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Old Mar 09, 2005, 06:15 PM
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LukeZ's Avatar
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Hobbico Quick Field Charger acting weird (or maybe it's just me)

I recently bought a Hobbico Quick Field Charger MKII and have been using it to charge my very first LiPo pack, a 2s2p 1500 mAh sucker.

Usually at the end of a charge, the little guy beeps and flashes its light for a bit but will eventually shut up, although the light keeps flashing: mostly to indicate a trickle charge is going on, at least in the case of NiCd and NiMH batteries.

Anyways, the other night I'm charging my pack after a long flight on the Easy Star. The voltage cutoff on my ESC had kicked in so I figured my pack was completely discharged, and it should take about 3 hours for the MKII to charge it, since the max rate it can do for LiPos is 1 amp.

On the mark, right at 3 hours, the charger starts its infernal beeping. This time, though, it doesn't quit. I finally go over there to see what the deal is. The light is flashing an alternating red and green, which the instructions list as an error condition (poor connection or reverse polarity).

However, I don't really think there was an error involved, since the packs charged just fine and it quit when it was supposed to. I measured voltage after the charge and it was 4.1 per cell dead on.

All the same, I don't like being given an error message. Has anyone else had this happen?

I will try to see if I can replicate it again, but I need to find time to go out and fly, as I don't really feel like listening to that motor go on for half an hour inside my apartment just to drain the batteries.

I will post my further findings here, if any.


Luke
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Old Mar 10, 2005, 04:38 PM
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Marseille, France
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I have a hobbico MKII charger. It usually takes about 2 hours to recharge my Thunder power 2C 1320mah before the green light is flashing. If you do the maths, a current of 1amp should charge this pack in about 79 minutes. This charging time will be correct if the pack is fully depleted. But you don't want to fully discharge a lithium battery. So, I expect that it should take 65 minutes to recharge a 1320 mah pack if the current draw is 1A. But this is not the case. During the charging process, my ampmeter shows 0.75A when I adjust the rate at 1A. That's why, it takes more than an hour to recharge my pack. The MKII charger doesn't give you more than 0.75 A to recharge a lithium battery.
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Old Mar 10, 2005, 04:43 PM
my passengers on landing
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Luke '
I had the exact same problem with my MKII. I've been using my charger for almost a year and a half now. First time this happened last week.
I recently picked up a 2 cell 650 ma lipo at the Wram show. First time I charged this one it charged up to 9.0 volts. Battery never got warm or showed any signs of over charging. I usually use my watt meter to monitor the charge but didn't this time because I was using it for something else. Again this is the only time I had this problem.
I remember reading some place that maybe the left side is better for charging lipos. Looked for that thread again but couldn't find it.
By the way the 9.0 volts was after the pack had rested from the charge overnight. I hooked it up to a motor I had in my test stand and run it down until the lvc cut in. Recharged the battery again (while monitoring) and everything went fine.
Jack
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Old Mar 10, 2005, 05:08 PM
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9 volts! Man, that's a bit scary, at least after all the horror stories I've heard.

As it turns out I was charging my LiPos on the right side... I will try to discharge them today and re-charge them again on the left side. I will post back what happens.
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Old Mar 10, 2005, 07:06 PM
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Haralson County GA. USA
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Quote:
Originally Posted by Cactus1552
Luke '
I had the exact same problem with my MKII. I've been using my charger for almost a year and a half now. First time this happened last week.
I recently picked up a 2 cell 650 ma lipo at the Wram show. First time I charged this one it charged up to 9.0 volts. Battery never got warm or showed any signs of over charging. I usually use my watt meter to monitor the charge but didn't this time because I was using it for something else. Again this is the only time I had this problem.
I remember reading some place that maybe the left side is better for charging lipos. Looked for that thread again but couldn't find it.
By the way the 9.0 volts was after the pack had rested from the charge overnight. I hooked it up to a motor I had in my test stand and run it down until the lvc cut in. Recharged the battery again (while monitoring) and everything went fine.
Jack
Are you sure about the 9V and this was a two cell LI Poly pack?
Have never read of MK II overcharging Li Polys .

Charles
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Old Mar 12, 2005, 11:37 AM
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Ok, well I ran down my LiPos yesterday flying, and charged them last night on the left-side charger, rather than the right. Took almost exactly three hours to charge a 3000 mAh pack at 1 amp. At the end it didn't give me an error message.

Although annoying, I suppose it's better to have a charger that sometimes claims there is an error when there isn't, rather than have one not notice an error that is. Course best of all would be if it didn't mistake anything.

If this happens again I think I'll call Hobbico and see what they say.
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Old Mar 12, 2005, 12:39 PM
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Yes, I.m sure it was 9.0 volts. I had it hooked up to my Whatt meter. And yes it is a 2 cell.
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Old Mar 12, 2005, 03:10 PM
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Then you have not only discovered a problem never before reported here on a MKII charger, but have most certainly lost a good deal of the normal lifespan of that pack that was up to 4.5V per cell. You are also lucky you didn't have a fire on your hands.
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Old Mar 12, 2005, 03:23 PM
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Quote:
Originally Posted by Cactus1552
Yes, I.m sure it was 9.0 volts. I had it hooked up to my Whatt meter. And yes it is a 2 cell.
I've never heard of results like that either.
You pressed the button 3 times and the MKII indicated it was charging a lithium by showing the green LED?

A NiCD or NiMH charge (one or two button press at the start) could easily go that high, and cause big problems.

Jim
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Old Mar 12, 2005, 05:25 PM
my passengers on landing
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Rhode Island
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I'm sure I pushed the button three times and I had a green light.
Her are some notes I had made :

E-Power 2 cell 650 ma. Came with 8.0 volt charge. Hooked up to Little screamer with 9 x 5 prop and test run with CC25 down to 6.0 volt cutoff. Recharged to 9.0 volts again hooked up to motor and run Pulled 758 ma according to watt meter.
Charged back up to 8.1 volts but only 380 ma. Again run to lvc 375 ma. This time charged back up 475 ma.
I had a problem before with the charger where it melted the shrink wrap on a 7 cell pack. Now the pack has a bad cell.
Been using this charger for over a year.
I charge packs on a 1/4 thick steel plate with flower pots upside down over them.(My cheap battery bunkers)
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Old Mar 12, 2005, 05:38 PM
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I'd play it safe and send it in to be checked out, something is definitely wrong.
Iím pretty sure they have a two-year warranty.
If it comes back giving close to 8.4V Iíll send the one I have in too!

Yes, unfortunately I believe missing peaks with Ni packs is common reading other peoples posts. Iíve had it happen a few times; it will do 20 charges just fine and then miss a peak.

Jim
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Old Mar 12, 2005, 09:22 PM
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I think you might be seeing a safety time out at 3 hours. I have had the charger terminate the charge on a cell I was trying to charge at a very slow rate. There is a note on the last page of the manual, in the trouble shooting section that hints to a 2 hour time out on not getting a peaks on Nicd, and Nimh, and 3 hours on lipo. I think you hit the 3 hour mark. To test it just charge at a bit lower current, and note the time that you start, and see what happens at 3 hours.



Dale
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Old Mar 12, 2005, 09:49 PM
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Doesn't the MKII act as a simple CCCV charger in Li mode? If so, it is limited to 4.1V per cell, and if set properly by the user cannot overcharge a good Li pack unless the charger is defective. The only two possibilities I see here are a defective charger or a user error. If the user is convinced that no error was made, then the charger must be defective. If the user decides not to return what is apparently a defective charger, then there will probably be a Li pack venting with flame in the near future.
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Old Mar 13, 2005, 10:07 PM
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Joined Sep 2001
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Luke: I do believe that you experienced the time out error.

All: A 1000mah battery (just for example) can not be fully charged in 1 hour at 1a. The battery will not take the current without the voltage rising too high. Therefore, the voltage limiter will kick in at about 45 minutes or so, and for the next 45 minutes or so, the current will decrease, while the voltage remains constant. This is pretty much a best case, and most chargers are closer to an hour for the final phase. So, 1.5-2 hours at 1c charging current is 'normal'.
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Old Mar 14, 2005, 06:51 PM
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Dale, you're absolutely right. I hadn't noticed that little bit in the manual before. The night that I got the error it was exactly three hours on the dot... a few nights later, when I didn't, it was about 2 hours and 55 minutes for the charge, as I recall. So that definitely must be it.

Well that's good to have that solved. I don't like getting error messages when I don't know what they mean: now I know my charger is working exactly as promised.

Thanks for noticing that,


Luke
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