[CLOSED]

[beckdg]

One can potentially charge a ton of lipos FAST. I sometimes charge @ 5C.

Tapatyped

 

[Chowderhead1972]

Pretty close as far as I read.

Though the wave is a square one and the current is still DC.

Alternating current changes direction and thus can be read as going from pos to neg and back in one cycle or hert(z).

DC (direct current) doesn't change polarity.

The square wave in this instance is merely representative of a switch turning off and on so many times per second (frequency or hertz).

A sine wave is representative of a motor being spun to make electricity.

Tapatyped

Square wave or Sine wave is still alternating peak to peak is it not. Granted in the textbooks it's not refered to as such but in the actual produced output the vertical bars on your oscilicope ar merely representative of motion or change not an actual signal or voltage in this case. My point is you're splitting vocabulary hairs at this point. At the end of it all the __________________ is chopped into _-_-_-_-_ and then filtered back to - - - - - - perhaps I have oversimplified but this is the basics of PWM.

 

[beckdg]

In dc it's peak to valley.

And a square wave will damage most electronics made for ac voltage.

It's far from splitting hairs.

A sine wave has no vertical or horizontal bars on an o-scope. A square wave is basically nothing but.

You got the basics of pwm. You understand it. Just clarifying a couple things for you and anyone who comes along.

ETA: A square output "pulses" whereas a sine wave "ramps" up and down. Square = suddenly here then suddenly there.

To make a sine wave... write the letter S on a piece of paper. Then turn the paper 90 degrees clockwise. It looks nothing like those lines. And the function is distinctly different.

And yes... if it's graphed on an o-scope... it's voltage... period.

Tapatyped

 

[Chowderhead1972]

But we aren't talking about putting a square wave into an ac load..
We are talking about its use across a nichrome coil, the nichrome, kanthal ti, n2? Is unaffected by the frequency of ac or lack thereof in a Dc current. You could argue that the coil could wiggle a little under low frequency ac but even still not violently enough to cause damage at the prescribed temps. lets not dive head first into digital power supply there is just no need.. We are talking about low voltage high amperage output used to power a very simple coil.

 

[beckdg]

But we aren't talking about putting a square wave into an ac load..
We are talking about its use across a nichrome coil, the nichrome, kanthal ti, n2? Is unaffected by the frequency of ac or lack thereof in a Dc current. You could argue that the coil could wiggle a little under low frequency ac but even still not violently enough to cause damage at the prescribed temps. lets not dive head first into digital power supply there is just no need.. We are talking about low voltage high amperage output used to power a very simple coil.

Don't do this.

We're talking dc current. Period. It's going to be flat and the signal (voltage) is going to be square as the voltage is pulsed on and off... not ramped.

There is no a/c inverter involved.

There is no need for further confusion... and I haven't had electrical engineering courses In 20 years.

Tapatyped

 

[Tbev]

Dude said he ran his truck [rc] around a track for 45 min on that pack, it's $40. I'd have to assume that should be able to fire a couple coils at say 150 w for quite a while. . .

 

[Tbev]

If anyone can recommend some good lipos, a charger, etc I'll start playing around.

Is everyone game to hop on the lipo train. I'd way rather go that direction than replace my old vtc's with he2/25r's

 

[Tbev]

Beck, how much money do you have in those cells and the charger?

 

[beckdg]

Wow

Just realized that was a max amps pack. Do your research on that scumbag. The specs are severely inflated and dangerous at the very least.

And the price is inflated twice to accommodate the spec(ial label).

100 efest cells can't hold a candle to Brandon and 1 max amp pack.

Expect the pack to last twice as long as a similarly rated cylindrical cell since it's a two cell (2S) pack. The specs mean the same thing across the board.

Tapatyped

 

[beckdg]

Beck, how much money do you have in those cells and the charger?

Those 5000mah+ 2s2p, 70c nominal packs were about $40 each. And they're damn good cells.

The power supply, I got for about $15 shipped on ebay and converted.

Search hp dps 600 2genewb for my how to on ultimaterc.

The parallel board was a few bucks... but with traxxas plugs I had to install them myself.

The charger itself I think was about 180. Check progressiverc for current pricing.

If i were in your shoes, I'd pick up a power lab right off the bat.

As far as smaller cells, I'd probably wind up with turnigy cells of one sort or another. I'd check with the boys running 1/16 and 1/18 scale and some flyers to see exactly what brands and lines are consistent these days. I don't have anything in those scales to know.

Tapatyped

 

[Tbev]

$100+ fire a charger is gonna be the nail in this coffin. I guess that's why the onboard charger or piggyback chasing board with the 1ma charger is how they go. If you could charge these things for twenty bucks I think it would be a green light, but that's a killer imo.

 

[Hemptation]

They make lipo chargers cheaper than that TBev. 30-40$ range.

And honestly. The 1 mod I have that has a lipo battery in it. Is a 3400mah. With a dna30. And it has been the most consistent least problematic mod owned. My local b&m owner picked up 3 from the Chattanooga show last November. Made by an engineer out of texas. All 3 are still strong and running great to this day. I think you are on the right track. I like the looks of the yihi chip to. From a build stand point. Seems like you can designate a shell for the chip and lipo. Separate. And sealed for the chip With removable section for lipo and bottle. Not an easy task. But doable

 

[beckdg]

$100+ fire a charger is gonna be the nail in this coffin. I guess that's why the onboard charger or piggyback chasing board with the 1ma charger is how they go. If you could charge these things for twenty bucks I think it would be a green light, but that's a killer imo.

My charger is capable of 30 amps at 1000 watts max rating. Your customers won't need anything like that. They can get chargers in the range you're talking. Though for long term investment for a supplier (you), the power lab would be the way to go. The red never be a need for an upgrade.

With my charger and a little ingenuity, I could charge all the cylindrical cells owned by every person who posted here simultaneously and still have quite a bit of headway.

Though the accuracy and dependability of the power labs would pay for itself once you're supplying lipos in mods to your customers.

Look for a list of inexpensive chargers posted by a user named billdelong on ultimaterc dot com.

Tapatyped

 

[Tbev]

I'm thinking of including two lipos and a charger with the mod, like a high end starter kit .

 

[beckdg]

Tom has always had stout, reliable packs...

http://spcracingbatteries.com/index.php?route=product/product&path=59&product_id=54

http://spcracingbatteries.com/index.php?route=product/product&path=59&product_id=53

I guarantee that 2s 50c pack will keep with or blow that 100c max amps pack out of the water. Tom also discounts or disposes packs that don't meet internal resistance specs.

Feel free to contact him. Hes a good guy and enjoys a good discussion amd helping people out. Tell him 2genewb sent ya.

You'll have to check physical dimensions yourself. I'm not good with visualizing and I'm rarely home to mock up something to gauge with.

Tapatyped

 

[ST Dog]

But we aren't talking about putting a square wave into an ac load..

No, you don't want that. That's averaging which a few mods have done and they have problems due to the high power pulses. So you hit the coil with a 100W pulse for 25% of the period, then 0 for 75%. Averages out to 25W, but those short 100W pulses cook the juice.
Not the same as sending a smooth, steady voltage/current.

and I haven't had electrical engineering courses In 20 years.

Me either, and I was VLSI. I haven't even analyzed (never mind designed) a boost circuit in 20 years.
That's why I didn't get into details

 

[ST Dog]

Those 5000mah+ 2s2p, 70c nominal packs were about $40 each. And they're damn good cells.

Those packs are huge though, way to big for a mod.

Cost is also why I stuck to glow fuel instead of electric.
I could refuel in a minute or so and run all day without $100s ($1000?) in batteries.

The charger itself I think was about 180. Check progressiverc for current pricing.

Sounds about right for a hobby charger. There was on I was watching on CandlePower that looked good, but the price was just going to be too high. I wanted something to adjust charge rate instead of just a few settings, plus a better CC/CV curve, control over cutoff current, discharge cycles for conditioning and balancing.

I checked and the 306B is currently $160 (plus a power supply).
But, 30A might be over kill for mods. The 10A 106B for $90 would be more than adequate for a mod.

$115 for a combo w/ 220W power supply, though again, for a mod, that seams excessive. A 90-100W supply should be more than sufficient, re-purpose some old laptop supplies

 

[ST Dog]

SPC LiPo Power, Lithium Polymer (LiPo) Battery Pack; 1500mAh, 30C, 3S, 11.1V Soft-Case

That one (3S1P) would make the boost circuit not needed. Simple down regulation then.
1500mAh 30C, so 45A, @ 11.1V would be nearly 500W available.
(equivalent to 3900mAhr in a 4.2V cell)

Even at 9V on a 0.5ohm build, that's 160W. ( or 4V across 0.1ohm).

 

[beckdg]

Those packs are huge though, way to big for a mod.

Cost is also why I stuck to glow fuel instead of electric.
I could refuel in a minute or so and run all day without $100s ($1000?) in batteries.



Sounds about right for a hobby charger. There was on I was watching on CandlePower that looked good, but the price was just going to be too high. I wanted something to adjust charge rate instead of just a few settings, plus a better CC/CV curve, control over cutoff current, discharge cycles for conditioning and balancing.

I checked and the 306B is currently $160 (plus a power supply).
But, 30A might be over kill for mods. The 10A 106B for $90 would be more than adequate for a mod.

$115 for a combo w/ 220W power supply, though again, for a mod, that seams excessive. A 90-100W supply should be more than sufficient, re-purpose some old laptop supplies

I run all day with $80 In batts. Then use them again and again.

Yes... way too huge for a mod... but still less costly than the tiny maxamps.

You're way over budget for a charger for these. $30 total tops for your regular consumer.

Tapatyped

 

[beckdg]

That one (3S1P) would make the boost circuit not needed. Simple down regulation then.
1500mAh 30C, so 45A, @ 11.1V would be nearly 500W available.
(equivalent to 3900mAhr in a 4.2V cell)

Even at 9V on a 0.5ohm build, that's 160W. ( or 4V across 0.1ohm).

Always figure any lipo for maximum half it's continuous rating be it for continuous or burst use. Many will puff well below that.

Tapatyped