Lipo C Rating Question - BLX100 ESC

[murphy0987]

HI Everyone,

I just bought my first Arrma, the Granite BLX 3S. Only taken it out once but awsome truck. I bought a gensacearespammers 5500mah 50c 3S lipo, which runs awsome in it. However I have a couple of 2s 5200mah 30c packs, and just want to clarify something about lipos and C ratings (and also the minimum lipo specs Arrma states)

Please correct me if i'm wrong here, but when I do the math, these 2s packs I have should output about 156amps (5.2amps x 30). And the Granite has a 100amp esc, so does that mean that these packs should be more than capable of running in the truck?

Ive notice that Arrma's minimum battery specs state a 5000mah 35c battery (175amp output) which to me seems a big overkill for the BLX100 which is only rated at 100amp? And even more interesting to me is that the minimum battery specs for the BLX185 which is rated at 150amps, has the same minimum battery specs as the BLX100..

So from my research, even though my 2s packs do fall slightly short of Arrmas recommended specs, I believe these packs should still be fine to run in the truck.

I'd like to hear other people opinions on this.

Thanks everyone.

 

[Sledgehog]

C rating on a battery is the maximum possible output, not the constant output which is much lower. Always use the recommended C rating given by the manufacturer.

 

[nino]

I'd run them. Nothing horrible can happen. Maybe they won't live to see as many charge cycles as they theoretically should, but they'll work.

But don't blame me if they go up in flames or something ?

 

[razorrc]

The C ratings are complete garbage and don't reflect any reality in this universe. So ignore the math, because it's not true at all.

That said, if it's a 25C or 30C battery, that's basically as low as they come and indicates it's not meant for high powered vehicles. I'd stick with at least 50C rated batteries. They're not really 50C, but at least sort of indicate they're mid-level batteries.

 

[slick2500]

The C ratings are complete garbage and don't reflect any reality in this universe. So ignore the math, because it's not true at all.

That said, if it's a 25C or 30C battery, that's basically as low as they come and indicates it's not meant for high powered vehicles. I'd stick with at least 50C rated batteries. They're not really 50C, but at least sort of indicate they're mid-level batteries.

Last time I checked the highest true c rate was something like 35-40c. The highest possible true c rate of a lithium polymer battery is 50c, and us civilians don't get those. Most consumer batteries have a true c rate around 20-35c. The random brand eBay/Amazon cheapos are probably closer to 10-15c.

 

[Outcastblxnut]

Run um. I run 2s 30 c for my daughter all the time

 

[murphy0987]

Thanks for the info guys. Sorry but I'm new to all this.

So if you run a battery thats C rating is too low, what will happen.

Does the esc still draw the amps that it needs from the battery, in turn putting a lot of stress on the battery. Which I'm assuming will overheat the battery and cause damage to it.

OR, does the battery not supply enough amps that the esc or motor requires, and if so, does this hurt the esc?

 

[Outcastblxnut]

Yes the later you quoted

 

[nino]

The battery may get warmer than a higher rated lipo. The truck won't feel as quick as the motor won't get the theoretical maximum voltage and therefore current that it would from a better pack... Neither will get damaged. The pack will degrade faster, but nothing catastrophic.
I say you test it out: if the pack gets hot after a run (above 50C / 125F), use it in less demanding vehicles. If the temp is OK, bash on.

 

[jondilly1974]

Thanks for the info guys. Sorry but I'm new to all this.

So if you run a battery thats C rating is too low, what will happen.

Does the esc still draw the amps that it needs from the battery, in turn putting a lot of stress on the battery. Which I'm assuming will overheat the battery and cause damage to it.

OR, does the battery not supply enough amps that the esc or motor requires, and if so, does this hurt the esc?

Both actually. If the battery cannot output enough amps at a given voltage (watts of energy), then the voltage will sag and the only way to keep the wattage up is for the amperage to increase. Increasing amperage is going to lead to heat. Both in the battery and in the ESC. If the amperage is high enough that it reaches or exceeds the ESC rating, it could hurt the ESC. Especially if you run it hot for long periods.

The moral of the story is try it and monitor temps. If it runs cool, you can rest assure it’s fine. If it runs hot, you will damage something at some point. The what or when is hard to predict precisely. If you want to ensure nothing happens, you have to be observant and stay ahead of it.

 

[razorrc]

From what I've seen, the lipo will puff and can catch on fire. I've seen ESCs burn, but not sure if this was due to the Lipos not being able to keep up.

 

[cjv29er]

I’d like to refresh this topic as I have the same concern as the threadstarter.

Earlier today I tried my 2-cell 5000mah Zop Power 25C on my Granite 3S BLX and it ran great...a little tamed from the other 3-cell 50C but it power punched through nicely, enough to do back and forth speed runs. Now will I ruin the battery quicker (or ESC) if I continue to use this? Or should I continue my quest to find the more appropiate LiPo?

 

[slick2500]

I’d like to refresh this topic as I have the same concern as the threadstarter.

Earlier today I tried my 2-cell 5000mah Zop Power 25C on my Granite 3S BLX and it ran great...a little tamed from the other 3-cell 50C but it power punched through nicely, enough to do back and forth speed runs. Now will I ruin the battery quicker (or ESC) if I continue to use this? Or should I continue my quest to find the more appropiate LiPo?

I run 4500mah 30c lipos in my Typhon 3s all the time, just keep the battery "amperage" above the esc "amperage". Those batteries are "125a" and the esc is only a "100a" esc. I put these things in quotes because c rates are made up numbers as are the amp ratings of escs.

 

[LibertyMKiii]

I ran a cheap Zee Lipo on a MMX and TP 4050CM pulling 180+amps through it.
I believe any LiPo can do this sort of activity, you just have to watch temps. Get a cheap IR gun on Amazon and check things often with any new equipment.

 

[jondilly1974]

Performance and temps will tell you the truth. Don’t be too worried about ratings per se.

 

[murphy0987]

I’d like to refresh this topic as I have the same concern as the threadstarter.

Earlier today I tried my 2-cell 5000mah Zop Power 25C on my Granite 3S BLX and it ran great...a little tamed from the other 3-cell 50C but it power punched through nicely, enough to do back and forth speed runs. Now will I ruin the battery quicker (or ESC) if I continue to use this? Or should I continue my quest to find the more appropiate LiPo?

I've run my 2s 30c packs a few times now in my granite 4x4 blx with no issues, I've checked the temps on my battery and esc and they have all stayed cool, so I'm happy to keep running them.