where the damage was done. :cry: Expensive lesson, but it could have been worse. I got a pretty good price on that eBay used battery. Actually I couldn't have bought the charger and extra PSU for that price new. So it'll be my standard: Pay, and watch my wife be happy again.