Parallax's NEW Self-contained Power-supply Charger
Matt Gilliland
Posts: 1,406
Hi everybody-
Not to deplete the world-wide supply of Lithium further, but I thought you Forum-istas might like a sneak-peak at the "Li-ion Power Pack/Charger - 2 Cell". A mouthful, for sure but the shortest name we could come up with that semi-adequetly describes what it can do.
Short spec list:
Input charging voltage requirement: 5-12 vdc (standard Parallax wall wart works well)
Output voltage: 7.4-8.0 vdc
Output Current 2.0 Amps
Amphour capacity: Nominally, 7.4 vdc @ 2200 mAhr (approx 16 watts)
It's a standard 3" x 4" form factor which makes it "stackable" with other devices - like the BOE or PropProto.
More to come here shortly...
-Matt
Not to deplete the world-wide supply of Lithium further, but I thought you Forum-istas might like a sneak-peak at the "Li-ion Power Pack/Charger - 2 Cell". A mouthful, for sure but the shortest name we could come up with that semi-adequetly describes what it can do.
Short spec list:
Input charging voltage requirement: 5-12 vdc (standard Parallax wall wart works well)
Output voltage: 7.4-8.0 vdc
Output Current 2.0 Amps
Amphour capacity: Nominally, 7.4 vdc @ 2200 mAhr (approx 16 watts)
It's a standard 3" x 4" form factor which makes it "stackable" with other devices - like the BOE or PropProto.
More to come here shortly...
-Matt
1024 x 768 - 43K
Comments
ps. shouldn't you have a sinister laugh in your post after the 7.4v@2200mAH statement? I know this could support a few of my evil plans that utilize a solar panel with an 8.6 volt output.... muahahaha!
Total height is just less than 1". Don't forget that the .dxf's for the enclosures are up on the product page - so if you know someone with a laser cutter you could always make the enclosure taller too...
-Matt
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Looks like your using a brown-out detector to drop the relay out to save the battery's when the voltage gets low?
I'm in the process of writing the Product Documents right now, but I'll share a few highlights of the circuit operation here:
a) the cells are connected in series (7.4-8.0 vdc) when it's supplying power to a *load*.
b) once a charging source is plugged in, the cell output power is shut-off, and the cells are disconnected from each other. Each cell is then independently charged and monitored for proper charging and safety.
c) there's independent cell temperature monitoring (both hot and to cold).
d) the cells can be re-charged 500 to 1000 times (or more) depending on the implemented charge algorithm. This board is set to charge slower than it could be, but that yields greater cycle life for the cells and nearly 100% charge capacity during its useful life - plus, it's safer too.
e) there's auxiliary jacks for connecting directly to a BOE, PropProto, etc. (a polarized cable is included).
f) we'll have "our recommended cells" available - or you can purchase/supply your own.
g) If you wear the cells out - they're easily replaceable.
h) blinky lights with answer-key right on the silk-screen.
-Matt
The short answer is yes.
If you wish to connect a solar panel as the charging source, then as long as the sun shines, you can pull power off the "charging" power input. When the sun-don't-shine, then the Cell output power jack is activated.
More on this, and other features as I wrap my head around the Product Doc this weekend.
-Matt
So should we include the cells with the board or should we make the cells available separately from the Power/Pack Charger? That's a question that maybe you'all can help answer. We'd probably only make enough to cover our cost on the cells anyway (since we don't make them), but I think there's value in one-stop shopping too.
One bundled product, or available separately?
-Matt
It's a floor wax! It's a dessert topping! (SNL ad parody)
I vote to keep them separate... allows us the flexibility to order extra/replacement cells if necessary.
Walter
This looks good!
You know, the shipping regulations for lithium batteries are quite strict, and there may be special labeling and costs involved that would not apply if you ship the charger without the batteries. The regulations are different for batteries installed in equipment vs batteries or battery packs shipped as such, and it depends too on the weight of lithium, and whether you ship air vs ground. International shipping has its own issues. You can find the regs online, but be prepared for a lot of legalese.
I'm curious if the board uses one of the many dedicated charger ICs available, or if it implements the charging in firmware on a µP?
I second this Idea I have alot of these batteries I just need Power/Pack Charger
Hey Tracy - great to see you on the forums as usual. We'll open-source the whole design, of course. Indeed, Matt has customized an off-the-shelf circuit (National parts?) and he'll convey that in the product document and a DipTrace-compatible export from Altium. As Matt described the product I noticed that it was really an excellent showcase of the charging circuitry and temperature sensors.
For me, I'm still working with the simple PB-137 that Chris Savage gave me a few years ago.
Ken Gracey
Since Li-ions can be *tricky* in many ways, we're using a canned charging chip, two actually. They're Microchip 73861's. Although there is a two-cell version of the chip available, we opted for reliability, safety and quality of charge.
As mentioned above, the cells (when the unit is plugged into the wall), are dis-connected from each other and charged independently. This assures no "out of balance" issues, as well as provides individual monitoring of each cell's status.
I think we'll offer the charger/pack and cells individually, as well as a "full kit". Probably not much of a discount for the full-kit because we won't be making anything on the cells themselves anyway. It also allows you'all to use whatever cells you want, either from us from some other source.
We will however *recommend* certain specifications of cells that would perform best in this device.
@_sam - no price yet, that's a Ken thing, and he's not privy to all the internal costs yet. If I we're to guess right now maybe $40? Don't quote me on that - I'm in engineering not finance ;-)
@ Tracy - Hi! Regs don't apply much because of the relatively low total wattage in the cells, and the fact that they aren't tabbed and connected in an array or "pack". It looks like our only issue for shipping these will be an extra sticker on the outside of the box. Ground, overnight, and Air are all acceptable modes of shipping.
@ Walter - like "would you like your apple pie with or without a-la-mode?
-Matt
Getting close to production - sometime next week if everything comes together.
The Board and cells will be available separately. You can use most any 18650 cell - I recommend getting the "good" ones.
The Board works with both "PCB protected" cells, as well as the less expensive "non-protective" cells. We'll be selling (only) the protected cells because of their increased reliability, safety, and under-voltage cut-out (which greatly increases cell/cylce life).
In this pic, the cells are being charged independently from each other...
For simplicty, think of this as a "non-plugged in" power supply (like a standard 7.5v wall wart). Once it's charged, the barrel plug / molex plug output cable (included) can be plugged into any device that has a 2.1mm center-positive jack (like a BOE, Prop Proto, etc.). For versatility we've included a standard 2 position screw terminal block too.
Here, the cells are connected in series delivering 7.4v (nominal) to a BOE running (4) continuous rotation servos.
-Matt
OBC
Paul
now here is a question can I use it as a normal charger for Li Ion cells so I can use them out side the parallax board .
Peter
@ Matt - I want it both ways!
Hi Peter - The Board is a stand-alone charger power pack. You can pop in (2) 18650 cells and the charger will charge the cells properly. You can then get power from the cells through one of the two different power output jacks.
If you want to just use the Board as a charger only, you can remove the cells when they're fully charged and put them into whatever device you wish.
-Matt
It would be quite easy to implement a UPS with the addition of a couple of external diodes. I'm still writing the Productdoc, and I'll be including several applications like this.
-Matt
Don
Yes, very close! Product Documentation is just about done. We're still waiting for the battery holders to arrive however -
I'll let you know as soon as the Lions are Roaring off the production line!
PS. I get the first two for my Robot Base Kit!
-Matt
Thank for the up date