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08-26-2008, 07:38 AM
| #1 |
| RCC Addict Join Date: Nov 2007 Location: Nine Mile Falls, WA
Posts: 1,229
|  Berg axles 2 motors and yes you need a bigger battery than what you normally use!!!
Hey guys, In recent weeks it has come to my attention that many of you are trying to run small packs with your Berg set-ups. STOP using them, two motors on a small pack will kill it. You need to remember that your doubling the amp draw with two motors. Now if your running say two 55T motors a 20C 3S 2100 should work fine. But if you step up to say a pair of 35T motors then I would suggest a 3S 25C 2200 pack. Now these packs are bigger but what's nice about the Berg units is that you have a wide open chassis to work with, meaning you can lay the battery right on the skid to help keep the weight down low. If you have any questions just ask. Jason |
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08-26-2008, 07:50 AM
| #2 |
| I wanna be Dave  Join Date: Jan 2004 Location: Detroit
Posts: 3,583
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At 7.2 volts I show a 55T motor only needing .6 amps to spin. Under load it only goes to about 1amp. I'll be running 1345mah 20C with 26.9 amps on my 11.1 pack. My 1345 is 18C with 24.2 amps for my 7.4 pack. I'd like to know WHY I need so many amps. Maybe JRH will step in and post some insight...he is the motor man. Last edited by binaryterror; 08-26-2008 at 08:01 AM. |
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08-26-2008, 08:06 AM
| #3 |
| I wanna be Dave Join Date: Oct 2005 Location: Columbia TN
Posts: 6,154
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Now who the heck is dumb enough to run t 35't with an 1100 pack.......  |
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08-26-2008, 08:08 AM
| #4 |
| RCC Addict Join Date: Nov 2007 Location: Nine Mile Falls, WA
Posts: 1,229
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Normal driving around is very easy on a pack very little resistance. Now take that rig and either bind it up in a crack or get it set on a ledge where the tires are grabbing then slipping and so on that load will create high amp draw and higher spikes. 55T lathe motors can spike high and a good li-po will take short bursts with no problems. But as I said your now doubling that amount with two motors. Jason |
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08-26-2008, 08:13 AM
| #5 | |
| RCC Addict Join Date: Nov 2007 Location: Nine Mile Falls, WA
Posts: 1,229
| Quote:
Funny you metioned that................  | |
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08-26-2008, 08:15 AM
| #6 |
| I wanna be Dave Join Date: Oct 2005 Location: Columbia TN
Posts: 6,154
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As cool as flames shooting out of a battery are, I recomend that you listen to Jason on this one. I will get my eyebrows back soon I hope....
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08-26-2008, 08:16 AM
| #7 |
| I wanna be Dave  Join Date: Dec 2005 Location: Happiness is a warm AK.
Posts: 12,563
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I told you guys!  |
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08-26-2008, 08:28 AM
| #8 |
| owner, Holmes Hobbies LLC   Join Date: Nov 2004 Location: Volt up! Gear down!
Posts: 20,290
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tIt does depend on whether the motor is a cheapo Integy or a fatty Handwound motor too. Integy 55t motors will smoke around 30 amps, and typically you won't stall out more than one motor at a time (wedged front). However to be safe I always recommend a battery that covers a near dead stall situation for a vehicle (but this assumes the vehicle is under control by the driver). Jason has covered the packs that he recommends for use, and I agree with him. I have made recommendations on packs that I carry as well here Lipo for your Crawler! I would get more in depth on the subject here, but I am saving up a lot of data and general recommendations for an upcoming article in the RC Driver Crawler edition. Three pages of me ranting about electronics! Sweet! |
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08-26-2008, 08:30 AM
| #9 |
| RCC Addict Join Date: Aug 2005 Location: VARCOR
Posts: 1,826
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With 35Ts, and a 20C 3S 2100, I only got about 15-20 minutes runtime (comp type running). With 45Ts, I can usually run 45min+. Thanks for the tip Jason. I will be replacing my batts soon, and will remember to try to stick to 25C. |
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08-26-2008, 08:34 AM
| #10 | |
| support@rc4wd.com   Join Date: Nov 2007 Location: Lancaster, Ohio
Posts: 1,417
| Quote:
 Thanks JRH . Very helpful thread Jason!
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08-26-2008, 08:35 AM
| #11 |
| owner, Holmes Hobbies LLC Join Date: Nov 2004 Location: Volt up! Gear down!
Posts: 20,290
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With a single Cobalt Puller I have wasted as much as 1300mah in merely 5 minutes at a comp. Good thing it was a 25C 2600 pack. It really depends on the terrain and driver a lot. I could do the same with a 35t.
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08-26-2008, 08:39 AM
| #12 |
| RCC Addict Join Date: Nov 2007 Location: Nine Mile Falls, WA
Posts: 1,229
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Robb you bring another good point into this. Runtime. All summer long I have been running 55t Lathe with a 3S 1100 and I can run one pack all day at a comp. ( I usually have a spare in my pocket) I can gennerally run that pack for a solid 30 minutes with no issues. But now take that same pack capacity even if it was say a 25C pack and your looking at about a 15 minute run time because you doubled the load. So that its self is another reason for the bigger packs. You'll get your runtime back up to the level you were at before. Jason |
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08-26-2008, 08:44 AM
| #13 | |
| RCC Addict Join Date: Nov 2007 Location: Nine Mile Falls, WA
Posts: 1,229
| Quote:
And we've seen what a 27T will spike at in a crawler as well. I think it was 80 amps geared at 24/87 if I remember correctly. Guys with the bergs the days of small packs mounted on the front axles is over they simply in most cases will require larger packs for the power consumption they have. Jason | |
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08-26-2008, 08:49 AM
| #14 |
| '08 2.2 National Champ  Join Date: Nov 2006 Location: UTRCRC
Posts: 5,585
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I'm sure I'm just missing it but I have never seen a 2200 25c pack on Maxamps.com. Could you give the link?
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08-26-2008, 08:51 AM
| #15 | |
| owner, Holmes Hobbies LLC Join Date: Nov 2004 Location: Volt up! Gear down!
Posts: 20,290
| Quote:
Right. Personally I don't think that axle mounted lipos are a good idea unless it is just a 55t machine wound. Everything else is just too power hungry for the space available. | |
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08-26-2008, 08:54 AM
| #16 | |
| RCC Addict Join Date: Nov 2007 Location: Nine Mile Falls, WA
Posts: 1,229
| Quote:
Jason | |
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08-26-2008, 08:55 AM
| #17 | |
| '08 2.2 National Champ Join Date: Nov 2006 Location: UTRCRC
Posts: 5,585
| Quote:
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08-26-2008, 08:55 AM
| #18 |
| Moderator Rule Breaker  Join Date: Feb 2004 Location: Austin, Tx
Posts: 5,970
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When you say a small pack, what is a small pack ? I thought mah= run time, the bigger mah the longer run time you will get. The C and burst rate is what I though a person should be looking at? |
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08-26-2008, 08:56 AM
| #19 | |
| RCC Addict Join Date: Nov 2007 Location: Nine Mile Falls, WA
Posts: 1,229
| Quote:
That's why I like the hung behind the Axle low COG battery tray on my GC2 Chassis. I can hang a 3S 1100 up to a 3S 2200 on that tray. Jason | |
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08-26-2008, 09:13 AM
| #20 |
| Say hello to my dactylion  Join Date: Jun 2004 Location: On the Boat to Whore Island
Posts: 4,470
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That probably explains why one of my 1550HV packs is starting to drop a bit in performance. Thanks for the information Jason.
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