DIYer's - Testing my old Power Tool batteries

[gtaus]

Have you even wondered how much battery life is left in your old power tool batteries? Well, I do. I bought into the Ryobi line of tools 15+ years ago. I have some batteries that are 10+ years old. I decided to buy a battery load tester to see how well some of my old Ryobi batteries are holding up. Of course, the battery load test would work with any brand power tool batteries.

Here is the MakerHawk Electronic Load Tester USB Load Tester 150W 200V 20A Resistor Adjustable Constant Current Battery Capacity Tester Module Intelligent Discharge Resistance Power Tester which I purchased, used, from Amazon for $39. A new unit sells for $49, but I like to save money where I can.

Here is a YouTube video describing how to set up your load tester to run a capacity test on your power tool batteries. NOTE: For my Ryobi power tool batteries, the battery pack BMS (Battery Management System) will automatically shut down the battery pack at a safe level so it can be recharged normally. You do not have to worry about draining the battery dead.

I have started testing some of my old Ryobi batteries and these are the initial results I got from a random 2 batteries.

40v, 4.0Ah LI battery 3 years old tested out at 3.40Ah (85%)
18v, 1.5Ah LI battery 8 years old tested out at 1.1Ah (73%)

I was overall pleased with these results as I use the crap out of my batteries, and they are still holding up pretty well after years of use.

Now that I know how to use this load tester and measure the capacity of my batteries, I plan on ordering an off brand Ryobi knock off and capacity test the pack to see if it is anywhere near their rated selling claims. I suspect not. But an off brand Ryobi knock off 40v battery is about 1/3 the cost of a genuine Ryobi battery, so I might give it a try.

FYI, in a separate thread, I mentioned that I had purchased an Amazon off brand Ryobi 40v battery for my chainsaw. First one failed at half charge. Repalcement battery sent as exchange but it also failed at half charge. So, I returned it for a full refund. Keep your return receipt, as seller claimed I never sent it back! Scam alert on some Amazon resellers!

Do you need a battery capacity load tester? Probably not. But I just wanted to see how well my old batteries are actually holding up. I figure if I get my 3 years warranty use out of the battery, they have lived up to their guarantee. I was pretty happy to see that an 8 year old battery is still good for 73% of it's rated capacity if new.

I'd be happy to answer any questions or comments anyone has. Understand that a battery testing thread on a chicken forum might not be the hot topic for most. But lots of us DIYer's use battery powered tools for our chicken coop builds and projects. Thanks for reading.

 

[Sally PB]

Thanks for reading.

Thanks for posting. Very interesting. Now I'm wondering how the DeWalt Batteries we have are holding up...

 

[Happy hen lover]

Interesting post. I have ryobis and hubby has dewalts . I bought off brand ones and seems like they went bad fast. Did get a deal on Ebay a few years ago on DeWalt ones, guy must have been laid off as I got a deal on one of those 4v ones ( hubby's fav.)

 

[gtaus]

Now I'm wondering how the DeWalt Batteries we have are holding up...

Yeah, now I can put some numbers and percentages on my old batteries. My idea is to move the weak batteries to use in things like a flashlight, keeping the stronger batteries for the saws and drills. I was happy to see that even my old batteries are still doing quite well, better than I hoped.

Now that I have proven that my old batteries are in better condition than I thought, I think I will spread out my replacement battery purchases a couple of years longer. Might save me some money.

 

[gtaus]

I bought off brand ones and seems like they went bad fast.

If I buy another off brand Ryobi 40v battery, I will be able to test it out and get a good reading on the true capacity of the battery - before the 30 day return period. I have heard that many of the off brand batteries are built with used batteries, possibly at the end of their lives. That would surely show up on this battery capacity load tester.

 

[Rangergord]

Interesting how long you have been able to keep your batteries going, ten years beats the pants off the first nicad cordless tool batteries! I am interested in rebuilding my Makita tool batteries. I need to get a mini spot welder to connect the individual 18650 lithium cells together. The manufacturers build batteries with brand name spec cells like Panasonic or LG. A better battery but a much higher price. Chinese made cells vary in quality but if you can find a good manufacturer there is a lot of money to be saved. The 18650 cell is used in most cordless tool batteries as well as laptop computer batteries. As far as I know they must be spot welded together properly or you could end up with loose connections when being used that could result in fire.

 

[gtaus]

Interesting how long you have been able to keep your batteries going, ten years beats the pants off the first nicad cordless tool batteries!

I still have 3 (out of 8) Ni-Cad batteries that are 15 years old and used in my rotation. Since they are only 1 Ah each, I just use them in my job site radio or flashlight. They never had much run time even when new - at 1 Ah - so ,I am thankful everyday for our LI batteries which are much better and more powerful.

I am interested in rebuilding my Makita tool batteries. I need to get a mini spot welder to connect the individual 18650 lithium cells together.

The 18650 cell is used in most cordless tool batteries as well as laptop computer batteries. As far as I know they must be spot welded together properly or you could end up with loose connections when being used that could result in fire.

Spot welders might be the ticket if you plan on making a number of battery packs. I do believe, however, that I have seen many people on YouTube using a soldering iron to build their battery packs. I don't know how much a spot welder costs, but soldering irons are pretty cheap.

If you really get into building battery packs, you might try to get ahold of batteries thrown out into a recycle bin. From a number of sources I have seen, often times a single bad battery cell can FUBAR an entire battery pack BMS and prevent the pack from working. You might be able to tear apart those discarded battery packs, test the individual cells, and rebuild a new (used) pack with the good used batteries.

Although I am all in favor of reusing and recycling material, I have heard from a number of people that rebuilding a few power tool battery packs is not cost effective compared to just buying a new battery pack, with warranty, if you value your labor time. New battery packs are expensive, but evidently manual labor to rebuild a battery pack would cost even more. Just suggesting the you run the numbers on your project before you invest lots of money.

Having said that, I just ordered a DC-DC charger (bypassing the normal BMS on the pack) to attempt to recharge one of my failed Ryobi 40v batteries that are out of warranty. I paid less than $15 for the charger, so if I get my $130 40v 2.6 Ah back in service, I will be really happy. Even if the DC-DC charger does not bring my old battery back to life, at least I will have been able to geek out and have a little fun trying.