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Old Mar 06, 2006, 04:02 PM
hos
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800mah CommonSenseRC discount batts reviewed for Esky lama 2

I got my 800mah batteries. I waited till I had the chance to borrow my Dad's multimeter to test how the stock Esky Charger was working. It did charge the battery to 4.25v/cell. This is a little high, but not too bad. I will update when I get around to adjusting it.

The batteries look good. I got 2 800mah batteries for $24.30 incl shipping. The 800mah comes with the proper JST connector for the lama, and the right size balance connector for the stock charger. As has been said, you need to reverse the wires on the balance connector. (see here http://www.rcgroups.com/forums/showthread.php?t=487112 or here http://www.commonsenserc.com/page.ph...rangement.html ) It is very easy to do and took less then a minute per battery. Simply release the tab that holds the wires in with a screwdirver or somerthing similar, and pop out the wire. You need to switch the left and right wires. I put some electrical tape around the first wire before removing the second so I didn't short it out.

It is about the same size as the stock battery. The only difference is that the wires aren't bundled on the edge of the battery and are on top in the shrink wrapping. I don't think it will fit in the stock battery tray. I think this tray is a pain and wanted to do do something different anyway. I used a rubber band, and will do the fuel tube mod when I get the chance to go to the LHS.

I flew it and got about 8-9 minutes off it for the first cycle. I expect that will increase to the 10 mins I got from the stock one after the battery gets broken in a bit (this is normal for all lipos). The heli seemed a little more stable in yaw during the bulk of the flight then with the stock one. It may be my imagination, but it may have a more consistent discharge then the stock battery which would account for this.

I do like the 800 mah because I think they are about the right size for this heli. I hear more weight gives them more stability, but that comes at a price. More weight means less flight time, and more motor and battey wear. If a 800mah can give 10 mins flight time, and a 1250 mah only gives 12 mins, the 50% addiional capacity is only giving you 20% more flight time.

All in all I'm happy with the batteries. The stock ones are about the same price for 1 battery, and you get 2 from common sense, so they are essentially half the price, and probably better quality. My lipo alarm courtesy of Thanh Tran should be delivered this week. I'm going to wait till I have it before I continue testing, so I don't damage the batteries. I will report back when I have it installed and start really putting some cycles on these batteries.
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Old Mar 06, 2006, 04:21 PM
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Oh you are so wrong.....

1320 mah at 60grams---->20 minutes

There are even lighter lipos
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Old Mar 06, 2006, 04:29 PM
hos
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I was going off what I had read here. Do you have a 1300 that does exactly this, or are you passing along what you have read here? One poster has said he has found a 1300 that is only 49 grams, but this is significantly lighter then some of the most expensive batteries you can find (thunder power and Dualsky). A little too good to be true.

Edited back to what it originally said.
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Old Mar 06, 2006, 04:37 PM
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Sorry for what seems to be a harsh comment. I didn't mean it.
Yes....I was trying to get the make and model of the lipo that the guy was referring to....

I do have the 60 grams lipo though. The Lama is a little lighter than the CX. It's probably why I could get 20 minutes...hovering....

20 minutes was "pushing it". Next time, I would stop at about 18 minutes to be safe.

But what I've found it that I really don't need 20 minutes of flying time. I usually do something stupid and crash before hand.
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Old Mar 06, 2006, 04:40 PM
hos
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Theoretically you shouldn't be able to get 100% more flight time off a battery with 65% more capacity. Are you being very exact in your timing? Perhaps a proper 800 mah (not the stock one) that is properly broken in will do more then 10 mins.

Edit: It is also worth noting that some say these batteries are just about broken in after 50 cycles. I think I was overdischarging my stock one and it only gave about 40 cycles before it puffed. It is suprising how easy it is to overdischarge. I tested the CSRC batt after I ran it and it was down to 6.6v unloaded!!! They should be discharged to about 7.4v unloaded. I will perform all other testing on the second battery as this one has possibly already been damaged.
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Old Mar 10, 2006, 07:57 PM
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how are they working now? How many flights?
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Old Mar 10, 2006, 09:06 PM
hos
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Well, 2 flights... I wanted to wait till I got my lipo alarm, which I did yesterday. I installed it and all was well. I had to remove the antenna which was wrapped around the tail boom to install the lights. I put it thought the tail and left it hanging down for the test flight. At the end of the flight (9-10 minutes) I dropped it too quick and the antenna got wrapped around the rotors bending the tail like a pretzel. I can't tell you how disappointed I was. But just like my first flight the tail seemed more steady then it ever was, and ran a good amount of time. I should get even longer run times as the battery gets broken in. I also adjusted my charger so that it cuts off at 8.4 volts (about 30 degrees clockwise). I'm now in the process of supergluing humpty dumpty back together again (the tail). Hopefully I can pull off what all the kings horses and all the kings men couldn't. I should be back in the air again tonght, at which point I will really start putting some cycles on them. Sorry for the wait.
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Old Mar 11, 2006, 01:55 AM
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hos,
I generally agree with most of your comments and think you have some good threads, but I think you will find some serious disagreement with the battery experts in the battery forums.. You mention the "breaking in" of lipo batteries as if they act like niMh cells. They are quite different and the official statements from battery company experts is that lipos do not gain any improvements from so called break ins like the nickle cells do. Matter of fact, each flight is slowly taking the lipos towards their eventual death from use.
That is my experience after years of using them, but I am not an expert. Hundreds of lipos and never had one get better. I do, however, follow the battery forums since it helps me get max performance from my pattern and 3D competition planes.
Ken
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Old Mar 11, 2006, 04:48 PM
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hmmm. I didn't know that. I thought I had read that somewhere on this forum. I'm sure CSI is correct on this. Good to know. So I'm getting about 9-10 minutes rightnow, so I guess thats as good as it will get. I will try and time it more precisely.
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Old Mar 12, 2006, 03:23 AM
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hos,
I am by no means a battery expert, just going on readings from the battery forums for a couple of years. There were some discussions on whether a lipo needed breaking in and it went back and forth for a while. Finally, some battery manufacturers got involved about a year ago and said that their batteries did not benefit or need any break in. Of course, anythings possible, and I wouldn't doubt that somehow you might have got increased performance on a specific battery brand?!
The Battery University site does state that lipos generally need to run through the shipped voltage, and then recharged before they attain peak performance.
Of course, anyone using niMh batteries definitely needs to understand that those batteries performance will drastically increase after several break in runs! They also lose their voltage really fast too when stored. Even overnight is too long, they still need a topping off before use.
Man, do I love lipo batteries!!!!!!

hos, what battery have you found to work real well as a replacement on the Lama? Seems all my old plane batteries that are small enough are already shot. Is that 800 working the best for you?
Thanks guys for the great thread.
Ken
http://www.batteryuniversity.com/partone.htm
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Old Mar 12, 2006, 08:50 AM
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I've just bought 2 commonsense budget 800 mah packs, have charged them with my new commensense charger (which seems really nice compared to the esky stock charger) but have not had a chance to fly them yet. And, I have been paying attention that I need to check/swap the polarity of the power connector. I also bought a balance connector to solder to my stock esky pack. I'll report on the success/failure of that too.

-- Bryan
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Old Mar 12, 2006, 09:48 AM
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Ken, the 2 S 1250's work extreemly well in my Lama. They weigh 60 grams,and do as hos noticed,seem to give a more constant flight time,and control.The extra capacity of the 1250's help the battery "not work as hard" towards the end of the flight.Capacity is about as important as voltage,in Lipo's. If you take a smaller (600-800mah capacity) battery,and fly for ,say 8 minutes. Then feel it,it will be warm,or hot depending on the battery's condition.If you take another battery with higher capacity(1000-1300mah) fly the same amount of time(8 minutes) it will be much cooler.It still has power(read amps,or fuel) in reserve,where the smaller battery is sucking fumes trying to deliver the required power(amps) to fly. Everyone talks about KILLING their batterys,if you really want to decrease your batterys lifespan,you run them down until they are HOT! Heat IS the enemey in batterys,as it is in motors. I fly my 3-D planes with 1320mah 3 S lipo's. After 15 minutes of hard flying the battery isn't even hardly warm(a good sign,your not over stressing the battery). RR
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Old Mar 12, 2006, 01:34 PM
hos
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Ken,
I said I trust you on this because you have obviously sepnt more time on the battery forum then me These are the only batteries I have tried as a replacement. I got a "good" stock one that did about the same runtime, 9-10 mins, so runtime is similar and what would be expected out of an 800mah. I do like the 800mah for these birds. I don't think a 60 gram 1250mah battery will push it too hard, though it will reduce motor life. I don't find a need for a higher capacity battery because you can only run it for so long and then the motors need cooling.

Aerowork,
You don't need to change the polarity on the commonsense batteries for thier charger. You only need to change the polarity on the stock battery for use with the CSRC charger. Soldering is not required. I linked how to do it in my first post.

RR,
I would think that a battery gives off a X amount of heat per mah used. If that is true the bigger battery isn't as hot just because there is more mass to heat up. If an 800mah battery is used like most do, 5 mins in the air, 5 mins rest, finish the cycle, it will not heat up to the point it is damaged. My 800mah's are barely warm after using them like this.
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Old Mar 12, 2006, 02:25 PM
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Happiness and ... Despair?

I hooked up my commonsense 800mah pack today. Like hos just said, I didn't need to change anything. My misunderstanding.

Flight time was OUTSTANDING!!!!! Easily 10 minutes or more. That's the happiness part.

Now the despair part. I was also testing my variable index gyro bar, trying to get rid of the toilet bowl effect. I may have overdischarged one of my nice new packs. Went to take off after an adjustment and there wasn't anything there. Oh crap. I'm seeing if it will take a charge. The commensense charger indicates yellow on one cell and green on the other, which is strange.

Later, when I get a balance connector soldered to my stock pack, I'll see if the stock lipos do any better when charged with my fancy new charger.


**update** my new lipos still seem alive. Whew.

-- Bryan
-- Bryan
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Last edited by Aerowerk; Mar 12, 2006 at 05:37 PM. Reason: new info
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Old Mar 13, 2006, 02:26 AM
CSI
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hos,
You have to be careful about your Mass theory. It's not so much about the mass in terms of size, but rather the ability of the battery to deliver amperage.
I have some 8C 1200 mAh 2s lipo packs. Their MAX amp delivery capablity is 9.6 amps (8 x 1.2)
Same Manufacturer 8C 1500 mAh 2s lipo have max amp delivery capability of 12 amps (8 x 1.5)

C rating of battery times amps of battery equals max amps to draw.

If you draw at these max amps you will heat up and kill that battery fast.
The larger capacity can give more amp draw for longer duration at ALL throttle settings over the smaller battery. Just as RR stated, that larger battery will stay cooler for most any flying you will do with the Lama...even with the rests you mention. The rests will help keep the smaller battery from frying itself, but your smaller capacity battery will always have to work harder than the larger size.
There is obviously a point reached where the larger size (weight) will be offset and by the power gained, and it won't be efficient anymore. Too large a battery has to work too hard to lift itself, thus heating up, but the small increases we are talking about won't really apply. Another variable is that "C" rating. Plug different C ratings into the above formulas and you can see what a large effect if can have. In some cases the larger size amps deliver can be minimized by having a smaller battery with a higher C rating.

RR, thanks for the info. I have been around these batteries for quite a while now, and been following threads in the battery forum for a good bit too.
Hope this all helps.
Ken
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