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Old 03-22-2012, 04:29 PM   #1
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Default Back to the hobby -LiPo Rx pack questions

I've been out of the RC game for the last 3 years, just as the lipo battery thing really started taking off. Planning on doing some limited racing this summer, so it's time to get my equipment back in order.

First up: batteries. I'm sure all my packs are shot (or will take too much to cycle and get back to speed) so that's where I"m looking first. Before I left, there was some issue as to whether or not to use lipos as your tx pack, or whether there needs to be a regulator in between the pack and the rx to keep from frying the Rx/servo/whatever. I'm running all Spektrum Tx/Rx gear and currently have a few HiTec servos installed in the MTX4 (not the hi voltage ones, those were just coming to market as I was taking a break). If I were to run that lipo pack, would it be better to get a regulator in between there, or replace the servos? What is the hot hi volt servo that works well for a touring car these days? Will the Rx get fried with the extra voltage? And which Rx packs are the rage these days?
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Old 03-22-2012, 07:43 PM   #2
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just stick to the 1700 mah metal hyd. plenty of run time and you got a less to worry about and just concentrate on your racing. Two races ago we had a car completely on fire from a lipo.
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Old 03-22-2012, 09:09 PM   #3
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I run a reedy life pack in my mtx4 and after running 30min with 2 digital servos it only took about 350mah to charge. Nominal output is higher and it lasts longer. I don't want to deal with lipo batteries myself. So I would recommend life batteries. I still don't have much experience with them though
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Old 03-22-2012, 09:28 PM   #4
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Quote:
Originally Posted by spenzalii View Post
I've been out of the RC game for the last 3 years, just as the lipo battery thing really started taking off. Planning on doing some limited racing this summer, so it's time to get my equipment back in order.

First up: batteries. I'm sure all my packs are shot (or will take too much to cycle and get back to speed) so that's where I"m looking first. Before I left, there was some issue as to whether or not to use lipos as your tx pack, or whether there needs to be a regulator in between the pack and the rx to keep from frying the Rx/servo/whatever. I'm running all Spektrum Tx/Rx gear and currently have a few HiTec servos installed in the MTX4 (not the hi voltage ones, those were just coming to market as I was taking a break). If I were to run that lipo pack, would it be better to get a regulator in between there, or replace the servos? What is the hot hi volt servo that works well for a touring car these days? Will the Rx get fried with the extra voltage? And which Rx packs are the rage these days?
1.) If you have no HV servos, you must run a regulator. or see your servos freak out and poof.

2.) If you have a spektrum such as the 3100 or one with telemetry, you'll be fine running a 2s lipo....most spektrum receivers can run up to 9.6v!
This is very versatile in being able to switch its position and more than ample run-time: http://www.amainhobbies.com/product_...-Balancer-Plug

3.) Keep a small digital voltage checker handy while at practice. When you come into the pits, check your voltage per cell...but most likely you will have way more than enough run time per charge.
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Old 03-23-2012, 01:46 AM   #5
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LiFe packs don't catch fire, don't need a regulator, don't self discharge, and hold a far more true Mah, just don't constantly run them down to zero and they are the best of the RX bunch.
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Old 03-23-2012, 02:18 AM   #6
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if you want the extra voltage from the lipo and you take care of your batteries you can run a lipo with spectrum and the new Ko Propo low profile RSx one10 servos.

i've used soft cell lipos for the last 4 years almost in nitro cars and nitro buggies. I have never had a pack blow up.

if a pack blows up in most cases it is poor care, or the user has allowed the pack to drop to a low voltage. charge every race day, and top up the battery before a final. If using in a nitro buggy wrap the cell in shock absorbing foam.

Life's can sometimes be larger than lipos so if you want less weight i think lipo is the way to go.

i would use the novak 6v regulator if i was running non lipo servos. the novak regulator is tiny and weighs about 10 grams.
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Old 03-23-2012, 11:59 AM   #7
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Thanks for the info guys. Since this is going in a touring car, the one issue as always is space. I wonder how to cram the lipo and regulator under the top plate and in the radio box on my MTX4 (which doesn't have much room to begin with). Of course, if the servos are replaced, the regulator becomes a non factor. I DO need to replace the servos in my Savage, though, so that may be something to consider (with the foam, of course)

For the LiFe packs, yo do or do not need that regulator? Those are 6.6v if I remember correctly. Since a fully charged NiMh pack usually peaks over 6v anyway, I'd think they would be OK, but I rather be safe than sorry. Also, what kind of size do those come in? I've got a 5 cell aaa pack that needs replacing, but that's another car and another day.

In the end I may end up with a regular 5 cell NiMh, but it's good to know what options I have
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Old 03-23-2012, 12:33 PM   #8
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LiFe is succesfully used without regulators. When running 2.4GHz you can also go with HV servo's so no regulator is needed.

If you do not want a regulator to put away you can also think of 2 or 3 simple diodes with LiPo or just 1 with LiFe. The well known 1N5402 is a simple cheap 3 amp diode.
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