What is the suitable wall adapter for 1 amp charging ?  - Page 1
Forum section: electronics / projects

author: Sai teja
author_rank: Regular Contributor
timestamp: March 23, 2018, 06:21:39 pm
content: Hello,I am using MCP73213 IC at 1 amp charging rate to charge the 2S Li-ion battery pack in our product. I tested my charging IC with 9V 1A AC - DC wall adapter and it's working.Is it a good practice to use 9V 1A wall adapter to charge at 1 amp rating?Soon we go into production. Please help me in this regard.Datasheet of the IC ishttp://ww1.microchip.com/downloads/en/DeviceDoc/20002190C.pdf

author: fourtytwo42
author_rank: Super Contributor
timestamp: March 23, 2018, 07:32:25 pm
content: It depends how trustworthy you think the wallwart supplier is ? but at the end of the day an amp is an amp!

author: Sai teja
author_rank: Regular Contributor
timestamp: March 24, 2018, 04:48:44 am
content: Is there any chance of decrease in life expectancy of 9V 1 A wall adapter if I use it for 1 amp charge rating ?

author: BravoV
author_rank: Super Contributor
timestamp: March 24, 2018, 06:32:24 am
content: Quote from: Sai teja on March 23, 2018, 06:21:39 pmAre your relying your business based on this forum's answer ?What is wrong with testing and trying it your self "first" on various adapters and then ask if there is a problem ?

author: jitter
author_rank: Frequent Contributor
timestamp: March 24, 2018, 07:11:58 am
content: Since the input range of the MCP73213 goes all the way up to 16 V, I might choose a 12 V/1 A adapter instead. With respect to a 9 V/1 A adapter, that gives you another 3 W of headroom and it is a more ubiquitous value than 9 V.Since this adapter is used for charging, it is not going to be run at 100% all the time. Once the cells get above a certain level of charge, the current will start to drop, so I don't see too much problems using a 1 A adapter, especially if it's a 12 V one.In 24/7 applications, you really do want to go 20 or more % oversize. My ISP once gave me a modem with a 15 V/1 A adapter that was running close to its limits. Within a year and a half it died and they supplied me with a 1.5 A version. That one has been running ever since and must now have done some multiples of lifetime of the first one (yes, it is an old modem, but as long as they don't change any standards or I uprade my speed, they probably won't replace it). But it goes to show that some headroom may have a drastic increase on life expectancy.

author: Mechatrommer
author_rank: Super Contributor
timestamp: March 24, 2018, 08:14:40 am
content: Quote from: blueskull on March 24, 2018, 07:44:15 am9V wallwart is not easily available here, not as easy as 12V one at least.Quote

author: fourtytwo42
author_rank: Super Contributor
timestamp: March 24, 2018, 08:22:05 am
content: Quote from: Mechatrommer on March 24, 2018, 08:14:40 amObviosly that change would require the OP to redesign the product as to maintain 1 Amp charge will require the MCP73213 to be able to dissipate an extra 3Watts of heat! Not simple given it's package.I think the OP may already be in trouble here as if they use a typical unregulated wallwart the output voltage may be unexpectedly high and the OP has not mentioned regulation, operating range or thermal issues in the design so far.

author: Mechatrommer
author_rank: Super Contributor
timestamp: March 24, 2018, 08:28:39 am
content: Quote from: fourtytwo42 on March 24, 2018, 08:22:05 amthe fact he's asking here for some trouble is he maybe open up to changes with some thought. he might even build a custom 8-9V SMPS from a 12V wall wart. but back to the OP, there is no answer to that as what type brand or hung low of wall wart he's using.

author: BravoV
author_rank: Super Contributor
timestamp: March 24, 2018, 08:50:47 am
content: We are not talking about a hobbyist here.Fact is, the OP is building a circuit for business, and their company does not even have an adjustable DC PSU to verify their designed circuit whether it works under different types of power source, say from good DC PS down to the most crappy one, and try to make a conclusion out of it. How hard is that ?

author: Ian.M
author_rank: Super Contributor
timestamp: March 24, 2018, 09:21:32 am
content: There is also the issue that if your product is a portable device specced for 12V input, you *WILL* get trouble with lUsers wiring it up to unregulated '12V' automotive supples that will typically be in the 13V to 15V range, with spikes and surges well outside that range, then expecting the resulting burnt mess to be replace under warranty.

author: Mechatrommer
author_rank: Super Contributor
timestamp: March 24, 2018, 12:58:22 pm
content: Quote from: BravoV on March 24, 2018, 08:50:47 amand i'm not sure if he even care if the chip goes into current limited mode due to thermal protection. just because the DS says 1100mA max, then thats the figure we get here.