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Old Aug 01, 2007, 01:23 PM
Insane Plane Killer
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USA
Joined Feb 2006
109 Posts
The reason they have that statement on their website regarding the CellPro charger is because they know what their charger can and will do. It may not be something to write home about when it comes to looks, but it does the job it was designed to.

Curious that an inexpensive charger as FMA's sell for such a reasonable price; while OTOH, brands costing more than twice what a CellPro can be had for have to daisy chain gadgets to them in order to balance the packs they are charging.
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Old Aug 01, 2007, 01:33 PM
No Guts, No Glory
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Simi Valley, CA
Joined Feb 2007
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Wow, know I now the real danger of a lipo catching fire ,thanks For my first charger, I thought I would invest in a good, safe charger, so got the Cellpro 4s. It is a great charger, but I thought that it would change settings as ''fast charging'' and charge according to what it calculates. So after unplugging it after charging my 3s 2100 batt, I plugged in my 2s 900 lipo thinking it would change modes. It charged my 2s 900mah battery at 2amps!! I luckily caught it in a few minutes though.
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Old Aug 01, 2007, 03:51 PM
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Ventura, CA
Joined Jul 2006
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Quote:
Originally Posted by flyin C
It charged my 2s 900mah battery at 2amps!! I luckily caught it in a few minutes though.
That isn't unusual for the Cellpro in the first few mins of charging.
I've been told (and I think it is written on their website now somewhere) that no damage will occur to the pack during this time.

What I'd like to try just to see what happens is to charge a pack with the input voltage to the Cellpro at say 11.5V, and then during the charge rapidly bump the input voltage up to say 15V and see what happens (simulate an engine starting). The control loop for current adjustment on the Cellpro isn't very fast and bench testing has shown the charge current to spike up with an increase of the input voltage for a few seconds until the control loop starts to kick in.

This may be common for other chargers too that use the MCU as the switching regulator controller vs having a dedicated power supply IC perform the regulation.

Quote:
Originally Posted by X-Terminator
The reason they have that statement on their website regarding the CellPro charger is because they know what their charger can and will do.
Sure wish it had an input fuse stock though. Right now if the FETs short they burn up. Wonder if there could be a situation where the FET shorts but they don't burn out and the Lipo is now connected to the input power supply.

Edit: just remembered there would need to be 2 points of failure to short the lipo to the input power supply. There is the step down FET on the switching power supply, but also the N-channel FET on the negative side of the pack that would need to either be shorted or driven into conduction to allow this failure mode to be a problem. Either way, a fuse should be added and if UL approved would likely be needed.
Dave
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Last edited by Probedude; Aug 01, 2007 at 05:17 PM. Reason: added disclaimer on other chargers.
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Old Aug 01, 2007, 07:55 PM
Trexazoid
Joined May 2001
252 Posts
Quote:
Originally Posted by flyin C
Wow, know I now the real danger of a lipo catching fire ,thanks For my first charger, I thought I would invest in a good, safe charger, so got the Cellpro 4s. It is a great charger, but I thought that it would change settings as ''fast charging'' and charge according to what it calculates. So after unplugging it after charging my 3s 2100 batt, I plugged in my 2s 900 lipo thinking it would change modes. It charged my 2s 900mah battery at 2amps!! I luckily caught it in a few minutes though.
I believe what Probdude said is accurate. Another thing is that are you sure you are in the Auto 1C mode? If you have select 2 amps manually it will charge at 2 amps. I'm not sure if it would actually drop the amps if you had it set to 2 amps and plugged in you 900mAh battery. I don't have that small of a battery so I can't test it.
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Old Aug 01, 2007, 08:13 PM
Sushiholic
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Lutz, FL
Joined Jun 2002
46 Posts
I'm new to LiPos. Those are some scary looking pics and I'm wondering if I should even keep them in the house. Should I be worried about storing my LiPos when they are not connected to the charger? Will the charge drop to a risky level if I don't use them or check them for a while? I may only get to use mine once or twice a month. I have two chargers, a Cellpro 4s and a MRC 977. If I can't store them in the house, where/how do I store them?

Thanks for any advice.
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Old Aug 01, 2007, 08:50 PM
Frequent Flyer
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Kalamazoo, MI USA
Joined Aug 2003
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Hi AsahiToro,

I'm guessing that most of us store our lipos in the house. It is extremely unlikely that an undamaged stored lipo is going to spontaneously ignite. Even so, I store mine in an ammo can away from flammables so if there is an incident it will be confined to smoke damage.

Lipos do not lose much if any voltage when stored. To prolong their life, store them at around 3.85v/cell unless you are flying regularly.

Regards,

Brian
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Old Aug 01, 2007, 08:56 PM
Trexazoid
Joined May 2001
252 Posts
AsahiToro,

I store and charge mine in my fireplace. With the metal grating pulled and the glass doors (if they really are glass) mostly closed. I also leave the flue open for the magic smoke to go up instead of into my living room. I fly regularily (try to fly everyday weather permitting) so I leave mine fully charged. However, since I live in the north I will be charging them to the reccomended storage voltage, sealing them up in zip lock bags and placing them in my refridgerator (not the freezer) for the winter months after my last flight of the season.
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Old Aug 01, 2007, 11:47 PM
No Guts, No Glory
flyin C's Avatar
Simi Valley, CA
Joined Feb 2007
2,024 Posts
Using my Cellpro 4s

I put it on 1C, but its charging my 2s 900mah battery at 1.2 to 2.4amps??? I don't understand? Shouldn't it charge at .90amps..
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Old Aug 02, 2007, 12:04 AM
Registered User
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Ventura, CA
Joined Jul 2006
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Quote:
Originally Posted by flyin C
Using my Cellpro 4s

I put it on 1C, but its charging my 2s 900mah battery at 1.2 to 2.4amps??? I don't understand? Shouldn't it charge at .90amps..
Eventually it will, though mine really settles around 1.2C. How long do you let it charge for before stopping it from the charge being too high?

What capacity was the last lipo you charged to completion on the Cellpro?

Dave
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Old Aug 02, 2007, 09:27 PM
damn you tree!
roballoba's Avatar
Foster City, CA
Joined Dec 2005
231 Posts
fyi: the big box was a power supply, the charger is small and sitting on top of it I think it was an older astro flight.

Thanks everyone for making this an informative read. I like the fireplace idea... I have three ammo cans - one for charging, one for seldom used packs, and one for currently used packs.

good luck and happy flying!
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Old Aug 02, 2007, 11:11 PM
Vampowered!
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Crestview Florida
Joined Dec 2003
1,816 Posts
My condolences to you for your damage. It is a hard lesson and one I have learned myself. It also takes guts to admit the mistake and more to share the images with others. Some folks dont really realize the potential of a 3S pack much less the destructive power unleashed by a 5S5000. Let me tell you it is unreal. Even in a controlled environment it is a scary event.
I prefer the Lipo Sack for containment. I know there is a knock off but I like to give credit where it is due....To Mark Wood. He is a former moderator here and contributes much to the hobby.
Be safe and charge safer.
Peace bro
Vammy
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Old Aug 04, 2007, 10:49 AM
Registered User
Joined Nov 2006
52 Posts
Hu guys im just a lipo beginner so i wanted to ask you if lipos should be discharged before charging and if yes should they be discharged threw the balancer or i can plug it directly to the charger?And i also heard that they should be ventilated during charge because they release some sort of gas?Is it trew?
Thanx
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Old Aug 04, 2007, 11:31 AM
Tree? That's a Tx weed!
crashsiegel's Avatar
Central Texas
Joined Apr 2003
2,434 Posts
Quote:
Originally Posted by Fedor
Hu guys im just a lipo beginner so i wanted to ask you if lipos should be discharged before charging and if yes should they be discharged threw the balancer or i can plug it directly to the charger?And i also heard that they should be ventilated during charge because they release some sort of gas?Is it trew?
Thanx
Fedor,
Lipos do not "vent" during charge unless you encounter a catastrophic failure. Lead-acid wet cells are open cells becuase they vent hydrogen during charge and need to be vented out of living space but lipos are sealed packages.

You are doubtlessly hearing hearing stories of lipo's "venting" - they can and when they do, it is majorily unpleasant. This is why I charge all lipo's in a small fire proof safe (Sentry 1100, was $19 at WalMart). And I store them in there also.

Also, never discharge a lipo below 3V/cell - this will damage/destroy it. Nickel cells should be discharged occasionally but not lipos.

Please read the sticky here:
http://www.rcgroups.com/forums/showthread.php?t=209187
It has much very good info you need.

I have had lipos since late 2003. Becuase I follow the rules for handling and using lipos I have never had a "vent-with-flame" incident, nor have I had any puff up on me. Almost had an incident once (IR thermometer caught the temp RISING fast!) but it was a direct result of a very hard crash.

So use the right equipment (lipo charger, lipo balancer, fire proof container), the right procedures (never leave unattended while charging, etc), don't overload (run at burst discharge rate for minutes at a time) and life will be good.
Enjoy,
Crash
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Old Aug 04, 2007, 11:31 AM
Space Coast USA
hoppy's Avatar
Space Coast
Joined Oct 2000
20,846 Posts
1. Do not discharge before charging. Lipos are harmed by low voltages which may be obtained by a deliberate discharge.
2. If you have the balance plug, use it. If packs are not discharged to more than 80% of capacity they will usually stay in balance.
3. Charging a lipo does NOT release gases nor should they get warm. If the packs are puffing and/or the getting warm, the packs are defective.
4. IMO, lipo's should be charged in a fire safe container and away from flamables. I use a tabletop BBQ. Others use Lipo Sacks, cinder blocks, etc etc.
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Old Aug 04, 2007, 12:37 PM
Registered User
Joined Nov 2006
52 Posts
Thanks a lot .I got my self the UH lipoguard.Yeah it also seemed to me littlebit bizzare that you should use some lipoguard and on same time ventilate.Because the lipogurad blocs tha gases.
Thanx
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