Go Back   RCCrawler Forums > RCCrawler General Tech > Electronics
Loading

Notices

Thread: School me on batteries

Reply
 
LinkBack Thread Tools Display Modes
Old 08-20-2012, 10:59 AM   #1
Quarry Creeper
 
Join Date: Jun 2012
Location: Vancouver, WA
Posts: 223
Default School me on batteries

I have a 2200mah / 20c 3s lipo running a brushless hobbies LT4 ESC and Tekin Pro4. I am seeing delays when pulling on the throttle forward and reverse. I am needing a higher C rating battery?

Is comparing a C rating on a battery to torque and the mah rating as the horsepower a safe bet?
t3yf5g is offline   Reply With Quote
Sponsored Links
Old 08-20-2012, 11:39 AM   #2
Rock Stacker
 
Join Date: May 2010
Location: Boise
Posts: 68
Default Re: School me on batteries

Depending on which Pro4 you're running, that is way underpowered. MAh is capacity, and C is current. C is multiplied by amp hours to determine safe recommended current load. 2200 MAh is 2.2 amp hours (move the decimal over three spots.) So 20c 2200MAh is capable of 44 amps load.

I haven't had much luck finding the actual watt rating of the Pro 4's but using the SC4x specs, assuming the 4.5=4600, 5.5=4000, and 6.5=3300...

4.5T=900w
5.5T=815w
6.5T=745w

Amps are watts divided by volts. As volts go down, amps go up, so I'll use 3.8v/cell as the nominal. So...

4.5T on 2S = 900/7.6=118 amps
5.5T on 2s = 815/7.6=107 amps
6.5T on 2s = 745/7.6=98 amps
6.5T on 3s = 745/11.4= 65 amps

That being said, I think the Pro4's pull more juice than the SC4x motors. If you want to stick with 3s 2200mah, I'd look for a minimum of 40c, for 88amp capability. The higher the better. If you go higher in capacity, you could get by with a lower C - i.e. 4400mah 20c also = 88amps.

Think of the C rating as the carburetor CFM. If you're trying to power a big block 454 with a 650 CFM carb, it's not going to be happy. And mah is the size of the gas tank.

***Edit*** Well, having too high of a CFM on a carb can cause problems too... Not so on C rating. You could run a 100C battery with a 10 amp load. Only downside is increased size/weight due to the heavier duty cells and wiring.

Last edited by tocsin; 08-20-2012 at 11:45 AM.
tocsin is offline   Reply With Quote
Old 08-20-2012, 11:47 AM   #3
owner, Holmes Hobbies LLC
 
JohnRobHolmes's Avatar
 
Join Date: Nov 2004
Location: Volt up! Gear down!
Posts: 20,290
Default Re: School me on batteries

Great reply tocsin, I would also say the battery is under rated for best performance. going forwards to backwards is the hardest you can hammer on a system.
JohnRobHolmes is offline   Reply With Quote
Old 08-20-2012, 01:31 PM   #4
Quarry Creeper
 
Join Date: Jun 2012
Location: Vancouver, WA
Posts: 223
Default Re: School me on batteries

Okay, that does make a lot of sense. I don't want a massive pack I have to figure where mount but still want some decent run time out of it.

At least it had enough juice to twist my front driveshaft I will be shopping for a battery as well.
t3yf5g is offline   Reply With Quote
Reply



School me on batteries - Similar Threads
Thread Thread Starter Forum Replies Last Post
School of Doom - School Made Video Trailer LR3 Chit Chat 8 09-24-2010 09:26 AM
school me on lipo batteries Mongo63 Newbie General 18 12-14-2009 03:10 AM
old school/new school chevy mud bogger josh hayes 1.9 Scale Rigs 0 10-01-2009 05:22 PM
School me on batteries and heat Philistine Electronics 5 03-01-2008 06:43 AM
Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On
Trackbacks are On
Pingbacks are On
Refbacks are On



All times are GMT -6. The time now is 01:45 PM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2024, vBulletin Solutions, Inc.
Content Relevant URLs by vBSEO ©2011, Crawlability, Inc.
Copyright 2004-2014 RCCrawler.com