SparkFun Forums

[Grimm Spector]

Ok, I have a 2Ah Li Poly from SFE and the Batt-CG-MAX1555

because I'm prototyping an idea out, and I want to give the battery some test charges and attach a load later with the charging system.

now normally I would want to attach my negative lead to the 'BAT' terminal on the MAX1555 board, and run my positive to the tail end of my load system and the input of my load system to SYS, completing the circuit and allowing a charge while the electronics are on...

however and excuse my newness, I am not that experienced currently, but this will not allow me to charge my battery while it's in the circuit if the circuit is shut off, so what am I missing?

I don't want to smoke the hardware, which is what I'm fairly certain will happen if I try to use the GND terminal near BAT because I assume all the grounds are common on the interior layer and I'll then have no load and the battery will short.

Hopefully someone can give me a nudge to the proper solution, something I should know but am apparently missing, thanks for your time everyone.

[Grimm Spector]

could really use some help, think I need more sleep to figure this out, I've never done an application using a battery source where I charge it, only disposable cells, so I'm at a loss for what I'm missing, and lack the extras to experiement freely.

[riden]

I am unable to answer your question since Li Poly and LiOn technology tter is fairly new to me. What I can advise is NOT to experiment until someone knowledgable has had a chance to reply. I agree the documentation is a bit sparse for those not familar with the chip or technology. Since there is a caution about using supplies greater than 5v (a regulator for safety would have been nice), there seems to be a lot of ways of damaging the charger. I'm sure someone who knows the Hows and Whys of this device will post later today or tomorrow.

[Grimm Spector]

I am unable to answer your question since Li Poly and LiOn technology tter is fairly new to me. What I can advise is NOT to experiment until someone knowledgable has had a chance to reply. I agree the documentation is a bit sparse for those not familar with the chip or technology. Since there is a caution about using supplies greater than 5v (a regulator for safety would have been nice), there seems to be a lot of ways of damaging the charger. I'm sure someone who knows the Hows and Whys of this device will post later today or tomorrow.

well the chip has a regulator and I accidentally bridge the connections had I looked more closely at the board I would've noticed, and the chip is now no more...

I imagine I should be doing something along these lines like I would with any other battery:


Anode to voltage source through chip to accumulate charge, capacitor out to GND on USB or EXT
Cathode free to device
SYS to Anode of device
when the USB or External power connects, the circuit is made to the batteries Anode, trickle charging

this makes more sense, but I won't know until I get a new chip now...

comments would be very welcome, I know a lot about battery chemistry and all that I used to work for a battery specialty store for 5 years, and I've worked with SLA, NiCd, NiMH and Li-Ion/LiPoly chemistries and know the charging rules though not the capacitance requirements for reach to be properly charged.

[riden]

well the chip has a regulator and I accidentally bridge the connections had I looked more closely at the board I would've noticed, and the chip is now no more...

Sorry to hear about that. It may have a regulator, but not short-circuit protection. Actually, what I was trying to say is that if I see a 2.5mm jack, I've conditioned myself (not necessarily rightly), that I can use my 6v (7.5v no-load) wall-warts that I use on all my projects. It appears that that would exceed the capacity of the chip. A regulator (7805/LM17 etc.) to limit the voltage applied to the MAX1551 would be handy to make it harder to toast the chip by applying too much voltage.

[Grimm Spector]

well the chip has a regulator and I accidentally bridge the connections had I looked more closely at the board I would've noticed, and the chip is now no more...

Sorry to hear about that. It may have a regulator, but not short-circuit protection. Actually, what I was trying to say is that if I see a 2.5mm jack, I've conditioned myself (not necessarily rightly), that I can use my 6v (7.5v no-load) wall-warts that I use on all my projects. It appears that that would exceed the capacity of the chip. A regulator (7805/LM17 etc.) to limit the voltage applied to the MAX1551 would be handy to make it harder to toast the chip by applying too much voltage.

good point, anyway I might not have fried the battery at least, I was quick to pull the power when it showed signs of bad, let's cross our fingers. and hopefully someone can point me in the direction of what I'm doing wrong, other than the shorting the bloody thing, that was just bad, I have a bit more sleep in me today

[Grimm Spector]

no one willing to tell me the proper way to hook it up without a circuit?

[ohararp]

When in doubt RTFM...or go to the manufacturer's website. The pic below should tell you how to hook everything up.

http://www.maxim-ic.com/quick_view2.cfm/qv_pk/4002

[Grimm Spector]

ryan

RTFQ, Q being the question not the inductance... <_<

I said WITHOUT a load, ie. remove load system, but I don't know if I can do that with the Li Poly or not or if there's some other way to do it without a load circuit past it....

[ohararp]

Basically, I use the microchip version of the max1555. It behaves very similarly and has the same package. I wanted to charge the battery and have my system turned off so I added a switch after the battery. The Conn-H2 header is used for current measurement.


For your design system add a switch from the max1555 system load point
to your design. This will allow you to turn your design on and off independently of the switch SFE provided on their dev board.

Next time please make your question a bit more clear. I had to dig to actually find your question. Hope that answers everything.

[Grimm Spector]

Basically, I use the microchip version of the max1555. It behaves very similarly and has the same package. I wanted to charge the battery and have my system turned off so I added a switch after the battery. The Conn-H2 header is used for current measurement.


For your design system add a switch from the max1555 system load point
to your design. This will allow you to turn your design on and off independently of the switch SFE provided on their dev board.

Next time please make your question a bit more clear. I had to dig to actually find your question. Hope that answers everything.

I see what I was doing wrong I think, thank you. I'll be a bit more detailed next time I was extremely sleep deprived when I wrote it sorry.