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-   -   Charging More Than 4S (http://www.Wattflyer.com/forums/showthread.php?t=73440)

garyp1029 03-27-2014 06:23 PM

Charging More Than 4S
 
I now have the Apprentice with its 3s 3200mAh battery. I am considering buying a new charger with greater flexibility, such as the Cellpro Multi 4, but am concerned about its maximum capacity of 4 cells. Since I am new to electric planes I really don't know if I would ever need to charge a battery with more than 4 cells. Almost all planes which I have so far considered require only 3 or fewer cells. Can someone give me some idea of the range of available planes with 4 or fewer cells as well as the range which would require 5 or more? Not detailed info on individual planes, but what size and weight of planes would require more than a 4 cell battery. Thanks. Gary

JetPlaneFlyer 03-27-2014 06:41 PM

That's a hard one to pin down exactly because it varies so much. I guess as a very general rule if you are talking about normal sports type models 55-60" span and greater are very likely to run greater than 4s.

Also high performance models like speed models, EDFs and helicopters often use 5 or 6s even at quite small sizes.

Personally I'd get (at least) a 6s charger. That will cover you for just about anything.

fhhuber 03-27-2014 07:11 PM

Depends on what you do... and we can't predict that.

I run up to 12S 5000 mah now, with plans to go to 18S 5000 mah. But I buy 3S and 4S packs for better cooling. A 6S pack tends to have the center 2 cells fail early.

More important than being able to charge high cell counts is being able to charge your packs at a good rate. A typical 50 watt LiPo charger can't charge a 4S pack at much above 3 amps. So even if you stick with 4S as your biggest pack you may need to look at higher power chargers.

Then there is the ability to charge packs in series and parallel. Commonsenserc.com sells an adapter for series charging a pair of 3S as if they were a 6S and there are "balance boards" for charging several packs in parallel. In combination with a high power charger you can get lots of packs charged all at once instead of spending half a day monitoring the charger for preparing to head off to the field.

Many things to consider when looking at new chargers...

JetPlaneFlyer 03-27-2014 08:39 PM

Wow.. 18s:eek:

I didnt know an ESC was even available that would handle 18s

You gotta be a bit careful at those sorts of voltages as you are getting up to a level where electric shock starts to be a realistic concern.

To the OP.. +1 on the advice to get a charger with a good healthy power output.

fhhuber 03-27-2014 08:56 PM

Many of us are already using voltages capable of potentially lethal shock ... 30 volts is enough through wet skin. 6 volts is more than enough if you pierce the skin at your fingertips. Anything that can produce 0.1 amp across the heart is plenty.

Always respect the potential of electric devices to give a lethal shock...

garyp1029 03-27-2014 08:59 PM

Thanks guys. I think the ICharger 106B, which has a max power of 250W and the capacity to charge 1-6 cells, is probably the way to go. The Cellpro Multi4 has just a 4 cell capacity and a 50 watt max. ICharger seems to have a very good reputation (as does the Cellpro) and the 106B charging range of 1-6 would probably be sufficient for quite a long time. In addition, the $90 cost is manageable. Any thoughts about this? Gary

swimmer 03-27-2014 10:23 PM

My up to date firmware Multi4 started giving me many problems shutting down on various alarms, incorrect cell count among others, during charging. FMA Direct wanted too much to repair it, they seemed to know the problem, plus I'd pay for shipping both ways. They did send me a connector, which I am very grateful for, which requires tearing down the charger and soldering a new 4-leg connector onto the board. Decided to lay it aside for now and purchased an original, not a clone, 50 watt iMAX B6AC. Since then I've had zero problems charging all my batteries 1 to 4 cell. Currently I am looking at various chargers in the 250 watt range to allow me to parallel charge more batteries than I can charge with the iMAX. I do believe, however, FMA Direct produces good chargers and they do have good customer service but at this point I just prefer another brand. The Multi4 also does not have a discharge feature which I like on the iMAX.

I use a ParaBoard from BuddyRC.com which I really like for parallel charging. It is very robust and I think priced right.

JetPlaneFlyer 03-27-2014 10:53 PM

Quote:

Originally Posted by garyp1029 (Post 943771)
Thanks guys. I think the ICharger 106B, which has a max power of 250W and the capacity to charge 1-6 cells, is probably the way to go.

Yes, I like my iChargers. The 106b is a great choice and will cover more most needs unless you want to fast charger the really big stuff.

JetPlaneFlyer 03-27-2014 10:59 PM

Quote:

Originally Posted by fhhuber (Post 943770)
Many of us are already using voltages capable of potentially lethal shock ... 30 volts is enough through wet skin. 6 volts is more than enough if you pierce the skin at your fingertips. Anything that can produce 0.1 amp across the heart is plenty.

Always respect the potential of electric devices to give a lethal shock...

Yes, I appreciate lower voltages can, in theory, cause electrocution. I'm not sure if it's ever happened in practice but the theoretical risk is certainly there.
The emphasis in my post was on the word 'realistic'... Higher voltages such as the 75v DC an 18s system will deliver have more potential (in all senses of the word) to produce that fatal 0.1A.

Anyway.. what ESC is available that can handle 18s? I know there are a few in use in large helis that do 14s but I've not seen anything for 18.

kyleservicetech 03-28-2014 01:40 AM

Quote:

Originally Posted by garyp1029 (Post 943763)
I now have the Apprentice with its 3s 3200mAh battery. I am considering buying a new charger with greater flexibility, such as the Cellpro Multi 4, but am concerned about its maximum capacity of 4 cells. Since I am new to electric planes I really don't know if I would ever need to charge a battery with more than 4 cells. Almost all planes which I have so far considered require only 3 or fewer cells. Can someone give me some idea of the range of available planes with 4 or fewer cells as well as the range which would require 5 or more? Not detailed info on individual planes, but what size and weight of planes would require more than a 4 cell battery. Thanks. Gary

Hi Gary
If you plan on staying with these electric models for a while, IMHO, it's wise to buy the best charger you can afford. There are a number of very good brands out there.

The brand used most often at the club I belong to is the Cellpro line. Several members have this unit, and are well satisfied with it.

http://www.store.revolectrix.com/Pro...llpro-10XP_205

As for me, I've got two Cellpro Powerlab 8 chargers, used in my giant scale models for charging a 12S2P A123 pack. Those packs are charged as a 6S4P with a Cellpro charging rate of 30 Amps. It's been working very well, after several years of use.

kyleservicetech 03-28-2014 01:42 AM

Quote:

Originally Posted by fhhuber (Post 943770)
Many of us are already using voltages capable of potentially lethal shock ... 30 volts is enough through wet skin. 6 volts is more than enough if you pierce the skin at your fingertips. Anything that can produce 0.1 amp across the heart is plenty.

Always respect the potential of electric devices to give a lethal shock...

Yeah
Try checking the output voltage of a common 9 volt DC alkaline battery with your tongue. I did it . Once. :censor:

As far as electric shock goes, something to be aware of, use particular so as to NEVER short out one of these high powered batteries with your watch band, or ring. That watch band or ring can turn red hot in a split second, and will likely result in a trip to the emergency room.

Long ago, a guy I know accidentally shorted his metal watch band across a car battery when replacing a starter. The red hot watch band did permanent damage to his wrist tendons.

gerrynj 03-28-2014 02:05 AM

I purchased several LiPos in 2S and 3S configuration. This way I can create my own packs
of 2S, 3S, 4S(2+2) and 5S (3+2) depending on what I am flying. I have a small charger which charges 2S and 3S at a max of 3Amps. I find this to be the most flexible setup for my needs.
Gerry

solentlife 03-28-2014 09:22 AM

Quote:

Originally Posted by fhhuber (Post 943770)
Many of us are already using voltages capable of potentially lethal shock ... 30 volts is enough through wet skin. 6 volts is more than enough if you pierce the skin at your fingertips. Anything that can produce 0.1 amp across the heart is plenty.

Always respect the potential of electric devices to give a lethal shock...

There's an old saying :

Volts = Jolts

Mill's = Kills

It's the ampage that kills - the volts are the driving force to assist the amps to kill.

I've seen a pal of mine have his wedding ring blown apart on his finger - near slicing his finger of ... a near flat car battery that was not enough to turn over the car engine !

Nigel

JetPlaneFlyer 03-28-2014 09:41 AM

But you wont get amps without volts.

An analogy is jumping from a height. Volts can be thought of as analogous to height, amps can be thought of as the impact when you hit the floor.

Yes it's the impact that kills you, not the height itself, but you don't need to be a genius to figure out that jumping from a great height (say a house roof) is far more likely to hurt you then jumping off a small height (say a kerb) because the impact will almost certainly be much greater.

To argue that voltage isn't important to the risk of electric shock is every bit as daft as claiming height is not important in the risk of jumping off things.... Yes, just like jumping, in electrocution there are other factors involved too, but voltage is still very important even if it's not what actually does the damage.

FWIW a number of national codes and standards set a 'safe' voltage where electrical systems can be worked on 'live' of around 50v.


PS.. The ring and watch incidents aren't electrocution. They are burns caused by touching a hot conductor (the ring and watch strap were the conductor). This is a TOTALLY different thing to electrocution which is where the electricity is conducted through the human body, but still something to be aware of for sure.

dahawk 03-28-2014 01:56 PM

+1 on the iCharger. I have the 206B and it can handle everything I have but make sure to get a decent power supply to feed it properly. Mine is a Juki 350W. Nice and quiet. Some guys are using PS's from desktop PC's. Check with EPBuddy or Progessive RC . Good price and service.

maxflyer 03-28-2014 07:27 PM

I popped for a PL8. I don't even charge anything over 3S at present, and may never. Point is, the ability of the PL8 to charge and discharge very quickly has changed my battery management capabilities, and saves me a ton of time. It now takes only a few minutes to charge or discharge my batteries. No more charging ahead of time and storing the batteries at full charge because I plan to fly, only to have to discharge them if I don't. I will likely make up for the cost over a season or two by not stressing and destroying my batteries.

dahawk 03-28-2014 07:42 PM

Another great choice. I was told when I got back into this hobby to just get the best charger I could afford. I didn't want to be buying a new charger every year or two. I think my Icharger will go up to 10C but I don't like the idea of ramrodding that much current.

waytooslow 03-28-2014 07:44 PM

My PL6 has been great -- granted it will only take me up to 6S - fast charges

kyleservicetech 03-29-2014 01:43 AM

Quote:

Originally Posted by JetPlaneFlyer (Post 943813)
But you wont get amps without volts.

An analogy is jumping from a height. Volts can be thought of as analogous to height, amps can be thought of as the impact when you hit the floor.

Yes it's the impact that kills you, not the height itself, but you don't need to be a genius to figure out that jumping from a great height (say a house roof) is far more likely to hurt you then jumping off a small height (say a kerb) because the impact will almost certainly be much greater.

To argue that voltage isn't important to the risk of electric shock is every bit as daft as claiming height is not important in the risk of jumping off things.... Yes, just like jumping, in electrocution there are other factors involved too, but voltage is still very important even if it's not what actually does the damage.

FWIW a number of national codes and standards set a 'safe' voltage where electrical systems can be worked on 'live' of around 50v.


PS.. The ring and watch incidents aren't electrocution. They are burns caused by touching a hot conductor (the ring and watch strap were the conductor). This is a TOTALLY different thing to electrocution which is where the electricity is conducted through the human body, but still something to be aware of for sure.

Yup
Part of the equation is the resistance of the item being given the electrocution treatment. Assuming a "Solid Voltage Source", of say 11 Volts on your LiPo battery, getting that across your fingers would likely not even be noticed, especially if your fingers are dry. On the other hand, static electricity can be very high in voltage, 15,000 volts or even more. But the amps are not available.

As for low voltage, I've got an AC transformer with a one Volt AC secondary in my workshop. That thing weighs about 20 pounds, and has put out a measured current of 1500 Amperes across a piece of 4/0 copper wire about a foot long. That transformer will heat up the heavy 4/0 wire to enough to melt solder in a minute or two. The shock hazard is zero, but you do not want to ever short out a wedding ring with it.

I just checked out current flow on my variable DC power supply, set to 18 volts, while placing my fingers across its output. With dry fingers, the current was 0.02 milliamperes. And with wet fingers, it jumped to 0.31 Milliamperes. Neither current was detectable as a shock. (That current though my body was measured with a $$$$ Fluke 87V digital multimeter.)


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