Kärcher’s 18V batteries aren’t supposed to stop accepting a charge, but it happens from time to time and it is annoying, your Kärcher 18V battery won’t charge anymore and nothing seem to happen on the charger end either. The first thought is that the battery has fallen asleep (deep sleep mode) because it was discharged below what the charger could sense or see as a battery.
So maybe it isn’t the battery? Well yes, this can be fixed before you send in a battery that might still work for replacement.
How to Jump Start Your Battery
Here is the trick for waking the dead battery with another known good battery. For this trick, you’ll want a second battery that works with the one that is not working (another 18v… 20v battery).
Before anything, you need to mark which terminal is the good battery pack’s positive and negative side. Your good battery will look very much like this, with obvious molded indicators for each contact. The wrong polarity could screw it all up in a hurry so go slow and get this part right. A digital multimeter will confirm your findings without any doubt whatsoever. On the good pack, you’ll read somewhere near 20 volts.
The next step in waking up a dead battery involve connecting both with some wire to jump start each other. Take positive side of your good battery and connect it to the corresponding side of the dead one. Do the same with the negative terminals. Even though this sounds like a recipe for disaster, they will shares their voltage together. Let it sit connected for about fifteen seconds; that should of being long enough to allow juice through.
At this point, keep an eye on it as the dead battery is trying to revive itself enough for its internal circuitry to turn on. If your connection isn’t good, heat could be generated. But assuming you’re doing everything right, nothing strange will happen (no spark).
The wire will sit still on each contact surface and the voltage of each unit will begin to balance out. Once time has passed, remove the wires from both batteries and part ways.
Plug the charger into the now-dead battery, and instantly it come alive as the charger lights light up. That’s a great sign that the reset was successful and the unit takes charge immediately. The wake-up method bypassed the safety lockout because of the low voltage state, so the charger indicator displays normally. You don’t need a new pack, so you are saving money in the process.
Most folks think if a cell is stuck, the battery is dead. Not so. It’s simply asking for a little help from its healthy neighbor.
Plug ’em in and give them a jumpstart, and presto; your charger will acknowledge the pack once more. Nothing fancy to do but get going. No costly replacement or repair required. Just like new!
