NIMH Receiver Battery Explodes? Why?
10-31-2008, 09:42 PM
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NIMH Receiver Battery Explodes? Why?
I was charging a Hydramax 6.0 Volt receiver battery that was mounted in the fuselage behind the canopy. I was using a Hobbico field charger set to 1.0 amp. Push the button twice till the light turns yellow setting the charge for NIMH, then when the battery is full the charger shuts off.
I went in the house and came back to load my plane and the side was blown out of the fuse. The last cell of the battery had exploded. Does anyone have a good idea why this happened or has this happened to you?
I realize the possibility of pushing the charge button the wrong number of times, this would use a Ni-cd rate of charge or Li-po. I really don't think that was the case here, The battery may have had a good charge before I started, I was Topping it off. I have been using the 1.0 Amp rate of charge on this 1450 ma battery for more than 50 charges with no problems. I also see that most of my sentences start with I. I would appreciate any input and Thankyou. Groundskeeper3404
I went in the house and came back to load my plane and the side was blown out of the fuse. The last cell of the battery had exploded. Does anyone have a good idea why this happened or has this happened to you?
I realize the possibility of pushing the charge button the wrong number of times, this would use a Ni-cd rate of charge or Li-po. I really don't think that was the case here, The battery may have had a good charge before I started, I was Topping it off. I have been using the 1.0 Amp rate of charge on this 1450 ma battery for more than 50 charges with no problems. I also see that most of my sentences start with I. I would appreciate any input and Thankyou. Groundskeeper3404
10-31-2008, 10:34 PM
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RE: NIMH Receiver Battery Explodes? Why?
groundskeeper,
I have not heard of this happening with NIMH batteries. I too, have a hobbico field charger which I use exclusivly for my NIMH transmitter battery. I use a MRX 989 for the receiver battery (4.8V NIMH) I believe the MRC 989 is set to .3 ma for the charge rate and the hobbico is set at .5 ma. I have never experienced any issue like the one you described. My caution would be to verify the ma charge rate for the 6 volt batteries. Perhaps 1.0 ma is too much for the nearly charged battery to accept. Honestly, what you described is frightening. I hope you find the cause and can share it with us so we can prevent it happening.
Another late thought crossed my mind. Perhaps it could be a failure with the charger. Like everyone i would have looked at the battery as the culprit. It could be the charger. I don't know how to test the charger for symptoms but if it failed during the charge process and sent a high stream of current into the battery pack I suppose it is possible to cause an explosion. Just I thought I had.
Sledge_78
I have not heard of this happening with NIMH batteries. I too, have a hobbico field charger which I use exclusivly for my NIMH transmitter battery. I use a MRX 989 for the receiver battery (4.8V NIMH) I believe the MRC 989 is set to .3 ma for the charge rate and the hobbico is set at .5 ma. I have never experienced any issue like the one you described. My caution would be to verify the ma charge rate for the 6 volt batteries. Perhaps 1.0 ma is too much for the nearly charged battery to accept. Honestly, what you described is frightening. I hope you find the cause and can share it with us so we can prevent it happening.
Another late thought crossed my mind. Perhaps it could be a failure with the charger. Like everyone i would have looked at the battery as the culprit. It could be the charger. I don't know how to test the charger for symptoms but if it failed during the charge process and sent a high stream of current into the battery pack I suppose it is possible to cause an explosion. Just I thought I had.
Sledge_78
10-31-2008, 10:45 PM
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RE: NIMH Receiver Battery Explodes? Why?
No, The plane flew every day this week after work and have not even had any hard landings. Does it sound like a damaged battery? I read on a package of AA size rechargables that the batteries should not be recharged if they have a full charge. Don't know if that applies to sub c size battery packs or not.
Am going back to a 4.8V Ni-cd pack temporarily after I fix the fuse. Have never had any problems with them, but I was enjoying not having to recharge after every flight. I know a lot of flyers use NIMH and I hope this is an isolated incidence.
This was a hand-me-down low wing trainer like a cherokee and I still am upset about the damage. I feel fortunate that my garage didn't burn down. Don't feel safe charging inside anymore and will probably just wait till I get to the field.
Am going back to a 4.8V Ni-cd pack temporarily after I fix the fuse. Have never had any problems with them, but I was enjoying not having to recharge after every flight. I know a lot of flyers use NIMH and I hope this is an isolated incidence.
This was a hand-me-down low wing trainer like a cherokee and I still am upset about the damage. I feel fortunate that my garage didn't burn down. Don't feel safe charging inside anymore and will probably just wait till I get to the field.
10-31-2008, 10:55 PM
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RE: NIMH Receiver Battery Explodes? Why?
Reply to Sledge 48 The battery is a Hydrimax ultra 1440mah 6.0V standard charge 11 hrs. at 140ma. I think your right about the charge rate. what does 140 ma convert to in amp?
10-31-2008, 11:02 PM
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RE: NIMH Receiver Battery Explodes? Why?
ORIGINAL: Groundskeeper3404
Reply to Sledge 48 The battery is a Hydrimax ultra 1440mah 6.0V standard charge 11 hrs. at 140ma. I think your right about the charge rate. what does 140 ma convert to in amp?
Reply to Sledge 48 The battery is a Hydrimax ultra 1440mah 6.0V standard charge 11 hrs. at 140ma. I think your right about the charge rate. what does 140 ma convert to in amp?
A good charger tapers the amps as the battery reaches it's peak voltage so attempting to charge a nearly fully charged battery will have no bad effect.
10-31-2008, 11:16 PM
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RE: NIMH Receiver Battery Explodes? Why?
So on my hobbico field charger I should turn it down to the lowest setting .2 and I should be good to go. .5 would be a quick charge. I will try another NIMH pack as I like way they hold a charge. But I still think I will charge at the field and not in my Garage. I guess I figured 1400 mah would take a 1.4A charge. My Bad.
11-01-2008, 12:03 AM
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RE: NIMH Receiver Battery Explodes? Why?
1400mah pack = 1.4A charge rate... Ground, depends on the cells used to make the pack. Some NiMh cells will take a 1C charge rate just fine. Considering what others have posted, the cells in your pack weren't rated for a 1C charge rate.
11-01-2008, 08:19 AM
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RE: NIMH Receiver Battery Explodes? Why?
Many fellows at our field buy their expensive chargers and brag about charging on the way to the field or at the field constantly but sure enough these same fellows always soon start *****ing about defective batterys and burning them up. Good lord batteries are not cooking utensils. Fast charging should only be used infreqently or your batterys are going to have their lives shortened.
C10 for a 1400 Mah pack is 140Map or .14 amp
C10 for a 1400 Mah pack is 140Map or .14 amp
11-01-2008, 09:36 AM
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RE: NIMH Receiver Battery Explodes? Why?
ORIGINAL: JohnBuckner
Many fellows at our field buy their expensive chargers and brag about charging on the way to the field or at the field constantly but sure enough these same fellows always soon start *****ing about defective batterys and burning them up. Good lord batteries are not cooking utensils. Fast charging should only be used infreqently or your batterys are going to have their lives shortened.
C10 for a 1400 Mah pack is 140Map or .14 amp
Many fellows at our field buy their expensive chargers and brag about charging on the way to the field or at the field constantly but sure enough these same fellows always soon start *****ing about defective batterys and burning them up. Good lord batteries are not cooking utensils. Fast charging should only be used infreqently or your batterys are going to have their lives shortened.
C10 for a 1400 Mah pack is 140Map or .14 amp
11-01-2008, 10:13 AM
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RE: NIMH Receiver Battery Explodes? Why?
Watch out when using the Hobbico fast charger. I burned up two battery packs using one of these chargers. Both were NIMH and they were not cheap packs. The automatic shut off did not work and the batteries were inside the airplane. I was fortunate the airplane did not catch on fire. I sent the charger back and they told me it was defective and sold me anohter at a reduced price but be sure of this..........I will never use this charger unless I am there keeping an eye on things if I ever use it again. For many years I would not even consider using a quick charger but I got lazy. I don't know when I'll ever use this quick charger again. There aren't any dire circumstances that require it's use........just as it was the many years I never had a need for one.
11-01-2008, 10:56 AM
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RE: NIMH Receiver Battery Explodes? Why?
I have had the older Hobbico field charger for years and never had a problem. Got the new one this year with the capability to do ni-cads, ni-mh, and lipos and I to had a bad experience doing a nimh. It was an 2000 mah 8 cell pack set at 1.2 amp and it got hot! I have charged same pack on my Trinton at 1c without any problems. The Hobbico works differently than the Trinton and I will only use it now at much less than 1c rates.
11-01-2008, 12:30 PM
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RE: NIMH Receiver Battery Explodes? Why?
Hi
I have the Hobico Accu-Cycle Elite and the temp sensor accessory. I have used the temp sensor with the Lipos but not with the nimh type batteries. Maybe it would be a good idea to use the temp sensor with the 1C rate for nimh packs.
Huck
I have the Hobico Accu-Cycle Elite and the temp sensor accessory. I have used the temp sensor with the Lipos but not with the nimh type batteries. Maybe it would be a good idea to use the temp sensor with the 1C rate for nimh packs.
Huck
11-01-2008, 01:16 PM
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RE: NIMH Receiver Battery Explodes? Why?
My Hobbico charger was the one that had the capability to charge all three kinds of batteries. The instructions say to never leave it alone while charging and I know why now. I plan on slow charging my batteries prior to going flying as I did for so many years. No real need for a fast charger anyhow unless I would happen to be out of town at a flying event or something of that nature.
11-01-2008, 11:59 PM
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RE: NIMH Receiver Battery Explodes? Why?
I had one blow the top off one of the cells and melt the back of the transmitter case. It was in my van sitting on top of my sun shelter. Burned a small hole in the shelter cover with charring all around the cover. I don't know when it happened as it had been in my van on trickle charge for months. Discovered it when checking the state of the charge on a nice day to fly.
It was a 2500 MAH NiMH transmitter battery. One can never be 100% sure what caused the problem. It should NEVER have happened while on trickle charge. I suspect the charge lead shorted out. The charger is a Litco Alpha 4. The charger still works fine so I don't think the fault was in the charger.
The best part is that only the battery compartment was fried. I got another transmitter and used the back cover from it. The transmitter still works like a charm.
It was a 2500 MAH NiMH transmitter battery. One can never be 100% sure what caused the problem. It should NEVER have happened while on trickle charge. I suspect the charge lead shorted out. The charger is a Litco Alpha 4. The charger still works fine so I don't think the fault was in the charger.
The best part is that only the battery compartment was fried. I got another transmitter and used the back cover from it. The transmitter still works like a charm.
11-02-2008, 06:27 AM
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RE: NIMH Receiver Battery Explodes? Why?
I noticed a couple of time above where the term C10 was meant to mean 0.1C. This is not correct and should be C/10; if they really mean 0.1 times the capacity of the battery. C10 means 10 times the capacity of the battery, not 1/10.
11-02-2008, 09:16 AM
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RE: NIMH Receiver Battery Explodes? Why?
ORIGINAL: Rodney
I noticed a couple of time above where the term C10 was meant to mean 0.1C. This is not correct and should be C/10; if they really mean 0.1 times the capacity of the battery. C10 means 10 times the capacity of the battery, not 1/10.
I noticed a couple of time above where the term C10 was meant to mean 0.1C. This is not correct and should be C/10; if they really mean 0.1 times the capacity of the battery. C10 means 10 times the capacity of the battery, not 1/10.
Thank you Rodney for the correction I omitted the / and did of course intend to mean one tenth of the batterys capacity.
11-03-2008, 11:52 AM
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RE: NIMH Receiver Battery Explodes? Why?
You can fast charge (1C) NiMH every cycle. If I had to slow charge cells, I’d probably never fly. The key is getting a pack made from cells that are designed for 1C charge rates.
Yes, a slow charge is easier on the battery even with cells rated for fast charge, but I get 3+ years life out of my batteries with 300-500 flights a year, 100 charge cycles a year, and I ALWSYS fast charge them at 1C, sometimes even closer to 1.5C. Considering shelf life and increased failure rates on older batteries, I always retire my batteries after 3 years, so as I see it , there is no problem fast charging. The reduction in battery life is not significant enough to matter.
But I’ll stress again, you must have cells rated for 1C charge rates, and there are plenty of NiMH cells that handle this charge rate just fine. A standard NiMH battery pack probably won’t handle this charge rate since cells rated for high charge/discharge currents are more expensive than normal cells. Get a pack made from NiMH cells rated for 1C and fast charge all you want.
Yes, a slow charge is easier on the battery even with cells rated for fast charge, but I get 3+ years life out of my batteries with 300-500 flights a year, 100 charge cycles a year, and I ALWSYS fast charge them at 1C, sometimes even closer to 1.5C. Considering shelf life and increased failure rates on older batteries, I always retire my batteries after 3 years, so as I see it , there is no problem fast charging. The reduction in battery life is not significant enough to matter.
But I’ll stress again, you must have cells rated for 1C charge rates, and there are plenty of NiMH cells that handle this charge rate just fine. A standard NiMH battery pack probably won’t handle this charge rate since cells rated for high charge/discharge currents are more expensive than normal cells. Get a pack made from NiMH cells rated for 1C and fast charge all you want.
11-03-2008, 11:54 AM
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RE: NIMH Receiver Battery Explodes? Why?
ORIGINAL: JohnW
You can fast charge (1C) NiMH every cycle. If I had to slow charge cells, I’d probably never fly. The key is getting a pack made from cells that are designed for 1C charge rates.
Yes, a slow charge is easier on the battery even with cells rated for fast charge, but I get 3+ years life out of my batteries with 300-500 flights a year, 100 charge cycles a year, and I ALWSYS fast charge them at 1C, sometimes even closer to 1.5C. Considering shelf life and increased failure rates on older batteries, I always retire my batteries after 3 years, so as I see it , there is no problem fast charging. The reduction in battery life is not significant enough to matter.
But I’ll stress again, you must have cells rated for 1C charge rates, and there are plenty of NiMH cells that handle this charge rate just fine. A standard NiMH battery pack probably won’t handle this charge rate since cells rated for high charge/discharge currents are more expensive than normal cells. Get a pack made from NiMH cells rated for 1C and fast charge all you want.
You can fast charge (1C) NiMH every cycle. If I had to slow charge cells, I’d probably never fly. The key is getting a pack made from cells that are designed for 1C charge rates.
Yes, a slow charge is easier on the battery even with cells rated for fast charge, but I get 3+ years life out of my batteries with 300-500 flights a year, 100 charge cycles a year, and I ALWSYS fast charge them at 1C, sometimes even closer to 1.5C. Considering shelf life and increased failure rates on older batteries, I always retire my batteries after 3 years, so as I see it , there is no problem fast charging. The reduction in battery life is not significant enough to matter.
But I’ll stress again, you must have cells rated for 1C charge rates, and there are plenty of NiMH cells that handle this charge rate just fine. A standard NiMH battery pack probably won’t handle this charge rate since cells rated for high charge/discharge currents are more expensive than normal cells. Get a pack made from NiMH cells rated for 1C and fast charge all you want.
11-03-2008, 01:52 PM
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RE: NIMH Receiver Battery Explodes? Why?
I just noticed that there is a label on the side of my Hobbico charger that deals with cell size and charge rate amps. When I had my problem with the nimh cells the one that got hot was set at 1.4 the other one that was fine was set just below 1.0. Both were 2000 mah 8 cell nimh packs, AA cells. The label says not to do AA cells above 1.0 max. I can charge these same packs on my Trinton at 1c or 2.0 no problem but the Hobbico is not designed to do it. Was my error, when all else fails read the instructions. Batteries! To much to learn with this electric stuff, where is my glow fuel?
11-03-2008, 04:21 PM
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RE: NIMH Receiver Battery Explodes? Why?
I usually limit my 2000mAh NiMH AA cell charging to about 300mA, and my 2500mAh A cell charging to around 500mA, since they get pretty warm at these rates when they near the end of the charge cycle. Any higher than that, they get downright hot near the end of the charge cycle.
