Granite How long should my battery be lasting

[Blurrrrp]

First off please excuse my ignorance. This is my first hobby grade rc. I bought the granite mega 4x4 v3. I've ran it 5 times total. The first time with the stock battery I had around 8 minutes of run time before noticing a drop off. I upgraded and bought 2 spektrum 2s 50c lipo batteries. I am still only getting 5-10 minutes of run time per battery. Does this sound right?

 

[NewSensei]

First off please excuse my ignorance. This is my first hobby grade rc. I bought the granite mega 4x4 v3. I've ran it 5 times total. The first time with the stock battery I had around 8 minutes of run time before noticing a drop off. I upgraded and bought 2 spektrum 2s 50c lipo batteries. I am still only getting 5-10 minutes of run time per battery. Does this sound right?

NiMh batteries can last for quite a while but they can also die within hours of buying. This is ultimately why I converted my mega to lipo/3s, this and more power

Also, did you change the jumper to lipo on your esc?

EDIT: I can tell you before I switched my esc I was seeing at least 20 minutes of run time. Now I average closer to 40...

 

[arrmadillo]

5 to 10 minutes definately does not seem right for a 2 cell lipo in that vechicle. You didn't mention the mah of the lipo, but even a 4000 mah will result in more runtime.

 

[Blurrrrp]

5 to 10 minutes definately does not seem right for a 2 cell lipo in that vechicle. You didn't mention the mah of the lipo, but even a 4000 mah will result in more runtime.

5000mah

 

[jondilly1974]

5000mah

How are you charging the lipos? What voltages are the cells after charging and after running?

 

[arrmadillo]

5000mah

Are you sure the lipo is fully charging, you should be getting way more runtime. Don't own the Mega but maby someone that does will chime in on advice.

 

[Blurrrrp]

How are you charging the lipos? What voltages are the cells after charging and after running?

Spektrum s150 smart charger. No idea what the voltage is

 

[Papajohn]

I experienced this in my v2 senton. Does the car cut power after 5-10minutes and then receive full power again once you turn it off and turn it back on? If so, I would suggest checking out the tuning chart for your esc and seeing what the LVC (low voltage cutoff) is set at.. it may be set at a high threshold. What I found was happening with my car on a 5200mah lipo battery, was a whole lotta voltage sag under acceleration so the power of the car would cut off as if the battery was dead after 3-5 minutes of full throttle driving. I wired a capacitor or “cap pack” to the esc and it fixed the problem. You can also opt to a higher mah battery, somewhere above 7000mah, which is what my brother has done with his granite which had the same issue.

 

[jondilly1974]

Spektrum s150 smart charger. No idea what the voltage is

Get yourself a $10 lipo checker so you can see what voltages the cells are at. This will go a long way in this hobby in figuring out things like this. ??

I experienced this in my v2 senton. Does the car cut power after 5-10minutes and then receive full power again once you turn it off and turn it back on? If so, I would suggest checking out the tuning chart for your esc and seeing what the LVC (low voltage cutoff) is set at.. it may be set at a high threshold. What I found was happening with my car on a 5200mah lipo battery, was a whole lotta voltage sag under acceleration so the power of the car would cut off as if the battery was dead after 3-5 minutes of full throttle driving. I wired a capacitor or “cap pack” to the esc and it fixed the problem. You can also opt to a higher mah battery, somewhere above 7000mah, which is what my brother has done with his granite which had the same issue.

Stock ESCs don’t have an adjustable LVC cutoff. They only have NiMH mode (no LVC) or LiPO mode (usually 3.6 - 3.8v per cell).

 

[Papajohn]

Get yourself a $10 lipo checker so you can see what voltages the cells are at. This will go a long way in this hobby in figuring out things like this. ??

Stock ESCs don’t have an adjustable LVC cutoff. They only have NiMH mode (no LVC) or LiPO mode (usually 3.6 - 3.8v per cell).

Yes, my mistake! Disregard checking the tuning chart. As said above though, a lipo checker would be good to determine if the cells in the battery are good first to rule out issues with the battery. However a higher mAh battery would help account for voltage sag and a capacitor would help as well. The tiny capacitor usually doesn’t suffice

 

[jondilly1974]

Yes, my mistake! Disregard checking the tuning chart. As said above though, a lipo checker would be good to determine if the cells in the battery are good first to rule out issues with the battery. However a higher mAh battery would help account for voltage sag and a capacitor would help as well. The tiny capacitor usually doesn’t suffice

A cap won’t usually fix a bad lipo or ESC. It can only help for super short periods, like fractions of a second. It just softens the initial draw on your packs.

 

[arrmadillo]

Get one of these, very cheap on Ebay, buy one in the US for a little extra, unless you like dealing with China. While your at it a temp gun is also mandatory.

 

[Blurrrrp]

Just had batteries checked at local shop and they are fine. Looks like I've got a problem with the truck. Any pointers on where I should start looking?

 

[NewSensei]

You could always spend a little money, if you have it, on a charger that shows cell voltages. I have a Tenergy charger that I like...

https://www.amazon.com/gp/aw/d/B00466PKE0?psc=1&ref=ppx_pop_mob_b_asin_title

 

[Blurrrrp]

Best I can tell the truck is overheating. My batteries weren't ever down past half way when I went to charge them but I didn't know any better. Whenever it starting acting like it was dying earlier I turned off the esc, unplugged the battery and let it cool down. Came back after 20 minutes hooked it up and had another solid 10 minutes of run time. No clue what the problem is so I guess I'll be calling horizon.

 

[jondilly1974]

Where are you driving?

 

[Blurrrrp]

Where are you driving?

Backyard. Dirt and short grass, fairly level

 

[jondilly1974]

Backyard. Dirt and short grass, fairly level

Grass is a heat generator. If you can avoid grass, it may run longer before heating up. Also make sure your ESC fan is working. Think about adding a motor fan as it’s usually running hotter than the ESC.

 

[Fyxxterzc]

Make sure you are charging your battery to 4.2 per cell (full charge). That would mean your 2s will have a max of 8.4v. A 5000mah battery should give you 25 min to 30min run time fully charged at 4.2 per cell. Full discharge should be 3.2-3.3 and you should always store at 3.75-3.8 per cell. Never let your voltage fall below 3-3.2 or go above 4.3 or the pack will swell/catch on fire eventually. Megas don't have a programmable lvc it's set to a factory 3.2. It may actually be set a 6.4 total voltage cutoff because there isnt a balance connector for any esc I've seen that reads individual cell voltage. V3 versions may have a balance lead if its ic5 though.

 

[jkflow]

Any idea what the charge level of your battery is after your 5-10min?
My guess, you are overheating and your ESC shuts down, not because the voltage is low.

Other alternative is that here is something in your drivetrain binding and cusing significant current draw.

Check that your ESC fan is running and if it does stop, turn it on and off, if you can continue to drive for another minute is simple ESC overheating.
If you can't run for another minute it;s something mechanical.