DNA with USB Charge Circuit

[Cyclin]

Hi there,

I am building a VV Box mod with the dna by Evolv and I was hoping one of you geniuses can answer a question for me.

I will be using 1 or 2 LiPo batteries (if two, then in parallel) and was wondering if this Basic USB Charge Circuit will work? If it will work on 1 LiPo batteries in a sealed boxmod, will it also work on 2 batts in parallel?

I don't recall if using two batts in parallel is still considered a single cell, or if it makes a difference to the charging circuit.

Thanks

Cyclin

 

[slimest]

This board should work with 1 or 2 cells in parallel. Good charger, but expensive. Anyway, you make the thing for yourself, do it

 

[BuzzKilla]

If you are going to be using two cells in parallel, eventually the cells are going to be out of balance.
you have to be either peak charge the cells individually or charged with a balance charger, every few cycles... you can go longer without doing so, but with lipos its in your best interest to keep the cells at a balanced voltage.

i would say, every 10 cycles take a volt meter to each cell, and if the cells are off by .1V it needs to be balanced....
In the RC world i ballance charge my lipos, every cycle, but they take more abuse and actually need it.

The darwin actually does this internally i believe.

there are many people that will say it is unnecessary, but i will advocate safety.

if you have the room in the PV for a larger single cell, it would be just easier to go that route. (for charging purposes)
Turnigy 2200mAh 1S 20C Lipoly (Single Cell)

The true risk of charging Lipo's in parallel is that if one battery is lower than the other, you run the risk of overcharging one of the cells, as the charger tries to peak charge.

over charging lipo's = fireworks....

if you already have a charger that is capable of balancing, go for it. If not, save yourself the hassle and worry and just use a higher mAh single cell.

EDIT:
the chargr you pointed out to is a 500mA max charger... it would take you almost 4.5hours to charge a 2200mAh battery.
Something to be aware of

 

[perlionsmitnick]

This one charges at 1.2A and can be used for li-ion or li-poly. I agree with the above to use a single cell and go high on the mah.

 

[Cyclin]

Good suggestion I think I will stick with a single batt then. Unless you can point me to a usb charge circuit that supports balanced charging. Also, as per the DNA datasheet the max charge rate the cicuit should use is 500mA isn't it? Or is it just the spec of the circuit they will be offering?

This one charges at 1.2A and can be used for li-ion or li-poly. I agree with the above to use a single cell and go high on the mah.

Would that circuit be safe to charge at this rate?

 

[BuzzKilla]

Isnt Evolv, coming out with a charging circuit?
Eventually... lol

On the datasheet, it states the evolv's own charger will be 500mA

the only balance chargers that i've seen are table top chargers.
but it would be nice if Evolv came out with a ballance charging board that can be wired up to the DNA... *hint *hint.. anyone listening!

 

[Cyclin]

Isnt Evolv, coming out with a charging circuit?
Eventually... lol

On the datasheet, it states the evolv's own charger will be 500mA

the only balance chargers that i've seen are table top chargers.
but it would be nice if Evolv came out with a ballance charging board that can be wired up to the DNA... *hint *hint.. anyone listening!

Ya Brandon said they would release it either this week or next week when I emailed him, but if this circuit I posted will work I think I will order this one, and then put Evolv's circuit in my next mod to see if there is a big difference in installation difficulty and performance.

 

[breaktru]

Hi there,

I am building a VV Box Mod with the DNA by Evolv and I was hoping one of you geniuses can answer a question for me.

I will be using 1 or 2 LiPo batteries (if two, then in parallel) and was wondering if this Basic USB Charge Circuit will work? If it will work on 1 LiPo batteries in a sealed boxmod, will it also work on 2 batts in parallel?

I don't recall if using two batts in parallel is still considered a single cell, or if it makes a difference to the charging circuit.

Thanks

Cyclin

That's the same charger I am using in my two MCU mods. Yes it takes about 5 hours to charge the two paralleled Li-pos (2000mah - 40C rating)
I don't mind the time. Have lots of mods to use while charging.
I don't think balancing is a problem with paralleled Li-pos. After all they come that way when you buy a li-po pack. (I read that on a hobby site).

See quote from sparkfun's tech: Sparkfun Charging Li-Pos

 

[Cyclin]

That's the same charger I am using in my two MCU mods. Yes it takes about 5 hours to charge the two paralleled Li-pos (2000mah - 40C rating)
I don't mind the time. Have lots of mods to use while charging.
I don't think balancing is a problem with paralleled Li-pos. After all they come that way when you buy a li-po pack. (I read that on a hobby site).

See quote from sparkfun's tech: Sparkfun Charging Li-Pos

Ok good to know, I ordered two 2200mah 1S 20C's in case I still wanted to put them in parallel. I just don't want it to be unsafe I suppose. Quick question on the wiring, I would wire the batts to the DNA and the charging circuit to the DNA seperate from each other, right? or do I need to wire the batts to the charge circuit?

By the way thanks for eJuice Me Up! I use it all the time I've also been following your thread here on ECF regarding the DNA, were you able to achieve a steady watt when firing or are there still fluctuations?

 

[breaktru]

Ok good to know, I ordered two 2200mah 1S 20C's in case I still wanted to put them in parallel. I just don't want it to be unsafe I suppose. Quick question on the wiring, I would wire the batts to the DNA and the charging circuit to the DNA seperate from each other, right? or do I need to wire the batts to the charge circuit?

By the way thanks for eJuice Me Up! I use it all the time I've also been following your thread here on ECF regarding the DNA, were you able to achieve a steady watt when firing or are there still fluctuations?

I found a disadvantage to using the charge pins on the DNA, at least on my setup.
By using the pins, the circuitry is live. I don't want to use diodes to block the reverse feed so I chose to break the charger negative side to the on/off 3rd pin of the on/off switch.

Still get fluctuations.
Glad eJuice Me Up is working out for you and thanks for following.

 

[Cyclin]

Ok I threw together a really basic layout. I believe its going to need changes I'm just a little rusty at this sort of thing. Would this even work? cause a fire? turn into a cheeseburger?

And if were to throw a voltage reader on this, where would I? This is the voltage reader I have a couple of at the house. Or do I need to use a watt reader?

 

[jmarkus]

you can use the volt meter and attach it between the board and the 510 connector to get loaded volts on the atty. you wont get a voltage readout unless you have an atty connected.

 

[BuzzKilla]

that diagram looks like the way the DNA was intended to be wired up...

got any ideas for case?

it would be interesting to see where you are taking this...

 

[Cyclin]

you can use the volt meter and attach it between the board and the 510 connector to get loaded volts on the atty. you wont get a voltage readout unless you have an atty connected.

Awesome thanks!

that diagram looks like the way the DNA was intended to be wired up...

got any ideas for case?

it would be interesting to see where you are taking this...

Ya the case I'm doing in russian birch, it will be a sealed mod with custom leather grip. I'm doing it on a 75 watt laser and cutting out 1/4" layers. Basically I lay in correctly sized wood, and let the laser vector-cut the outlines. Right now I am using an outline of a custom pistol grip, so basically first I cut out the whole grip with a rectangle out of the middle for the voltage reader. The laser can go to the .001" so I measure it all with digital calipers first. Then I keep cutting out layers of the 1/4" in a way to build each compartment then placed the electronics in, and the last couple layers of 1/4" to seal off the electronics compartments and complete the case. This way I should be able to fit everything in the exact way I'd like. A little extra epoxy in the places where the atty connector, usb, switch, and potentiometer and the holes cut out to show LEDs should make the seal nice and tight

 

[jmarkus]

awesome, can't wait to see it!

 

[slimest]

There are very good chargers made on contemporary platform, inexpensive and miniature enough. You can easily adjust charging current from 100 ma to 1A by resoldering only one resistor. Today I got two boards, ordered two more
5V Mini USB 1A Lithium Battery Charging Board Charger Ultra Small Module | eBay