Rebuilding a Roomba Battery for Less

[sageman]

was it getting the red light and returning to the base or just returning to the base

[Prof. Prevaricador]

It was getting the red light...
I also think that it should run longer.
It only run 3 times until now and I'm unplugging the roomba as soon as it gets green.

I probably should charge it for 12 or 16 hours to get a good charge in the batteries.

P.S.- I had a little trouble soldering the batteries tabs although I was cleaning and scraping the surface before soldering. Do you know a more effective method of soldering to the surface of these batteries?

[mfortuna]

Try charging the battery overnight. Once charging status goes green the robot goes into trickle charge mode. This should help top up the battery to full capacity. The first few runs should be until the roomba stops with low battery status.Charge overnight before next use. It should help condition the battery.

It is possible you may have a defective cell. If repeated overnight charging does not get you past 1 hour something may be wrong.

Also, it sounds like you ran the first mission with the batteries charged to whatever level they were off the shelf? This is not a good idea since you have no knowledge of each cells capacity. Some may have been over discharged and potentially damaged from the first 20 minute run. I kinda doubt it but it is possible.

You should always charge a new pack before first use. It doesn't matter if you purchased it assembled or built it yourself, it should be fully charged before using.

[Prof. Prevaricador]

I will try charging the battery overnight and see if the run time improves.
You are right, I ran the first mission with the batteries off the shelf without charging first...
I really hope I didn't ruin any of the cells!
How could I test the individual cells? With a multimeter measuring the voltage and amperage?

[mfortuna]

If you go to vic7767's home page you can see how to perform a load test on the battery. While you are doing the load test you could measure each cell and see if any are underperforming. The cells will start out at something greater than 1.2V each, and then tend drop from their maximum to about 1.0V over time. After they reach 1.0V they tend to discharge faster and when they get to .9V you should stop the test. Since these are unmatched cells you will probably see a wide range of voltages.

I would say run the load test on a fully charged pack for 10 minutes and then measure each cell under load. If some cells are way lower than the average then they are suspect. for example, if all cells except one are in the range of 1.10V and 1.15V and the other cell is at 1.00V I would suspect it as being marginal.

[Prof. Prevaricador]

After charging the battery overnight I got the same run time... 1 hour
When I get the time I will test the individual cells like you suggested.
Just to clarify, I must measure the voltage of each cell under load or can I do it with without load?

If I can improve this battery I will probably use it to get charged from a solar panel.
I'm thinking in buying a solar panel and start testing with this battery I don't want to directly connect the panel to the roomba before testing properly...

[vic7767]

You can measure each cell after a cleaning mission is complete.

[mfortuna]

IMHO it is best to measure during the load test. That is why I suggested measuring 10 minutes into the load test.

The steps are:

Charge the battery.

Attach the load device (lamp).

Wait 10 minutes.

Measure all 12 cells and record the measurements.

Measuring the cells under no load, even when a mission has been completed may not be that accurate. Cell voltage tends to bounce back once load has been removed.

[Prof. Prevaricador]

Thank you both.

I will measure each cell and replace the underperforming cells.

[iwan]

how did the tests go? i am very curiouse, because i am planning to build my own battery to...

[newmom]

[quote="Gordon"][quote="Masterrer"]Gordon, I think I need to clarify a bit.
Take a look at this picture:

ScoobaCell-inAPS.jpg

You are all so brilliant, so don't laugh at my question. How do you take apart the Roomba battery case in order to get the old batteries out? I bought the special screwdriver and removed the screws easliy, but I can not pry the top off the casing for anything. is there a secret?

[Gordon]

... How do you take apart the Roomba battery case in order to get the old batteries out? ... is there a secret?

The secret is: The lid is bonded (as in "glued") to the lower portion of the case! So you must crack the glue-joint via mechanical force.

Fortunately, member mundt1 wrote a very nice procedure for you, and you would have found it by reading all the posts in this thread! <hee><hee> Or you could have searched for it by use of a few key words. Here it is: viewtopic.php?p=21639#p21639

[Spirit Force]

I'm back to try out another lithium battery for Roomba. This time I'm going with 5000 mAh lipo battery. I got the battery and it fits nicely! Only problem I currently have is the PCB. I all ready got one PCB that didn't work so, if I can find a suitable PCB this project will enter into testing phase. Also if someone knows about suitable PCB for 4S lipo pack let me know!

[iMayne]

Took me awhile to read all posts. My brain kept messing up as I see both 400 series and 500 series batteries being discussed. Not sure if the 500 series was mentioned more than the 400 series.

My concern is only with the 500 series batteries; building one with li-ion battery cells. Someone said that they built one but got the err 5 when Roomba is docked and no error code when charger is plugged directly in the side of the robot. I have lost tracked as I'm not sure if the topic changed to the 400 series batteries.

Is there a specific topic for building a 500 series battery for less? To much confusion with 400 series and 500 series in here. To be honest, I'm not sure reading so long made my brain upset

[vic7767]

Due to the nature of the charging system on the 500, 600, and 700 model Roombas it is very difficult to design a LI-ion battery solution without the err 5 issue. If the battery built and the charger and 500 model Roomba are matched well then there is a successful charging process. That happened to me one time using a 535 Roomba and some 1050 mAH cell phone batteries.

[iMayne]

Due to the nature of the charging system on the 500, 600, and 700 model Roombas it is vert difficult to design a LI-ion battery solution without the err 5 issue. If the battery built and the charger and 500 model Roomba are matched well then there is a successful charging process. That happened to me one time using a 535 Roomba and some 1050 mAH cell phone batteries.

Things are getting clear now. ProTech Robotics once sell the li-ion batteries for the 500 series and now they don't. Seemed they had issues with them.

Someone said when charged directly, no error code. But when on home base, err5 comes in. No wonder iRobot sticked with NiMH batteries.

Maybe a circuit can be integrated to prevent the err5???

[vic7767]

I received the err 5 during both types of charging environments using 500 model Roombas, LI-ion packs via direct charging and home base charging except for one good test using a 535 for both home base and direct charge.

[TechGuy]

The Roomba firmware was decided for NiCd and NimH battery. Therefore, no one dares to charge Li-Ion battery without a Li-Ion external controller. When the Li-Ion controller detects the Li-Ion battery is fully charged, it disconnected itself from the charger. When Roomba 500, 600 and 700 detects this condition, it will flags it as Err5.

You can still use the Li-Ion battery. But you cannot schedule your Roomba.

Roomba will not drain the Li-Ion battery to dead as the Li-Ion controller will disconnect itself from Roomba when the battery level is getting low.

[iMayne]

You can still use the Li-Ion battery. But you cannot schedule your Roomba.

In summery, Roomba wont charge successfully with a li-ion battery when robot on the home base? Ok.

[TechGuy]

Roomba will charge the Li-Ion battery. But I need to reset it before starting a mission. I am using one as I do not schedule my 560 and 580. I will not build another one after this one is dead.