SparkFun Forums

[geekything]

I notice the LiPo charger mentions it's in limited availability and will ship as soon as possible. So my question is: are they constantly trickling (haha! pun!) in on a steady basis, or is there an expected shipment date, or?...

Also, am I safe running two of the LiPo packs in series and/or parallel? I seem to remember that this is kosher with LiPos?

Thanks!

-marc

[sparky]

Hi,

We should have more chargers in 10 days.

Not sure about the parallel charging but I can give you my experience. I don't mean to scare anyone: I had two 1200mAh batts (samples from the supplier) wire in parallel to run the port-o-rotary. Charged em up, had a night out on the town (good time showing it off to waitresses). Came home, hooked up the batts to the charger (single plug connection), and went to bed.

Next morning I noticed the charger had the red fault light lit and the charging light was off. Batt 2 was also bubbled up - the silver covering was blown up like a ballon. Not too extreme, but obviously the cell gave off a gas. Needless to say, I don't use that cell anymore but may use the other.

Pete-o commented that unless the packs are matched, one cell will have a larger charge current untill they match. This over current could have cause the gas exhaust.

I'm pretty happy with the charger though. Performed well.

-Nathan

[pittuck]

ever thought of carrying the smaller nicad battery packs / a smart charger?

On my PDA i have notes for a smart charger usign a PIC + some digital pots + 2x LM317's

If i get it working on vero i will get a PCB made, somming u may be interested in?

[sparky]

Most definitely!

We've already got a -dV/dt NiMH based on a single LM317. It's also covered in this months issue of Servo based on a thermistor (I think the go into -dV/dt charging).

-Nathan

[pittuck]

well with 2 u can get constant current and voltage. stick a pic in and a 2.5V reference chip and u have a smart charger, add some LEDs + some knobs for voltage select and vola, well kinda!

What i was thinking was a 1, 2, 3, 4 -> 9V selected through a led matrix / LCD (mini one or somming) with .2, .4, .6, .8 sub divisions + a 8mA - 400mA charge rate...

Possibly even put in a choice for trickle charge using a mode select button...

I dunno, i will look into circuits in a bit!