My CRT.5 conversion w/ ET & radar data

[Tobbe]

How big battery could you get to fit in a CRT.5? Would a regular 1:10 battery-pack be too big?? Going to order som MaxAmp LiPos for my B4 and later maybe convert a CRT.5, so if the LiPos would also fit in the CRT.5 I use in B4 I would save a lot of money

[jnev]

You can fit a normal 1/10 scale truck battery in it fine, even without the extended chassis. I will actually be running a 4s pack in mine on the stock chassis.

1.) What are the runtimes like with the Neu 3s and 4s 2500's?

2.) What do you use for a balancer?

3.) Could you post a few chassis shots with the Neu batteries

-Thanks, Brad

[Tobbe]

Originally Posted by jnev

You can fit a normal 1/10 scale truck battery in it fine, even without the extended chassis. I will actually be running a 4s pack in mine on the stock chassis.

That's nice to hear. Thank you!

[Finnster]

I got some ET data for some of the spd runs. Same setup as in the vid, but no radar, but spds are about the same. What is interesting is that the amp draw and wattage is so much lower than when I had mashers on with much lower gearing. Top spd then was only 50 on even with 1400W. Barely a 1000 and it pulls to 60. I could prolly even gear up a bit for a few more mph as I know the setup will handle it.



Here is some ETs for 3s. Top spd was 50mph, Again, amps are pretty low.

Also, notice the little voltage spikes after the big drops from the spd run? I think that is from the motor braking. The graph shows a hard accel from a stand still (ramping up the thr gradually as not to flip,) finally WOT (the big spike halfway thru the peak,) wattage/amps tapering off at full spd, then thr release and coast for a few seconds, then motor brake to stop it. Then repeat. Cool

[Finnster]

To answer a few ?'s:

The batts trays I made from a project box from Radio Shack. This one I think Had to cut up and mod a bit to fit the batts tight, but works well. Its bolted down thru the chassis holes for the gas tank and engine. Added a couple screws since the vid for more security. Added two more from the top after the tray came apart at end of 60mph vid.

I have the Ofna ext chassis. The limiting factor is width. I chose the 2100 and 2500 batts are they are ~35mm wide. Compared to a 44mm wide lipo, they are much smaller, and fit perfectly on the chassis. I have a 4S 3200 batt for my rustler, and it looked way too big on the chassis, and dangerously overhung on the sides. It wouldn't fit under the std body. The RCM chassis is much wider and will accommodate std 1/10 scale batts, but obviously not the stock body.

I was aiming for lightweight, so runtime is, IDK, 12-15min driving hard. Really depends on driving. I am pretty sure it will do a 15 min race (which was goal) and 100% sure it will do a 10 min race. Bashing lasts a good long time.

The Neus have Kokam taps. The best balancer to get is the Astro blinky. Very simple, but will fit any type of tap out there. I have a hyperion and TP balancer, and an assortment of adapters, but w/ the Blinky I don't need any of all that extra crap and it works well. $25 too.

[Finnster]

Pics as requested. Couple notes: The tray came apart at end of 60mph video. I used an ABS cement to put the tray together, but it didn't bond well to the plastic. I redid it w/ Gorrilla glue, but rear tray shifted during drying and backend sticks out too much from the side. Fit snug first time (see 1st pics in earlier post) and only over hung by ~2mm. Need to fix this, but, eh works for now. Pic makes the repair look worse than it is tho.

Basically the tray is the project box quartered, slimmed down to 35mm wide, and a single strip of ABS attaching all the quarters together. Thin padding foam from T2 batt tray runs the length. 2 3mm from below, now 2 3mm from top bolting all quarters down for extra strength.

Top w/ batt:



3s batt from side:



LED Headlights:



Comparing 35mm wide batt to 44mm ("1/10th scale") batt. 35mm batt is shorter and less wide but taller. Fits better on OFNA chassis IMO.

[Finnster]

A few updates:

I fragged my LMT.... :(

I was running very hard in the grass w/ the 18/46 gearing. I should have changed it first, but thought I'd just go for a quick spin and pushed it too hard for too long. One solder trace melted (its not a hi-amp version) and the truck stopped. I fixed the solder traces, but the motor is still cogging. ESC os fine, so motor will need to get repaired....dammit.

On the upside a have a 540 12s that I put in, and so far so good w/ it. Much less TQ than the LMT, but that might be ok given just how powerful the LMT was. The feigao is fast enough but not so wheelie prone.

I also went up to 10K in the diff, 3K diffed out badly. I'm working on doing Go-ride's .5 shock mods bc the shocks are really lacking. Hopefully I'll get it all together for the little RCM mini-bash on June 8th @ barnstormers. Should be fun to run against some other BL CRTs.

[Finnster]

Well, went thru a 12S after the 1/8" shaft snapped, then snagged a 50mm 2200 kv medusa, and now I run that on 4s packs. Very nice, and very reliable. Got some 4S 30C 2100 Zippy packs for less than $40 and they freaking rock. Standing backflips easy if you are not careful. Also did the BB shock mod a while back as well. Essential. Led lights were removed in front until further notice. Bad crash damaged one and haven't fixed it yet.

3K front diff/10K/2K
27.5wt oil in Ft on jato pink springs
35 wt in rear on HPI blue springs 71 gF/mm (from hellfire, slightly lighter than the LX1 yellow springs)

Got to race it against RCM Mike and Arct1k's .5s at the barn over the summer. Fun little race, but it was ran with the 12s. The medusa would have been nice for some extra punch, but otoh the setup was very light w/ align 140g 3s 2100 packs.

Race vid:
Also, the UTube link for the 60mph vid got messed. A redo:
BTW, the medusa/zippy is just as powerful. Haven't done a speed run, but the feel is awesome. Love the motor.

ET Data on newest setup: 13/46 gearing on Medusa/4S and Masher tires. 90A peaks on a half spent pack and I was only dropping 2V (3.9V ->3.4V/cell) That's a 43C load!


Pics:
(Crt.5 vs Hyper ST)


The Fleet: