Ripple voltage questions

[dure16]

Infraction V2. Castle MMX(6) and 1520. Zeee 3S 100C 7.2ah (2). General bashing - geared for 60mph.

I’m seeing 13% ripple voltage. I’ve read that anything over 10% can kill the ESC.

1. Do I need a cap pack?
2. Can I add it at the battery connector instead of splicing the ESC leads?
3. Is there any other way to reduce ripple? Better batteries?

 

[Diem Turner]

Infraction V2. Castle MMX(6) and 1520. Zeee 3S 100C 7.2ah (2). General bashing - geared for 60mph.

I’m seeing 13% ripple voltage. I’ve read that anything over 10% can kill the ESC.

1. Do I need a cap pack?
2. Can I add it at the battery connector instead of splicing the ESC leads?
3. Is there any other way to reduce ripple? Better batteries?

1. Yes. As you correctly identified, anywhere you have ripple voltage above 10%, a cap pack should be used.
2. Although it is recommended to splice the cap pack in as close to the ESC as possible, I have seen it spliced in at the battery connector and it appeared to function as it should. If you can, splice it at the base of the ESC power leads.
3. No. Batteries will make no difference. The only other method (that I'm aware of) is using an ESC that has lower ripple by default such as the XLX2. I realize this isn't the most practical ESC for all applications, but when it comes to ripple voltage, the XLX2 is king.

I spliced some 8mm bullets to my ESC leads so I can disconnect my cap pack when taking the car apart. It's a bit cumbersome when the cap pack is permanently affixed to the ESC. Now, you might ask why I have a cap pack attached to my XLX2. It's not because it needs it. I just put it in because I paid a lot of money for it during my MMX8S days and figured, "it can't hurt" and I have a penchant for overkill.

 

[dure16]

1. Yes. As you correctly identified, anywhere you have ripple voltage above 10%, a cap pack should be used.
2. Although it is recommended to splice the cap pack in as close to the ESC as possible, I have seen it spliced in at the battery connector and it appeared to function as it should. If you can, splice it at the base of the ESC power leads.
3. No. Batteries will make no difference. The only other method (that I'm aware of) is using an ESC that has lower ripple by default such as the XLX2. I realize this isn't the most practical ESC for all applications, but when it comes to ripple voltage, the XLX2 is king.

I spliced some 8mm bullets to my ESC leads so I can disconnect my cap pack when taking the car apart. It's a bit cumbersome when the cap pack is permanently affixed to the ESC. Now, you might ask why I have a cap pack attached to my XLX2. It's not because it needs it. I just put it in because I paid a lot of money for it during my MMX8S days and figured, "it can't hurt" and I have a penchant for overkill.
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Thanks for the detailed response! I like the idea of using connectors to make it removable.

 

[Diem Turner]

Thanks for the detailed response! I like the idea of using connectors to make it removable.

Anytime bro. I've tried both and can definitely recommend the practicality of the connectors

 

[Tex Koder]

1. Yes. As you correctly identified, anywhere you have ripple voltage above 10%, a cap pack should be used.
2. Although it is recommended to splice the cap pack in as close to the ESC as possible, I have seen it spliced in at the battery connector and it appeared to function as it should. If you can, splice it at the base of the ESC power leads.
3. No. Batteries will make no difference. The only other method (that I'm aware of) is using an ESC that has lower ripple by default such as the XLX2. I realize this isn't the most practical ESC for all applications, but when it comes to ripple voltage, the XLX2 is king.

I spliced some 8mm bullets to my ESC leads so I can disconnect my cap pack when taking the car apart. It's a bit cumbersome when the cap pack is permanently affixed to the ESC. Now, you might ask why I have a cap pack attached to my XLX2. It's not because it needs it. I just put it in because I paid a lot of money for it during my MMX8S days and figured, "it can't hurt" and I have a penchant for overkill.
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I love the idea!
Locking that up in my brain for future use

Especially with the way you've soldered the connectors right up to the base of the battery cables!!
Can't get any closer than that!

 

[dure16]

I have a hobbywing cap pack on the shelf. Is there any reason I can't use it with the castle MMX? This guy:

 

[Diem Turner]

I have a hobbywing cap pack on the shelf. Is there any reason I can't use it with the castle MMX? This guy:


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Nope, no reason. A cap pack is a cap pack.

 

[dure16]

Nope, no reason. A cap pack is a cap pack.

Thank you

 

[Diem Turner]

Thank you

Well, one thing worth looking out for is what voltage the cap pack is rated for. It's fine if the cap pack can handle more voltage than you're running (though it won't be quite as efficient) but I don't think you want to run more voltage than the cap pack can handle or you'll probably blow the caps.

 

[dure16]

Well, one thing worth looking out for is what voltage the cap pack is rated for. It's fine if the cap pack can handle more voltage than you're running (though it won't be quite as efficient) but I don't think you want to run more voltage than the cap pack can handle or you'll probably blow the caps.

I've looked high and low and can't find the specs on this cap pack. Hobbywing only lists specs for their 1/10th scale packs online. They list this one as 1/8 scale but no other details.

 

[Diem Turner]

I've looked high and low and can't find the specs on this cap pack. Hobbywing only lists specs for their 1/10th scale packs online. They list this one as 1/8 scale but no other details.

Then I think it's fair to assume that the cap should be able to handle as much voltage as the XR8. So up to 6S/25.2V.

 

[ArrmaFreek2022]

1. Yes. As you correctly identified, anywhere you have ripple voltage above 10%, a cap pack should be used.
2. Although it is recommended to splice the cap pack in as close to the ESC as possible, I have seen it spliced in at the battery connector and it appeared to function as it should. If you can, splice it at the base of the ESC power leads.
3. No. Batteries will make no difference. The only other method (that I'm aware of) is using an ESC that has lower ripple by default such as the XLX2. I realize this isn't the most practical ESC for all applications, but when it comes to ripple voltage, the XLX2 is king.

I spliced some 8mm bullets to my ESC leads so I can disconnect my cap pack when taking the car apart. It's a bit cumbersome when the cap pack is permanently affixed to the ESC. Now, you might ask why I have a cap pack attached to my XLX2. It's not because it needs it. I just put it in because I paid a lot of money for it during my MMX8S days and figured, "it can't hurt" and I have a penchant for overkill.
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I agree with all except that using better batteries will in fact help with Ripple voltage. Here is a good explanation:

https://www.radiocontrolinfo.com/ripple-voltage-in-an-esc-explained-and-how-to-improve-it/

 

[Diem Turner]

I agree with all except that using better batteries will in fact help with Ripple voltage. Here is a good explanation:

https://www.radiocontrolinfo.com/ripple-voltage-in-an-esc-explained-and-how-to-improve-it/

Cheers, much appreciated.

 

[Jerold]

Infraction V2. Castle MMX(6) and 1520. Zeee 3S 100C 7.2ah (2). General bashing - geared for 60mph.

I’m seeing 13% ripple voltage. I’ve read that anything over 10% can kill the ESC.

1. Do I need a cap pack?
2. Can I add it at the battery connector instead of splicing the ESC leads?
3. Is there any other way to reduce ripple? Better batteries?

Ripple voltage is actually a voltage droop under load. By adding caps it temporarily increases your C-Rating for a very short period of time. If you add a cap pack keep the connections close to the ESC and stout. Resistance is not your friend. If you want more gory details, I have another thread on it.
https://www.arrmaforum.com/threads/ripple-voltage-explained.49930/

The C-Ratings don't apply for all situations and there is no standardized testing method. If you want to understand more about battery testing there is a good thread on RC Groups. To cut to the chase look for the report spreadsheets and you can see where different batteries place. Not every battery is tested and I "think" they are all 6S. So you many not find your exact battery.
https://www.rcgroups.com/forums/showthread.php?1767093-Battery-Load-Test-Comparisons

 

[Moirae]

I wonder if the capability of the esc is also part of the problem? I don't know what the gearing is like but castle explicitly states on their website

"Not recommended for use in high speed 1/8th and larger applications (IE Arrma Infraction and Limitless, Traxxas XO-1)"

Maybe the cap pack will be a bandaid?

 

[dure16]

I wonder if the capability of the esc is also part of the problem? I don't know what the gearing is like but castle explicitly states on their website

"Not recommended for use in high speed 1/8th and larger applications (IE Arrma Infraction and Limitless, Traxxas XO-1)"

Maybe the cap pack will be a bandaid?

The specs also say this ESC supports on-road and off-road cars up to 15 pounds, and I'm well below that. I have it geared pretty low which works in my favor as well.

I think they mention "high speed" to ensure you're not speed running these big cars. But I'm definitely making some assumptions there .

Does pushing an ESC hard increase ripple voltage?

 

[Diem Turner]

The specs also say this ESC supports on-road and off-road cars up to 15 pounds, and I'm well below that. I have it geared pretty low which works in my favor as well.

I think they mention "high speed" to ensure you're not speed running these big cars. But I'm definitely making some assumptions there .

Does pushing an ESC hard increase ripple voltage?

Yes.

 

[Moirae]

The specs also say this ESC supports on-road and off-road cars up to 15 pounds, and I'm well below that. I have it geared pretty low which works in my favor as well.

I think they mention "high speed" to ensure you're not speed running these big cars. But I'm definitely making some assumptions there .

Does pushing an ESC hard increase ripple voltage?

Just thought I'd mention it because I blew a mm2 on 4s in a typhon 3s. Granted it was a 3770 kv tp motor but still. I was geared for about 75 mph and pop

 

[dure16]

Just thought I'd mention it because I blew a mm2 on 4s in a typhon 3s. Granted it was a 3770 kv tp motor but still. I was geared for about 75 mph and pop

Ouch! I appreciate the advice. I'll upgrade the ESC if I can't get this ripple under control.

 

[Jerold]

I wonder if the capability of the esc is also part of the problem? I don't know what the gearing is like but castle explicitly states on their website

"Not recommended for use in high speed 1/8th and larger applications (IE Arrma Infraction and Limitless, Traxxas XO-1)"

Maybe the cap pack will be a bandaid?

Yes and no.

Some ESCs have lots of capacitance to make up for batteries and line losses. But that is not sustained current. The batteries provide the sustained current. The caps are literally a small cache of energy close to the ESC.

If you over gear the car, it can put stress on the ESC and/or the battery. Voltage droop (AKA Ripple Voltage) is a sign that your power system (the batteries) cannot provide the current requested. In this case I don't believe that you are pulling too much current through the ESC, the tend to burn up when you do that. Remember you can't give current something has to pull it.