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Old Jan 16, 2013, 03:21 PM
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United States, NJ, Lebanon
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Originally Posted by JLT_GTI View Post
If you charge only one i wouldnt go over 200mAh ..
If you are not in a hurry 100mAh is perfect..
If you have more than one battery you can use one of those "octopus" adaptors that allow to charge up to 6 batteries at same time.. you have to sum the capacities of all batteries and they should be at similar charge levels, and adjut the charge rate at close to that (or better lower)

for example.. if you charge 5 X 160mAh packs, is 5X160 = 800mAh , charge set to 800mAh, or 500/600 if not in hurry .. the softer you charge them the longer they will last (in total battery life, not in flight)
Thanks for the detailed response. I don't quite understand, but I do understand your point that it is safer to charge a battery at a lower rate than a higher rate.

The 250mah battery that comes with the Mossie is recommended to be charged at 0.7amps. So the 150MAH that came with the champ can be charges at ?.?amps?

Thanks for your help again.
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Old Jan 16, 2013, 03:34 PM
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Quote:
Originally Posted by Dennist73 View Post
Thanks for the detailed response. I don't quite understand, but I do understand your point that it is safer to charge a battery at a lower rate than a higher rate.

The 250mah battery that comes with the Mossie is recommended to be charged at 0.7amps. So the 150MAH that came with the champ can be charges at ?.?amps?
??

what part you dont understand? i wouldnt charge a 250mAh batt at 0.7A , thats charging it at 3C .. LiPo charging is usually 1C or less (C being the capacity of the battery)
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Old Jan 16, 2013, 03:44 PM
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United States, VA, Fluvanna
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Quote:
Originally Posted by Dennist73 View Post
The 250mah battery that comes with the Mossie is recommended to be charged at 0.7amps. So the 150MAH that came with the champ can be charges at ?.?amps?
I wouldn't charge a 250 mah at .7 A even if they recommend it. More like .2 or .3 A. And you can charge your 150 mah at .1A or .2A. I don't charge at a higher rate than that using my good charger. The little charger that comes with the UM planes charges at about .3A but I know someone who puffed some batteries in a 4 port Celectra which nearly caught on fire afterwards.

For example, I might charge 1 UM battery at .2A but when I charge them as a group I calculate using .15A per battery, so I charge 5 or 6 at .9A.
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Old Jan 16, 2013, 03:55 PM
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United States, NJ, Lebanon
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Originally Posted by GooberSB View Post
I wouldn't charge a 250 mah at .7 A even if they recommend it. More like .2 or .3 A. And you can charge your 150 mah at .1A or .2A. I don't charge at a higher rate than that using my good charger. The little charger that comes with the UM planes charges at about .3A but I know someone who puffed some batteries in a 4 port Celectra which nearly caught on fire afterwards.

For example, I might charge 1 UM battery at .2A but when I charge them as a group I calculate using .15A per battery, so I charge 5 or 6 at .9A.
Thank You.
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Old Jan 16, 2013, 11:36 PM
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Joined Mar 2008
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Dennist, here's a good "easy to read" and understand about lipos. I refer to this all the time:
https://sites.google.com/site/tjingu...arging-how-tos

Has the formula/math that the other Guys were trying to explain. Go to "Parallel charging" link. It is quite simple

Mike.
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Old Jan 17, 2013, 11:30 AM
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I would love to see a 1c brushless Champ hit the production schedule at HH.
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Old Jan 17, 2013, 12:52 PM
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United States, WI, Sheboygan
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Quote:
Originally Posted by JLT_GTI View Post
If you charge only one i wouldnt go over 200mAh ..
If you are not in a hurry 100mAh is perfect..
If you have more than one battery you can use one of those "octopus" adaptors that allow to charge up to 6 batteries at same time.. you have to sum the capacities of all batteries and they should be at similar charge levels, and adjut the charge rate at close to that (or better lower)

for example.. if you charge 5 X 160mAh packs, is 5X160 = 800mAh , charge set to 800mAh, or 500/600 if not in hurry .. the softer you charge them the longer they will last (in total battery life, not in flight)
There is a forum devoted to batteries and chargers; a lot of the threads deal with lipo safety. I strongly encourage EVERYONE to check it out. Even the smallish batteries powering ultra micro aircraft are dangerous if handled improperly. That said, there are some rules of thumb that one can apply.

First, it's a good idea to use a timer to avoid discharging a lipo too far i.e. flying it too long. In general, limiting flights to 5 minutes or less will add dozens of flights to a battery's life.

Second, discharging a battery much more than halfway during the first few flights will also shorten its life rather dramatically.

"C" is a multiplier of the battery's capacity in amps; for a 200mAh battery 1C=0.2A. The "C" value on a battery is its maximum safe DISCHARGE rate; my batteries all have a C rating above 5. In general lipo batteries can be safely charged at 2C assuming their C rating is higher than that.

Charging a 160mAh battery at 0.3A (approx 2C) will prolong its life; charging it at the mfr's suggested rate of 0.7A will almost always shorten its life - good for the guys selling batteries, not so good for you and me!

It is good to "break in" a battery by charging it at a number lower than 1C for the first few flights. After that, charging at 2C should be safe even though the battery might be able to handle more.

I've charged my 550mAh batteries at 2C (1.1mAh) for more than a year with no apparent ill effects. I also never fly more than 5 minutes.

I use a programmable charger. It gradually reduces the charge rate as the battery approaches the full charge. It also lets me see how many mAh are being "put back" into the battery.

The goal is to never fly the battery down to the point where it takes more than 80% of its capacity to fully recharge, i.e. I never fly my 550mAh batteries down to the point where it takes more than 440mAh to recharge them.

Post-flight voltage is an indirect (but not foolproof) way of measuring mAh. I never fly any of my batteries below 7.5V regardless of their rated capacity.

Flying the battery too long is like adding sand to the gas tank; it won't accept as much "gas" (mAh) the next time. If the post-flight voltage ever drops below 7.0V then it means the battery probably has lost a little of its capacity; over time the accumulated losses will render the battery useless.

DON'T TAKE MY WORD FOR ANY OF THIS! GO TO THE CHARGER/BATTERY FORUM AND DO YOUR HOMEWORK! Too many fires have been started through improper handling of lipos.
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Old Jan 17, 2013, 04:08 PM
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United States, NJ, Lebanon
Joined Nov 2012
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Quote:
Originally Posted by 1Pilgrim View Post
There is a forum devoted to batteries and chargers; a lot of the threads deal with lipo safety. I strongly encourage EVERYONE to check it out. Even the smallish batteries powering ultra micro aircraft are dangerous if handled improperly. That said, there are some rules of thumb that one can apply.

First, it's a good idea to use a timer to avoid discharging a lipo too far i.e. flying it too long. In general, limiting flights to 5 minutes or less will add dozens of flights to a battery's life.

Second, discharging a battery much more than halfway during the first few flights will also shorten its life rather dramatically.

"C" is a multiplier of the battery's capacity in amps; for a 200mAh battery 1C=0.2A. The "C" value on a battery is its maximum safe DISCHARGE rate; my batteries all have a C rating above 5. In general lipo batteries can be safely charged at 2C assuming their C rating is higher than that.

Charging a 160mAh battery at 0.3A (approx 2C) will prolong its life; charging it at the mfr's suggested rate of 0.7A will almost always shorten its life - good for the guys selling batteries, not so good for you and me!

It is good to "break in" a battery by charging it at a number lower than 1C for the first few flights. After that, charging at 2C should be safe even though the battery might be able to handle more.

I've charged my 550mAh batteries at 2C (1.1mAh) for more than a year with no apparent ill effects. I also never fly more than 5 minutes.

I use a programmable charger. It gradually reduces the charge rate as the battery approaches the full charge. It also lets me see how many mAh are being "put back" into the battery.

The goal is to never fly the battery down to the point where it takes more than 80% of its capacity to fully recharge, i.e. I never fly my 550mAh batteries down to the point where it takes more than 440mAh to recharge them.

Post-flight voltage is an indirect (but not foolproof) way of measuring mAh. I never fly any of my batteries below 7.5V regardless of their rated capacity.

Flying the battery too long is like adding sand to the gas tank; it won't accept as much "gas" (mAh) the next time. If the post-flight voltage ever drops below 7.0V then it means the battery probably has lost a little of its capacity; over time the accumulated losses will render the battery useless.

DON'T TAKE MY WORD FOR ANY OF THIS! GO TO THE CHARGER/BATTERY FORUM AND DO YOUR HOMEWORK! Too many fires have been started through improper handling of lipos.
Thanks again, As I get more engaged in this hobby there is obviously more to learn and money to be spent to take the proper precuations.

I just ordered a LiPO charging bag and I'm having it shipped overnight. If I plan continuing to use the variable rate charger on my 250Mah and now my 150MAH batteries, I better do it right and not risk burning the house down.
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Old Jan 17, 2013, 05:44 PM
Scout CX | mCX2 | mSR | 120SR
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Canada, AB, Edmonton
Joined Dec 2011
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Quote:
Originally Posted by Dennist73 View Post
Thanks again, As I get more engaged in this hobby there is obviously more to learn and money to be spent to take the proper precuations.

I just ordered a LiPO charging bag and I'm having it shipped overnight. If I plan continuing to use the variable rate charger on my 250Mah and now my 150MAH batteries, I better do it right and not risk burning the house down.
The original Lipo Sack brand are highly recommended... the developer is a RCG member. If they ever experience an "event" they will be replaced for free They are more expensive but you can't put a price on safety. I own 2 and will be buying more... I keep my lipos in the sacks which then sit inside ammo boxes (purchased from my local surplus store) with the lids open.

Be aware that some of the cheap knock-offs are actually flammable !!!???

http://www.liposack.com/
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Old Jan 17, 2013, 10:19 PM
I am GBLynden
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United States, WA, Lynden
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So today I took my Champ up to 750 feet. It was a pretty good accomplishment, especially when you consider it was in the 30's, daylight was fading, and it only took about four minutes to climb up there.

My next goal is 1,000 and to have my buddy record it with either his tri-copter or his Bixler. He flew his Bixler just over two miles away from us today using some new FPV equipment.
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Old Jan 17, 2013, 11:17 PM
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Did you lose sight of it?
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Old Jan 18, 2013, 02:05 AM
I am GBLynden
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Did you lose sight of it?
I could still see it actually, but it was pretty small. I have taken it up a little higher than that in the past, but there was no way to measure it (judging by how much of it I could still see of course). Today there was a way and some day soon I will take it even higher!

My next goal is a clean 1,000. I took some unneeded Velcro off it tonight, so it should be able to climb even quicker the next time up.
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Old Jan 18, 2013, 06:08 AM
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Joined Jan 2013
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How long were you flying at 30 degree's at 750 that is going to be a lot colder and a lot shorter in battery life? 4 minutes to get up, rest must been coasting home, Did you hit lvc?
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Old Jan 18, 2013, 01:48 PM
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Canada, AB, Edmonton
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hare,

we just had a discussion about lipos and cold in another thread. If your lipos are warm when you put them in you shouldn't see a noticeable decrease in flight times... they generate their own heat while they're being used at these current levels.

... this has been my experience with all my lipos ranging from my small 1S 150mah (Champ size) up to my 2S 5000mah even in sub zero (OC/32F) temperature. We maidened my buddy's Flyzone Beaver last week in sub freezing temperature and the experience was the same... 3 back to back packs timed for 10 mins each no problem... lipos were kept in his pocket. Even his Futaba Tx which runs on lipo was fine and it isn't even running at current levels that would heat the battery.

What didn't fare so well were the brand new Duracell alkalines in my camera

His 808 #16 keychain camera was fine too... ran non-stop for over half an hour.
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Old Jan 18, 2013, 06:07 PM
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Anyone knows if the new version charger for the V911 helicopter works to charge the batteries we use in these planes (Champ, T-28, MSR, etc)

i just saw it , charges 2 batts and its really cheap in online stores (around 4$) , it would be fantastic to make a multicharger feed by a LiPo

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