R/C Tech Forums

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

Reply
 
Thread Tools Search this Thread
Old 12-04-2007, 04:06 PM   #241
Tech Elite
 
Join Date: Jun 2005
Posts: 2,570
Trader Rating: 26 (96%+)
Default

It will be too light, but you can stick weights w/ a lower cg in various places in the chasis. This will allow you to run a better handling truck.
party_wagon is offline   Reply With Quote
Old 12-04-2007, 04:38 PM   #242
Tech Addict
 
swopemike's Avatar
 
Join Date: Jun 2006
Posts: 526
Trader Rating: 6 (100%+)
Default

Quote:
Originally Posted by Craps View Post
Our new indoor track has a stock truck class with 6 minute quals and 7 minute mains. I am using a 4000 mah li-po even though I have several spare 8000 mah li-pos, for the reason I want the lighter weight advantage over the voltage advantage the 8000 will have at 7 minutes that I feel will not make that much difference power wise. Voltage/more power or superior handling with weight reduction.....I go with the lighter weight on the stock truck. They're is a real example right there.

Good luck!
Air8, I think the above explanation is a very good one and puts it in relative perspective.

Truck is very much about driving and handling way more than absolute power....

Then again, I also enjoy absolute power It's something to take triples from oh, say, a 20 foot run-up. And then have so much torque from throttle and brakes that you can correct your mistakes in the air. I think that's one of the best parts.

So nobody has tried a 3.5 ? I'm hearing people say 5.5 to 6.5 is ideal. Having driven the 4.5 and a 13.5 it's hard to imagine having less power. Then again maybe it would be nice not to have to run a locked clutch and diff and maybe my spur gears would last longer not to mention the occasional cracked motor mount from a missed quad attempt. That was the last time I ran offroad last year. Glad I had a spare on hand that was fun changing the chassis out before the main.
swopemike is offline   Reply With Quote
Old 12-04-2007, 07:02 PM   #243
Tech Champion
 
air8's Avatar
 
Join Date: Apr 2007
Location: Hutch, KS
Posts: 5,748
Trader Rating: 7 (100%+)
Default

Ok guys I appreciate the comments. My main goal here was to determine if there was a noticeable difference between the Mah of the Lip batteries. Through you guys I see there won't be much difference. Thanx again.
__________________
--Driver...you are cleared into the track.....Smoke On.

--"U Ain't Fast!!"
Chris Pearce
air8 is offline   Reply With Quote
Old 12-06-2007, 12:15 PM   #244
Tech Master
 
Join Date: Sep 2007
Posts: 1,299
Trader Rating: 20 (100%+)
Default

I have run both batteries and lap times were the same.
xxxtruck is offline   Reply With Quote
Old 12-14-2007, 03:33 PM   #245
Tech Addict
 
swopemike's Avatar
 
Join Date: Jun 2006
Posts: 526
Trader Rating: 6 (100%+)
Default

If I buy a 3,000 or 4,000 mAh pack now for short heats and races, can I later wire them in parallel to get 6,000, 8,000 or 12,000, etc. packs ? What I mean is, are there any issues with balance when using that many cells? I understand series vs parallel wiring and all, just wondering if I'm missing anything else practically speaking.

Do you only balance the cells in series against each other or is it every cell in series or parallel against every other cell ? I'm assuming it's just all parallel cells in one series against all the others (for 2s packs).

Do you need to balance cells every charge or just periodically ? I don't have a balancer, but I have an ice charger. Can I just occasionally recharge the (parallel) cells individually so they are both fully charged separately?

Running multiple packs in parallel would be for low turn BL truck racing at high loads and/or long mains... the worst case scenario is a heavily weighted truck on a large (1/8 scale) oval track where amp loads can be very high, 80 or more continous average over a race. I want to be sure I don't make a flaming fireball out of my T3 by over-discharging one cell.
swopemike is offline   Reply With Quote
Old 12-14-2007, 07:17 PM   #246
Tech Elite
 
Join Date: Jun 2005
Posts: 2,570
Trader Rating: 26 (96%+)
Default

Yeah, you can wire them up in parallel. At the ready race there were actually orion racers wiring up two of their carbon packs in parallel to run the 20 minute mains. How often you need to balance the cells all depends on the quality of the cells. However, your post has a is going to contradict what I am fixing to say. I am going to guess that you are on a budget since you are running a t3 and looking to run a small lipo pack. You must make sure that your lipo is capable of discharging the needed amount of current & this is the c rating times the ah. A 3ah pack would need a 30c discharge rating to discharge at 30 amps, however a 10c 8kmah pack would discharge at about the same rate. Just be careful in purchasing your lipos & make sure they can handle the discharge load if you go with a smaller pack. I personally run a 2s 3p a123 pack in my xxx-t that I built from a dewalt 36volt pack.
party_wagon is offline   Reply With Quote
Old 12-14-2007, 11:08 PM   #247
Tech Elite
 
glassdoctor's Avatar
 
Join Date: Aug 2006
Posts: 2,250
Trader Rating: 4 (100%+)
Default

pw meant to say 3000mah would need to be 30c to do 90amps.

hey guess what pw? I have some A123 cells to play with now. Picked up a dewalt pack and plan to try a 4s2p and 5s2p in a 1/8th
glassdoctor is offline   Reply With Quote
Old 12-15-2007, 10:48 AM   #248
Tech Elite
 
Join Date: Jun 2005
Posts: 2,570
Trader Rating: 26 (96%+)
Default

I would run the 5s 2p pack w/ a milder motor, it will give you more run time. power equals amps*volts=watts. I believe that a system delivering power in the 700-800 watt range is the most idealistic power for this class because it is the closest to a .21 nitro. However it will still have lots more bottom end. A motor drawing 100 amps @ 7 volts w/ a 8kmah 7 volt pack will have the same power & run time as a motor drawing 50 amps @14 volts w/ a 4kmah 14volt pack.
party_wagon is offline   Reply With Quote
Old 12-15-2007, 12:32 PM   #249
Tech Addict
 
swopemike's Avatar
 
Join Date: Jun 2006
Posts: 526
Trader Rating: 6 (100%+)
Default

Quote:
Originally Posted by party_wagon View Post
Yeah, you can wire them up in parallel. At the ready race there were actually orion racers wiring up two of their carbon packs in parallel to run the 20 minute mains. How often you need to balance the cells all depends on the quality of the cells. However, your post has a is going to contradict what I am fixing to say. I am going to guess that you are on a budget since you are running a t3 and looking to run a small lipo pack. You must make sure that your lipo is capable of discharging the needed amount of current & this is the c rating times the ah. A 3ah pack would need a 30c discharge rating to discharge at 30 amps, however a 10c 8kmah pack would discharge at about the same rate. Just be careful in purchasing your lipos & make sure they can handle the discharge load if you go with a smaller pack. I personally run a 2s 3p a123 pack in my xxx-t that I built from a dewalt 36volt pack.
re: budget, yeah I've sold my touring car stuff and looking at going back to only dirt racing occasionally. Between family, house etc. just not going to spend the $$$ and time I have in the past. The T3 seems to do fine locally; it's ~2000 vintage FT with steel diffs and rpm parts. (although the upgrades people mentioned to make it even tougher sound like a good idea too). I didn't want to drop $155 for a maxamps 8000 when most of the indoor racing is not 20 minute mains... thought I would buy 1/2 the capacity now, then in summer just buy another pack and solder in parallel for the long dirt oval mains (75-100 laps).

Which DeWalt pack is that and what kind of mAh and runtime do you get, with which motor/esc combo (I have Novak) and what kind/size track ? How much do these cells weigh ? Where did you get that particular pack (Lowe's ?). Maybe that is my "cheapo" hobby option to play around with especially running a 3.5 to make up for lower starting voltage.

I assume as long as I'm not averaging over 20c (really probably want to stay below ~70% of that, maybe 15c for the average) I'll be OK. I have measured avg amps by mAh put back in after a heat, and the time of the heat... this is actually overstated (conservative) because maybe 10% of the mAH put in by the charger is lost as heat, so I figure it's good for an estimate of average amps. I do understand the xC discharge concept. I was just wanting to know if folks have actually tried this, and did they have any unusual problems I haven't considered. The fact that they are running 2 carbon 3300 packs (and somebody mentioned some running 2 4800 packs) makes me feel better about it. But I was going to get the maxamps packs, so I didn't know if they had more issues with balancing, and if they needed to be balanced every charge or not, and if you can balance them by charging the each set of series cells (one charge using 1 cell LIPO setup on Ice, then repeat on the other series cells).

I don't think it's any more complicated than the above, but just trying to confirm from someone who's actually done this, before I sink $$$ into something.
swopemike is offline   Reply With Quote
Old 12-15-2007, 01:36 PM   #250
Tech Elite
 
Join Date: Jun 2005
Posts: 2,570
Trader Rating: 26 (96%+)
Default

The a123 cells are 2300mah 3.3 volt cells. You can purchase a 10 cell (36 volt pack) off of ebay for around $100. My pack weighs around 450 grams w/ the wiring. I like it because I have wired up a wiring harness to run the pack in parallel and charge them in series so I can actually charge the 6900mah 6.6 volt pack as a 6s 2300mah pack in 15 minutes instead of 45 minutes. If you are running dirt oval then the stock ft t3 should work great. If you are running only oval then I would dremel out a side of your battery slot and run the truerc.net 8kmah 10c 7.4volt lipo over against the inner side of your chasis. They sale for like $90 shipped w/ all the plugs. If your also running off road then you can leave your chasis as is and use foam to keep the pack standing up on its side because it will be too wide for the battery slot laying down. If your running regular off road then don't dremel out the side of the battery slot. The maxamps 4kmah pack would also be a good choice if you don't plan on running longer mains. You could actually get two of the truerc packs and run them standing on their side in your battery slot w/ 16kmah which would give you tons of run time.
party_wagon is offline   Reply With Quote
Old 12-20-2007, 03:03 PM   #251
Tech Elite
 
Join Date: Jun 2005
Posts: 2,570
Trader Rating: 26 (96%+)
Default

Has any one been running the 1/8th scale buggies on the same race day as these trucks? I would think they would compliment each other and both allow for maintanance free 20+ minute mains.
party_wagon is offline   Reply With Quote
Old 12-27-2007, 06:49 PM   #252
Tech Champion
 
air8's Avatar
 
Join Date: Apr 2007
Location: Hutch, KS
Posts: 5,748
Trader Rating: 7 (100%+)
Default

If I were to use a quality lipo, should I be concerned without balancing? Say I was using a battery with the Enerland cells, would I need to balance the battery once a month....once a week....or don't worry about it?

Thanx
__________________
--Driver...you are cleared into the track.....Smoke On.

--"U Ain't Fast!!"
Chris Pearce
air8 is offline   Reply With Quote
Old 12-27-2007, 07:44 PM   #253
Tech Master
 
Join Date: Feb 2007
Location: Mt. Holly, NC
Posts: 1,181
Default

Hook the balancer up everytime you charge!
Craps is offline   Reply With Quote
Old 12-27-2007, 08:38 PM   #254
Tech Addict
 
scott54's Avatar
 
Join Date: Jun 2007
Posts: 693
Trader Rating: 5 (100%+)
Default

I might run the Outlaw Truck race at CRCRC in a couple weeks. But all I have are Orion 4800's. So obviously I need to get another pack. I have a XXXT-CR so I have a little wider battery tray than the MF2's and MF1's and I'm running a 6.5. What lipo should I pick up for this class to race 20 minutes?
__________________
TLR Racing - ARCS Speedway - B-Fast Racing - Dialed RC - G-Force
scott54 is offline   Reply With Quote
Old 12-27-2007, 08:59 PM   #255
Tech Master
 
Join Date: Sep 2007
Posts: 1,299
Trader Rating: 20 (100%+)
Default

8000mah will do it no problem.
xxxtruck is offline   Reply With Quote
Reply

Similar Threads
Thread Thread Starter Forum Replies Last Post
Slash Class and Losi Desert Truck Class Races bigmanrc Georgia Racing 22 09-22-2008 06:05 PM
FastCats' WinterBlast - Indoor - A-Main Offroad Truck Video Hyper 7 Canadian R/C Scene 0 03-23-2008 10:45 AM
TRAVER MULLENS WINS INT. ARENA TRUCK A MAIN AT PRO SERIES FINALS porter Kansas/Missouri Racing 23 11-24-2007 12:18 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 02:45 AM.


We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.
Powered By: vBulletin v3.9.2.1
Privacy Policy | Terms of Use | Advertise Content © 2001-2011 RCTech.net