It was a hard decision

[jnev]

It was a hard choice, but I finally decided to not buy the CRT.5 and just finish the original project I started... the buggy (Xterminator). I just need to ask a few final questions before I sell my unneeded parts, old charger, batteries, etc and buy my new needed parts.

1) First, I was wondering what the difference between the 5mm bore 32 pitch pinion gear and the 5mm bore mod1 pitch pinion gear. I was planning on getting one of them as an 18t gear, but then I realized that the mod1 pinion is $18 and the 32 pitch one is $12. What is the difference between them and which is recommended for me? I am running a 46t kyosho spur by the way if that helps.

2) I am a little unsure about two of the Max Amps batteries. I was originally going to get the 4s2p 8000 pack, but the price went up from before. And now I am looking at the 10,000 4s pack and the price is way less than the 8000 pack... I'm still learning about lipo batteries so if you can help that would be great. Here are the two link to both batteries:
http://www.maxamps.com/proddetail.ph...-8000-148-Pack
http://www.maxamps.com/proddetail.ph...10000-148-Pack
I also saw the 8400 and 9000 packs, but have never see anyone use them. If you can recommend me one of these 4 packs, that would be great. I am just looking for very long run time...

BTW - I will be running the MM esc and an 8xl motor with the rc-monster heatsink with a ubec on 4s lipo.

Thanks.

[BrianG]

1) Mod1 and 32 pitch are different pitches. There are more teeth per inch in a 32p gear. The Kyosho spur is Mod1, so you need to get Mod1 pinions. Next time you are at your LHS, put a 32p and Mod1 side by side and you can tell the difference right away. If they carry Traxxas parts, put a Revo spur (Mod1) and Jato spur (32p) side by side.

2) As long as you have the discharge current rating you need, you can use any lipo cell you want really. It usually comes down to what physically fits. The 8Ah packs are made with 4Ah cells in 2p config. So, a 4s 10Ah pack only has 4 cells, while the 4s2p 8Ah pack has 8 cells, which is probably why the 8Ah packs cost more.

[Patrick]

The less cells you have the less chance there is of them going out of balance isn't there?
To me the 10 000mah pack sounds the best, if you have room for it and don't mind the extra 100grams.
Though 100grams could add a bit more heat if your running it for that long.

[BrianG]

That is true. If they will fit, the 10Ah pack will have a little longer runtime and thinner package since it only needs a 1p arrangement.

[jnev]

Thanks for the replies guys. I will buy the mod1 18t pinion and then probably buy the Max Amps 10Ah pack. It may not fit my battery case right away, but a little modifying won't hurt. :)

I am almost positive the superbrain 989 will be able to charge this battery.

Thanks again for the help guys. I'll keep you all updated with the buggy.

[Patrick]

Will an 18t pinion be a bit overgeared? It should be ok for speed runs, but if your going to use 10000mah, that's along time to be running.
The MM and/or 8xl might get a bit hot after running that long on a high gearing.
I could be wrong and it might work ok, but if it was me I would try it on a smaller pinion first (maybe 15 or 16) to see how that goes and then gear up later if temps seem ok.

[jnev]

Thanks for the info. Since this is more of a basher buggy than a racer, I was hoping to have a little more speed. But I guess I could just order two pinions and see which works better... speed wise and temp wise.

That 10Ah pack is going to be BIG. IIRC, there is more than half an inch difference between the 10Ah packs and the 8Ah packs in width. If you already have battery trays, it's probably going to take a bit more than a "little" modification to make them fit. The 10Ah packs are also about .7" longer than the 8Ah packs. That's a lot of space to try to find on a buggy chassis.

You also have to remember that the battery has to fit under the body. If you are only going to be bashing, I'd go with the 4S 5000mAh packs and run the MM/8XL on a 14/46 gearing (but no higher than 16/46). You should get lots of trouble free running with that setup. It's what I settled on with my buggy.

I'd also stay away from the maxamps 6Ah packs. Unless the copper tab cells are a significant improvement over the older cells, they won't deliver nearly the current they are rated for. All of mine self destructed with the same setup that you are talking about running.

[jnev]

Oh, wow, I didn't realize that the 10Ah pack was that much bigger. I do need decent run time, so I will probably go with the 8000 pack then, since I will only have 1 battery to run at the beginning. Then maybe later, add the 5000 pack.

As for gearing, I think I will try a 16t pinion instead of the 18t and just watch the temperatures. From your experience with this set up, does it run really hot? Even with a heatsink on the motor and the original heatsink on the MM esc?

Also, what kind of run times are you getting approximately with the 5000 pack for comparison on the track, bashing or anything?

Thanks again for the help.

Before you get the 8000 pack, just make sure that it will fit under the body with the battery trays that you are using. Even the 8K pack is pretty big. What you should really do is make up some mock battery packs with cardboard and make sure that they will fit. Running 16/46 with the 8XL and the MM, the 8XL got hot. On occassion, it was too hot to touch. IIRC, 180s or so. The Feigao motors are great for the money, but they are inefficient. They are going to get hot. It just takes longer.

I mentioned the 5K packs because you said something about the maxamps packs. I run the Kokam 4800 packs and all I can say is that I get at least 15 to 20 minutes out of them (running 14/46 gearing). Since I run with nitro guys, I just change batts when they shut down to refuel and lets their engines rest. The batts are about depleted by then anyway. I've just never had the LVC cut out on me, but it wasn't far off.

I'll tell you this. 16/46 is going to be fast. Probably faster than any nitro on a track. I don't think I ever clocked my setup, but it was fast enough for the track. At 14/46, it is competitive with the nitros which is fine for me.

If you are going to be running a 4S setup, you might want to consider getting some really good batteries at some point. Don't get me wrong, I'm a big fan of maxamps products as far as bang for the buck goes; but I have gotten even my 8Ah packs pretty close to their temp limits. Since I've gone to the Kokams for my 4S configurations, I haven't had to worry about the batteries over heating. The flightpower packs are really nice and will dump current on demand without breaking a sweat.

I know that cost is a concern, but you really do get what you pay for when it comes to lipo packs. One of the reasons that I went with 5S was so that I could have a lower current draw system and be able to run less expensive packs. I'm running a cheapo truerc 5S 8Ah pack on the 8XL with a Compro controller and the battery doesn't even get warm.

As far as I'm concerned, I think that you should go with the 8Ah pack, if you have the room. If you don't, then look at the 5Ah packs. What ever you do, you have to run some sort of heatsink on the motor and a fan on the esc.

[jnev]

Thanks so much for the info.

How is the "cheapo" 8000 pack working for you besides for the temp, since you mentioned, it stays cool. If I run 5s, then I can gear down to a 14t pinion since I will have the additional speed from the voltage increase. I also am not sure about the size Truerc 5S 8Ah pack. But I tested the size of the Max Amps 4s 8Ah pack and it actually fits perfectly in all directions. I am just slightly worried about how hot it will get.

Is there any fan that is recommended thats bolts right on to the MM esc with few if any modifications?

Thanks again.

[jnev]

Bump... anyone have any experience with the True-rc 5S 8Ah pack and the Max Amps 4s2p 8Ah pack and how they compare, in terms of durability and performance. I just like the True-rc pack because it is about $100 dollars cheaper than the Max Amps 8Ah pack.

Thanks

truerc packs do what they say. It is a solid 10C, if not higher, pack. I've been running my 5S2P 8Ah pack in my 13lb muggy with a Compro controller and Feigao 8XL. The truck is stupid fast for something so big and heavy. Controller gets to about 150, motor about 180, the battery, I didn't even temp it, because was only barely warm.

The maxamps pack 4S2P is a nice pack. I have a few of them, but they are the older non copper tab cell packs. As I said, they are nice packs, but I don't know about the ones I have being true 20C packs. For some reason, we were able to heat these packs up pretty good, but not over the max recommended temp. I can't explain why these heated up the way they did, when the truerc pack runs so cool in a hotter setup. I believe that the new packs made from the copper tab cells are better than the ones I have.

I've been using Kokams and Polyquest packs for my 4S setups and the truerc packs for my 5S setup. I just wouldn't use the truerc packs in a setup that would demand a bunch of current. BTW, the 5S2P 8Ah pack won't even come close to fitting in my buggy with the body on.

[jnev]

Thanks. I just ran into the dilemma of running 5s on the MM esc. Unfortunately, I just realized this. I have heard people being successful with this set up, but I'd rather not risk it. Now I can just run the True-rc 4s 8Ah pack with the MM and 8xl, or wait for the MMM which I hear is actually going to be released earlier than anticipated... and then I would run 5s with it.