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Jan 15, 2004, 05:54 PM
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Steviewonder's Avatar

Voltage cut-off for TP 2100?


I have recently purchased a 3s1p Thunder Power 2100 li-poly battery and was wondering what voltage I should program the CC Poenix-35 to cut-off. It is powering a Hacker b20-15L 4:1 in a Groove 480.
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Jan 15, 2004, 06:03 PM
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Shortman's Avatar
9V cutoff is the norm


Steven
Jan 15, 2004, 06:24 PM
Registered User
Steviewonder's Avatar
Thanks
Jan 15, 2004, 10:16 PM
KG7TTQ - Las Vegas
mark_q's Avatar
I've always used 7.2v with no problems.

Mark
Latest blog entry: 390 Degree Geared Pan and Tilt
Jan 15, 2004, 11:13 PM
Nimble with Gimbals
An e-mail I received directly from Thunder Power:

Quote:
The 3v per cell limit is under load. We recomend no lower than 2.9v per cell under load. Typically, this will only happen near the end of the flight or if you are pulling too much current. At 6C or 12.6 amps under load, you should get over 3.2v per cell for 8-9 minutes. If you are running higher current, it is possible, but only in short burts. Short bursts to right around 3v per cell under load (typically 15-20 amps) are fine, as long as you do not do it for extended periods near the end of the flight.

Thank you,

Thunder Power Batteries
Jan 16, 2004, 12:06 PM
Use the 4S Luke
feathermerchant's Avatar
Steviewonder
Note the quote from TP above. The combo you have in the groove usually draws about 20A static. That is a lot to ask of the 2100's.
Kirby ran 2 ETEC 1200 in paralell (slightly better than one TP 2100) and they came out hot. Just prop for no more than about 15A and you should be OK.
Jan 16, 2004, 12:21 PM
It's the last plane honey
SlowRider's Avatar
Steviewonder,

I'm using the TP 2100 3s with a CC Phoenix 35 and have the LVC set at 9v. I'm running a Himax 2015-5400 in a C gearbox with a APC E 9x6 prop. WOT static reads 14.1A @ 145W. I can fly for 10 to 11 minutes at 1/2 to 3/4 throttle before power noticeably drops. When I detect the drop in power I'll land and have not yet had LVC cut in. The motor temp is 115 deg. and the battery is 90 deg, air temp is typically 45 deg when I fly (Winter).

Full charge is typically 12.52V and after 10-11 min. of flight the pack voltage comes back to 11.35V.

Andy
Jan 16, 2004, 06:07 PM
KG7TTQ - Las Vegas
mark_q's Avatar

As recommended


OK, a little more detail since I am the only one here daring to go to 7.2v on a TP2100. My plane, with a Mega 16/15/7, 9x6 apce and CC25 pulls 15.1a static @ 162w on a just charged pack. I have used the Castle Creation recommendation as printed on their programming instructions:

"9.1 Cutoff Voltage
Option 4: 7.2v cutoff for 9-12 cell NiMH packs, or 3 cell Lithium Packs"

I also have the cutoff type, 9.6, set at option 2, "Soft Cutoff".

My plane, a Vermaont Belle, AUW @ 21.3oz fly very briskly for 12 to 15 minutes. I always land when I have noticed the power has dropped significantly. The lowest unloaded voltage I have seen to date is 10.64v, immediately after landing. The highest temp, 112F and the most mah returned to a pack - 1966mah.

Mark
Latest blog entry: 390 Degree Geared Pan and Tilt
Jan 17, 2004, 02:08 AM
It's the last plane honey
SlowRider's Avatar
Mark,

You may want to do a search in the CC Forum, I believe I saw a post that said 7.2v for a 3s is a misprint, and that it should be 9v for a 3s, ie., 3v per cell.

Andy
Jan 17, 2004, 02:12 AM
If you use 7.2v for a 3 cell pack it is a LAST RESORT cut off! If you fly to the cut off once or twice in a few hundred flights, its not going to kill the pack, but if you do it every time you fly, it will ruin the pack in a few dozen flights!

Using 9v is the proper cut off voltage for the 3S 2100 packs. True, you could use 7.2v and land when the power feels weak, but you may only gain 1-3 minutes over using 9v, and its not nearly as safe.
Jan 17, 2004, 10:19 AM
Registered User
Steviewonder's Avatar
Thanks for all the info- I think I'll try 9v to be safe.
Jan 17, 2004, 10:50 AM
KG7TTQ - Las Vegas
mark_q's Avatar

GAA!


As far as flying to the cutoff, I have never done that. With soft cutoff it decreases current ahead of the voltage drop and the plane loses alot of power long before you actually get to the cutoff. I will fly again (soon) and check the pack voltage under load at the end of my flight and see what's up.

Also, with regards to the Castle Creations misprint, it is still shown in the PDF manual posted on their website. I will do a little more research and find out what's up with that as well and change my cutoff to 9v (after the above test) in the meantime.

Thanks all - Mark
Latest blog entry: 390 Degree Geared Pan and Tilt
Jan 17, 2004, 01:29 PM
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Shortman's Avatar
It kinda sucks, my Hacker Jeti 18-3P doesn't have programmable cutoff, it just cuts out at 5V! So I am just going to fly 10 minute flights and be safe.


Steven
Jan 17, 2004, 03:07 PM
Registered User
Bonez's Avatar

Factory Info - TP and Castle Creations


From an earlier post:

I emailed a few questions to Thunderpower regarding their lipo's. Here is what I received:

<1) What is the recommended ESC cutoff setting (7.2 or 9 volts)?>

9V is perfect. It leaves a nice cushion of 5-10% in the packs which is excellent. Using 7.2v is ONLY a last resort - if you fly to this cut off more than once you will ruin your 3 cell packs. Using 9v you can fly to the cut off all the time and will get excellent battery life and longevity.

<2) If I charge the batteries on a Friday and get blown out for the weekend should I cycle the battery (discharge and recharge) prior to usage a week later?>

Thats the beauty of LiPos - they lose next to no charger over a few MONTHS time! We left a battery sit for 30 days (2100 mAh). It was charged, then sat in our shop. After 30 days, we tried to "top it off" and the pack only took 100 mAh. After 1 week, you lose virtually no charge.

<3) Do LiPo's have any memory?>

Another beauty of LiPos - no memory! As long as you dont overcharge, overdischarge or overheat, packs will last for hundreds of flights and you never worry about discharging them anywhere but in the plane. Charge today and fly in 2 weeks and pack is still fully charged and so on.

Enjoy your new packs! Thank you,

Thunder Power Batteries


I also sent Castle Creations a question on voltage cutoff and they said definitely use the 9-volt setting. They will be revising their instructions supplied with their ESC's.
Jan 17, 2004, 03:23 PM
Nimble with Gimbals
Thank you for backing up what I've been recommending for months. Do you mind if I quote your e-mail, Bonez?


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