550 Mega run time

[FlipSide]

Hello, first post here for me. I lurked a bit and I really enjoy the place so far, I didn’t know anything about RC 3 weeks ago... I will need one for myself sooner than later (I’ll start another thread eventually about that).

My 9 Y.O. son got a Granite 4x4 with the 550 mega brushed motor from his grandpa this christmas. It’s an amazing little machine and my kid is having a blast. The run time is really deceiving however. We have a 3300 mAh and a 2400 mAh Ni-MH batteries and we get probably between 5 to 10min runtime (100% throttle limit, in snow). I did not measure the run time precisely. Does that seem about right in terms of run time to expect...or could there be a problem? One thing is for sure, such short run times will not work out if they are normal. I initially thought the car stopped working because it was overheating, but the motor, battery and ESC did not seem too warm at all.

Basically, is there something wrong with the truck? Do I simply need batteries with a bigger capacity?

Another noob question: I have a charger that can run at 1A, 2A, 3A and 4A. I did not find the info regarding the charging current my batteries can withstand. Should I charge at 1A or can I go higher/faster?

Thanks in advance for your help.

 

[DoNoHarm]

You can charge the 3300 at 3.3a and the 2400 at 2.4a.

 

[arrmadillo]

Welcome, been a very long time since I ran Nimh, the runtime wasn't great, especially with 2000 mah batts.

 

[slick2500]

Hello, first post here for me. I lurked a bit and I really enjoy the place so far, I didn’t know anything about RC 3 weeks ago... I will need one for myself sooner than later (I’ll start another thread eventually about that).

My 9 Y.O. son got a Granite 4x4 with the 550 mega brushed motor from his grandpa this christmas. It’s an amazing little machine and my kid is having a blast. The run time is really deceiving however. We have a 3300 mAh and a 2400 mAh Ni-MH batteries and we get probably between 5 to 10min runtime (100% throttle limit, in snow). I did not measure the run time precisely. Does that seem about right in terms of run time to expect...or could there be a problem? One thing is for sure, such short run times will not work out if they are normal. I initially thought the car stopped working because it was overheating, but the motor, battery and ESC did not seem too warm at all.

Basically, is there something wrong with the truck? Do I simply need batteries with a bigger capacity?

Another noob question: I have a charger that can run at 1A, 2A, 3A and 4A. I did not find the info regarding the charging current my batteries can withstand. Should I charge at 1A or can I go higher/faster?

Thanks in advance for your help.

You mentioned snow, how cold was it when you were running? Cold temps = shorter run times. Below freezing and you can expect very short run times.

 

[Camaroboy383]

Yes that run time sounds about right for those packs.. my daughter has one as well.. the factory 2400mah nimh pack lasts about 5-7 minutes depending on throttle input..

I switched it over to lipo, she runs 5200mah 2s packs and gets about 17-20 mins out of those, and it's faster on lipo for sure..

 

[FlipSide]

It was around 0 Celsius today. I just did another run and the fully charged 3300 died after 5minutes 30 seconds.

Yes that run time sounds about right for those packs.. my daughter has one as well.. the factory 2400mah nimh pack lasts about 5-7 minutes depending on throttle input..

I switched it over to lipo, she runs 5200mah 2s packs and gets about 17-20 mins out of those, and it's faster on lipo for sure..

Thanks! Should I expect the same run time from Lipo and NiMH packs having the same capacity? Also, I guess brushless motors are more efficient than brushed. Do you get noticeably longer run time with a brushless setup?

 

[dillon_mitko]

It was around 0 Celsius today. I just did another run and the fully charged 3300 died after 5minutes 30 seconds.


Thanks! Should I expect the same run time from Lipo and NiMH packs having the same capacity? Also, I guess brushless motors are more efficient than brushed. Do you get noticeably longer run time with a brushless setup?

I run a 5200mah 3s pack on my 3s and when the pack was new I ran about 15 mins full throttle most of the time. You can also take out the little things that make your battery tray smaller to run a 6000-6500 ish mah battery for a lot of run time.

 

[Cheapbastard]

It was around 0 Celsius today. I just did another run and the fully charged 3300 died after 5minutes 30 seconds.
Thanks! Should I expect the same run time from Lipo and NiMH packs having the same capacity? Also, I guess brushless motors are more efficient than brushed. Do you get noticeably longer run time with a brushless setup?

You will actually get longer run times from a lipo of similar capacity plus lipos hold their charge and voltage better than nimh. The performance will be will be more consistent throughout the run before you hit low voltage cutoff but by then you would have noticed the drop in performance. Just make sure if you use a lipo you change the jumper on the esc to lipo so the esc will cut power to the motor and not damage the battery. I would strongly suggest reading up on lipos https://rogershobbycenter.com/lipoguide and moving to lipo batteries then grab one or two 2s 5000mah+ lipos.

Yes burshless motors are more efficient but it depends on the size and kv of the motor. A higher kv motor could be faster but be less power efficient than a similar size lower kv motor. Stock motor is 12t brushed motor so if you went with a (same size) 20t brushed motor you could get longer run times but you would lose top speed with similar gearing. If you want same speed but longer run times I would suggest a 3650 size brushless motor around 3000-3300kv.

Here's a video of 3650 3000kv motor in a Granite.

 

[SCIP]

Following...
Kids got two Granite 4x4 Mega RTR setups. Fun but same issue ~5 min at 100% and ~8 min run time at 75%. Trucks cut off at those times, approx. We thought it was over heating as we are in grass/weeds however it's not deep or thick. Using 7 cell, 8.4V, 2400 mAh NiMH.
Thinking I'll upgrade to longer run time LiPo 2S batteries and might go to Brushless motor for them down the road. Welcome other thoughts.

 

[FlipSide]

You will actually get longer run times from a lipo of similar capacity plus lipos hold their charge and voltage better than nimh. The performance will be will be more consistent throughout the run before you hit low voltage cutoff but by then you would have noticed the drop in performance. Just make sure if you use a lipo you change the jumper on the esc to lipo so the esc will cut power to the motor and not damage the battery. I would strongly suggest reading up on lipos https://rogershobbycenter.com/lipoguide and moving to lipo batteries then grab one or two 2s 5000mah+ lipos.

Yes burshless motors are more efficient but it depends on the size and kv of the motor. A higher kv motor could be faster but be less power efficient than a similar size lower kv motor. Stock motor is 12t brushed motor so if you went with a (same size) 20t brushed motor you could get longer run times but you would lose top speed with similar gearing. If you want same speed but longer run times I would suggest a 3650 size brushless motor around 3000-3300kv.

Here's a video of 3650 3000kv motor in a Granite.

Very useful! Thanks!

 

[BruceB83]

My son has a Granite 4x4 and he can get about 30 minutes of play time on his 2s 5000mAh LiPo battery. Note that’s not wide open throttle for 30 minutes. That’s a mix of driving, spending time playing turtle upside down, playing “tag” with his brothers Granite 2wd, etc. The battery that came with it barely lasted 10-15 minutes and I did notice performance degrade where as the LiPo seems to run pretty consistently the whole time.