Kraton Holy jeez, new Kraton...

ShadyD

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  1. Kraton 6s
So I buckled down a and bought a Kraton and everything I needed to go with it: 2 Lectron Pro 3s batteries, a Dynamite P2 charger, BatSafe, cable extensions, etc etc etc.

First off, this is my first lipo truck, and my first brushless. Holy jeez, this thing can haul! I'm used to my extremely slow TRX rock crawler. This is a whole different beast.

Did some speed runs to start, which had all my neighbors out watching me, with all of us giggling like little kids as it rocketed by.

Took it out into the yard and tried it out on a makeshift plywood jump, and had a lot of fun. Probably landed it more on its head than it's wheels, but not a spot of damage except scuffing the wing. My neighbor told me a nearby park has a BMX pump track, so that's where I'm headed next weekend!

Only strange thing, the lipo LVC seems set kind of high, and there doesn't seem to be a way to change it. The cutoff happens at 3.7V it seems - at least, that's what the charger reads on the lowest cell when I put the batteries on to storage charge after use. Anyone else have that happen? I thought the cutoff should be closer to 3.4V. That's what the AMain Hobbies video on lipo care recommended.

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SenorWickedStix

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I’m the opposite. Lol I bought a used Kraton first about a month ago and just purchased a crawler. (Should be delivered tomorrow 😀😀) My Kraton has the Spektrum electronics and I just go till the low battery thing yells at me on the radio. (Smart batteries) My cnhl batteries I’ve run twice now and have had no low voltage cut off yet. 🤷‍♂️ (I’m assuming the car would shut down??)
 

ShadyD

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I’m the opposite. Lol I bought a used Kraton first about a month ago and just purchased a crawler. (Should be delivered tomorrow 😀😀) My Kraton has the Spektrum electronics and I just go till the low battery thing yells at me on the radio. (Smart batteries) My cnhl batteries I’ve run twice now and have had no low voltage cut off yet. 🤷‍♂️ (I’m assuming the car would shut down??)
So on mine, the top speed will suddenly drop, like someone flips a switch. I can drive it a bit more, but at power top speed and acceleration. After another minute or so, during which time I'm driving it back to the house, it will cut off completely. The fan still works, there is still power to the truck, I can move the steering servo, the truck just won't drive.

I'm assuming that's the LVC, correct? It's happened at the exact same voltage each time, which is why I'm assuming that's the cutoff. 3.7V each time.
 

RedOctobyr

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Awesome, congrats on the new truck, that sounds great!

What you're describing sounds like LVC, to me. What's the temperature in your region at the moment? LiPo batteries are weaker (and exhibit more voltage sag under a load) when they're cold. That could contribute to the voltage sagging enough to trigger LVC, while showing 3.7V on the charger. Batteries with lower C discharge ratings (exaggerating, like 10C instead of 100C) will also show larger voltage sag under a load.

How many mAh is your charger putting back into the packs?

This seems to agree that the LVC cannot be adjusted: https://www.arrmaforum.com/threads/firma-150-esc-adjust-lvc.37772/

I'm waiting for my truggy to arrive as well, and also discovered that there's a BMX track not too far away. I'm hoping that will be a fun spot to play.
 

ShadyD

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Awesome, congrats on the new truck, that sounds great!

What you're describing sounds like LVC, to me. What's the temperature in your region at the moment? LiPo batteries are weaker (and exhibit more voltage sag under a load) when they're cold. That could contribute to the voltage sagging enough to trigger LVC, while showing 3.7V on the charger. Batteries with lower C discharge ratings (exaggerating, like 10C instead of 100C) will also show larger voltage sag under a load.

How many mAh is your charger putting back into the packs?

This seems to agree that the LVC cannot be adjusted: https://www.arrmaforum.com/threads/firma-150-esc-adjust-lvc.37772/
I think its putting in between 2500 and 3000 mAh if im reading the charger correctly and adding the storage charge to the balance charge. That also seems low to me. Temperature today in the mideast was a balmy 60 degrees. Batteries are 5200 mAh 50c.
 

milehighspeed

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Step one: Check the LED on the ESC when it happens. The LEDs could give you a picture of what's happening. If its low voltage cut off then it will flash red, with short pulses. LVC can happen for many reasons besides the batteries actually being low...(Redoctobyr noting voltage sag as one example). Too much load can trigger the LVC. One way to check that is when it happens, shut everything down, unplug, wait a few minutes, plug it all back in and go and see if it runs fine again. If so, that means your batteries aren't handling the load for whatever reason or sending "false" info to the esc causing it to LVC... that could be batteries aren't good and healthy, C rating is too low or false advertised, your driving with too tall gearing, driving in too "thick" of terrain (tall grass, sand), esc isnt reading the battery cell count correctly (ie, thinks its 4 cell vs 6cell). It could be many things if LVC is cutting too early but start with checking the LED to see if its LVC.
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ShadyD

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Step one: Check the LED on the ESC when it happens. The LEDs could give you a picture of what's happening. If its low voltage cut off then it will flash red, with short pulses. LVC can happen for many reasons besides the batteries actually being low...(Redoctobyr noting voltage sag as one example). Too much load can trigger the LVC. One way to check that is when it happens, shut everything down, unplug, wait a few minutes, plug it all back in and go and see if it runs fine again. If so, that means your batteries aren't handling the load for whatever reason or sending "false" info to the esc causing it to LVC... that could be batteries aren't good and healthy, C rating is too low or false advertised, your driving with too tall gearing, driving in too "thick" of terrain (tall grass, sand), esc isnt reading the battery cell count correctly (ie, thinks its 4 cell vs 6cell). It could be many things if LVC is cutting too early but start with checking the LED to see if its LVC.
View attachment 267315 View attachment 267316
Thanks man, I had just been reading this section of the manual. I'm thinking I might take the Kraton to a local park to hoon around, I'll check on the ESC LED when it cuts out. These are brand new Lectron Pro 50c batteries, so I'm hoping they are not faulty/misadvertised.
 

Xpress..

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Keep in mind LiPo batteries have a break-in period that usually takes 5-10 cycles before they're ready to tackle heavy loads. Your first 5-ish runs (especially on LP batteries) should be on 50% power setting in your transmitter and limiting full throttle runs to a few seconds. If you didn't do this, well I hate to be the bearer of bad news but those batteries will only continue to get worse. Running LiPo cells for almost the entirety of their availability in the RC market, I've learned to do this over the years and my cells last forever (even brands like Thunder Power that everyone seems to hate on for being low quality, yet I have TP cells with over 1000 cycles on them and no signs of puffing).

LVC will trigger a bit higher on Spektrum ESC's because they want to avoid you running your LiPo's too low. If your batteries sit st 3.7v/cell after your run, then you're golden. Running lower LVC settings can lead to premature battery degradation.
 

ShadyD

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Ah, well, certainly didn't run at 50% throttle, but also didn't run full speed very much. So hopefully will be okay. I did a lot of reading before I bought these, and this is the first I've heard of a break in period. The more you know....

I actually have no problem with the run time, I get a good amount of time so far out of my batteries as long as I don't get nuts with them. I was just surprised because some of the Lipo How To's on sites like AMain Hobbies had suggested setting the cutoff to 3.4-3.5V. As said though, I have no prior experience with this, so if 3.7V is a good setting, good with that.
 

RedOctobyr

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I actually have no problem with the run time, I get a good amount of time so far out of my batteries as long as I don't get nuts with them. I was just surprised because some of the Lipo How To's on sites like AMain Hobbies had suggested setting the cutoff to 3.4-3.5V. As said though, I have no prior experience with this, so if 3.7V is a good setting, good with that.

I don't mean to speak for Xpress.. , but I don't think we're talking about setting the LVC itself to 3.7V. Rather, using an LVC setting (such as 3.4) that has the packs sitting at 3.7V when there's no load on them, and you're checking them with a charger or LiPo checker.

Their voltage will sag as a load is applied. So if you actually set LVC to 3.7V, for instance, you'd probably get a very short runtime. And the packs might show more like 3.9V when you checked them, after LVC triggered at 3.7V.
 

ShadyD

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Ahhhhh.

Okay, I get it. So the LVC might actually be in the 3.4 to 3.5 range, but that checks voltage under load. So while they might read 3.7 on the charger, they would be lower when running. That makes sense. Actually, that's quite obvious, not sure why that didn't occur to me.
 

RedOctobyr

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Yup. And, the ESC's LVC can usually only measure the overall pack voltage, it can't actually see individual cells. For for a 3S pack, using 3.4V, it's just looking for 3 * 3.4V = 10.2V. But as you'd alluded to earlier, it would trigger the same way with 2 cells at 3.5V, and one at 3.2V, for 10.2V total, if the cells were performing differently.

Also, if you want an easily-adjustable option, which also shows the voltages (like if you stopped and removed the body), you can use something like these LiPo alarms. The cutoff voltage is adjustable, and it reads from the LiPo balance leads. So it's actually reading individual cell voltages, and it's not influenced by voltage drops through the ESC wiring, and the main electrical connectors. They beep when you hit the alarm threshold:

https://www.amazon.com/LiPo-Battery-Checker-Monitor-Indicator/dp/B07BQWSXC4
 

ShadyD

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So the red blinking LED on the ESC, so its definitely the LVC. I drove it today at 50% throttle, and honestly, that was plenty fast for hooning around the neighborhood. Got around an hour of fun on one set of batteries. The batteries read about 3.68V when I stuck them on to storage charge.

I did get a couple of fun pictures cranking the thing through the dead leaves.

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milehighspeed

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The batteries read about 3.68V when I stuck them on to storage charge.
So to me that’s sounding pretty normal. Means under load for brief periods it’s probably sagging to 3.4 or less which is why LVC is tripping. If ur looking to reduce the LVC cutting as much, (and don’t want to risk stepping down the LVC set point), then gearing down is a good option typically. Gives you more torque, Takes load off the motor and thus demand on the pack. However, Don’t go too low with the gearing that your just full throttle all the time because it doesn’t give the speed ur wanting. That circles you right back to where you started…there is a sweet spot in between👍 “Heavy finger” is a sure way to get lots of LVC lights. 😂.
 
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