This thing is a blast! Finally got the chance to ride around the neighborhood for a little while. Everything seems ok, the 30A I have set per motor is perfect for my skill level. -20A for braking is also just right, maybe a tad too strong but that’s good to have for emergencies. The motors are fine with this, after a slight climb for a few hundred feet, they’re barely warm to the touch. Getting going from stand still is great, I would say just as smooth as the boosted esc was, I won’t mess with the settings anymore.
Can’t talk about range just yet, only went for about 1 mile tonight and all the cells read around 3.35v.
Another good news is that I found a way to sort of monitor the voltage while riding. As I mentioned above, this Flipsky VX1 remote has only LiIo built-in pack voltage monitoring. If I set it for 12S, it will look for 12S LiIo voltage which is significantly higher than my LiFePo4 pack. This gave me the idea to just set the remote to a lower voltage pack. Setting it to monitor 10S voltage seems about right for my actual 12S LiFePo4. With the pack fully charged it had all 4 lights on and a little after starting it settled on 3 lights. This is good, it means I will see how the voltage drops while riding. Initially my plan is to open LLT app and check the voltages as each light on the remote goes off and this will give me an idea of how much actual charge we have left.
Good idea to treat 12s LiFePO4 similar to a 10s Li-Ion pack. For the purpose of a state of charge indicator.
Keep in mind that LiFePO4 chemistry will live in a narrow range (from 3.2-3.3V per cell) for the vast majority of its charge or discharge cycle. Li-Ion doesn’t have such a flat zone where the voltage remains nearly constant like LiFePO4 does. Don’t expect the indicators you have (empty, 1/4, half, 3/4, full) to map directly to true state of charge or be a precise predictor of range. As you mention, you’ll just have to experiment. To figure out how they corresponding to the pack’s capability.
Background: all of my boards are 10s Li-Ion, except one oddball with a 12s LiFePO4 pack. I charge them all with 10s Li-Ion chargers (acknowledging the LiFePO4 cells only get up to 3.5V, a bit shy of their 3.6V max voltage, amd that’s OK). One neat thing about LiFePO4’s flat voltage profile is very consistent voltage(power) delivery throughout the entire ride. As opposed to Li-Ion which you can feel a performance decrease below 20% SoC vs. fully charged.
You could look at a datasheet for the specific cell. Expect to see a sharp drop-off below 3.2 or 3.1V, with very little capacity available below 3.0V. Even though you can discharge to 2.5V you wont experience much capacity below 3.0V.
For reference this chart is a capacity test I’m running for a different cell of LiFePO4 chemistry. Blue line is voltage thru 3 stages: initial charge to full, full discharge cycle, full charge cycle. Notice that almost all of the capacity exists between 3.3 and 3.1V.
I’d recommend soft cutoff starting 3.0V and hard cutoff 2.8V. I think thats what I run on my pack. Though I can remember exactly… it may be more aggressive like 2.8 and 2.5.
I have it set currently to 2.90 - 2.55. No idea what sag I should be looking at with these cells but I will monitor closely as I run it down for the first time riding.
My only worry is that when I get close, some p-groups might go too low so I might increase the cut-off voltages by a little.
Almost did a range test today.
I say almost because I ran out of daylight faster than the battery
Charged up the pack 2 days ago and today before heading out, all cells were at a little over 3.4v
After about 7 miles, it’s sitting at about 3.28v. Completely happy with these results so far but I am looking forward to a full range test.
Everything else was fine, the motors were barely warm to the touch and it really is powerful enough for me. For now I’m not looking to go any faster on it, 20mph is pushing it already for me.
One thing I’d change if I could… is the wheels. I’d try bigger wheels if it would make the ride a bit smoother on less than perfect asphalt. These 75mm orangatangs are quite rough even on the tiniest of imperfections on the road.
Just wanted to say this has been a lot of help. Trying a similar project (already have the deck setup and a p42a pack in a boosted xr shell) but wasn’t sure about using a V1 drivetrain
To anyone who cares: the flipsky VESC 4.2 dual plus and an anti spark switch fit insanely well in a boosted board each enclosure. The mounting holes line up and it only requires a basic laser cut adapter for the VESC heatsink to work
Those cells he has are the last of the 100% capacity A123s that are “used”. I wish I had them now!! You can get 90% capacity ones for super cheap these days:
Still alive, the board is actually still working strong, and I haven’t touched anything on it. I don’t even remember how to connect to the vESC
I’ve been riding it around town, not that much in all honesty but everytime I go out, I want to ride more.
I feel a new project getting closer: I really want bigger and softer wheels. I don’t know if I can do that with these motors. The cloudwheels caught my eyes but the smallest ones they have are 105mm and we’re on the stock 75mm orangatangs. Might only work with significant modifications.
On the other hand, I’m not opposed to starting out with a completely new platform and just moving my electronics over. Open to suggestions.
I’ve been sitting on this for a little while. My 12S2P pack is good. The vESC should also work fine with what I have in mind.
Technically, I could even use the Loaded deck and just new trucks (with belts and proper pulleys, new (cloud)wheels and maybe new motors. The original boosted motors might even work at first.
I’m still poking around here for ideas but if there’s a good set of trucks which could work for this purpose, please let me know. I haven’t been following this scene for the past couple years, I don’t know what goodies are out there.
This thing is a blast! Finally got the chance to ride around the neighborhood for a little while. Everything seems ok, the 30A I have set per motor is perfect for my skill level. -20A for braking is also just right, maybe a tad too strong but that’s good to have for emergencies. The motors are fine with this, after a slight climb for a few hundred feet, they’re barely warm to the touch. Getting going from stand still is great, I would say just as smooth as the boosted esc was, I won’t mess with the settings anymore.
