you need to pulse it at a point before the circuit board. The bottom picture shows how to check the true voltage of a Ryobi 18v battery.Yes, the test leads are reversed but you can still see the voltage (minus the negative sign). To charge a 40V battery, you will need a voltage source of 40V. Cant the same be achieved by touching the terminals when it is still fully assembled?! Cut the end off of your AC adapter. It is, to the best of my knowledge. IT IS VERY IMPORTANT TO NOT MIX THE TWO UP. I've been doing maintenance and handyman work for the last several years and I'll be including little home and garage tips and tricks that I learn along the way as well. Living in TN, I've already had to mow my yard several times this spring. I know I'm sure to get comments saying I should have bought LiFePO4 batteries, but I hadn't seen enough good examples online to justify the added cost of the batteries and charger. You have successfully joined our subscriber list. The battery cells are not replaceable, and you should recycle the battery properly. The battery control board meters the power to a tool or the charger and will always display a lower number. You will see a dramatic increase in surface charge. There's a hidden screw under a piece of plastic. The red LED should flash several times. You can find replacement battery packs at most hardware stores or online retailers. Multi-meters vary the settings, so read your users manual. Skelly. Get these 12V and 18V adapters from Amazon, and they will work great. I know my smart charger for my 12-volt car batteries requires a minimum voltage of 9.5 when charging any 12-volt battery. When a Lithium-Ion battery is being charged, the lithium ions move between the cathode to the anode through an electrolyte solution contained in a battery cell. Damage to a lithium cell can release the lithium and cause fires or explosions. For Cheap! When I contacted RIGID about a 6 year-old deceased battery they refused to honor their much touted lifetime warranty. 18 volt dual chemistry battery charger (24 pages) . Total nonsense. Even on a good battery thats relatively high in charge, the part that sticks into the tool will read 18.27, but the overall voltage of the cells will be 19.53, for example. This means that if a 12 V battery got discharged and went down to 6V, as soon as you connect a voltage source above 6, it will start charging. If your reading is a negative number, then you know that you have it reversed.GND indicates ground, or the negative terminal of the battery. The last way to charge your Ryobi battery without the charger is to use a solar charger. Also, keep them indoors. Your rechargeable battery is now fixed. The RYOBI 48-Volt 30 in. Charging a rechargeable battery with another fully charged battery is also a great hack. Just cut it off. If you still only get a red flashing light and the battery won't charge, boost the battery some more. Quick Tip: Get yourself this inexpensive voltage meter by Amazon Basics to properly check your battery voltages while you charge and discharge it. A common misconception with the newer Lithium-Ion batteries is that it doesnt matter if you leave them on charge because of the sophisticated technological changes that have been made to chargers. Therefore, every manufacturer provides a dedicated charger for the batteries, often inside the package. Okay, so now we have discussed how to charge any battery, lets move on to Li-Ion batteries. This same technique is also used in Fast Charging. Cordless tools have become common in most homeowners tool collections. That's right. but I think that would expose the system to moisture. When you insert the battery pack into the Ryobi charger, it tests the voltage and gives a defective battery error. To fix this, you need another Ryobi battery or charger to jump the controller circuit. We suggest that you not try to open the Ryobi battery charger. This could mean that the battery has one or more cells that have gone bad, or has fallen under the minimum charging voltage. The lady I talked to said that I had to be reasonable in my expectations. Charging: Fast charging . Then hold them down again. To remove the screws on the battery, youll need a T10 security bit (T is for Torx, or the star-like pattern seen in the picture below) and a nut driver. The battery is not failed, its faulty/badly manufactured. I'm Robert and this blog started with my journey of learning about battery banks, generators, and power outage preparations. By accepting all cookies, you agree to our use of cookies to deliver and maintain our services and site, improve the quality of Reddit, personalize Reddit content and advertising, and measure the effectiveness of advertising. If you keep repeating the process over and over without giving the battery enough time to lose the surface charge, then within 30-60 minutes to may find that all of those micro charges added up to make the battery cross the minimum voltage threshold. Note: If you aren't used to doing this sort of thing, or using things like a "multimeter" this is going to seem crazy and hard and way out of your DIY league. ~ karen! I never kept track of what voltages worked and didnt. The parasitic draw of the tool depleted the battery to the point where it cannot be recognized by the charger, but it should be able to be revived! If any cells have less than 3 volts, replace them to fix the charging problem. Or you're going to hang a picture. I plugged in my iPad for more than 1.5, Read More Why is My iPad Battery Charging Slowly? Keep your batteries and chargers in a dry environment and avoid getting them wet. Ill tell you what I learned as far as salvaging a Ryobi battery or retiring it for good. It's an antique, found in an old hardware store. #1 I was trying to see if I could charge the Ryobi P102 Lithium battery without the original charger (a working battery). If the cells are relatively even, then we can continue. You'll be lucky if you 2Ah battery is now a 0.5Ah. Now connect the terminals in the same polarity. Remove the 2 plastic side pieces. Not very scientific, I know, but its pretty basic.The thermistor is under the black tape on the side of one of the battery cells. You can test the voltage of individual cells and replace the defective ones. The simple answer is because it reduces their lifespan and, if it is a Ni-Cad battery, there is a slight chance the battery could explode.