My Battery Tender charger has been a trusted charger for all my batteries for years now, it has been my only choice to charge all my lithium batteries. It is portable, charges conveniently, has a great indication system and almost never bothers me with errors.
It has charged my most drained batteries and given them new lives time and time again, but sometimes, batteries just die out without a warning which makes you stuck trying to figure out and troubleshoot.
I have run into situations like this a few times and sometimes the batteries can be saved with a little trick, other times you just have to let go and spend a big buck trying to fix or replace them.
I also have a short video about this topic which you can watch below before you continue reading this article.
On the video I showed the two scenarios in which you can use a Battery Tender to charge a dead battery. The first one is you see a flashing red light on the display and the second one is when you see flashing red and green lights.
2 Cases When a Battery Tender can Charge a Dead Battery
Here’s what I have learned from trial and error, follow along to give your dead lithium battery a last chance to charge and revive.
Case 1: Flashing Red
If you are not familiar, this is how the Battery Tender charger indicates a dead battery, by a flashing red light. I hate seeing it every time it comes up, it displays when your battery is no longer charging or the voltage is below the base voltage of 3V.
It doesn’t always mean that the battery is completely dead, here’s what I did to recharge a similar battery:
First, I checked the voltage which was around 1V, confirming that the battery is too drained to charge, then I checked if the battery was swollen or damaged, as it is dangerous charging damaged batteries.
Once assured that it was just a low voltage issue, I took another good battery I had laying around to jumpstart the dead battery.
For that, I took jump clamps and connected the positive and negative terminals of the two batteries and let it charge for a few minutes.
After a while, I checked the voltage again and this time it showed a charge of around 4V, making the battery fit to charge again. I put it back on the Battery Tender charger and as expected, it started charging again.
I also have a short video in which I demonstrated the steps I discussed above and you can watch it below.
Case 2: Flashing Red and Green Light
The flashing of red and green lights on the display usually indicates that the polarity of the battery clamps is incorrect, but sometimes, an inner short circuit in the battery also makes the charger flash red and green lights.
In this case, you can again try the jump start method but it is very less likely that the Battery Tender can charge the dead battery again.
So yes, a Battery Tender can charge a “dead” battery but only if it is a draining issue and the battery isn’t too far gone. I hope this helps you next time you have a battery issue.
And before I forget, I also have a short video about this topic which you can watch below.
