Paradise Robotics Forum
Robotic Lawnmowers => Lawnbott => Topic started by: Radjack on May 10, 2011, 01:26:32 PM
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Hey guys,
I got Bubba out working this week and have noticed a serious decrease in the length of his work time per cut..
I think it was around 2-2.5 hours last year per outting, where this year it seems to be between 48-69min. The display reads about 2880 after charging 12 hours, where last year it read 2950 or so.
Any thoughts?
Battery is 10 months old. This was its first winter, i charged it 2-3 times over winter to keep it full.
Anything i can do as far as testing?
I think batteries have one year warranty?correct?
Thanks
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Maybe battery. What model do you have? You might want to check if your charger is indicating a fast charge(red light instead of green). I had a similar problem and needed to replace the Battery charger and that fixed the problem.
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Talked to kyodo today, I guess there is a feature that limits the bots runtime when the grass is sparse... He suggested that when the grass gets longer he should stay out there longer.
All the voltages where fine, just need longer grass!
Phew!!
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My standard answer about this is "What does the lawn look like?" If the run time is short, but the lawn looks great, there is no problem. If the lawn is not being maintained when it worked fine in the past, then there could be a problem. The battery getting old is the most likely cause. You can also try shining up the plates and recharging nuts to ensure they are making good contact. Poor contact could affect the charging time, too.
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Update**
I kept a close eye on Bubba all weekend, and after 30-60 min, he would head back to charger with low battery. After charging for 12 hours the battery only got up to about 28.5 volts or so, i guess it should be closer to 29.5V...Called kyodo today and they sending out a new Li Ion battery today since it is less than 1 year old and still under warranty...
Not sure why the battery didnt winter well but hopefully this gets him working like new again. I charged him for 10-12 hours 2 or 3 times throughout the winter, to keep him fully charged.
Will keep you updated after i get the new battery.
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I charged Junior's battery about every 2 months throughout the winter but it only took about 1/2 hour for the voltage to get back up to 29.
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28.5V after charging is odd. It makes me wonder if there is a problem with the power supply. You can check the output voltage of the power supply by disconnecting the round connector (press the metal tab and then pull it out of the transmitter). Put the meter probes across both pins while it is turned on being careful not to short the probes to the metal connector housing. You should get something between 29.3 or 29.5V. If so, the power supply is fine. If you get 28.5V, the new battery will only charge that high, too.
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The 2 charging plates in the house had a voltage of 29.5 when we tested it...
I got the new battery this morning and hopefully will get a chance to install it and run bubba.
Update...
Installed new battery and he is charging up as I type, hopefully by tomorrow I will be able to see what happens with the new battery.
Update...
It has been 19 hours of charging and the battery is still at 28.6V. I will leave it to still charge a bit longer but I am pretty concerned that something else is wrong for it not to get up over 29V.
The plates are reading a solid 29.43V, any ideas why this new battery won't fully charge just like the old one?
I should also mention that there is a splice in the wire from the ac adapter to the charging station, but since the voltage is a solid 29.43, I don't think that should be an issue.
I am sitting at work thinking about this problem and wondering about the contact between plates and the knobs...could the plates be dirty, or they just arnt making good contact? could there be a voltage regulator problem?
Will keep updating...
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Went home and cleaned all the terminals up, let it charge all night and he got up to 28.9V this morning...
I think i will just let it keep sitting there "paused" and charging until the Voltage stops rising, maybe a new battery takes longer than i thought to get up to full charge.
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If you have the FM filter inline with the charger I would recommend that you remove it.
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It has been in line with charger since i got the system. It seemed to work fine all last year.
Why would I remove it?
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it maxed out at 28.9V.....
I let him run and got 91 min run time....
I am not sure what to do next, waiting on a call back from kyodo for more ideas...
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In my case the FM filter effected the charge reading of the battery to the charger. It kept dropping the charger output to a maintenance level and would not bring my battery up to full charge. Just unplug it and give it a try. You can't hurt anything by removing it.
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Also, where are you reading the battery voltage? The best place is on the display. After the robot gets going, it flashes the battery voltage (4 digits).
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If that was the case for me gyro, the charging plates would not read 29.43 V correct?
It seems to me that the problem either lies inside the robots charging system, or the battery itself. The max charge is regulated and not allowing the battery to fully charge.
Kyodo is sending me a third battery, as they think it is the batteries as well...
We will soon see when I get a third one...
Battery voltage is read using a meter across the terminals, but I always keep an eye on the display as well for quick reference. It has always been the same value. (or darn close)
Will keep you updated...
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Sorry to ask again but have you checked if your charger is going to a fast charge indicated by a red light on the charger instead of a green light? I had the same problem. I could charge for 48 hours and only get to the mid 2800 reading. My charging plates would read 29.3 as well. Replaced the charger and problem solved.
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Ya there is a solid green light on the battery charger...
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Check this out. Have the mower go out and when it returns to the base station because it is low on battery, immediately check your charger light. It should be red and not green. The red light indicates fast charging mode and it gets the charge up faster and will switch to green after a couple of hours.
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I will check that...
If this is the case how do fix it? Replace charger?
How would have this changed from last year to this year?
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Unfortunately the charger can malfunction and go bad. Replacement is what worked for me. Keep us posted... As suggested by gyro, take the filter out to make sure it isnt malfunctioning. It can go bad with time as well.
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Filter is out as of this morning, and last night about 20min after the bot went in to start charging the light on charger was still solid green, i will try to catch it again this afternoon/tonight to see if i ever see any red. We will see...
Third new battery from kyodo should arrive wed or thurs this week...
Will keep updating until i figure this out.
Keep the suggestions coming. :)
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When diagnosing a similar issue, I found that the problem was in the cable from the charger to the hut. I was able to verify this by using my winter charging cable. I ended up running my own wire in parallel to the charging cable which solved my charging problem.
I think that they know about this issue since one of the items in the upgrade package last year was a new cable.
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The bot came in just now and the charger stayed with a green light.
The cable issue sounds like a very real possibility, any idea what was wrong with the cable? Over the winter I made the cable longer, so there is now a splice in it... Since the voltages all remained the same I figured it was all good.
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I noticed the connections to the charging plates were crimped and then glued in place with silicone instead of soldered.
I thought this was the problem, but I can't be sure. The best clue I have for sure is using my winter charging cable charges fast and full.
The wire itself seems adequate, so that leaves added resistance at the conectors at one end or the other.
If you have a voltmeter, try measuring the voltage drop accross the cable while it is charging. If you see any appreciable voltage drop from the source end of the cable to the charging plates, there is abnormal resistance in the link.
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Is the splice in the charger wire soldered? If a new battery does not fix the problem, you might want to take a closer look at the splice. Although the voltage is correct, the current could be getting restricted if the connection is poor. You would still get a good voltage reading but the charge time will increase (similar to the behavior you are observing; so that's why I am mentioning it as a possibility).
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Filter is out of line and the run times have went up drastically with the old batteries....
I would estimate that the run time has gone up 30-40% from where it was when i started complaining.
Any one have more info on what this filter is doing, and if it serves any useful purpose in North America?
Should everyone be removing it?
I still havnt recieved the new battery from kyodo....
Will keep updating
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The filter will remove interference with AM Radio waves. If you are running without your filter, you or your neighbors will have trouble listening to the AM Radio. Something seems amiss with your charger, because it should trigger a fast charge after running low. I assume your mower is scheduled to mow daily? Twice daily? Good to hear you have increased runtimes...
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ya it is scheduled to run twice daily...
lack of AM radio...I dont think that will be a huge problem. :)
Just got the new battery from kyodo this morning...
I doubt it will react any differently but we will give it a try over the next few days.
The deeper we dig into this, the more i think it is simply the splice i have in that cable. If the resistance went up, that would mean the current would drop to the battery, therefore not providing enough for the battery to charge. I will have to do some testing to see...
will keep updating
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"Over the winter I made the cable longer, so there is now a splice in it... Since the voltages all remained the same I figured it was all good."
This is the source of the problem. There is resistance in the cable, this creates a voltage drop across the cable. The voltage will never get higher due to the resistance. The only way to solve it is to reduce the resistance. It could be how the splice is soldered, it could be the wire itself. Fatter wire will have lower resistance.
The upgrade included a fatter cable to the LB35XX charging base (this was not an issue for the other models). The fatter cable reduces the resistance and allows the battery to charge higher. If you did not get the upgrade, then making the cable longer increased the resistance even more.
Here is a tutorial on basic electronics so you can understand what is going on:
http://www.electronics-tutorials.ws/dccircuits/dcp_4.html (http://www.electronics-tutorials.ws/dccircuits/dcp_4.html)
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I only made the cable longer by a foot or two, to reach the new base location. The length should not be an issue, but the splice might be...
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It would be best to solder the splice. Are you using the same guage wire as the original cable? If not, you could be creating a safety hazard. Make sure the new cable is not getting warm. If it is, use a thicker wire.
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Exact same wire, no heat.
I charged up the new battery and it got up to 29.0V, which is slightly higher than the other two batteries.(28.8V) I will run with it over the next few days and see what kind of charge and run times i get out of it.
The only thing that i have different at the moment is the filter has been removed. Once i get these results i will plug the filter back inline and compare results again.
Will let you know the results when i get em.
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Hey Radjack, At one time I had the same problem. Was told that the batteries were bad after spending for new batteries, I still had the same problem. KA sent me a new bump switch and that cured the problem.. I now have some extra good batteries if any one need them...
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So the results are in, and now i am more confused...
With filter out of the system:
The New battery ran for 2+ hours right out of the box. It charged up to just over 29V and ran for 2+ hours for a few days.
I then put the filter back into the system. This returns me to the original setup, but with the 3rd battery installed.
To my surprise he stills charges to over 29V and runs for 2+ hours.
I guess with those results it must have been something up with the 1st 2 batteries...
I will continue to keep on eye on Bubba, but i guess he is all back to normal. (or so it seems!)
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my professional charges to 2800, then starts discharging while still in the house. the light stays green on charger. robot mows for 1/2 hour, returns to charge. is battery dead or is charger shot?
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Something else to check for short run time. I recently got Billie Back from Reform School(KA) and at least for a short time was pleased that he had been reformed. AND THEN he started to be rebellious. Short runs got down to an hour. I did the usual checks and found nothing. Then by chance I noticed him wanting to pull off of the wire. After cleaning the castor's found them still not free.. One of the bearings was seizing up. Bottom line, all of the info from the high tech engineers never once mentioned to check this. Tip... Check castor's every once in awhile. A sticky castor makes for hard work for the little guy..
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Shep - never would have thought about a sticky caster causing a short run time. That's a new one and I think I will write it down :)
Whitey - it sounds like one of the cells in your battery went bad and is now low. It is pulling the voltage down on the other cells once they get charged up. It sounds like you need a new battery. We have them in stock and they are not too expensive, or you can upgrade to Li by sending us your battery charger. Li has waaayy longer life than Lead Acid and also lighter (less wear and tear on your motors) and better for the environment.
Cheers,
Robotlady