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980 battery performance

PostPosted: October 4th, 2018, 8:15 am
by gregj
I got my 980 on the 26th of Nov 2015. It has been a while.
It has performed 713 jobs, running time of 682.5h.

Question is, how do I know the battery is still up to snuff, and moreover - how do I find out the remaining capacity of that battery. It's a regular default stock battery that came with the hoover. On Monday, it has run out of power after 58 minutes - and stopped halfway through the room - presumably on its way to the charger. You might say, I do interpret this as a sign.

Thoughts?

Re: 980 battery performance

PostPosted: October 4th, 2018, 9:24 am
by vic7767
The common failure on the Lithium pack is that a single cell will go bad thus creating your symptom. Three years operational service is on the fringe. Most Lithium OEM packs average around five years.

Re: 980 battery performance

PostPosted: October 4th, 2018, 11:25 am
by gregj
ok, so it sounds like mine should still have some life in it left.
Any way to test the capacity?

Re: 980 battery performance

PostPosted: October 4th, 2018, 12:54 pm
by vic7767
You can connect a 12vdc auto bulb (like a turn signal or running light). The lamp should remain bright for about 70 minutes for the OEM 1800 mAH pack.

Re: 980 battery performance

PostPosted: October 4th, 2018, 5:09 pm
by gregj
Any chance to do it with a meter? I'm good with those :-)
If it's 1800mAH, it should allow me to draw 1.8A for an hour. I need to find something that draws 1.8A. What's the voltage? It's probably on the battery itself.

Re: 980 battery performance

PostPosted: October 4th, 2018, 5:16 pm
by vic7767
You could use a meter with close to 2 amp load. The pack voltage is 14.4 but when fully charged should read about 17.4 vdc. Time how long the pack remains above 12 vdc.

Re: 980 battery performance

PostPosted: October 26th, 2018, 5:28 am
by gregj
So the issue is, that the robot only goes on for about an hour before returning to home-base to top up. Then - after 90 minutes - resumes for 5 minutes and finishes the job.
It used to go on for about an hour and a half. The battery is 3 years old.

So I bought a third-party battery (TLDR: don't buy this one): https://www.amazon.co.uk/gp/product/B06 ... UTF8&psc=1 . I thought because it is supposed to have a higher capacity - it will last longer. Nope. Left it charging overnight, ran a job in the morning - lasted 45 minutes before the robot went back to top up.
I have now returned it and ordered the original iRobot battery for nearly £100. iRobot has charged me shipping as well, bastards.

Once the new one is in, I'll measure the old one's performance. I don't have a constant load that could do 30W for over an hour - sadly - but I'll try finding something to test it with.

Re: 980 battery performance

PostPosted: October 26th, 2018, 11:27 am
by gregj
Btw, @vic7767 - how do you measure voltage? if I measure between the bigger contacts - it's only 40mV. I'm guessing that's wrong. If I measure between smaller and bigger pad (diagonally) - it's 2.7V ¯\_(ツ)_/¯

Re: 980 battery performance

PostPosted: October 26th, 2018, 11:35 am
by vic7767
The 2 large contacts are ( + ) and ( - ), the two smaller contacts are the thermistor used to report battery temperature.

Re: 980 battery performance

PostPosted: October 27th, 2018, 7:52 am
by gregj
another question, if you don't mind. I did put a new battery into Roomba, it's been on the charger for more than 12h now. But in the app - the battery doesn't look fully charged yet. Bit odd.

Re: 980 battery performance

PostPosted: October 27th, 2018, 10:39 am
by vic7767
One way to determine if the pack is charged is to use a terminal program and monitor the USB SCI channel charging data that is send out once per second while the 980 is on the charging dock.

Re: 980 battery performance

PostPosted: October 28th, 2018, 8:11 am
by gregj
sadly I don't have the hardware to monitor USB SCI channel.

This is the screen I'm talking about: https://www.dropbox.com/s/596eh8j9zfwos ... 9.png?dl=0

It's been charging since 8pm previous day.

Re: 980 battery performance

PostPosted: October 28th, 2018, 9:52 am
by vic7767
Don't know what's going on with the app. Maybe remove the battery, delete and reinstall the app then see what happens.