Battery Charger

Question

My battery charger is not charging and the green light is always on? I have been able to charge a few times now without issue and this happened just yesterday. Cannot charge my robot now....

Is there anything I can check/do to get this working again?

all_your_robot_r_belong_to_us · Answer

Decided to open it up to see if anything was burnt. Everything looks normal?

Dunning-Kruger · Answer

Can you check what voltage your Lipo is at now?... A long shot, but if the voltage of your lipo drops below 3V per cell (6V where we're concerned) then it will no longer charge again... Also have you tried unplugging the charger for an hour or so and then trying again?

Rich · Answer

@Richard, notice no battery is connected to the charger yet the green light is on... The charger may still be charging the battery, have to checked the voltage before trying to charge it then after it being on charge for a bit?

Dunning-Kruger · Answer

Doh... @Rich See, now I know why they pay you the big bucks... Rich is right, maybe your charger is still able to charge... Check your batt voltage....

Nomad 6R · Answer

maybe am wrong but this looks not wright to me.

Robot Doc · Answer

It seems Nomad18.08 has spotted a couple of FETs that look smoked.

Nomad 6R · Answer

this is also strange,the screw looks old.

WayneA · Answer

@nomad18.08 If I may: R16 appears to have at some point gotten really warm. I doubt it has anything to do with what your seeing, but something to check.

Nomad 6R · Answer

wayne yes some chargers get really hot.thats why they are in metal cases. its hard to see cause the pic is not very clear.

all_your_robot_r_belong_to_us · Answer

thanks for all the detective work. i will try to get some clearer pic's up and check if that is a burn on the board. didn't notice it when i took it apart. @nomad18.08, not sure what you mean by "this is also strange,the screw looks old." i did take it apart to take the pic's.

the charger was getting very hot. to say warm is not accurate because i could not even hold it when it was charging.

it is not charging the battery which is how i discovered this problem.

will post pic's soon.

all_your_robot_r_belong_to_us · Answer

here are some better pic's. in the one pic, the resistor appears discolored. there does not appear to be any burns on the other pics and were just shadows in the previous pic's.

Nomad 6R · Answer

well you cant use this one try to get another one.

Rich · Answer

Have you measured the voltage on the 2S balance port of the charger?

all_your_robot_r_belong_to_us · Answer

yeah, i'm pretty sure this one is dead unless i can replace that resistor. not likely for me since i don't do stuff like that. @rich, not sure what you said means, "2S"?

Rich · Answer

The plug that has 2 cells 7.4v above it, measure the voltage between the outside 2 pins, that will confirm if it is charging the battery despite the LED being always on or not.

Dunning-Kruger · Answer

2S means a 2 cell lipo... each cell is 3.7V so two makes 7.4V

Rich · Answer

@Richard, charge voltage is higher than 7.4v. The voltage across the outside 2 pins should be around 8.4v and it should be 4.2v between the first and second pins and 4.2v between the second and third pins. Here's a good guide on everything Lithium Polymer

Dunning-Kruger · Answer

Blimey... It's a Christmas miracle, it is... Nomad just received a store credit... Oh, man I am going to get crap for this one.... Good on ya' @nomad.... Cheers...

Dunning-Kruger · Answer

@Rich, I was just explaining the normal voltage of a 2S lipo battery itself... Yes, I do know the charger will charge a 2S battery to around 8.4v when fully charged...

Nomad 6R · Answer

rr i got two wright this time. thats two brain cells activated hehe thanks

Dunning-Kruger · Answer

@nomad... awesome.... Doing great... and good eyes by the way...

Rich · Answer

Well, you didn't exactly get it right, you gave a solution... Tto be honest, buy a new balance charger isn't an ideal solution and it's not actually been determined that the charger isn't charging. It could be a coincidence that the green light is always on but if the battery is under volt it wont charge, this would be a battery problem and a charger problem. We don't know the voltage of the battery at the moment, we don't know the output voltage of the balance charger either. The green light remains lit on one of my balance chargers despite it being fully charged and balanced. On occasion it has turned off but it does remain on too. It's not one of my ones from EZ-Robot but it is the exact same design, just rebadged as something else. Another user may see this topic and instantly think the balance charger is faulty when it may not be.

Nomad 6R · Answer

rich well i disagree, using a faulty charger can ruine your batt too. the learn section tells you how the charger works,red&green led. and averyone is asumed to read the hole topic.

Rich · Answer

We haven't determined that the charger is not charging though, all we know is the green LED remains on all the time. We also haven't determined if the battery itself has become damaged. A new balance charger for a battery that has been damaged due to under voltage (possibly through the use of a faulty charger) will not solve the issue either. The whole topic doesn't give this information. Diagnostics is incomplete.

all_your_robot_r_belong_to_us · Answer

here is a pic showing voltage from the terminals on the charger as requested. also a pic of the battery terminals tested. the battery is showing >8v; does that mean it is charged? i know the robot complains when the voltage drops below 6.6v. when i discovered the issue, it charged for at least 4 hours. i am worried that the charger will not shut off and possibly ruin the battery (or catch fire) if the charger is faulty.

Nomad 6R · Answer

rich you have a point there not knowing iff its the batt or the charger. aldo the green led chouldn lid up when there's no batt connected. i do have some info about a bad batt.you can see on a charger iff the, batt is bad.the led on a charger goes out or blink red. so i gess we bolt earn 1.5 credit all your robots good find and good reason to by new one.

Dunning-Kruger · Answer

Looks to me that your charger is actually charging or at least outputting... Your battery is pretty much fully charged, by the way...

Rich · Answer

Balance charger voltage is correct and therefore will charge the battery. Battery voltage is OK, it's not fully charged (8.4v) but it's close. Which is good news. You should never leave a LiPo battery unattended while it is charging. The balance charger charges at 1A, divide the battery capacity by the charge rate to find the time required to charge it. A 1600mAH battery charged at 1A would take 1.6 hours to charge. I'm not sure, but believe that you cannot overcharge a LiPo since the charge voltage is the same as the battery voltage when fully charged. The voltage of the battery therefore cannot increase above the charge voltage. However, as I said I am not 100% sure of this. I will need to look it up (unless someone else chimes in). In the mean time, do timed charges based on the above calculation, check the voltage of the battery when you take it off charge and check it's 8.2-8.4v

all_your_robot_r_belong_to_us · Answer

okay, since the battery has been charged, does that mean that the charger is still charging it and that it won't overcharge the battery? i don't know enough about electronics other than putting a voltage meter on batteries to see if they have a charge. i am worried that it will ruin my battery or worse, cause a fire.

all_your_robot_r_belong_to_us · Answer

@Rich, sorry, didn't see your post until after I posted. I will try your recommendation. Just to be clear, I should read 8.4v on a fully charged battery and that it should take ~1.6 hours to fully charge the battery. Is that from 0v on the battery or from the 6.6v? Can I use the charging connector on the bottom of the robot to check the voltage or do I have to pull it out each time?

Rich · Answer

No no no no no. Never 0v on the battery! Never below 6v on the battery! From around 6.6v however my example above is for a 1600mah battery. EZ-Robot batteries are 1300mAh. It will take about 1 hour 20 minutes to charge (give or take). Yes you can measure the voltage on the connector. On the connector it's the outside 2 pins for total voltage. One thing I just remembered though, on first charging Six with the EZ-Robot charger my green light never turned off. Turning the robot on while it was charging fixed this, it's been working fine since. No idea why, not really recommended but shouldn't do any damage if it's only powering it up then turning it off after a few seconds.

bobjacon · Answer

Is it possible that this indication occurs if the charger circuitry has detected operating temperatures inside the charger enclosure that are above factory specified levels? Bob J

all_your_robot_r_belong_to_us · Answer

@bobjacon, don't think so. this happens when the charger has not been charging for hours and is cool to the touch.

Aerius · Answer

Will that create any issue if I let the charger connected to the batteries when I am using the EZB and servos. I am presently developing and testing scripts for my Inmoov robot.

CochranRobotics · Answer

You dont want to leave the charger plugged in when using the battery.

Aerius · Answer

Tanks Dave, What could append?

CochranRobotics · Answer

Worst case, blow up the battery. it could also fry the the electronics in the battery causing a surge to power to go to the ez-B.

Aerius · Answer

Tanks for the advice! I gess I could make a circuit to automaticly isolate the EZB when it sense a low batterie condition and let the charger do his job, and after bring back the EZB back on line. Do you have any other sugestion?

CochranRobotics · Answer

The issue is that lipo's dont like being full. It would be safe to do this when the battery is at about 3.9v per cell and cut off when at about 4.05v per cell.

CochranRobotics · Answer

A better option would be to get a variable power supply that supplies the needed amps (min of about 20A). This would let you adjust the voltage to what you need and allow you to work on things without needing the battery plugged up. To make a full Inmoov function I would look at a 50A supply but, until you get to that point, the 20A will be fine.

Aerius · Answer

Tanks Dave I'll be looking for it

pacowang · Answer

Well since I'm in a chatty mood and I think I soaked this thread in, I purchased the lipo and charger from EZ-Robot a few months ago and since day one the charger has always had the green indicator light on irregardless if a battery is plugged in or not. The charger is putting out 8.6 v and the lipo is at 8.6v. I just leave it run over night. Poor quality control. Maybe things have gotten better from China for EZ-Robot now. I live with it because it is working for the time being and why go through the hassle of return shipping charges and then the wait for another drop shipment from China? No thanks

all_your_robot_r_belong_to_us

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