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MRC/Altech Marketing USA . JR-Spektrum . E-flite

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Main Discussion > Smart Charger... Stupid Human
 
 
vidmarv
Senior Heliman
Location: ft walton beach, FL

Hi all,

Got a new charger yesterday <http://www.runryder.com/helicopter/t425355p1/>;

I was able to charge a Parkzone 3s 11.1 2200mAh battery with no problems. It completed the cycle and showed proper levels (twice). This morning, I went to charge the little E-flite batteries from my Blade CP (EFLB0995 - 3s 11.1v 800mAh E-Flite) and am not quite sure what I'm doing.

When the charger ask for the amperage, I entered 0.8A, which I got from the charger I have been using prior to this one (E-Flite EFLC 3105). The battery doesn't appear to have that spec on it.

After leaving the battery on the charger for about 35 minutes,it indicated 12.5v and 430mAh, at which point I cut it off, due to concerns. I assume the mAh rating is what is being put back in the battery as when I charge the 2200mAh battery, I end up with around 370mAh when it says< "completed".

Lest you say, "RTFM", I would tell you that I have and there is NOTHING in it giving the specs for charging this, or any other battery. I've looked online and can find nothing.

Given that these numbers SEEM awfully high, and I tend to follow the advice given on this forum, which is, "if you think it's wrong, it probably is"....

Can you guys tell me if I've got this right?

The charger DID NOT indicate the charge was complete. When it reached these levels I shut it down due to paranoia. I did start it off with this input....

Lipo Charge
0.8A 11.1V(3S)
Balanced charge

Any advice is appreciated. I really don't want to blow anything up today and info on this seems quite sparse.

Many thanks.

VM

Perfectly sliced air every time!
04-18-2008 02:43 PM
 
 
beeflyer2
Veteran
Location: Woodstock, GA

Everything sounds fine to me, let it finish charging!

For your 2200mAh pack, charge at 2.2A. If you use 80% or less of the pack's capacity (recommended) you should be charging back no more than 1760mAh.

For your 800mAh pack, charge at 0.8A. If you use 80% or less of the pack's capacity (recommended) you should be charging back no more than 640mAh.

For either one (both 3S) the final voltage should be 12.6V.
04-18-2008 02:52 PM
 
 
vidmarv
Senior Heliman
Location: ft walton beach, FL

Thanks for the clarification

I guess I should sleep in a Holiday Inn Express tonight! I had the numbers reversed in my head. I had thought I should only put 20% back in the packs. This makes much more sense! I was ready to grab my flac jacket and welding mask to take it off the charger! Many thanks. Nothing like heli's to keep one humble!

VM

Perfectly sliced air every time!
04-18-2008 03:00 PM
 
 
Jlerch
Heliman
Location: Parrish, Florida

You had an 800maH battery. The charger had put 370maH back in it, or less than half the capacity assuming the pack was empty to start with.

A 3 cell pack will get X amps at any voltage less than 12.6 volts (4.2v per cell)
  • X being 0.8 in this case,
  • For other batteries it will be whatever the charge rate for that battery, usually 1x its capacity.
  • An 0800 mAh battery gets charged at 0.8 amps
  • An 1800 mAh battery gets charged at 1.8 amps
  • A 2200 mAh battery gets charged at 2.2 amps

Once the voltage reaches the 12.6 volt limit, the charger will start backing off the amps being fed into the battery to keep the voltage at 12.6. When it takes 0 amps to maintain 12.6v the charge is complete..

James Lerch - ManateeRC Member - Blade 400 - Raptor 60 - Lots of sim time
04-18-2008 03:03 PM
HOMEPAGE  
 
 
vidmarv
Senior Heliman
Location: ft walton beach, FL

So...

Is this what they are referring too when they say, "Never exceed 1C (1x capacity) charge rate"?

What does the "c" refer too in that statement?

VM

Perfectly sliced air every time!
04-18-2008 03:16 PM
 
 
Drunk Monk
rrProfessor
Location: Preston, UK

C = the capacity of the battery


Stephen

I only open my mouth to change feet.....
04-18-2008 03:32 PM
 
 
vidmarv
Senior Heliman
Location: ft walton beach, FL

Exponential depletion?

Am I correct to assume that the depletion of my battery during flight is exponential? Which is to say, the longer I fly, the faster the battery is depleted?

VM

Perfectly sliced air every time!
04-18-2008 04:08 PM
 
 
Jlerch
Heliman
Location: Parrish, Florida

If you fly consuming a consistent power (ie constant alt hover), you battery will have a linear power output until right before you kill it by over discharging it. (running it less than 3 volts per cell).

For instance, here's a flight on my Blade 400 with a $30 "Zippy-H" 2100mah 30C battery.



James Lerch - ManateeRC Member - Blade 400 - Raptor 60 - Lots of sim time
04-18-2008 04:35 PM
HOMEPAGE  
 
 
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