this chart is what most of us are using for general amperage capacity. Green is continuous red is burst generally with allowances for airflow. All the copper wire on the chart is assumed to be silicone 200°c super fine flexible conductor.
You should be good for 5a safely as long as the cable doesn’t route through anything as a tight bundle and is isolated with fish paper from the cells you could do comfortably.
I like to oversize my charging connections because i also like to charge at high rates. 50.5v x 5a = 252w of charging isn’t nothing but it should be fine. If you’re overly concerned you should open the enclosure and charge then feel around on the cable and your connections for anything that gets hot. That’s what i did the first time i changed at 3000w. Hot isn’t necessarily bad as long as it’s not too hot or in the wrong places.
Also keep in mind the cell’s rated maximum charge rate is not realistic or achievable, specs max charge rate is a single cell in free air with close monitoring of the cell temperature. Ive been able to get to 50% of that reliably in a tight enclosure but have to make allowances for my temperature rise and monitoring closely. (Fyi my bms was the bottleneck not the cells )
I accepted 5.5x2.1 but then adopted 5.5x2.5. The metal bodied ones rated at 10 amps.
I did have one develop slop., enough that torquing it hard to the side could blow my charge port fuse.
I think that was more vibration related than high charge rate heating.
I have pushed my latest 5.5x2.5 to 9 amps and it stayed cooler than expected, but I have 16awg on both sides of connection wicking away heat.
I used glue lined heat shrink up the silicone wires, and some gorilla grip clear to pot the heatshrink to vonnector end, as stress relief.
Heatshrink helps the clear GG stick. There is likely better products for this, but it has proven solid for 2K miles.
I eliminated my power button and filled the hole with another 10 amp 5.5x2.1, but it is not wired up. I thought of using both in parallel to charge, but It stays cool enough on one, that i have not bothered.
Monitor it for heating, and have a charge port fuse.
Monitor it when your battery is low, so the charger is outputting its maximum amperage rate for a good amount of time.
I have some precision cotton swabs that can fit inside the barrel on plug and on both sides of the pin on the receptacle. I put a little Caig Deoxit d5 onto a swab every so often, and scrub the interior leaf spring contact on the side, and the Pin, and the swab always comes out grey.
Hey, I made some circuits to control my accessory lights and want to upgrade it.
Right now I have a 60v→12v stepdown converter (power source) where the GND connects to a protoboard I have with 12 n channel MOSFETs. The +ve of the power source is split to different lights (loads). Each MOSFET connects to the GND on each load and has a digital output pin from my Arduino on the gate, making it a voltage gated low side switch.
This has worked for everything but I want to now add a second stepdown converter to power 24v accessories. GPT says I should use high side PROFETs like https://www.infineon.com/part/BTH50015-1LUA because it’s better for things like my music amp if it’s always grounded. I’d like to put this all into a custom PCB but I know nothing about making one yet…
Is the best way to have both 12v and 24v switches on one PCB controlled by my Arduino?
Hey, I have a maker x dv6 pro and am planning to upgrade FW from 5.03 but not sure if i should go to 6.05 or 6.06. I see those are the 2 that are available on maker x site for the DV6 pro and just want to know which is more stable. Thanks!
Driving a high-side transistor with an Arduino is doable but you need to handle level shifting and stuff (because the gate potential of the transistor is relative to your high-side power, not ground)
For a simpler circuit, I’d consider solid state relays. They’re exactly like relays, but with no moving parts. Electrically they’re basically what you’d need to do anyway to control a high-side transistor.
FYI, most stepdown converters (especially cheaper ones) draw a non-negligible amount of current, even when there’s no load connected. Not really an issue unless it’s left plugged into your battery for too long(because it’ll overdischarge and kill it)
If you do use SSR, consider having it switch the input to the stepdown converter(s) instead of the output. This will remove the parasitic current draw as a concern.
Note; If the Arduino is also getting power off the 12v converter (and thus would have a chicken-and-egg scenario with the power), consider moving it to the 5v on your motor controller. The few mA of just the Arduino would likely be a non-issue for the esc.
Working on getting a good setup down for the power wiring in my 4WD 20S build - wondering what are / are there any respectable standalone on/off switch solutions for 20S out there?
I’ve been using this Flipsky antispark for other 12S setups OK so far but it’s at the edge/under rated for 20S. So that + dodgy rep (seen posts that failure might damage ESC / battery) is making me doubt it for this.
Right now for on/off I have a QS8 loopkey I open the box for - I had a panel mount XT90 on the outside but the keys kept frying after a few times just like the threads on here said ha. I see there are actually panel QS8 you can get so I’m thinking I’ll also try one of those to move the key to the outside at least.
Yeah using an ESC with a switch built in seems like the main path I picked up reading on here to get away from the loop key on 20S, I’m not a huge fan of built in proprietary features so I was hoping to keep my on/off solution standalone / modular rather than eventually switching to a different ESC.
Has anyone used VSS on 5.03, and how does it compare to 6.05/6.06? Just looking to see if it is worth updating the firmware. I am also trying to get sensors back up and running in these motors, but that’s a WIP
I had a few antispark die on 16S. Whether it’s the pre charge resistor, long coil, or both with the wire reducing the strain on the resistor this works. It’s also useful as a failsafe so I’m not putting 2k amps through stuff when the pre charge fails, or for just testing using only this loopkey might save your ass.
edit: Oh also someone on here before had this extremely interesting observation that there is a point between being connected through the resistor and being connected normally where no contact is made, and having extra load / longer time in this zone can worsen the bang
This is interesting and getting into the actual electrical engineering stuff I have no knowledge on. So I’m a bit confused on what’s going on with the coil - is that two wires you coiled up yourself joined together? Or some sort of preexisting product?
I’m also not sure I understand the parallel setup - is it two loop keys, one on + and one on - ? Or splitting the battery output and loop keying the + on each one?
Right now I just have the one QS8 loop key on the main + and then after the key it splits to the two dual vesc
The 2 different colors are just the scrap wire I had on hand, I should have made it even longer or thinner. The loopkeys are in parallel the same way you would increase current capacity by doubling up the same wiring, still going to and from the same place.
I plug in the loopkey with the long thin piece of wire first, (turn on remote and VESC to confirm it’s on and nothing is broken but this is optional) and then connect the 8awg loopkey. I have loopkeys between cell group 8 and 9 instead of batt to VESC but I don’t think that matters.
I am basically just using a long thin piece of wire as a resistor to precharge in a way that cant fail, and a second XT90 to carry all the current.
Thanks! Appreciate the diagram and I think I get the two key concept now - so it sounds like the coil has an advantage in avoiding failure over having a resistor of an estimated equal value inline there instead?
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