Beginner Question Thread! 2023 Edition

[Egtscs]

Please sanity check my lighting setup before I plug anything in to test/explode:

1: does anything look wildly off here? Is this gonna explode?

2: if the voltage supplied is within spec; am I correct in believing that current doesn’t necessarily have to be regulated for stuff like lights or a voltage meter? I could technically connect my 12v automotive lights directly to a 1000+CCA car battery’s terminals and they’d only draw the 1.5a they’re supposed to. Right?

3: this Buck converter I’m using comes with a fuse holder and a fuse, I have no idea what the fuse is rated for or if it’s even likely to blow anywhere near that rating. Power is already coming through the BMS which I consider somewhat protected, as well as all the things powered off the converter being pretty inconsequential for safety in a failure. How important is it that I replace that (probably untrustworthy) fuse?

3.5: if I do replace that fuse, how much headroom should be left for inefficiency? (Assuming that I did the math right, which is bold to assume) Math says it should draw about 1.25a at 48v to convert to 5a at 12v. Would a 58v 2a fuse leave an acceptable amount of headroom for inefficiency while still cutting off power before severe damage?

[Dnollie]

I have a question, if I buy a focbox unity with mr60 connectors, how can I connect the phase wires of the motors?

[tech.shit]

Replace the connectors on either the motors or the ESC.

Soldering is an invaluable skill.

[Dnollie]

Ok. That’s what I thought. How are you doing @tech.shit?

[tech.shit]

Just got a new dwelling. Slowly building things up. Trying to seize my silver linings.

[Pecos]

Looks good but I can’t see if the polarity on all the connectors is good, if that is correct then the layout seems good

The lighs and other 12v devices down stream of the buck will draw their full load so as long as they all add up to less than 5a you should be good. No need for anything else to limit the load. If you wanted to fuse the load of the buck you could to protect it but with the line fuse it should be good. If you want to size that fuse the buck is 60w output, do 60w/36v will be the highest amps on the line side of the buck so 1.7a rounding. A 2a fuse will probably do ya and protect from a short or buck failure. Sizing fuses (in this instance) is about finding the amperage that the circuit requires and then going to the next higher standard size.

You said it was feed from the load side of the bms? This is good to prevent any parasitic drain running down the battery.

[Egtscs]

First off I really appreciate the confirmation of things.

@Pecos

I can’t see if the polarity on all the connectors is good

I think they’re all good, I was pretty meticulous but that’s definitely gonna be added to the list of things to check.

@Pecos

60w/36v will be the highest amps on the line side of the buck so 1.7a

I hadn’t even considered the higher current draw as the battery voltage drops, worth keeping in mind for future reference. Good tip.

@Pecos

You said it was feed from the load side of the bms?

I’m about 99.9% sure yeah.

Beginner Question Thread! 2023 Edition

This may be a silly question but I genuinely cannot seem to find an answer with the keywords I’m using I have a used 12s llt BMS which looks like this: [PXL_20241109_023453297] Is there a standard for which contacts are used for charge vs discharge? Or is that handled within the BMS, they’re shorted anyways and I’m just complicating things for myself?

This BMS has 2 contacts on either side that seem to be interchangeable for charge/discharge according to:

@Akbrock47

It doesn’t matter afaik.

@Evwan

That’s a common port BMS. Charge and discharge to C- (don’t discharge for your escs through it. )

Both of them know better than I do and I’m pretty sure “common port BMS” just means that either contact can do charge or discharge.

[Pecos]

Yup, charge&discharge on that bms are the same port. Same as most of the jbd bms i use. Looks great man, can’t wait for the rain to stop for a full day. I tried to do snr yesterday and froze my ass off and bailed, the damp just shot through my gear. Gotta remember i cant hang at 40f at night. During the day it was fine. Gonna get a heated vest and better gloves

[sugandese]

SSS56 Inrunner Motor Adapters

[sugandese]

Been thinking it would be cool to run something like the max 6 up front for 4wd Hobbywing. Has anyone seen or designed a simple way of attaining gear reduction like 11 or 12:1 using compound gears?

[Dnollie]

Would a makerx d100 work with a 12s2p liion battery, and dual trampa uncensored 6376 motors? Is it overkill? I found a great deal with one.

[Pecos]

It should work fine, I could be wrong but i think the tradeoff is lower maximum amperage ratings for the higher voltage range vs the dv6pro. The minimum voltage is easily within 12s ranges.

Remember the known can bus issues if you are going 4wd and afaik the smart reverse still doesn’t work right. Sold hardware though - still blows my mind how cool the makerx stuff runs

[Dnollie]

Shouldn’t be a problem, I’m only going 2wd

[Dnollie]

When it comes to charging, the battery already has a bms in it, do I just let it do its thing? How will I know when it’s sufficiently charged? (2a charger, rated for 12s2p, 50.4v)

[Egtscs]

Most chargers have an indication light for example:

My 50.4v 2a charger shows solid green when unplugged, solid red when charging, solid green again when full.

My 50.4v 5a charger shows solid green when unplugged, solid red when charging, flashes between red and green when near full, and goes solid green when full.

You can also monitor the battery with a Bluetooth Smart BMS if you have one, most (almost any) batteries you buy from a builder here will have a smart BMS while the majority of pre built packs (like meepo, Ownboard, Tynee, etc.) won’t have any “smart” capabilities

[SternWake]

My boards, I can check voltage at the fused charge port. One premade, I couldnt.

I use one of these directional inline wattmeters.

https://powerwerx.com/watt-meter-analyzer-inline-dc-powerpole?gad_source=1&gclid=CjwKCAiAjKu6BhAMEiwAx4UsArezOPbLxJxkkuLIxE9tCOCrsTU4s0k5bCZY8QYAbCC818c3k0oHjRoCFTwQAvD_BwE

There are many clones of this type of meter, and the cheapest ones have some issues I wont go into. I chose this link as it shows the anderson powerpole connectors, which I put on my charger outputs, and my batteries and my watttmeters

These wattmeters will display amperage flow, in one direction. If reversed they will still show voltage, but amps will read zero.

These wattmeters showed that the 2 amp chargers which came with some low $ prebuilts, are pieces of dangerous junk.

They would supply too high a voltage, and the red light would turn green as soon as 0.33 amps tapered.to 0.32amps.

It showed that these chargers would never actually stop holding the battery at too high a voltage which at best is just bad for the battery longevity, and at worst equals a fire.

The BMSs seem to allow upto 4.25v per P group before disconnecting, so basically if I did not.manually disconnect charger within 5 minutes.of the red light going green, overcharging would commence.

If I blindly trusted the chargers provided with my premade skates, its possible that a battery could have burned down my home at worst, or at best destroyed the baTteries prematurely.

I feel it is unwise in the extreme to simply trust that a charger is providing the correct voltage,.or that it will actually stop charging when the battery is full.

[Pecos]

Solid advice, a good bms and a good enough multimeter are my diy minimum requirements. Leaving batteries on a cheap charger is a bad idea in all cases and bad for the battery

[MichaelWA]

Radium makes 30mm to 44mm adapter.

[Evwan]

this adapter goes the wrong way. he needs a 44mm mount to 30mm motor adapter

[Pecos]

I wonder why the adapter doesn’t have a countersink on the opposite side to make it fit both ways…. Threads - the threads can’t be put on both sets of holes. Took me a second but im gonna post it anyway