Li-ion & NiMH (not as long)

[Del Rykert]

Seeing the pictures reminds me was charging a 1/4 scale Cap the nicad pack
shorted after charging for 45' to an hour. Luck was with me as I was home
when the smoke detector started wailing in the basement. Smoke was pouring
out of the fuselage and I grabbed the pack and wiring trying to pull it
apart giving myself a nasty burn. Dikes and rag (to grab the hot components)
stopped the carnage. I shudder to think how lucky I was.

        Del

----- Original Message -----
From: "Henderson,Eric" <eric.henderson at gartner.com>
To: <discussion at nsrca.org>
Sent: Monday, December 16, 2002 6:44 AM
Subject: RE: Li-ion & NiMH (not as long)


| Jerry,
|        My experiences with Li-ions and NiMH's are very positive to date.
The
| Li-ions are in all my patter and big planes. (1.20 or more). The NiMH's
are
| really great in my sport planes, R/C cars and boats.
|
| The only pack I "killed" was when I accidentally charged an NiMH with
Li-ion
| charger. The charger expected the voltage to reach 8.4V and, of course it
| never did. An NiMH 5-cell gets up to 6V plus.  The pack melted and died
| open.
|
| I made the mistake because I had been swapping packs in and out for
| duration-tests with digital servos and had a brain fade. I normally use a
| battery indicator. For NiMH's I now use the string-of-LED type for 6.0V
low
| warning. For Li-ion's I use a C-Volt LCD display. The same regulator works
| for both. The C-volt will handle either pack. In the mistake scenario I
was
| using a C-Volt unit and did not check the reading before I plugged in the
| charger.
|
| It showed me that a charger can fry a pack VERY quickly and that I was
lucky
| that I did it to a pack that did not burn up.
|
| The postings on certain batteries going up like road-flares should/must be
| taken seriously. NiMH's and Nicads can and do burn up. Luckily they do not
| tend to burst into a welding torch flame. (I am not saying that they
| wouldn't burn, but the intensity tends to be different). They all can
cause
| fires.
|
| With the lighter technology batteries I do not leave them plugged in once
| the charging LED goes green, They do hold their charge well and very
rarely
| take a charge when I go to top them up before a flight. I have seen the
| results of a plane burning and what it did to a house. Very, very
worrying.
|
| I will continue to use Bern's packs, both Li-ions and NiMH's. I personally
| take and have taken Mike Hester's warnings very seriously. (We should not
| shoot the messenger on this one BTW) I had a taste but did not have to eat
| the whole meal - fortunately.
|
| Regards,
|
| Eric.
|
|
| -----Original Message-----
| From: Wade & Barbara Akle [mailto:wb_akle at msn.com]
| Sent: Monday, December 16, 2002 8:58 AM
| To: discussion at nsrca.org
| Subject: Re: Li-ion & Nimh (long)
|
|
| Jerry,
| Thanks for a balanced assessment. I was getting very confused. Still one
| more question, I am using the NiMH also as flight batteries (6V with reg)!
| do you see any problems to be aware of (other than cost)?
| Wade
|
|
| ----- Original Message -----
| From: "Jerry Budd" <jbudd at QNET.COM>
| To: <discussion at nsrca.org>
| Sent: Sunday, December 15, 2002 9:35 PM
| Subject: Re: Li-ion & Nimh (long)
|
|
| > Hi all,
| >
| > Someone a few postings back on this thread asked what the advantages
| > of Li-Ion batteries were.  Well, here's my story.  I switched to
| > Li-Ions early last summer to try and get the Gator Giles G-202 I was
| > flying at the time under the 5kg weight limit for the Nats.  I had
| ...............................Sorry this posting ran so long, but some
| topics just can't be fully
| > discussed in a couple of paragraphs.
| >
| > Thx, Jerry
| >
| > FWIW - For reference here's an exchange of eMail's on this subject
| > posted to the list back in Sept '02 on this topic:
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