Can I swap qs8 connectors on a battery with Ec5 connectors?

[Kratonwatch]

Title says it, but here’s more info. I am converting my k8s power system to max 5 w/ qs8 connectors for 8s. I’m a little worried about pulling so much power through the ec5 connector, but the wires as well are like 6 or 6.5mm on the battery side.

I don’t want to replace my batteries just yet, but I also don’t want a fire. I’ve seen people go ec5 to qs8 on forums, but it still seems sketchy

 

[DavidB1126]

Well 1st, I wouldn't run a kraton on 12s, unless your kevin talbot.
Uhh, not too into plugs, but I think QS8s are the biggest that there are? I seen alot of speed runners use them with no issues.
Welcome!

 

[Kratonwatch]

Well 1st, I wouldn't run a kraton on 12s, unless your kevin talbot.
Uhh, not too into plugs, but I think QS8s are the biggest that there are? I seen alot of speed runners use them with no issues.

I’m curious to know if pushing power from 6mm cables (4s batteries) to esc through qs8 connectors and 8mm wires is going to be an issue considering the difference in wire gauge

 

[DavidB1126]

I’m curious to know if pushing power from 6mm cables (4s batteries) to esc through qs8 connectors and 8mm wires is going to be an issue considering the difference in wire gauge

No clue. @tntpoof might be the person to ask?

 

[Kratonwatch]

No clue. @tntpoof might be the person to ask?

Ty anyway! I’m sure there will be heat in batteries and connectors, but hopefully not enough where it’s cause for concern

 

[tntpoof]

stay with the 8's. why go to a smaller plug.makes no sence to me. My 1cent worth is 8's.600 amp vs 240 B amps or 120 amp c

 

[Mrgoodwrench35]

It's completely fine to do as you intend. I wouldn't want to risk running Ec5's either as their current rating is much lower than Qs8's. That's what I run on all my 8s stuff. I would also suggest getting the V2 Qs8 anti-spark. Good stuff.

 

[tntpoof]

He be running 12 cells.its not fine its a fire wanting to happen.

 

[Kratonwatch]

He be running 12 cells.its not fine its a fire wanting to happen.

Alright so I won’t run it 12s. I thought maybe one day I’d throw packs in and see what happened. This is 99.9% of the time an 8s rig. Sorry y’all, edited the post.

 

[Mrgoodwrench35]

My comment was in reference to the 8s platform. At 12s, the car would destroy itself long before it could catch fire. 12s wouldn't make much of a difference to the connectors anyway since the esc and motor are depicting the current flow, not the connector or the battery so I'm confused as to why you think that would catch fire.

So as I said, it's OK to run the QS8's.

 

[Jerold]

The current is the problem not the voltages, so 12S or 8S shouldn't matter. Connectors that are used in commercial products have lots of well documented specs, including max voltage and current ratings. In the case of 12S (50V) or 8S (33V) it's not going to matter a whole lot. If you were going from 8S to 80S I might be more concerned.

This link is useful
https://blog.ampow.com/rc-battery-connector-types/

In that link they have current ratings based on the diameter of the connector. It should give you an idea of what you can do with any connector. For reference QS8 is an 8mm connector. A QS8 is typically rated at 300A.

• 2mm Bullet = 25 Amps
• 3.5mm Bullet = 50 Amps
• 4mm Bullet = 90 Amps
• 5mm Bullet = 120 Amps
• 5.5mm Bullet = 130 Amps
• 6.0mm Bullet = 150 Amps
• 6.5mm Bullet = 160 Amps
• 8.0mm Bullet = 200 Amps +

QS8 will be more than robust. I have pulled >500A through QS8 connectors, on speed runs, and they hold up fine for that application. The difference is bashing is a much longer duration. However if your pulling 500A for 20 min your motor will be toast.

The down side to the QS8, is they are a bit finicky to solder. Make sure you mate them before you heat them up to prevent warping the plastic, use flux and a high power soldering iron. Lots of YT videos out there on it.

Also the black on black doesn't show well when it's NOT seated. In that case you burn up the connector. Not to brag, but I'm what you call an expert at burning up QS8s.

The connection is very stiff and always double check it, you might think it's fully seated and it's not. The car turns on fine and might even run OK but all the current ends up going through the 5Ω path or has limited contact with the low resistance path. Either way it smells good.

The Max 5 ESC uses 8AWG wire which is correct for QS8s.

 

[Kratonwatch]

Thank you everyone!!

 

[Mrgoodwrench35]

I just watched a guy running 12s in a 1/5 outcast, for nearly 2 hours straight, 3 sets of packs, all on Qs8's and the connectors never even got warm, let alone catch on fire.

 

[Mrgoodwrench35]

I just watched a guy running 12s in a 1/5 outcast, for nearly 2 hours straight, 3 sets of packs, all on Qs8's and the connectors never even got warm, let alone catch on fire.

I also just recently learned that there are Qs10's that speed run guys are using. Complete overkill for 8s, I think even 12s.

 

[Jerold]

I also just recently learned that there are Qs10's that speed run guys are using. Complete overkill for 8s, I think even 12s.

I think it's over kill.

With a good QS8 you can run 500A through them for a short time without issue. I wouldn't do it all day, but for a 20sec speed run it's fine. Even if it gets a bit warm it shouldn't be enough to damage it. If your connectors are getting hot, there is a problem or you are abusing them.

You can follow the wire gauge on your ESC. If it's 8-10AWG an 8mm connector should be more than enough.

The problem is the resistance of the connector turns into to heat. Smaller connectors have less contact area and generate more resistance. The reality is you won't see the power loss until you are going way fast at the absolute limit. You "probably" won't melt a connector until your pulling 800-1000A.

RC connectors specs are pretty loose. If you were designing it into a product, like a washing machine, there would be a complete data book with all the specs about voltage, current, mating depth, insertion cycles, ... I have yet to see any of this on any RC connector with the exception of the Perfect Pass QS8s states they are good for 600A burst. However, a "burst" is not defined by time. Which still makes it a toy.

Toys as they may be, they are the empirically the best we can get at the moment. No one is going to spend a few hundred thousand dollars to design a proper power connector for an RC application.