DIY Charger - Possible Project

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.

Are you making these to sell? Will you be sharing your Eagle files here? If you’re not doing this as a community shared project, then do whatever works best for you. If you ARE going to share the files, then it might be nice to keep in mind OSH Park pricing as well, which is $5 per square inch with free shipping for three copies on all 2-layer boards. A lot of members here use Eagle, and also OSH Park. With that fixed pricing, the smaller the design is, the better.

Probably not. I don’t want to string anyone along. I’m doing this in my spare time.

If I get as far as having boards made, I’m open to selling extras at cost. I live in Wales. Postage to the US is going to be a few £’s.

I’ve been satisfied with PCBWay and haven’t looked elsewhere.

I’ll keep OSH park in mind. I’ve never used them. At a minimum I’ll check against their design rules.

Absolutely YES. I’ll also share my bill of materials.

Thinking about including this optional module in the project. Stay tuned.

I would consider a PCBA (assembly) group buy for a bare board with sub-mm pitch parts installed. The LTC4015 is QFN38.

I need to get a rough schematic / block diagram up.

I opened up my Lii-402. They sanded off the numbers.

Almost blank sheet of paper. I’ll make the untested LTC4015 library available if anyone wants it.

Mine arrived yesterday. They sanded most of the part numbers… I’m not going to post any images. There are a couple of videos on YouTube if you are curious.

It is about what you would expect. A micro controller for the display board and another one on the mother board. There are a few power transistors and chokes. The USB power out circuit is at the top by the jacks.

LTC4015E arrived. I’m working on the design. Stay tuned.

…maybe downscale your pictures: