The Ford Barn

philipswanson · 08-12-2020, 03:51 PM

I blew my Battery Tender by starting the car with it still hooked up and powered. I suspect a diode blew inside of the Battery Tender from generator current. To avoid this, simply unplug the Tender before starting the engine. Luckily it was still under warranty and a new one is on the way.

Phil

51 MERC-CT · 08-12-2020, 03:58 PM

Are you referring to the brand name 'Battery Tender' or a different manufacturer?

philipswanson · 08-12-2020, 04:25 PM

Yes, it is a "Battery Tender" brand. It's probably good advice with other brands too.

Phil

glennpm · 08-12-2020, 06:33 PM

Yeah too bad they don’t include an outlet wire circuit breaker for over amperage protection.

leon bee · 08-12-2020, 07:18 PM

That's good to know.

flathead48 · 08-12-2020, 07:44 PM

Sponsored Links (Register now to hide all advertisements)

Thanks, I have a battery tender and am always starting the car without unhooking it. Thanks again for the heads up.

koates · 08-12-2020, 09:01 PM

Most standard type battery chargers should NEVER be used as a power supply for testing electrical components such as lights or motors as they are not designed to do this. Some large chargers have the capability to supply a couple of hundred amps for a short period to jump start cars. Battery chargers are just battery chargers ONLY. Regards, Kevin.

Frank Miller · 08-13-2020, 08:03 AM

I think you may have had a bad unit. There has to be protection for high amp draws. They put out like a 1/a and that is it. Generator current should go to the battery before the tender because that is the path of least resistance. It is a good idea to unplug it first because you do not want to drive off with it plugged in.

Automotive Stud · 08-13-2020, 08:18 AM

That's probably good practice, I've been known to start the car with the tender plugged in. There is a fuse in the line of the leads that go on the battery. That came in handy for me one time when I was switching the charger to another battery that had a lead on it and mistakenly hooked the two batteries together.

Step-down · 08-13-2020, 05:28 PM

I’ve seen on BT a line fuse on the positive cable and I assumed it was to stop back feed over load

08-12-2020, 03:51 PM	#1
philipswanson Senior Member Join Date: Oct 2015 Location: Bonita, CA Posts: 1,374	Don't Blow Your Battery Tender I blew my Battery Tender by starting the car with it still hooked up and powered. I suspect a diode blew inside of the Battery Tender from generator current. To avoid this, simply unplug the Tender before starting the engine. Luckily it was still under warranty and a new one is on the way. Phil

08-12-2020, 03:58 PM	#2
51 MERC-CT Senior Member Join Date: May 2010 Location: East Hartford, Ct Posts: 5,898	Re: Don't Blow Your Battery Tender Are you referring to the brand name 'Battery Tender' or a different manufacturer? __________________ DON'T RECALL DOING SOMETHING FOR MYSELF BASED ON SOMEONE ELSE'S LIKES OR DISLIKES

08-12-2020, 04:25 PM	#3
philipswanson Senior Member Join Date: Oct 2015 Location: Bonita, CA Posts: 1,374	Re: Don't Blow Your Battery Tender Yes, it is a "Battery Tender" brand. It's probably good advice with other brands too. Phil

08-12-2020, 06:33 PM	#4
glennpm Senior Member Join Date: Sep 2014 Location: Wiscasset, Maine Posts: 1,980	Re: Don't Blow Your Battery Tender Yeah too bad they don’t include an outlet wire circuit breaker for over amperage protection.

08-12-2020, 07:18 PM	#5
leon bee Senior Member Join Date: May 2017 Location: Arkansas Posts: 611	Re: Don't Blow Your Battery Tender That's good to know.

08-12-2020, 07:44 PM	#6
flathead48 Senior Member Join Date: May 2010 Location: Saratoga Springs, NY Posts: 1,110	Re: Don't Blow Your Battery Tender Sponsored Links (Register now to hide all advertisements) Thanks, I have a battery tender and am always starting the car without unhooking it. Thanks again for the heads up.

08-12-2020, 09:01 PM	#7
koates Senior Member Join Date: May 2010 Location: Melbourne Australia. Posts: 2,077	Re: Don't Blow Your Battery Tender Most standard type battery chargers should NEVER be used as a power supply for testing electrical components such as lights or motors as they are not designed to do this. Some large chargers have the capability to supply a couple of hundred amps for a short period to jump start cars. Battery chargers are just battery chargers ONLY. Regards, Kevin.

08-13-2020, 08:03 AM	#8
Frank Miller Senior Member Join Date: May 2010 Location: Auburn, MA Posts: 2,106	Re: Don't Blow Your Battery Tender I think you may have had a bad unit. There has to be protection for high amp draws. They put out like a 1/a and that is it. Generator current should go to the battery before the tender because that is the path of least resistance. It is a good idea to unplug it first because you do not want to drive off with it plugged in. __________________ “The technique of infamy is to start two lies at once and get people arguing heatedly over which is true.” ~ Ezra Pound

08-13-2020, 08:18 AM	#9
Automotive Stud Senior Member Join Date: May 2010 Location: New Jersey Posts: 832	Re: Don't Blow Your Battery Tender That's probably good practice, I've been known to start the car with the tender plugged in. There is a fuse in the line of the leads that go on the battery. That came in handy for me one time when I was switching the charger to another battery that had a lead on it and mistakenly hooked the two batteries together.

08-13-2020, 05:28 PM	#10
Step-down Senior Member Join Date: May 2012 Location: Hat City (Danbury CT) Posts: 647	Re: Don't Blow Your Battery Tender I’ve seen on BT a line fuse on the positive cable and I assumed it was to stop back feed over load __________________ "I can't cry as long as I know the Lord has risen "

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