First post, first MMM, first Savage conversion... Questions! - RC-Monster Forums

OptimusV6 · 11:49 AM

Hi everyone,

I have been reading the forum for a while, but this is my first post.

Yesterday I ran for the first time my Savage, which was converted from a Savage SS (don't know if a 25 or 4.6) to an electric using the MMM and 2200kv combo (trying to emulate a Flux). Besides changing the TVPs, adding the motor plate and battery boxes (and some other stuff), I locked the tranny using HPI part number HPI 100905 and following this instructions (http://www.savage-central.com/Evo-Fo...t_-_83049.html). I am using the stock 44/20 gearing. The batteries I used are a pair of Pro-Match 2S 25c 5200 mah connected in series.

I had a lot of fun with the truck, however, I need your help to clarify some questions/concerns I have:

1. I was not able to do a standing flip, let alone even wheelie the truck with 4s power. My slipper clutch seems tight enough, as well as my rear suspension. Is this normal?
2. Using my GPS, I calculated a top speed of 33.6 mph (not bad, but I was expecting something close to 40 mph... my mini Revo does 33 mph with a 2200mah 2s using stock gearing). Again, is this within range?
3. This is more related to the batteries, they're brand new and I think I only got like 15 minutes of runtime (not heavy bashing, just running on the road). After that the first battery was charged at 1c for 62 minutes, the voltage went from 6.23volts to 8.40 volts, but the charger only "pushed" 2340mah. These are not my first lipos and I have a decent charger (Triton EQ), but I feel that the mah should have been much closer to 5200. I did not charged the second battery completely as it was late already, but it started charging from around 6.8 volts.
4. I know this one is a hot issue here, but as per Patrick, I should be able to run 6s with the stock 20t pinion right?

Sorry for the noob questions, but I don't know anyone with a Flux so I cannot benchmark anything (my friends all run Slashes or mini Revos).

Thanks!

Joe

bruce750i · 08.23.2010, 01:31 PM

Welcome, new guy.
New lipos only come half charged from factory, Did you charge them to 100% before your 1st run? Charge em up and try your back flips, wheelies and speed runs again. Check punch control settings with castle link, calibrate esc to your radio. Watch you temps.
If you were asking about the 1/10 scale revo, I might could see some comparison value with the MERV, But it's a HPI Savage.
Good luck.

OptimusV6 · 08.23.2010, 03:00 PM

I charged the batteries when I got them... that's why I'm a little concern about the performance of the truck... of course, it may just be that the batteries are bad, that's why I need to know how a Savage Flux running on 4s is suppose to behave. I will definitely try to charge the batteries again and run the car tonight. Thanks for the reply.

thzero · 08.23.2010, 04:07 PM

1. I don't remember. My buddy was running 4S on his Flux for awhile and I know it would wheelie on command. However, until he went to 6S I don't recall trying any standing backflips. Probably depends on tires and how much traction you are getting.

2. Depends; what is your overall gear ratio with the Savage SS? What size tires are you running? Flux has some pretty tall ones (6.3" diameter) but it should run around 40mph OOB on 4S (according to the Script Asylum computations).

Total gear reduction for a Flux is 14.65491, for a Flux with the bullet proof diffs its 14.27623. Flux gearbox is 44/18 x 29/32 which is the same as a Savage X's 1st gear (2-speed gearbox).

Also what is the Punch set too on the MMM? Maybe its too low, you could try setting it higher and see if that gives more instant power to the engine.

4. Yes. Theoretically (again script asylum) says that'll be ~64mph. Probably want to run with less than 100% punch. Also probably should monitor temps more frequently.

OptimusV6 · 08.23.2010, 05:36 PM

I am not trying to actually get the 64mph top speed, but the more I think about it, it may be an issue with the batteries. I have a 2s and a 3s lipo both 20c 5000mah... I know that the combination is only 100 amps, but I want to see how the truck behaves (I know those batteries are functional). Of course, I will not go all out to not damage the esc/motor.

swiftneed · 08.23.2010, 05:49 PM

thats strange my friend has the new stock savage which is 2200kv and has 3s and he does back flips instantly hi new guy it should do it easy

swiftneed · 08.23.2010, 05:51 PM

maybe try your punch control on the radio and make sure you are full throttle

suicideneil · 08.23.2010, 06:27 PM

Definately check your radio and esc settings, might be worth going through them again and looking at the epa and such. On the esc, plug it into the castlelink ( if you have one, if not buy one ) and tweak a few things:

Punch control needs to go down to make the motor more punchy, so if its at 100% set it to maybe 50% and try it again.
Start power is fine on low or medium-low
Timing is best left on low.
Maybe check the throttle curve to make sure its normal- diagonal line.

Traction and slipper settings will play a large part too, but I've seen plenty of box-stock Fluxs do standing backflips and wheelies on 4s lipo, so take a look at those too.

t9dragon · 12:28 PM

You probably need to check your slipper clutch and make sure the pad is still intact. On 4s lipos you should be getting wheelies on demand, the backflips come when you go to 6s lipos.

Here is a short clip of my Flux on 6s.
http://www.youtube.com/watch?v=8fBGA8U6oGA

OptimusV6 · 08.24.2010, 01:45 PM

Thanks for the replies! Yesterday the charger was only able to push around 2,300 mah to each battery. I tightened the slipper clutch, adjusted the settings on the MMM and ran the savage again... sadly, I got similar results: Not even a wheelie and a top speed of 29mph. Today hopefully I will be able to try the truck with my other lipos which are 20c 5000, so I need to be aware of not demanding to much from the esc.

Now, a question for the experts in this forum (including everyone who has replied here :) )... If the batteries are only charging up to, let say, 2500 mah and are supposed to have a discharge rate of 25c... does it means that they're only delivering 62.5 amps to the esc? How will this affect the performance of the truck given that the charger shows around 8.37volts to each pack?

Again, thanks! I will post again after trying with the other lipos.

Joe

Arct1k · 08.24.2010, 01:59 PM

No you are getting completely mixed up on ratings and capacities...

a 20c 5k pack should support 100amps continuous - About the minimum recommended batteries - ideally you'd be at 125amps for a 4S setup.

The fact that you are only putting 2500mah back into each pack is a little worrying...

Pictures of everything would be helpful

What's_nitro? · 02:12 PM

Even if you bought the packs new, they might be made from old cells or were just on the shelf for too long. Try cycling them with your charger at a 1C charge/discharge and see what capacity you get from them. The rule of thumb for high-power setups is 75%. So if your charger says the battery holds less than ~4000mAH, you should get new packs. If they still have decent capacity then I guess they are just overrated packs, or the problem lies elsewhere.

thzero · 08.24.2010, 02:13 PM

Even the 25C 5200MaH are barely over that min. recommended 125amps.

[QUOTE=Arct1k;377890]a 20c 5k pack should support 100amps continuous - About the minimum recommended batteries - ideally you'd be at 125amps for a 4S setup.

Also what gearbox and which internal gears you are using, which diffs, what tires, etc.

Quote:

Originally Posted by Arct1k

Pictures of everything would be helpful

OptimusV6 · 08.25.2010, 03:01 PM

Well, after using another set of lipos... I GOT WHEELIES!! Also, I verified my tranny and diffs. and they have the same teeth count that the Flux has (so no gearing issues).

Of course, there was something else... the rear right tire started coming off, and after inspecting the rim I noted that the hex had damaged the rim (made it round).... I don't know if I made this yesterday or if the rim was already damaged (I bought the nitro roller used). I now need at least one new rim. Once again, is this normal? Should I backup the slipper? Is it a good idea to get the hpi hub conversion part 87229 (assuming that rims that use the bigger wheel nut are stronger)?

Sorry for the noob questions and thanks in advance.

Joe

suicideneil · 08.25.2010, 03:11 PM

Loosening the slipper will help, but loosen it just a tiny bit too much and it tends to melt easily.

With 14mm hexes and big power its not unusual to strip them, pretty normal really- 17mm hexes will be a great upgrade, doesnt have to be the HPI hub-conversion as there are lots of just normal hexes that will fit in place of the 14mm version- some are better/ less sloppy than others, depends on the price really but the HPI kit is quite nice all the same ( might be worth having a poke through the Savage sub-forum here and seeing what people are running ).