Battery chargers

J

jdw1222

Joined
Apr 2, 2005
Messages
301
Location
SC Coast
Had 2 times recently that I have had a Battery completely drained. The “smart” charger i have won’t do anything to charge it. I have to trick the charger by connecting it with a spare battery before it will even start charging.

Is this just the way these chargers are now? Anything else to try if I don’t have a spare battery laying around?
 
The instruction manual for your smart charger might include how to force it to charge.

My generic 6-amp buzz box charger has a lot going for it.
 
My Noco chargers have a function that allows the user to force a charge for a period of time, even if the battery is below the required voltage threshold for automatic charging. After one or more force charge cycles, the automatic charging program can take over.
 
The auto charger will tend to “bump” the battery. Leave it on for a while and it may start charging. If not, I use a trickle charger to get it going. What you did is fine.
 
jdw1222 said:
Had 2 times recently that I have had a Battery completely drained. The “smart” charger i have won’t do anything to charge it. I have to trick the charger by connecting it with a spare battery before it will even start charging.

Is this just the way these chargers are now? Anything else to try if I don’t have a spare battery laying around?
Click to expand...

Yeah - that's how they work. I had an extremely dead battery once that wouldn't start charging until I put it on a 1A manual charger for an hour first. These newer chargers aren't really designed to charge a completely dead battery. It needs to sense a minimum voltage first. My charger had a 7-segment display that displays voltage when powered on but before the charging settings are selected. When it does start charging it flashes between an approximate percentage of charge and "12" indicating it's charging at a nominal 12V battery. It was less than 7V and refused to start charging until it was up to maybe 10V. I think it's something to do with the safety of charging a battery that dead.

And in that case that battery was gone and needed replacement. It might start when fully charged, but overnight it would no longer start.
 
Another issue I have had is the charger is made for both 6v / 12v setup. If the battery is dead and I finally get it to charge the charger thinks it’s a 6v and won’t charge like a 12v
 
jdw1222 said:
Had 2 times recently that I have had a Battery completely drained. The “smart” charger i have won’t do anything to charge it. I have to trick the charger by connecting it with a spare battery before it will even start charging.

Is this just the way these chargers are now? Anything else to try if I don’t have a spare battery laying around?
Click to expand...

they do this because they want to make sure you didn't reverse polarity. I use the same solution you did, though thinking about getting a dumb charger aswell
 
jdw1222 said:
Another issue I have had is the charger is made for both 6v / 12v setup. If the battery is dead and I finally get it to charge the charger thinks it’s a 6v and won’t charge like a 12v
Click to expand...

Yeah - I've got that problem with a few of mine. I have (or at least had) two versions of the Schumacher 1.5A maintainer. The newer version (which I can't find now) was light with a switching power supply, but an auto detect for 6/12V charging. The older one has a manual 6/12V switch and I could feel the weight of the transformer.
 
I think one needs two chargers in today's smart charger world. Of course the smart charger, and also an old analog charger.

Use the analog charger to bring some voltage to the battery, then switch over to the smart charger.

Here is a picture of my setup. Currently trying to bring a very "dead" MB OEM AGM battery back to life.
PXL_20211122_104048012.jpg
 
jdw1222 said:
www.homedepot.com

VECTOR 15 Amp Automatic 12V Battery Charger with 50 Amp Engine Start and Alternator Check BC15BV - The Home Depot

The VECTOR Battery Charger and Battery Maintainer, BC15BV, is a charger, maintainer, reconditioner and quick booster that also helps to extend battery life and reverse battery damage. It is designed for
www.homedepot.com
Click to expand...
I have the black & decker version of the same charger. I had the same issue when trying to charge a heavily sulfated battery that still showed 12V, but wouldn't accept charge current (but none of my 10 different smart chargers worked on that battery). I have not seen the 6V/12V issue you describe.

My solution was to put 16V on the battery via a DC power supply to force charge it for a few hours. then put it on the smart charger to finish it off. that brought the battery back to 90% of its original CCA. variable DC supplies are a handy thing to have around the shop. they give you precise control over voltage and current to desulfate and charge a battery https://www.amazon.com/dp/B08C7PQRPQ/
 
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