R/C Tech Forums

Go Back   R/C Tech Forums > General Forums > Electric On-Road

Thread Tools Search this Thread
Old 06-15-2005, 08:56 PM   #61
Tech Adept
FaiLip's Avatar
Join Date: May 2005
Location: New Zealand
Posts: 133

Originally Posted by loopedeloop
You gotta agree wit this guy (hick)

It seems plain ridiculous to me to spend NZD$130.00 for a Matched pack for my kids when a maxamps pack x 2 only cost $112.00 shipped to NZ.

One of the fastest guys n my club uses unmatched GP3300 stick packs and is very hard to beat.

Sometimes megabuck packs are simply not necessary, and the majority of club racers wouldnt even notice the diff between the two.(my opinion)

(hunching down waiting to get flamed )
Agree and Disagree.

This year at the New Zealand National, the Top 5 guys were all running Matched pack. All of these guys have at least one 18 laps race. I was there and I don't think I was that much slower. With my non matched pack, I made the only 18laps other than those 5 guys. However I don't blame my battery, If I have more tyres (foam), I would have more 18 laps race, so for me even with Matched pack I don't think I could have done any better.

However I do realise the different of matched and unmatched pack at the end of the race, with a minute to go, my car was always the slower than the rest of them. I reckon that's the only different I can tell, maybe I am just not as good as those guys that won the race to tell the difference. But if I have money, I will be going for Fusion or Promatch
FaiLip is offline   Reply With Quote
Old 06-15-2005, 10:47 PM   #62
Tech Adept
Hick's Avatar
Join Date: Jun 2005
Location: Purgatory, AZ
Posts: 132

Great batteries, Promatch, World Class, and Fusion, I have run them myself.

Though not conclusive, I have found that lets me know how my battery performs under a load is to do a static test.

You need a string of discharge bulbs, 20A to 30A, your choice.
A multi-meter of your choice (with a good battery in it)
A stop watch.
Pencil and paper.

Connect the discharge bulbs to a fully charged battery, I have an Auto-Cut off.

Then attach the multi-meter on the end of the discharge bulbs. (I have a pig-tail on mine with a Deans Plug, I stuff my multi-meter probes in the slots).

At the same time, press the button on the Auto-cut off to activate the bulbs and start the stop watch.

Record the voltage at 15 second increments on the paper.

You can use graph paper to chart these readings or get fancy and put them on a spread sheet.

All this will give a visual representation of what your battery is capable of doing at a specific time. Establishes a baseline to check your batteries performance against some time in the future. Also allows for comparison between batteries.

Your graph will indicate a heck of a lot of power at 0 to 15 (varies) dropping off rapidly between the 1st and 2nd minute (varies) and "levels" with a slow declining line to the 4-5 minute mark. At the end of run-time the battery will fall off rapidly again. I am only concerned how the battery performs for 4 1/2 minutes. At the end of 4 minutes my cheap battery packs are putting out 7.2 volts.

You then can visualize the rest, or actually see how it performs on the track. Again this is not conclusive, due to the variable loads on a motor during a race. But I find, it is a good place to start and helps be determine when to retire the pack and get a new one.

You can attach the multi-meter probes to the battery, the voltages will be slightly different, but the graph will be the same. I have found that for every tenth of voltage drop you loose 500+ rpm. But always do your testing the same way.

Lastly, you could be overgearing your motor and getting it toooooo hot! Heat plays hell on any electrics. Causes an increase in resistance, which ain't good! Be aware of compound resistance tolerances, hot battery, hot ESC, and a hot motor, equals more resistance.

Last edited by Hick; 06-15-2005 at 10:59 PM.
Hick is offline   Reply With Quote
Old 06-16-2005, 06:16 AM   #63
Tech Champion
Join Date: Jun 2004
Location: St Louis
Posts: 7,868
Trader Rating: 198 (100%+)

Hick I understand your test but. You are not using constant amps with the bulbs. With Ohms Law if voltage decreases (as what happens when discharging) and resistance stays the same current flow will decrease. That is whty you will see 7.2 volts at 41/2 minute. You need a discharger that can change the resistance as your voltage drops to maintain 20 or 30 amps.
dodgeguy is offline   Reply With Quote
Old 06-16-2005, 09:48 AM   #64
Tech Master
Join Date: Apr 2003
Posts: 1,141
Trader Rating: 32 (100%+)

cba tester is good, but limited on total power.
gulio is offline   Reply With Quote
Old 06-16-2005, 09:58 AM   #65
Tech Adept
Hick's Avatar
Join Date: Jun 2005
Location: Purgatory, AZ
Posts: 132

You actually have decreasing voltage and increasing resistance. Heat of the bulbs and internal battery resistance as it heats up.

Like I said, this is not a conclusive test. This is what I came up with. Check out a battery this way, recharge it an put it on the track to test. Even though new varibles are introduce, you know what to expect from the battery.

Being the tight-wad I am. I didn't have to buy anything, it was stuff I had around the house. It does give one insight to his batteries performance.

Last edited by Hick; 06-16-2005 at 10:27 AM.
Hick is offline   Reply With Quote

Similar Threads
Thread Thread Starter Forum Replies Last Post
WTB: Matched 6C 3300s and up!!!!!!!!!! tenC R/C Items: Wanted to Buy 9 05-07-2006 09:23 PM
6 CELL 3300S impdog R/C Items: For Sale/Trade 0 01-30-2006 03:35 PM
gp 3300s impdog R/C Items: For Sale/Trade 2 01-23-2006 04:16 PM
Matched SMC 3300s Almost new! f2000racer R/C Items: For Sale/Trade 3 02-26-2005 05:27 PM
3300s now 2800s warlord385 Electric On-Road 25 05-01-2003 03:26 PM

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
Thread Tools Search this Thread
Search this Thread:

Advanced Search

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 Off
Trackbacks are On
Pingbacks are On
Refbacks are Off

All times are GMT -7. It is currently 12:56 PM.

Powered By: vBulletin v3.9.2.1
Privacy Policy | Terms of Use | Advertise Content © 2001-2011 RCTech.net