how much can the 6600mah battery charge?

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calibur010011
 
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how much can the 6600mah battery charge?

Post by calibur010011 »

Hi,

I was curious if anyone could suggest a way that I could calculate the charging capacity of the Tenergy Li-Ion 18650 6600mAh #31002 in my charger project. I've gotten some of them off eBay and they don't seem to be charging my phone as many times or devices as many times as I would suspect. I'm sure 6600mAh isn't the same amongst devices even if they are 3.7mAh li-ion. Any resources or calculators would be greatly appreciated. Googling wasn't too much help, but maybe it was my terms. Thanks

Battery Seen here: http://www.tenergybattery.com/index.php ... 3&Itemid=1

Snipeye
 
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Re: how much can the 6600mah battery charge?

Post by Snipeye »

6600mAh is a measure of capacity - that's also called 6.6Ah. It's a standardized unit, though (battery manufactures in particular) have been known to fudge the numbers - there is this:

http://hackaday.com/2011/03/14/battery- ... ty-claims/

That could help you get the actual capacity of your battery. Good luck!

calibur010011
 
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Re: how much can the 6600mah battery charge?

Post by calibur010011 »

Hey Snipeye,

Thanks for the response. I appreciate the resources. I will look into it. I just find it odd my 2600mAh battery (extended) for my Verizon Droid Charge doesn't get charged to its full capacity. It goes most of the way. I have 2 of each type of battery (the 6600's both in a blue wrapping or the popular seen white) from two different sellers and I am getting similar results. I thought these things could charge a standard battery (about half the extended) 4-5x? I figured if I just subtracted 6600-2600=4000mAh would probably be wrong. Accounting for heat loss and things like that would probably make a difference. They are both Li-ion 3.7v batteries though. Just has me puzzled. Was hoping I wouldn't have to build something and could get a round about idea. I will look into it. Thanks for any future suggestions as well. take care

Snipeye
 
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Re: how much can the 6600mah battery charge?

Post by Snipeye »

Well, there are a few factors you need to consider:

1. I'm assuming you're charging it through something like a mintyboost or similar - that means you need to boost the voltage from 3.7v to 5v (USB spec) before you can do it. Even at 90% efficiency, 6600mAh at 3.7v becomes about 4400mAh at 5v.

2. The charger (inside your phone) that regulates charge of the battery is not 100% efficient, so you lose more there.

3. The battery is probably not actually 6600mAh - it's almost definitely less.

4. Efficiency of everything goes down as heat increases, generating more heat, etc, etc.

Under ideal circumstances, yes, 6600mAh battery could charge the 2600mAh battery once and have 4000mAh left over, then it could charge it again and have 1400mAh left over - so it could charge it about 2.5 (a little more) times. However, real-life is hardly ever idea. Hope I cleared that up for you!

calibur010011
 
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Re: how much can the 6600mah battery charge?

Post by calibur010011 »

Hey Snipeye,

yeah that's definitely along the lines I was thinking. I was hoping to build some sort of mega pack charger. I could put them in parallel, but I've heard that can produce a horror story if they aren't exactly the same in voltage. Its a bit of a disappointment to say the least. The idea of losing almost a cells worth of juice to inefficency. You are right in assuming I am using the minty boost. You think I should modify it to be around 4v? Or is it usually 5v for proper electronics charging? I notice most portable electronics chargers are around 5v. Or maybe I should have a higher voltage pack like 7.4v? Or maybe the minty boost doesn't step down it steps up? Thanks snipeye

calibur010011
 
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Re: how much can the 6600mah battery charge?

Post by calibur010011 »

Also just to note I noticed once the battery reaches 3v it crashes to .57v according to my meter; normal?

Snipeye
 
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Re: how much can the 6600mah battery charge?

Post by Snipeye »

... you should have a protection circuit on that (usually built-in to the package) that prevents it from being dropped lower than 3.2v... nominal voltage on li-pos is 3.7v, they charge up to 4.2, and dischange down to 3.2 - going outside that range is bad for the battery. (From what I understand)

calibur010011
 
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Re: how much can the 6600mah battery charge?

Post by calibur010011 »

I agree thats what I find is so strange. Funny thing is though as soon as I plug in to charge it back up it jumps to 3.09v. So maybe its only letting a trickle through?

Snipeye
 
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Re: how much can the 6600mah battery charge?

Post by Snipeye »

That's probably it, actually - the protection circuit is working by barely allowing anything through. Sounds like you're good.

calibur010011
 
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Re: how much can the 6600mah battery charge?

Post by calibur010011 »

Yeah just a BANNED blow after all the work I put into making a custom enclosure I'm getting cut this week. Does getting a higher voltage battery supply with the same capacity last longer than the 3.7v one? Thanks

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Franklin97355
 
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Re: how much can the 6600mah battery charge?

Post by Franklin97355 »

Does getting a higher voltage battery supply with the same capacity last longer than the 3.7v one?
Probably but most of this depends on how you designed your charging circuit.

calibur010011
 
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Re: how much can the 6600mah battery charge?

Post by calibur010011 »

Ah, well The charging portions are just the solar lipoly charger from adafruit and a mintyboost. I don't know if that helps. Just thought I'd share. I understand if it isn't a simple answer. A resource to read I don't mind instead either. Thanks

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