Charging issues with USB LiIon/LiPoly charger - v1.2 SKU: ADA259 and 3.7v 2000mah Lipo

I have 4 of these, and even when left over night they are still displaying the ‘charging’ LED, I have tried different USB adaptors and even followed the directions for setting the charge rate to 1000ma.

I have checked the battery voltage and even after 10hrs of charge it only went from 3.76 to 3.85

Am I missing something? I thought that these would be a straight fit any help in getting this sorted would be great.

Hi Sean,

I would have thought the ADA259 would charge up to 4.2V - it would be a bit hard to half-split the issue if you don’t have another charger. I’ll checkout a few things on this side of town and get back to you by tomorrow all going well.

Hi Sean,

The module definitely charges LiPo’s to 4.2V. There are two variables at play still which make it hard to isolate what is exactly the problem.

  1. Charger module could be faulty
  2. Batteries may have been left to discharge (not kept at a safe storage voltage of 3.8-3.85). If LiPo drops below 3.0V then it can compromise the chemistry within the battery. This can lead to all sorts of interesting outcomes, including totally inoperable batteries or lost capacity

Perhaps you have a makerspace nearby where you could network to find an alternative charger module? This would help isolate the issue

Hi Graham,
I have picked up a Freetronics Lipo charger this afternoon, and currently have a battery on charge now. Will see if the voltage goes up, it will be charging at 500ma so will check in an hour or so.

So having these batteries sit in the project draw from May till last week could have been long enough for these to discharge to below a safe level?

Is there any chance they will recover if they are used and recharged? I have these driving a single 1W led at around 200ma.

Hi Sean,

It’s a bit hard to say - getting a totally different LiPo charger is a good place to start though as you’ll be able to half split the issue with more confidence.

LiPo’s do all sorts of strange things below 3ish volts. Sometimes they can degrade so quickly that they puff up and no longer work. Either way, never leave LiPo’s charging unsupervised, especially suspicious cells, just in case they do begin to overheat and become unstable.

So the new charger was indicating that it was fully charged and the cell was reading 4.01- i will check the other units next week to see what they are reading.

If they are all sitting on or around that then I guess there wasn’t any issue. Just strange the AdaFuit charger wasn’t reading as fully charged.

So maybe the protection circuit is designed to max out at 4v, do you have any more info on these bateries? I have tried to look at the data sheet on them but your store is showing a bad link.

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I have just discovered that you have what maybe a more appropriate charger for my project. The SparkFun Battery Babysitter.

I am making LED art lights that are driven from the Lipo batteries, they draw very little around 75mA. So I am getting a good amount of run time from the 2000mAh battery.

I hate leads and have been looking for options on how I can use battery power as an option. Seeing as I suspect people will leave these on till they can’t run anymore.

I just don’t want to damage the Lipo cell by over discharging them, do you think that the SparkFun charger/battery manager would be a better option?

My current thinking is maybe best to replace the charger with this more refined charger, can you tell me if the mounting holes are in the same or similar position between the two chargers?

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Yep, there are plenty of options out there! You should always design with the low voltage state in mind (automatic shutdown, etc).

One of my favorites is the Adafruit LiPo Charger V2 - note it has the low voltage LED signal which can be used in a number of different ways. Another handy built-in feature is load-sharing; it will automatically switch over to non-LiPo power instead of continuously charging/draining the battery. There is also a temp sensor input - useful for outdoor projects.

The takeaway is to design your project while covering all those edge cases (flat batteries, overheating etc). These modules take care of the harder to do stuff such as smart load sharing, allowing you to take the reins on other things such as how/what the shutdown sequence should be (even if it’s as simple as an audible / visual queue to pull power).

I’m very curious to hear how this project goes Sean!

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Hello Graham,
Okay I have checked out the Adafruit Lipo Charger V2. It has a similar foot print so it will work in my enclosure. I notice that the delivery time is quicker than the ‘Babysitter’, is that do to stock levels?

The ‘Babysitter’ will it stop power to the LED? If so it might be a better result for my project. Do you have any of these in stock?

So you would recommend the Adafruit unit over the SparkFun for my project? I don’t mind which way I go but am looking for the most straight forward option.

look forward to getting some pointers and would be looking to purchase parts this week.


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Stock levels are entirely live - be it local or overseas stock. But yeah, a delivery date of today +2 days is local stock.

I don’t know enough about your project to make the call between modules Sean - both are entirely open source so you’ll be able to check every little feature out and make that choice. Heck, grab one of each :slight_smile:

Would be great to hear how you get on though, datasheets are nice but actual feedback is even better!

So after more reading tonight I am swinging towards the Adafruit unit. While the Sparkfun ‘Babysitter’ can do more, it doesn’t seem to have any inbuilt signal for low V. It would seem you need to have an exterior controller to take the info and convert it to an action.

Where the Adafruit unit would be a straight forward hook up of LED’s to inform the user that the V’s are low and you need to charge. The only reserve I have is will these different chargers from the same manufacturer maximise the battery better, which is what I was originally having issues with.

I had my test unit run continuously over the weekend to get an idea of the run time I would get from the battery. In the first 24hrs I only lost a little over 300mV. Unfortunately it plummeted over night dropping from 3.68V at 10:39pm, down to 2.62V at 8am this morning.

It was this process that has made it acutely aware of the need to have some Voltage warning on the lights, so I don’t destroy the Lipo’s.

I charged it up again today and it only got to 3.8V after 7hrs charging, not sure if it damaged it running it so low. But it charged and showed no signs of issue. Luckly it was my test unit that got this treatment and not the display items.

I then used the Freetronic charger tonight and it took it up to 4.12V in around 1.5 hrs. I might have been in luck that the lights are pulling a long slow draw and not making the battery discharge at at rapid rate.

So my main concern is it’s almost like the Adafruit chargers are stalling at 3.8V. Not sure if it’s the units I have but it would seem that it is consistent as that is the problem I was having from the start, with 3 of the 4 units hovering around the 3.8V mark after being on charge for at least 8hrs.

I don’t want to be swapping the current chargers for another one that is not maximising the batteries. I know its hard to diagnose the problem, thanks for the advice on parts to date.


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