Lipo battery swelling up

Projects General Guidance
1

Hi,

I've been field testing my arduino project for a year new and recently found that the lipo battery (which charges off a Powerboost 500 charging board) has begun to swell up.

here's a photo...
https://photos.app.goo.gl/ZmaHBAF6HLKejubGA
The battery on the left is the one swelling, the one on the right is a new one for comparison.

It's only been through about 100 recharge cycles, so I'd expect it to last longer.
However, a swollen lipo is bad news, also a fire risk I believe?

Has anyone else had issues like this?

thanks

2

Hi,
Ops pic.

batts.jpg
batts.jpg1067×582 99.8 KB

Thanks.. Tom... :slight_smile:

batts.jpg
batts.jpg1067×582 99.8 KB

3

By the time a Lipo gets to that state it should really be retired. The fire risk is minimal but real if you carry on charging it.

Good lipos will usually last more than 100 cycles unless they are abused (overcharged or over discharged). What is the capacity of your Lipo? Is it specified for a 500mA charge rate?

Steve

4

It's a 400mAh battery.

I was under the impression that the power boost 500 could handle any charging requirements for this battery and also handle over/under charging?

Am I correct?

My main concern here is fire safety.

thnx

5

Hi,
If you look at the Adafruit site that gives tutorial and spec, the Powerboost 500 is programmed to charge at 500mA, which is way to much for your 400mAh battery.

If you look at the spec sheet for the MCP73831 you will find the position of the program resistor and the equation to work out its charging current limit.
The board looks like it is setup for a 2500mAh battery.

Tom.... :slight_smile:

6

Tom,

thanks for the reply. I never realised that was the case.

Can you recommend a similar but more appropriate charging unit?

I need to to boost 3.7v to 5v for my project.

thanks

7

I use these to charge 3.7V LiPo cells. They charge with USB and output 5V at 1A.

8

groundFungus:
I use these to charge 3.7V LiPo cells. They charge with USB and output 5V at 1A.

thanks.

I did look at this but couldnt quite figure out the voltage setting. It's the little cross head screw isnt it?

Do you these units to be fairly robust and reliable?

9

It's the little cross head screw isnt it?

Yes, it is a potentiometer on the board.

Do you these units to be fairly robust and reliable?

I have 3 in use for several charge cycles each with no problems so far.

10

There's another potential cause of battery swelling, and that is continuing to charge a battery which is already fully charged. That can happen in UPS mode when the project load is present while the battery is being charged. Most chargers terminate charging when they detect that the charging current has dropped to 10% of the full constant current charge rate. But if the load current is greater than 50mA (in this case), then the current seen by the charger will never drop below that level, and charging will never stop. The Adafruit listing for the Powerboost 500C says it can be used in UPS mode but I would question that. It uses the MCP73831 charger, which I believe is susceptible to this failure-to-terminate problem. If the red "charging" LED never goes out, while your project is powered up, you have this problem.

11

skyboyflyboy:
My main concern here is fire safety.

I have some ceramic flower pots to store and charge my batteries in.

ceramic pot.jpg

ceramic pot.jpg

12

Do you use the saucer for a lid?