ndb8fxe

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Hello All,

My current setup is a 1/4 scale (77") sukhoi, Spektrum system with a couple 645's and a couple of 5645's powered by a 3s 2500mah lipo.

The problem is that I got called away for work and didn't get back for a month and the lipo was plugged in to the regulator. Even though the switch was off this drained the lipo down below the min voltage and ruined the battery.

So I need a replacement rx battery. I'm thinking of getting rid of the regulator and going with a life battery. I'm completely new to this technology so am seeking advice on what to get.

Thanks,

stangman67

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Life all the way! I use a single radical r/c 2300 mah in my quarter scale with dual outputs to a dual switch, one for ignition and one for the receiver.

ndb8fxe

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OK, probably a dumb question: are LiFe the same as A123?

Thanks.

stangman67

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Yep one and the same

ndb8fxe

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Thank you!

JoeAirPort

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Nope they are not the same. LiFe Source is lithium IRON phosphate. A123 is lithium NANO phosphate. There's no comparison in the performance between the two. A123 kicks LiFe's *****. LiFe is not bad though. It just ain't A123.

Read the Tech notes at the bottom of this page/link:
http://www3.towerhobbies.com/cgi-bin...?&I=LXYAS9&P=0

Here's some A123 info:
http://www.a123systems.com/a123/technology

nmking09

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Life's are fine for RX packs.

JoeAirPort

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I agree, LiFe will be more than enough for this 77" ARF. Just making sure people understand that A123 and LiFe are not the same thing.

rctom

They are similar but not identical. LIFE has, in my testing, about 50% of the current capacity of an A123, but has the advantage of greater total capacity.

I tested a 3200 mah LIFE pack against the regular 2300 mah A123 pack that we are all using. My testing involves putting the pack under an increasing load until the supplied voltage drops to 5.0 volts, then measuring the current flow out of the pack. I do this for a full discharge, not just for a few seconds.

I found that the LIFE 3200 pack would supply 15 amps in this test whereas the A123 2300 pack would supply right at 20 amps. The two packs were the same size physically. The LIFE pack was producing about 5C where the A123 was making almost 10C.

In practical application the LIFE pack would be fine for almost any plane, I flew it extensively in a 50cc plane until I left the switch on for several days and ruined it.

They charge the same and are both safe,

TF

stangman67

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Learn something every day, I thought they were the same. The important thing is you are staying away from nimhs and mini lipo bombs. Lipos scare the **** out of me sometimes, even though i use them extensively for r/c truck racing. I have heard way too many stories of people losing their houses due to lipo fires.

ndb8fxe

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Okay, thanks guys. After I read that they were the same I ordered a couple. Now I'm just worried about charging. My charger says it will charge Li-Fe, but doesn't say anything about A123. Will I need a new charger?

stangman67

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Both life and a123 2 cells are 6.6 volts, and have similar charge/discharge characteristics and I use my Triton eq set on LiFe to charge my a123s all the time and it works just fine.

ndb8fxe

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Thanks again Zach.

JoeAirPort

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I have read (about A123) that as long as you don't exceed the 7.4V max voltage an A123 can be charged up to it won't hurt it. So you might want to keep an eye on the voltqage the 1st time you charge it to make sure it doesn't go over 7.4V. I think Dick Hanson said this in another A123 for dummies thread...somewhere. Either here or FG.com.

Wingman26

Anytime you use a voltage regulator be sure to put it on the switched side of the circuit, so that any time the switch is turned off the battery is completely isolated from the regulator.

JoeAirPort

My Feedback: (41)

That's a very good point but I don't think he planned on using reg's when he went to the LiFe battery pack. I agree though, the regulator on the wrong side of the switch was the cause of the original failure. Glad you mentioned that.

ndb8fxe

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I hear you about the switch. I bought the plane used and that's the way it was set up. I didn't know any better, but ignorance is no excuse. My Fault for sure.

When a servo's specs show 4.8v or 6v is it safe to run the 6.6 of the A123?

Once again, thanks to everyone for the help.

stangman67

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Yes on pretty much any modern servo, it is ok to power them with 6.6 volts.

Mikecam

Some more info.

http://www.hangtimes.com/a123_batter...iants_faq.html

ndb8fxe

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Just got the A123s in. I installed one in the plane and all I can say is Wow! I haven't charged it yet, but the servos are super fast compared to the lipo/reg that I was running. Still won't be able to fly it till next week, but I'm looking forward to getting this bird back in the air. Thanks to everyone for the help.

JoeAirPort

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I noticed mine were faster too. It's gotta be that solid voltage that refuses to drop when the battery's loaded.

ndb8fxe

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Alright, finally got a day off and need to charge the batteries. My charger(Venom-Pro) says it charges Li-Ion/Polymer Battery/Life Battery, but I can't find Life in the on screen menu. What settings are you using to charge these batteries?

Thanks,

Edit: Disregard, figured it out.