Internal usb charging; best/safest method?

[Java_Az]

Ok pretty much have it figured out. This third chip i have works fine. After looking threw some data sheets it seems like there are two different kinds of short circuit protection. One is called PASS the other is external short protected. It seems PASS is internal and external short protection. which i believe senses battery resistance for the internal protection. since IMR's have really low internal resistance it is tripping my short protected PASS PCB's. could get around it by adding a .150ohm or 150milliohm high wattage resistor from the battery to the protection circuit. That would make the internal resistance about the same a a regular Li Ion. Or just make sure you buy a protection PCB that is External Short Protected.

 

[CraigHB]

Interesting, wouldn't have known that. Not really clear, which are the ones that work?

 

[Java_Az]

Interesting, wouldn't have known that. Not really clear, which are the ones that work?

The bottom one doesn't work with my CGR18650CH Panasonic's Top PCB does work. If for short Circuit it has exterior / external short protection the PCB should work with IMR's. At least i am 98% sure going to order some of these for single cell Protection Circuit Module (PCB) for 3.7V Li-Ion Battery (6.0A limit) there data sheet sucks so i had to go to the manufacurers web side to get detailed specs http://www.ayaatech.com/shop/?type=detail&id=416. Thought about adding a 100 or 150 milliohm resistor to my PCB that has PASS short protection, but once you get up to one that can handle 15 watts or more they get pretty big. Just for testing i will add a long piece of wire that measures 100 milliohm to the PCB that has PASS for short protection to see if it will work. My guess it it will once the added resistance is in place.

 

[CraigHB]

Thanks,

Nichrome wire is good for making a small down and dirty very low value resistor. Just splice some 20 to 24 AWG inline with the normal run.

 

[Digital-Dragon]

Okay, glad to be hearing about this... Any links to non-pass protection pcbs would be great.

I've looked at the spec download for this one and there was no pertinent info there. What do you guys think?
Protection Circuit Module (PCB) for 3.7V Li-Ion Battery (6.0A limit)

And what I would really like to use is an 18650 batt holder with built in protection pcb like this, but again, I'm not sure if it is non-pass...?
Battery holder : Li-Ion 18650 Battery Holder (1S1P) With 2.6" long 20AWG & PCB (1S1P-18650)

Edit: I wish I didn't need to ask for help with the leg work, but I have little experience shopping for electronics of this sort... You guys rock!

 

[Java_Az]

Okay, glad to be hearing about this... Any links to non-pass protection pcbs would be great.

I've looked at the spec download for this one and there was no pertinent info there. What do you guys think?
Protection Circuit Module (PCB) for 3.7V Li-Ion Battery (6.0A limit)

That is exterior protected here is a link to better specs http://www.ayaatech.com/shop/?type=detail&id=416

Adding resistance on the battery side did make the PASS PCB work. hooked about a 6 foot piece of 22 awg to the battery holder and then to the PCB. ( no Nichrome on hand ) If i switch the 6 foot wire out with a 2 inch wire it no longer works. 100% sure it has to do with the internal resistance of the batteries On the PASS PCB's. I am going to order a few of those 6 amp PCB's today. kinda sucks because i will not have to modify my design to fit the long .... PCB.

EDIT: Looks like those holders have exterior short protection http://www.ebay.co.uk/itm/5-x-1S1P-3-7V-18650-Holder-Battery-Build-in-PCM-Protection-Circuit-Module-/160772739163?pt=LH_DefaultDomain_3&hash=item256ecd505b#ht_3068wt_1004

 

[Digital-Dragon]

Excellent, thanks for the links!

Did you mean you WILL have to modify your design? Because that's why I like the idea of using a batt holder with built in protection... I've only seen them with that 3A limit though, which seems like it will just barely cut it, at least for my purposes. If I could find them in a 4-6A version I would feel much more confident...

 

[Java_Az]

Excellent, thanks for the links!

Did you mean you WILL have to modify your design? Because that's why I like the idea of using a batt holder with built in protection... I've only seen them with that 3A limit though, which seems like it will just barely cut it, at least for my purposes. If I could find them in a 4-6A version I would feel much more confident...

Yeah i for sure got to change my design since the one i planned on using was round. Not too big a deal i might beable to squeeze it in with no major changes.

3 amps would work fine for a unregulated mod. If you going to boost to 5 volts, you can use over 4 amps on the input side of the regulator when the battery gets down to around 3 volts. So if boosting that holder wont cut it rated @ 3 amps.

I Ordered up some of the 6 amp PCB's they should be here Monday or Tuesday i believe i will post up results if they work or if i just wasted more money.

 

[jasl90]

Take a look at these...
EEVblog #176 – Lithium Ion/Polymer Battery Charging Tutorial | EEVblog - The Electronics Engineering Video Blog
EEVblog #259 - PSU Rev C Schematic - Part 12 | EEVblog - The Electronics Engineering Video Blog

 

[Java_Az]

Almost forgot to update this. Got the new protection circuits and soldered one up. So far it is working great. Tiny little thing it is. Thought it was going to be bigger. Will see what happens when the battery gets down to 3 volts. This booster is going to want 4+ amps on the input side at that battery voltage.

 

[JZXJ]

You could always buy a 1000mah eGo passthru, at the mini usb connector is a charger pcb. $18 or so with shipping and you have all the pieces for the mod waiting to be pillaged, except for the wiring, I would choose something that won't snap if you look at it funny. Maybe 20guage nichrome and you can even custom route the wiring without having to anchor it.