DIY Charger - Possible Project

Texas Instruments has too many choices. Lots of reading ahead.

bq24190 Lithium only.

bq25601

bq25890 and bq25892 Lithium only.

bq25898

The features look good but it comes in a microscopic DSBGA package. It has 42 pins in a 2.8 x 2.5 mm package. PCB layout and assembly will be challenging. I will probably skip this part because of the package.

bq24725a

bq24735

For later — I2C keypad scan IC. May be handy if I put a keypad in the device.

PCA9557 I2C and SMBUS I/O expander - 8 bit parallel port

Will do!

I’m surprised no one has jumped in to tell me this It has already been done.

I’ll work on this when I have time.

Analog Devices:

ADP5350

I like the 1.5MHz switching frequency.

5 Channel LED driver. The charger could double as a dim flashlight :slight_smile: It is suppose to be a backlight driver.

Full I2C programmability. I2C fuel gauge and temperature sensor.

AD5062 Linear

Fully programmable I2C.
AC or USB power. USB 3.0 with external USB controller chip.
Limited to 1.5A though.

Of interest for later:
AD7824 Battery monitoring system. Primary use is monitoring series cells in automotive applications. Could be useful.

So far, I like LTC 4015, ADP5350 and AD5062.

The TI parts look like they will be too hard for a one-person DIY.

I never saw this until today. Now I’m watching to see what happens. :nerd_face:

Cool project, Andrew.
Thank you!

Wish I could help in some way but this is beyond me.
Good luck with it, I will be watching and learning.

ADP5350 maxium fast charge current is only 650ma. Otherwise it was looking good. It has a lot of extra functionality that could have been usefull. I’m going to keep that one in mind for future projects.

I will probably go with the LT4015 but am going to look at the AD5062 first.

ADP5062 has great features:

  • Standalone or I2C control. In standalone, basic settings by jumpers
  • Thermal limiting and battery temperature limits.
  • Very low external part count.
  • Battery Isolation FET. Useful
  • USB or external adapter power.
  • Battery short detection.
  • Dead and weak battery trickle charge rates.
  • Optional JEITA battery temperature charging rates —> reduce rate if battery is too cold or too warm. Adjusts CV voltage too.
  • Programmable Charging termination voltage between 3.6V and 4.5V in 0.02V steps. :slight_smile:
  • Programmable fast charge current between 50mA and 1300mA in 50mA steps
  • dead battery, trickle, watchdog and safety timers :slight_smile:
  • programmable LDO for system power - I can use the 5062 to provide power the rest of the device.
  • Good application support including PCB layout guidelines.

Layout guidelines are sooo helpful.

The part is missing a few features. 1.3A charge current is below my design spec of at least 2A. 1300mA just barely covers the standard charge rate for some 18650 cells. I’d like to be able to test and use rapid charge rates too. An INR8650-30Q or 25R can rapid charge at 4A.

Panasonic NCR18650B standard charge rate is 1.625A

1.3A is not enough. I like the ADP5062 but it won’t work.

http://www.batteryonestop.com/baotongusa/products/datasheets/li-ion/SANYO-NCR18650B-3400mAh.pdf

The MAX1645 and 1647 are primarily meant for use with smart batteries. Not what I’m looking for.

I’m going to give the LTC4015 a closer look.

For those reading along, here is the product page and datasheet again.

Datasheet: http://cds.linear.com/docs/en/datasheet/4015fb.pdf

I would approach this from a different direction, battery charger ICs are designed for minimum cost low parts count commercial projects and can be fussy to operate outside designed goals. Starting with the goal of flexibility and maximum control I would use something like an arduino with software to control and measure current and voltage with basic power chips instead of battery specific.

I’ve thought about that. I agree that most of the battery charger ICs are designed to be part of a device like a tablet or laptop.

In the end, I may end up going with the flexible option.

Before I do that, I want to explore the more integrated parts to see if there is one I can make work.

I’ve already eliminated quite a few of the low part count ICs so because they don’t meet requirements.

Going the Arduino + power supply route puts the parts count up a lot and possibly the load on the Arduino. It means my code and external hardware is responsible for safety checks.

Some of the charger ICs have programmable temperature, voltage and time checks. They go into a fault mode if when any of the limits are exceeded.

Since I plan to have 4 independent chargers, part count is important.

==

I’m impressed by just how few external parts the new charger ICs need.

This is an SLA charger I built in 2012. It charges a single 6V battery. Look at the parts count!!

OnSemi have a couple of parts that might have worked. They are in microscopic packages.

OnSemi also have a controler for next-generation power packs. Along with supporting the latest high speed charging protocols, the IC can communicate with the device it is charging.

It was interesting to look over but not useful for this project.

I’m sure we will see much smarter power packs in the near future.

I bought a Litokala 500 engineer from Alibaba for $14 shipped, taking one of them apart might be instructive. The insides of one of the USB doctor measurement devices might be useful too.

i ll check back in 3 months if the project is still going strong.
i will be off on Xmas season vacation until mid January, enjoying ski trip with family and friends.

have phun :person_facepalming:

bye.

I ordered two LTC4015E samples. (commercial temp range)

Time to get on with block diagrams and Rev. 0 schematic.

I may need to update Eagle on my machine. I own a paid license.

Good idea. I’ve got an Lii-500 on the way :slight_smile:

I’ll open it up and post in this thread. That may not happen until after Christmas or it could be next week. Shipping from China is unpredictable.

Any suggestions on form factor?

My initial thoughts are 100mm x 100mm 2 layer to hit the $5.00 for 10 deal at PCBWay. 4 layers takes the price to $49.00 Still a bargain.

OR

Arduino shield.

OR

suggestions?

They are also running an $88 for 10 PCBA deal. That puts the impossible to DIY TI and On Semi parts back into the running.

I generally use Eagle early in the design process to get a rough schematic and block diagram. Eagle is a bit quirky but works better than any freeware I’ve tried. I also use LTSpice to simulate parts or all of a project. I don’t much care for the schematic capture in LTSpice. I often use Eagle to get my ideas down and then go on to simulations.

Cadsoft GMBH sold out to Autodesk last year. :cry: My Cadsoft EAGLE 7.4.0 doesn’t play nice with MacOS 10.12. :disappointed: I’ve installed Autodesk Eagle 8.4.3. I’ll need read up on what’s new and then merge my device library.

EAGLE 8.4 includes spice. I may stop using LTSpice and do capture and simulation in Eagle.

For those following along, here is the product page:

There are plenty of tutorials on YouTube and now support from Autodesk.

Eagle runs on Windows, MacOS and Linux.

Subbed and following this thread.