Lithium Battery Charging help needed - Page 1
Forum section: electronics / beginners

author: peps1
author_rank: Regular Contributor
timestamp: January 16, 2015, 08:05:14 am
content: I just got someLithium Battery Charging PCBsin the post, and being totally new to the world of lithium battery charging was wondering if the mAH of the batteries I want to charge with this matters, or if I can use for example anything like a 8650 3.7V 5000mAH or small 250mAH through to say, 1100mAH 3.7v Li-ion polymer?

author: Maxlor
author_rank: Frequent Contributor
timestamp: January 16, 2015, 11:04:10 am
content: yes, it matters. Most batteries specify a maximum charge current of 0.5C to 2C, with 1C being the most common. The C means the battery's capacity. So, if you have a 250mAh battery and the max charge current is specified as 1C, the charge current should be 250mA max, whereas with a 3000mAh battery, it should be 3000mA max.If nothing is specified, assume 1C max current for both charging and discharging. If you have the time though, a lower max current will reduce the battery's aging.

author: peps1
author_rank: Regular Contributor
timestamp: January 16, 2015, 11:28:50 am
content: How would I adjust the charge current?

author: ion
author_rank: Regular Contributor
timestamp: January 16, 2015, 11:30:14 am
content: I believe with lithium, standard charging currents are more like 0.7C.Personally, with an unknown battery I'd stick to 0.5C for safety.

author: sleemanj
author_rank: Super Contributor
timestamp: January 16, 2015, 01:00:26 pm
content: Quote from: peps1 on January 16, 2015, 11:28:50 amLook at the datasheet for the charge management IC on that board you have purchased. You will almost certainly find that the current is set by way of a resistor value.Locate the resistor on the PCB, take it off, replace it with one that gives the current you want.For example, for the common TP4056, these are suitable values as taken from datasheets, I'd hazard a guess on your board that it will be R3 (see if it's 1.2k or thereabouts), and probably the same values will work.Code:30k = 50mA20k = 70mA10k = 130mA5k = 250mA4k = 300mA3k = 400mA2k = 580mA1.66k = 690mA1.5k = 780mA1.33k = 900mA1.2k = 1000mA (default)This looks close enough (but not exact) to R = 1000 * (1.2/A)

author: eas
author_rank: Frequent Contributor
timestamp: January 16, 2015, 10:04:38 pm
content: Quote from: peps1 on January 16, 2015, 08:05:14 amI assume you mean 18650, and if you do, you should know that you do not have an 5000mAh 18650. They don't exist, though that doesn't stop people from lying about it. The largest capacity 18650 right now is 3,400 mAh, but you can be pretty sure that you aren't getting one of those when you buy one that claims a capacity of 5,000mAh. My guess is that you'll be lucky if it has 2000mAh capacity.

author: peps1
author_rank: Regular Contributor
timestamp: January 17, 2015, 04:28:43 am
content: Quote from: sleemanj on January 16, 2015, 01:00:26 pmThanks sleemanj, you are 100% correct, it is a TP4056

author: IanB
author_rank: Super Contributor
timestamp: January 17, 2015, 04:53:14 am
content: Quote from: peps1 on January 16, 2015, 08:05:14 amYou posted this question with a link to what you bought. Here is what it says in the description when following that link:QuoteIt seems to answer some of your questions.

author: peps1
author_rank: Regular Contributor
timestamp: January 17, 2015, 05:00:48 am
content: Obviously I disagree that the listing answered my questions, or I would not have made this post.

author: IanB
author_rank: Super Contributor
timestamp: January 17, 2015, 05:05:39 am
content: So, you asked this question:Quote from: peps1 on January 16, 2015, 08:05:14 amAnd yet the information in the listing says this:QuoteCall me crazy, but it looks like this answers your question.

author: peps1
author_rank: Regular Contributor
timestamp: January 17, 2015, 05:25:25 am
content: Again, obviously not, or I would not have made the post. I think my questions have been far better answered by the helpful members here who grasp the concept of a "Beginners section" than that single line in the item listing.But, thanks for popping by and contributing