Sorry to keep rehashing the same subject. But I just want to get this straight. Can you guys can please confirm.
I have a stock E Revo Brushed with 2 550 Titans
Looking to have more runtime. Already have 7 cell 8.4 volt 5000mah Nimh only getting about 15min runtime. I don't race. Just for bashing around.
I am looking to move into Lipo
Went to LHS. They basically said Lipo was fine with the stock EVX-2 ESC. As long as the voltage of the packs was no more than 7.2 or 8.4. and that I should run a LVC. Said if I wanted more runtime look for Lipo with more "Mah". So I asked them if I could run "SMC 9000mAh/28C, 7.4V, Soft Case Lipo" with the idea that I am still only putting 7.4volts through the ESC. You guys have lots of experience experimenting with different setups. Would this work without killing my ESC?
Yes those will work fine. You will get long runtimes, and your system will never be wanting for power.
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Perfect! I figured if I was going to move to Lipo it would make more sense to buy a big pack (if it worked) that I could also use when I switch to brushless. Now I just need to get a LVC.
Those big packs are going to add some weight to the truck. If you want to stay with a brushed setup, take a look at swapping the twin Titan 550 motors for a Titan 775. They are great motors, plug right in, and they are used on the Summit so it is basically a drop in with the rest of the truck and ESC. It should give more torque than the 550s, which will more than make up for the increase in weight.
Thanks Cainam wasn't even thinking about the weight. I was just trying to get the runtime higher. Would the 9000 Lipos weigh more than the 7cell Nimhs?
They say a good rule of thumb is that a LiPo pack weighs half as much an NiMH pack of the same capacity and voltage...
...so a 7.4v 9000mAh LiPo *should* weigh less than an 8.4v 5000mAh NiMH.
Project: BL Revo Race Quad & BL G-Maxx G3R CF Revo
I would definitely recommend changing out your motor. I fry the 550's when I use a good 7 cell pack, and I'm suspicious that a high capacity Lipo would be even worse, unless you never drive in grass and take the time to check motor temps throughout the run. I don't have the patience for that.
My 550's are still working fine. I mostly run my E Revo in a dirt construction site and a school yard. So I'm trying to make upgrades that won't be redundant if/when I move to Brushless. Might look at moving to a 775 if my 550's pack it in really soon. As my next purchase are Lipo's and a charger. There is a lot of cost right there. Unfortunately my kids have drained my money tree. I might have to wait to purchase the MMM conversion till I get enough funds together. The 775 might be a cheaper interim upgrade. Is the single motor plate that is needed for the MMM conversion the same one for the 775?
Last edited by Cooleguana; 05-17-2009 at 08:46 AM.
It isn't the voltage of high capacity LiPo's that kills the stock Titan motors, it's the runtimes. If you don't stop and check the motor heat, the motors will die in just 1 to 2 runs.Originally Posted by msmst25
Sometimes. . . Sometimes not. The first set of the 550s I had melted the copper brush holders less than 3 minutes into a run. That wasn't enough time to build up much heat. That was on hard packed dirt, and only running 2X6 cell packs.Originally Posted by Jakey
Assuming your motor did not fail as a result of assembly error or material issues, then I stand by what I wrote in my earlier post.
I won't say it wasn't an assembly problem, but it was both motors. It wasn't slow down a bit, keep running anyway, and then it stopped. It was running fine, then it almost flipped over foreward from full speed, and BOTH motors were locked up. This was maybe the 5th run. I wasn't that upset - it was a good excuse to go with brushless, anyway.Originally Posted by Jakey
Jakey so your saying that my quest for longer runtime with the 550's might end up killing them? They are not meant to be run for longer times then the standard 5000nimh will run them? I guess it also depends on the conditions their run in too (deep grass, etc.) I currently don't have a temp gauge. But so far with the 7cellnihms the motors don't seem to be scorching hot.