Have tech questions? Will answer.

[JSterrett]

Using the water analogy...

If you have 2 hoses emptying into a pool, at say 2 gallons/minute each, your total flow into the pool will be 4 gallons/minute.

I could also be wrong here, but this has always been my understanding.

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[mikemcE]

Just don’t put the batteries in the pool......


Hang up and Drive

 

[drzoo2]

just need to confirm, wiring two 2S packs in parallel will double amp hour rating, but will C rating (amp output rating) also double?

Assuming your batteries are IDENTICAL in every way. Age, manufacturer, ratings, ect.......

Then you can ALMOST add C ratings. Unless you can measure the "Source Impedance" of each pack, you should derate by a good margin to be safe.

if just one of these is not true then your asking for trouble.


A "C" rating is really a point where "heat" generated from a battery is WITHIN the batteries ability to safely "dissipate" that heat. You can say that the "C" rating is technically a way of specifying safe operating temperature. An important characteristic that determines this is "Source Impedance"


When battery packs are assembled, ideally the impedance variation Cell to Cell is exact. When under load, each cell should discharge at the same rate. Because of cost and other considerations cells are within a range of each other and not exact, hence the need to balance charge. Variation can exist by the same manufacturer. Some packs could easily meet the desired C rating for that model while others could be marginal. Without measuring, You would have no way to knowing.

So, all that said, using the hose analogy above.....
One hose may be exactly 1/2 diameter while the other is 7/16. Which of the two is going to empty their reserve faster?

 

[JSterrett]

Assuming your batteries are IDENTICAL in every way. Age, manufacturer, ratings, ect.......

Then you can ALMOST add C ratings. Unless you can measure the "Source Impedance" of each pack, you should derate by a good margin to be safe.

if just one of these is not true then your asking for trouble.


A "C" rating is really a point where "heat" generated from a battery is WITHIN the batteries ability to safely "dissipate" that heat. You can say that the "C" rating is technically a way of specifying safe operating temperature. An important characteristic that determines this is "Source Impedance"


When battery packs are assembled, ideally the impedance variation Cell to Cell is exact. When under load, each cell should discharge at the same rate. Because of cost and other considerations cells are within a range of each other and not exact, hence the need to balance charge. Variation can exist by the same manufacturer. Some packs could easily meet the desired C rating for that model while others could be marginal. Without measuring, You would have no way to knowing.

So, all that said, using the hose analogy above.....
One hose may be exactly 1/2 diameter while the other is 7/16. Which of the two is going to empty their reserve faster?

If you were responding to me, I was going more for "general theory" rather than practical application. I totally agree that running anything at 100% of it's ratings is asking for trouble.

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[Voodoobrew]

I am 100% about everything I said except that specifically regarding C ratings. I have never cared to understand C-ratings because I don't push my batteries at all and they never feel warmer then ambient temperatures to me. Crawlers are pretty easy on batteries.
examples: with rough hypothetical numbers
1x battery
5,000mAh
50 amps max drain before thermal detonation er whatever
5 amp charge rate
12 volts

2x batteries in parallel
10,000mAh
100amps max drain
10 amp charge rate
12v

2x batteries in series
5,000mAh
50amps max drain
5 amp charge rate
24v

I have a pool guy so I have no idea how many hoses it takes to fill a pool in one hour.

 

[drzoo2]

If you were responding to me, I was going more for "general theory" rather than practical application. I totally agree that running anything at 100% of it's ratings is asking for trouble.

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Your analogy was spot on. I was taking it 1 small step further to explain variation in cell drain.

Hose size vs. electrical impedance. Both are resistant to flow, one water, the other current. "thumbsup"

I am 100% about everything I said except that specifically regarding C ratings. I have never cared to understand C-ratings because I don't push my batteries at all and they never feel warmer then ambient temperatures to me. Crawlers are pretty easy on batteries.

I agree through the question I was answering was can you add C ratings? Not the viability of running 100% available current. Margin is good in both cases.

 

[bquin]

sooo will a brushed 400 puller 20t handle a 4 cell? Ive looked and couldn't get a solid answer........geared properly of course

 

[Voodoobrew]

Holmes has stated in the forums here any of his brushed motors could handle 4s. But you should monitor the temperatures.

:Edit: I cant for the life of me find the post so I may be mistaken, he has said his 35t motors handle 4s no problem, and I run the 550 crawlmaster 10t on 4s, never gave me any problems the car it is in is 100:1 though.
as long as you gear down enough it won't get hot.

 

[bquin]

Holmes has stated in the forums here any of his brushed motors could handle 4s. But you should monitor the temperatures.

:Edit: I cant for the life of me find the post so I may be mistaken, he has said his 35t motors handle 4s no problem, and I run the 550 crawlmaster 10t on 4s, never gave me any problems the car it is in is 100:1 though.
as long as you gear down enough it won't get hot.

good enough for me..... "thumbsup"

 

[Voodoobrew]

4s will wear out the replaceable brushes faster though.

 

[revin9k]

Hello everyone, I have a problem with my servo glitching. I swapped raidos to a dx4c with 4ch rex so I can use my servo winch. When ever I plug everything in I sometimes, depending on where the rex is get crazy glitching in my servo. This only happens when I use everything with the servo winch plugged in. This raido and rex work fine in my other crawler using only 2 channels. Not sure why I'm getting this glitch. I tried moving around the esc wire, batt wire, servo wire and sensor wire to see if I was getting emi but nothing seems to fix it completely.

Eletronics used
Mamba x, holmes puller pro, holmes shv500v2, spektrum dx4c and rec, powershift rc servo winch, 3s lipo

Any help is much appreciated. I will post pics in the am for reference. Thanks

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[JohnRobHolmes]

4s is fine on my motors with proper gearing. The 20t is slow enough that it will be a very nice balance.


Your servo winch is powered through the rX via the mamba x internal BEC? Sounds like it is freaking out the RX, you might need to up or down the BEC voltage a tad.

 

[JohnRobHolmes]

The remedy is buying a $40 HW 1080 and enabling freewheeling. Why spend more on something less capable.

Maybe somebody would like to support a US made product and a US company dedicated to crawling that would like to add in freewheeling to the firmware. I can't compete with a completely china made price, but we are here if people need help and I'm proud to say I've helped grow the crawling market for 13 years now.


I do plan to add freewheeling and drag ramp into the next firmware update.

 

[Browneye]

Maybe somebody would like to support a US made product and a US company dedicated to crawling that would like to add in freewheeling to the firmware. I can't compete with a completely china made price, but we are here if people need help and I'm proud to say I've helped grow the crawling market for 13 years now.


I do plan to add freewheeling and drag ramp into the next firmware update.

Please list your product so it can be found. We love to support HH. "thumbsup"

 

[Inspector86]

Maybe somebody would like to support a US made product and a US company dedicated to crawling that would like to add in freewheeling to the firmware. I can't compete with a completely china made price, but we are here if people need help and I'm proud to say I've helped grow the crawling market for 13 years now.


I do plan to add freewheeling and drag ramp into the next firmware update.

I would love to buy a BLE but it is currently out of stock on your site! Any estimate of when it will be back in stock?

 

[JohnRobHolmes]

Not totally sure, but around two months would be a safe estimate. A supply issue out of my control cause the stockout, I placed my order about 6 months ago.

 

[Voodoobrew]

Maybe somebody would like to support a US made product and a US company dedicated to crawling that would like to add in freewheeling to the firmware. I can't compete with a completely china made price, but we are here if people need help and I'm proud to say I've helped grow the crawling market for 13 years now.


I do plan to add freewheeling and drag ramp into the next firmware update.

Offering freewheeling would be awesome!
I assumed by your comments in this thread it wasn't going to happen. http://www.rccrawler.com/forum/elec...s-trailmaster-ble-pro-update.html#post5871595

 

[JohnRobHolmes]

No more updates in the BLE. bRXL and BR mini are still fair game for progress.

 

[revin9k]

4s is fine on my motors with proper gearing. The 20t is slow enough that it will be a very nice balance.


Your servo winch is powered through the rX via the mamba x internal BEC? Sounds like it is freaking out the RX, you might need to up or down the BEC voltage a tad.

John thanks for the comment. I went in my castle link and dropped my bec voltage to 6v. You were correct that it was turned up to 8v but, at 6v it's still doing the exact same thing. I'm not sure what else to do now. I took a short video of the problem. https://youtu.be/_lzXzTAT08Y

Do I need to bind the raido and rec when swapping them to a different truck with a different steering servo? If so then that could be it.

John I got a sanwa m12s today for my racing buggy. Will the shv500v2 be compatible with the fast response or do I need to reduce or modify it? Sorry this spektrum technology is all new to me

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[Voodoobrew]

John thanks for the comment. I went in my castle link and dropped my bec voltage to 6v. You were correct that it was turned up to 8v but, at 6v it's still doing the exact same thing. I'm not sure what else to do now. I took a short video of the problem. https://youtu.be/_lzXzTAT08Y

Do I need to bind the raido and rec when swapping them to a different truck with a different steering servo? If so then that could be it.

John I got a sanwa m12s today for my racing buggy. Will the shv500v2 be compatible with the fast response or do I need to reduce or modify it? Sorry this spektrum technology is all new to me

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You have avc enabled in the receiver, thats what the twitching is, its designed to correct your steering while racing, to disable it you ad a second bind plug to the receiver while binding or go into avc settings on the remote and set them all to zero but do not disable avc on the remote. Most people prefer to disable it while binding.