New Battery questions by implication
06-30-2004, 03:32 PM
#1
New Battery questions by implication
For the last several years I, and many others, have used the trickle charge system described by Red Scholefield with great success and little effort. Batteries seemed to last a very long time and maintained a good capacity.
However, recently several incidents in the local area have raised a question about the newer Nicad high capacity batteries. It seems that several of us have had a pack suddenly develop an open cell. In most cases I have asked, they were the newer cells, but apparently of varying capacity. The latest one of mine that failed was a 1400 mHr 4 cell pack that was less than 2 years old. It failed while I was starting my plane up at the field one day.
The implied question is there, but not clear. Are the new technologies being used in manufacture allowing (or encouraging) sudden failure?
However, recently several incidents in the local area have raised a question about the newer Nicad high capacity batteries. It seems that several of us have had a pack suddenly develop an open cell. In most cases I have asked, they were the newer cells, but apparently of varying capacity. The latest one of mine that failed was a 1400 mHr 4 cell pack that was less than 2 years old. It failed while I was starting my plane up at the field one day.
The implied question is there, but not clear. Are the new technologies being used in manufacture allowing (or encouraging) sudden failure?
06-30-2004, 03:43 PM
#2
Senior Member
RE: New Battery questions by implication
Did you do a failure analysis? If you stripped the heat shrink off, were there any jumpers between the cells open or was the open internal to a particular cell? Had the pack ever been subjected to a very humid environment, i.e. dunked in a lake or ????.
Had the pack ever been subjected to very high current draw? A close inspection of the dissassembled pack might give you a clue.
Had the pack ever been subjected to very high current draw? A close inspection of the dissassembled pack might give you a clue.
06-30-2004, 04:50 PM
#4
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RE: New Battery questions by implication
Hi Jim
I have found Red to be a very friendly guy. He always answers e-mail promptly. If you have never contacted him directly, I would suggest giving it a try.
He is extremely knowledgable about batteries, and always helpful to modelers in need. I bet he has the information you seek.
He is a moderator in the battery clinic here on RCU or can be contacted through the battery clinic at http://www.rcbatteryclinic.com/
If you should contact him, let us know the results
JR
I have found Red to be a very friendly guy. He always answers e-mail promptly. If you have never contacted him directly, I would suggest giving it a try.
He is extremely knowledgable about batteries, and always helpful to modelers in need. I bet he has the information you seek.
He is a moderator in the battery clinic here on RCU or can be contacted through the battery clinic at http://www.rcbatteryclinic.com/
If you should contact him, let us know the results
JR
06-30-2004, 07:37 PM
#6
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RE: New Battery questions by implication
ORIGINAL: Jim Branaum
For the last several years I, and many others, have used the trickle charge system described by Red Scholefield with great success and little effort. Batteries seemed to last a very long time and maintained a good capacity.
However, recently several incidents in the local area have raised a question about the newer Nicad high capacity batteries. It seems that several of us have had a pack suddenly develop an open cell. In most cases I have asked, they were the newer cells, but apparently of varying capacity. The latest one of mine that failed was a 1400 mHr 4 cell pack that was less than 2 years old. It failed while I was starting my plane up at the field one day.
The implied question is there, but not clear. Are the new technologies being used in manufacture allowing (or encouraging) sudden failure?
For the last several years I, and many others, have used the trickle charge system described by Red Scholefield with great success and little effort. Batteries seemed to last a very long time and maintained a good capacity.
However, recently several incidents in the local area have raised a question about the newer Nicad high capacity batteries. It seems that several of us have had a pack suddenly develop an open cell. In most cases I have asked, they were the newer cells, but apparently of varying capacity. The latest one of mine that failed was a 1400 mHr 4 cell pack that was less than 2 years old. It failed while I was starting my plane up at the field one day.
The implied question is there, but not clear. Are the new technologies being used in manufacture allowing (or encouraging) sudden failure?
Higher capacity Ni-Cds or Ni-MH have a higher propensity for internal shorts
and overall shorter service life. It is a simple manner of trying to cram 6
lbs of stuff in a 5 lb bag. Heavy marketing pressures to get more capacity
in the same volume required a number of design compromises, thinner
separator, tighter wound rolls, small mandrel on the winder . . . . all of
which lead to a higher inherent short rate. Now if the cells in your case
were actually open circuit, i.e. no connection internally, infinite
resistance if measured with an ohmmeter. There is nothing in the higher
capacity designs that would contribute to this . . . . so it would be a
manufacturing flaw (very rare in Sanyo cells). Cells from China on the other
hand have some quality problems off and on.
06-30-2004, 11:06 PM
#7
RE: New Battery questions by implication
Thank you Red. BTW, you are right again and I blew it again. It IS an internal short - DUH.
However, you have confirmed a thesis of mine about the subject.
Again, thank you very much. This will be shared all around here.
However, you have confirmed a thesis of mine about the subject.
Again, thank you very much. This will be shared all around here.
