Li-ion & NiMH (not as long)

[Henderson,Eric]

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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