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Old Dec 19, 2002, 06:22 PM
Highflier
Guest
n/a Posts
Battery charging question

This question is really about 8-9 cell e-flight packs not transmitters or
reciever packs.

The more I want to fly the more I spend on Battery packs. For a really long
day I am going to have to start charging at the field. Charge rates at 2c
are generally acceptable which means 1 pack~ = 30 minites of charging. For
my full out flying gets me about 7-8 minites of run time. thus I have
ordered a second charger. Now I can complete a charge every 15 minutes. I
would like to improve on that so here is the question

Can 2 similer 8 cell packs be connected in series with a charger that is
capable of 20-24 cell packs? Thus 1 charger could charge 2 packs at the
same time.

My concerns are obviously what is the result if 1 pack can take about
1500MAH of charge while the other pack might only take 1400 MAH or charge.
Will series charging even out the packs.... Will the charger likely peak
when pack 2 is done still leaving a less then full charge on pack 1. Or
worse yet not peak until pack 1 is done thus over charging pack 2.

If this would work I could create a adaptor plug for 5 bucks which is a heck
of a lot cheaper then buying another charger for $100.00

Obviously I should have enough packs to have some cool down time between run
and charge.

Highflier

PS. I have both Nicads and NIMH packs but I obviously would only use 2 like
packs with this process.

Charger 1 is Astroflight and charger 2 (on the way is a Triton)



Old Dec 19, 2002, 10:32 PM
Olie M. Narky
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n/a Posts
Re: Battery charging question

"Highflier" <jims1441@comcast.net> wrote:

>Can 2 similer 8 cell packs be connected in series with a charger that is
>capable of 20-24 cell packs? Thus 1 charger could charge 2 packs at the
>same time.


This is a question for Red Scholefield, but my guess is that his answer will
be "absolutely not!" The concerns you expressed in the next paragraph pretty
well summed up the situation. You would only confuse the battery charger.

>My concerns are obviously what is the result if 1 pack can take about
>1500MAH of charge while the other pack might only take 1400 MAH or charge.
>Will series charging even out the packs.... Will the charger likely peak
>when pack 2 is done still leaving a less then full charge on pack 1. Or
>worse yet not peak until pack 1 is done thus over charging pack 2.


--
_____
\__________________|__________________/
(O)

Old Dec 20, 2002, 03:12 AM
All under control, Grommit!
leccyflyer's Avatar
United Kingdom, Aberdeen
Joined Sep 2000
12,473 Posts
Provided the packs are identical- same cell type, same capacity, same chemistry and discharged to the same level - then a decent charger will charge multiple packs connected in series. To the charger it just looks like a single pack with a larger number of cells - after all the individual packs are connected internally in series.

You can daisychain a number of packs together to charge them in this manner- it is critical that they are the same though, and all must be discharged to the same voltage *before* connecting them together to charge. So you naturally wouldn't want to connect together say a pack of CP1700s with a pack of CP1300s or a pack with 75% of it's capacity left with a pack with only 50% of it's capacity left. Chargers with a built in discharge function should allow you to discharge down to a preset voltage per cell- various people use 1v, 0.9v, 0.8v and some people even discharge their cells completely- I wouldn't recommend that myself though.

Brian
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Old Dec 20, 2002, 03:22 AM
The Natural Philosopher
Guest
n/a Posts
Re: Battery charging question


Olie M. Narky wrote:

> "Highflier" <jims1441@comcast.net> wrote:
>
>
>>Can 2 similer 8 cell packs be connected in series with a charger that is
>>capable of 20-24 cell packs? Thus 1 charger could charge 2 packs at the
>>same time.
>>

>
> This is a question for Red Scholefield, but my guess is that his answer will
> be "absolutely not!" The concerns you expressed in the next paragraph pretty
> well summed up the situation. You would only confuse the battery charger.
>



I think the answer is 'certainly, provided they are identical cells and
at an identical state of charge'. After all, what is a 16 cell pack but
two 8 cell packs in series anyway?


>
>>My concerns are obviously what is the result if 1 pack can take about
>>1500MAH of charge while the other pack might only take 1400 MAH or charge.
>>Will series charging even out the packs.... Will the charger likely peak
>>when pack 2 is done still leaving a less then full charge on pack 1. Or
>>worse yet not peak until pack 1 is done thus over charging pack 2.
>>



You would likley as not get a mushy peak on the charger, and possibly ne
rarher hot pack. But less than 10% difference should not make a huge
difference, as that is proably inside normal production tolerances of
teh cells.

If, however, they are different *types* of cells I would be more
circumspect.


>


Old Dec 20, 2002, 04:32 AM
A.T.
Guest
n/a Posts
Re: Battery charging question

Yes,
Refer to http://www.hitecrcd.com
and click on "Products" and then on "chargers". Download the manuals for the
CG335 ( X 4 packs or more upto 24 cells) and CG340 ( X 2 or more packs upto
16 cells). Packs must have similar voltage and capacity.
regards
Alan T.

Alan's Hobby Web Links
http://homepages.ihug.co.nz/~atong/
.................................................. .............

"Highflier" <jims1441@comcast.net> wrote in message
news:YgGdnWCq1tL6_Z-jXTWcog@comcast.com...
> This question is really about 8-9 cell e-flight packs not transmitters or
> reciever packs.
>
> The more I want to fly the more I spend on Battery packs. For a really

long
> day I am going to have to start charging at the field. Charge rates at 2c
> are generally acceptable which means 1 pack~ = 30 minites of charging.

For
> my full out flying gets me about 7-8 minites of run time. thus I have
> ordered a second charger. Now I can complete a charge every 15 minutes.

I
> would like to improve on that so here is the question
>
> Can 2 similer 8 cell packs be connected in series with a charger that is
> capable of 20-24 cell packs? Thus 1 charger could charge 2 packs at the
> same time.
>
> My concerns are obviously what is the result if 1 pack can take about
> 1500MAH of charge while the other pack might only take 1400 MAH or charge.
> Will series charging even out the packs.... Will the charger likely peak
> when pack 2 is done still leaving a less then full charge on pack 1. Or
> worse yet not peak until pack 1 is done thus over charging pack 2.
>
> If this would work I could create a adaptor plug for 5 bucks which is a

heck
> of a lot cheaper then buying another charger for $100.00
>
> Obviously I should have enough packs to have some cool down time between

run
> and charge.
>
> Highflier
>
> PS. I have both Nicads and NIMH packs but I obviously would only use 2

like
> packs with this process.
>
> Charger 1 is Astroflight and charger 2 (on the way is a Triton)
>
>
>



Old Dec 20, 2002, 08:22 AM
John Beard
Guest
n/a Posts
Re: Battery charging question

I agree, yes! I do it, the bec will bring down the level to much
the same rate on each pack. Make sure you run them until the
bec cuts in and I see no problem.
Re cooling, use a tube with a old pc fan to bring down
the temp' faster. That saves even more time, but 2 chargers
is a must if you wish to fly all day. Anyway think what all that
air time would cost you in liquid fuel, your 's in.
Have a good Christmas.
John.

--
Remove hat to reply.

"A.T." <atong@ihug.co.nz> wrote in message
news:atur3o$vt5$1@lust.ihug.co.nz...
> Yes,
> Refer to http://www.hitecrcd.com
> and click on "Products" and then on "chargers". Download the manuals for

the
> CG335 ( X 4 packs or more upto 24 cells) and CG340 ( X 2 or more packs

upto
> 16 cells). Packs must have similar voltage and capacity.
> regards
> Alan T.
>
> Alan's Hobby Web Links
> http://homepages.ihug.co.nz/~atong/
> .................................................. ............
>
> "Highflier" <jims1441@comcast.net> wrote in message
> news:YgGdnWCq1tL6_Z-jXTWcog@comcast.com...
> > This question is really about 8-9 cell e-flight packs not transmitters

or
> > reciever packs.
> >
> > The more I want to fly the more I spend on Battery packs. For a really

> long
> > day I am going to have to start charging at the field. Charge rates at

2c
> > are generally acceptable which means 1 pack~ = 30 minites of charging.

> For
> > my full out flying gets me about 7-8 minites of run time. thus I have
> > ordered a second charger. Now I can complete a charge every 15 minutes.

> I
> > would like to improve on that so here is the question
> >
> > Can 2 similer 8 cell packs be connected in series with a charger that is
> > capable of 20-24 cell packs? Thus 1 charger could charge 2 packs at the
> > same time.
> >
> > My concerns are obviously what is the result if 1 pack can take about
> > 1500MAH of charge while the other pack might only take 1400 MAH or

charge.
> > Will series charging even out the packs.... Will the charger likely peak
> > when pack 2 is done still leaving a less then full charge on pack 1. Or
> > worse yet not peak until pack 1 is done thus over charging pack 2.
> >
> > If this would work I could create a adaptor plug for 5 bucks which is a

> heck
> > of a lot cheaper then buying another charger for $100.00
> >
> > Obviously I should have enough packs to have some cool down time between

> run
> > and charge.
> >
> > Highflier
> >
> > PS. I have both Nicads and NIMH packs but I obviously would only use 2

> like
> > packs with this process.
> >
> > Charger 1 is Astroflight and charger 2 (on the way is a Triton)
> >
> >
> >

>
>



Old Dec 20, 2002, 02:42 PM
Mathew Kirsch
Guest
n/a Posts
Re: Battery charging question

"Highflier" <jims1441@comcast.net> wrote in message news:<YgGdnWCq1tL6_Z-jXTWcog@comcast.com>...
> Can 2 similer 8 cell packs be connected in series with a charger that is
> capable of 20-24 cell packs?


Yes, but not two "similar" 8-cell packs... Two IDENTICAL 8-cell packs.
They need to have cells of the same chemistry, the same capacity, and
roughly the same state of charge. Run both packs down to the BEC
cutoff, let them cool, then charge them together in series as if you
were charging one huge pack.
Old Dec 20, 2002, 03:32 PM
The Natural Philosopher
Guest
n/a Posts
Re: Battery charging question


Mathew Kirsch wrote:

> Yes, but not two "similar" 8-cell packs... Two IDENTICAL 8-cell packs.



I see you live in perfect land where every cell off a production line is
identical to every other.

Sigh. How nice to Believe in Perfection.



Old Dec 20, 2002, 03:52 PM
John Beard
Guest
n/a Posts
Re: Battery charging question

This guy just like a fight ;-)
See post "Which ARTF Bipe" and see.
John.

--
Remove hat to reply.

"The Natural Philosopher" <a@b.c> wrote in message
news:3E038A97.80409@b.c...
>
>
> Mathew Kirsch wrote:
>
> > Yes, but not two "similar" 8-cell packs... Two IDENTICAL 8-cell packs.

>
>
> I see you live in perfect land where every cell off a production line is
> identical to every other.
>
> Sigh. How nice to Believe in Perfection.
>
>
>



Old May 19, 2004, 09:00 PM
David AMA40795 / KC5UH
Guest
n/a Posts
Re: Battery charging question

The Deans Ultra will carry more than the 15A inserts of the Anderson
Power Pole connectors. However, there are higher current inserts that
fit the small housing that go to 45A - well more than Deans.

Here's the website for the "sermos" connectors.....

http://www.andersonpower.com/products/pp/pp.html

David

On Wed, 19 May 2004 06:40:14 -0500, "Mike Norton"
<junk_norton@comcast.net> wrote:

>I prefer Sermos; they seem to hold up very well, are easy to connect and
>disconnect, and keep both the battery and charger contacts covered. Also,
>since the + and - contacts can be soldered or crimped separately and
>installed in their separate housings which are then locked together, you
>will miss the joys of soldering the battery leads to the contacts and
>shorting the battery while doing it. They are a little larger than the
>Deans, and the Deans Ultra will carry more current.
>
>Other than that, I heartily agree with Mr. Fubar ;-)
>
>-- Mike Norton


Old May 19, 2004, 09:01 PM
MonkeyBoy
Guest
n/a Posts
Re: Battery charging question

Thanks, everyone, for the helpful information!

-MB
Old May 23, 2004, 09:00 PM
Fred McClellan
Guest
n/a Posts
Re: Battery charging question

On Sun, 23 May 2004 21:49:40 GMT, dougmc@frenzy.com (Doug McLaren)
wrote:


>
>Well, I'm hoping it was a peak charger, though I could have been more
>explicit there. If it's not a peak charger, then yes, this would be
>very bad. Which is why I asked for a model number.
>
>If it's a peak charger that charges at 1 or 1.7 amps, and can do NiMH,
>it will be fine. (For NiMH, 1A would be better than 1.7A -- the
>batteries would last longer.) But I'm not aware of any brand of
>charger of any sort that only has those two options, which makes me
>wonder what he's getting, or if he's even described it right.



IIRC, the original post mentioned a 1000/1700 mAh JR brand charger.

The only thing I found in that range from JR, on the Horizon site, is
a wall wart.

Not too many peak detection smarts in one of those.

As you said, a model number would have helped.
Old May 24, 2004, 09:00 PM
Jeff Hartley
Guest
n/a Posts
Re: Battery charging question

On Sun, 23 May 2004 21:49:40 GMT, dougmc@frenzy.com (Doug McLaren)
wrote:


>Well, I'm hoping it was a peak charger, though I could have been more
>explicit there. If it's not a peak charger, then yes, this would be
>very bad. Which is why I asked for a model number.


Sorry, I don't know the model number. Apparently JR do a "standard"
50ma charger and a 120ma charger for use with batteries of 1100mah or
more. It is the 120ma charger I have on order.

I can only go on the word of the shop that it is the correct charger,
if it isn't it will go back....


Regards, Jeff.
Old May 24, 2004, 09:00 PM
Jeff Hartley
Guest
n/a Posts
Re: Battery charging question

On Mon, 24 May 2004 00:46:41 GMT, Fred McClellan
<notthe-plumber@mindsprang.com> wrote:


>
>IIRC, the original post mentioned a 1000/1700 mAh JR brand charger.
>
>The only thing I found in that range from JR, on the Horizon site, is
>a wall wart.


that's the one Fred.

>
>Not too many peak detection smarts in one of those.
>
>As you said, a model number would have helped.


I can't find one one despite intensive searching. Believe me, I want
the correct tool for this job and if you can suggest the correct
charger I'll order it.

I've been out of the hobby for 20 years or more, the last radio sets I
came into contact with were all dry cell and nicads were only just
becoming widely available (affordable). It used to be that the radio
side was the simple bit and the techie bit was the building. It seems
to be the opposite way around now or am I just getting old ;-)
Regards, Jeff.
Old May 24, 2004, 09:00 PM
Doug McLaren
Guest
n/a Posts
Re: Battery charging question

In article <thj4b0pecl1uriqalfkutdqjsaaivcc6eb@4ax.com>,
Jeff Hartley <antispam> wrote:

| >IIRC, the original post mentioned a 1000/1700 mAh JR brand charger.
| >
| >The only thing I found in that range from JR, on the Horizon site, is
| >a wall wart.
|
| that's the one Fred.

Then don't use it! Send it back

As Red suggested, it'll fry your batteries quickly. You could use it,
but monitor your batteries for temperature and take them off once they
start getting warm, but you'd only have to forget once and it would
cook your batteries. I have to wonder why they even sell this -- I'm
guessing it's not being sold as a charger.

| I can't find one one despite intensive searching. Believe me, I want
| the correct tool for this job and if you can suggest the correct
| charger I'll order it.

Get something like this --

http://www2.towerhobbies.com/cgi-bin...?&I=LXCTZ5&P=7

$50, but it'll charge both batteries at once and at a reasonable rate.

Don't forget to pick up some charge leads as well.

There are better chargers, but this one will do what you need now. It
doesn't cycle, and won't charge over 8 cells, so if you ever do get
into electrics you'll want something better. But for glow planes and
gliders, this will do very well.

If you want one that can do everything, get this --

http://www2.towerhobbies.com/cgi-bin...&I=LXCJG7&P=ML

but it's $130. But I love mine ...

| It used to be that the radio side was the simple bit and the techie
| bit was the building. It seems to be the opposite way around now or
| am I just getting old ;-)

I think that the radio side is still the simple side. But maybe I'm
just not acting my age

--
Doug McLaren, dougmc@frenzy.com
`To invent, you need a good imagination and a pile of junk.' --Thomas Edison
 


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