Limitless First time speed build.

[Tirefryer426]

Yes, internal resistance is via the balance port.
And all LiPo battery chargers behave this way. Lithium Ion as well. Charging starts to slow down over 80%. Even if you aren't balance charging.
From what I know, there are two reasons. One is heat management, the other is as someone else mentioned - so it doesn't over shoot the charge target.
Think of it like pouring water into a glass. You start slowing down toward the top so you don't spill.
Balance charging can definitely take some additional time. But I absolutely agree with Liberty, if you are seeing extended balance times you should check your internal resistance. What i'm seeing in that picture looks high.

 

[wadedog]

I'm just starting out myself and my goal is to start with a 70 to 80 mph run and when that gets easy make a change to my setup. If you're just starting off and want to go 150 to 180 mph you must have more time and money than I do to build a new Limitless every week Just saying start slow.

Have you ever driven a rc over a 100 MPH you will crash

 

[mat60]

Have you ever driven a rc over a 100 MPH you will crash

No and yes. To be honest with you I should be in a less expensive hobby. Like playing cards. I'm going to have fun while it lasts.

 

[wadedog]

No and yes. To be honest with you I should be in a less expensive hobby. Like playing cards. I'm going to have fun while it lasts.

The need for speed go big or go home i have the same problem may first my speed build WAS stretched typhon XLX2 1721 8s my first 132 second pass power pole.

 

[LegacyIV]

Welp there you have it positive goes last. Skip to 23:20

I did it and no spark. But when I pull out the esc plugs, they touched when I let them go, they did make a pop sound and left a scar. Assuming that's just some residual 8s power flowing through the esc.

 

[wadedog]

I have finally got to make a couple of passes yesterday. Made a decent pass 103 but had a carbon fiber dog bone come apart have no idea why

 

[#ARRMArcfanboy4life]

What brand of dogbone?

 

[Dan B.]

I have finally got to make a couple of passes yesterday. Made a decent pass 103 but had a carbon fiber dog bone come apart have no idea why



View attachment 284367

View attachment 284368

View attachment 284370

Very cool, man. And you mounted your antennae through the body mount standoffs?!?! That’s awesome dude, did you build your standoffs or modify some existing ones? I love seeing fresh details like that. Nice work!

 

[wadedog]

I’m some that I have made my self a friend of mine has used a set his PB 145 with on problem.

Very cool, man. And you mounted your antennae through the body mount standoffs?!?! That’s awesome dude, did you build your standoffs or modify some existing ones? I love seeing fresh details like that. Nice work!

Yes I made the stand-off Thank you

 

[Jerold]

OP, I beg you do some research on electronics and wiring before you continue. If you continue with this level of knowledge you're going to at best detonate an ESC and worst your house.

Great build!

I know what you mean. Every time I mess with the wiring I triple check everything, it's easy to get messed up. And ALWAY make sure your QS8s are fully inserted.

You shouldn't see a spark using both sides QS8 connectors, they are anti-spark. However, if you are using bullets and QS8 you can see a spark if you connect them in the wrong order.

There are 4 terminals in the QS8 connector pair. Only the female positive terminal of the QS8 pair is anti spark. This is marked on the connector.

So if you are using male bullets with the female QS8 and you connect the positive terminal last you shouldn't see any spark. If you connect the negative last you may see a spark.

The way this works is there are actually three contacts in the female connector. The Negative side is just a passive connection with little to no resistance (.1 or .2 Ωs). The positive side has two contacts. A smaller outside contact that has a series 5.1Ω resistor and the inner one with no resistor.

In these two pictures, the first one is partially inserted and the second is fully inserted.

When you insert the connector the smaller resistive path makes contact first. The current goes through the resistive load and suppresses the spark. This is where you need to be careful, because the car will power up and act normal, until you smoke a connector.

Then when completely inserted the inner ring (no resistance path) and will carry the current. When fully inserted the 5.1Ω resistor has 0A and carry no current.

 

[wadedog]

What brand of dogbone?

I made them I have never had a problem with them tell I made a set for a friend his PB 145 with no problem.

 

[LegacyIV]

Great build!

I know what you mean. Every time I mess with the wiring I triple check everything, it's easy to get messed up. And ALWAY make sure your QS8s are fully inserted.

You shouldn't see a spark using both sides QS8 connectors, they are anti-spark. However, if you are using bullets and QS8 you can see a spark if you connect them in the wrong order.

There are 4 terminals in the QS8 connector pair. Only the female positive terminal of the QS8 pair is anti spark. This is marked on the connector.
View attachment 284381
So if you are using male bullets with the female QS8 and you connect the positive terminal last you shouldn't see any spark. If you connect the negative last you may see a spark.

The way this works is there are actually three contacts in the female connector. The Negative side is just a passive connection with little to no resistance (.1 or .2 Ωs). The positive side has two contacts. A smaller outside contact that has a series 5.1Ω resistor and the inner one with no resistor.
View attachment 284380

In these two pictures, the first one is partially inserted and the second is fully inserted.
View attachment 284384View attachment 284383

When you insert the connector the smaller resistive path makes contact first. The current goes through the resistive load and suppresses the spark. This is where you need to be careful, because the car will power up and act normal, until you smoke a connector.

Then when completely inserted the inner ring (no resistance path) and will carry the current. When fully inserted the 5.1Ω resistor has 0A and carry no current.

Thank you i will run the car the car when i get off work. As for the spark when the esc bullets were taken out and hit each other when i let go of them, is there an explanation or was i correct saying thats just some residual 8s power flowing through the esc.

 

[Dan B.]

The capacitors in your ESC discharging. Don’t do that, you’re actually shorting the positive and negative sides in the ESC. But hey, XLX2’s are cheap to replace anyway.
If you have naked bullets coming off your ESC you should make them different lengths so they don’t automatically short out, as they’ve been designed to do now.
You didn’t see a little puff of magic smoke when that happened, did you?

 

[LegacyIV]

The capacitors in your ESC discharging. Don’t do that, you’re actually shorting the positive and negative sides in the ESC. But hey, XLX2’s are cheap to replace anyway.
If you have naked bullets coming off your ESC you should make them different lengths so they don’t automatically short out, as they’ve been designed to do now.
You didn’t see a little puff of magic smoke when that happened, did you?

Ok thank you ill make sure to not let it happen again. And no smoke, only loud pop and scar left on the bullets.

 

[Dan B.]

Ok thank you ill make sure to not let it happen again. And no smoke, only loud pop and scar left on the bullets.

That’s good. Have you tried to power it up since? I’d just put a small battery on it to see if it’s ok.
I know others here don’t agree, but from where I sit screw bullet connectors. Just go QS8’s. It’s basically idiot proof at that point, and I think we’ve all had days where we need that. I’m not at all convinced about the “added resistance in the harness argument” either. The way I see it, they’re still 8mm bullets, right? They’re just protected from shorting, protected from big-time sparking, and protected from reversing polarity, things that a naked bullet isn’t. I have a single QS8 on my XLX2 and then I connect either a series connector (as others have recommended), a parallel connector, or just run a single battery. All are options at that point.
Your life just got a whole lot simpler and a whole lot safer, and every connection is still made with an 8mm bullet.
https://www.radiocontrolpower.com/product-page/qs8-anti-spark-series-harness
https://www.radiocontrolpower.com/product-page/qs8-parallel-harness
These guys have them pre-made and they’re awesome.

 

[Jerold]

Yup that was just discharging the caps on the ESC. Although it should be pretty harmless to your ESC, other than it can pit your connector, I wouldn't make a game of it. There is also the possibly of you you getting a zapped, it's a little tiny zap and but still a zap.

Caps store charge and release it quickly. Once they are charged they keeps it until there is a path to ground, then it gives as much current (instant current) as it can. Which is the spark you are seeing. If you had a shorted it with a small resistor, the current would be controlled and you wouldn't get a spark.

I don't think anyone does this but if you want to safely discharge the ESC after running it you can could use QS8 female jumper or just get some axial resistors (100Ω or less) and stick that in there.
https://www.radiocontrolpower.com/product-page/qs8-female-jumper-wire-connector
https://www.ebay.com/itm/3247653426...5ybALL78zvEJEQ%3D%3D|ampid:PL_CLK|clp:2047675

Just go QS8’s. It’s basically idiot proof at that point, and I think we’ve all had days where we need that. I’m not at all convinced about the “added resistance in the harness argument” either.

I'm not sure what added resistance you are referring too?

 

[Dan B.]

I'm not sure what added resistance you are referring too?

Others here, and Raz, have said 8mm bullets are the least resistive possible setup and everywhere you can avoid an actual connector is for the best. I’m not buying it, they’re all 8mm connectors. And I got the RCP series harnesses in 6 gauge, those things have massive cables. I’ll bet my series setup is running fewer ohms than Raz is with his 8-10 gauge cables with bullets.

I don't think anyone does this but if you want to safely discharge the ESC after running it you can could use QS8 female jumper or just get some axial resistors (100Ω or less) and stick that in there.

I’m not sure why anyone would want to do this in the first place, and if one did then how could it be safe for the ESC? You’re still momentarily shorting the circuit, and there’s no way that can be healthy for the ESC. Unless I’m just really missing something. Not that that has ever happened before…

 

[Jerold]

Others here, and Raz, have said 8mm bullets are the least resistive possible setup and everywhere you can avoid an actual connector is for the best. I’m not buying it, they’re all 8mm connectors. And I got the RCP series harnesses in 6 gauge, those things have massive cables. I’ll bet my series setup is running fewer ohms than Raz is with his 8-10 gauge cables with bullets.

I’m not sure why anyone would want to do this in the first place, and if one did then how could it be safe for the ESC? You’re still momentarily shorting the circuit, and there’s no way that can be healthy for the ESC. Unless I’m just really missing something. Not that that has ever happened before…

Oh, the resistance make sense and Raz is correct. More resistance means less current at the far end. When I built my car I started down that path, 8ga short wires, minimal connectors, etc.. But then figured it wouldn't make a difference until I start pushing the limits, which I'm not even close to yet. But if i ever get there I will probably build a new car anyway.

I'm not sure why it would make a difference to discharge the caps. Caps do degrade over time, so if they were left charged for years "maybe" they would degrade? But there is so many other factors, like temperature and simply age that contribute. Eventually they will wear out anyway. But if someone was concerned about it they could do it and it would be better to do it safely and controlled than use a paper clip.

Using a wire would be a short as it's essential 0Ω. If you use a resistive load to discharge the cap it's not a short. However, it is a quick connection, but that's not physically different than a contact inside a switch. Using the resistive load is exactly what the QS8 connectors do.

The reason you get a spark when plugging in the battery is the caps a are instantly drawing a butt ton of current, the 5.1Ω resistor slows that draw and suppresses the spark.

 

[Dan B.]

Oh, the resistance make sense and Raz is correct.

Please enlighten me. What is the difference in a QS8 connection (8mm bullets, shielded) and naked 8mm bullets? I’m just not buying it.
Sure, if you were trying to push that many amps through a IC5/EC5 or an XT90, then yes I would of course agree. But I do not agree that a QS8 has more resistance than an 8mm bullet. Who has an ohm meter handy?

 

[Diem Turner]

Please enlighten me. What is the difference in a QS8 connection (8mm bullets, shielded) and naked 8mm bullets? I’m just not buying it.
Sure, if you were trying to push that many amps through a IC5/EC5 or an XT90, then yes I would of course agree. But I do not agree that a QS8 has more resistance than an 8mm bullet. Who has an ohm meter handy?

I don't think you're going to be able to measure the resistance of a single connector with most MM as the resistance probably won't be more than a few mΩ. In a pinch, it might be possible to measure the resistance with a regulated vape mod. Those can measure resistance down to 50 or maybe 30mΩ. I'm gonna give that a try right quick to see if it'll register.