Timely issue to build on top of the recent battery tender thread.

My car battery is dead (haven't used the car for a 2-3 weeks).

I connected the battery tender but the unit is flashing red - not connected to battery properly (or something along those lines). I'm guessing it means that the battery is too dead to charge?

What to do?
1) jump the car, drive around a little and then try the battery tender?

2) replace the battery.

3) Get a CTEK?

Other?

I've had a condition where the battery was low and the car wouldn't start (it would make noises but wouldn't start). The battery tender would recharge the battery. In this case, nothing other than silence when I turn the key....

This is one of the reasons that I like the old school chargers. Doesn't matter what condition the battery is in, it will run a charge to it. Today's smart chargers don't like to do that.

What I have done is taken another battery, run a set of jumper cables to it, and then hook the charger up to the dead battery to get it to run. On occasion it will catch on that you're attempting to trick it and shut off, so you may need to restart it a few times.

so that the leads don't spark if you touch them with the BT plugged in and the leads loose and contacting each other there has to be some voltage for the BT to start. You can easily fake it out with applying some form of voltage (9v battery even works) briefly. briefly connecting another battery via jumpers will do as well.
But the hopes of recovering a battery that is truly dead to the point a BT won't try are very low.

Yep, hate that.

"Smart" charger will not come on unless it can tell / sense enough voltage to verify it is not hooked up backwards.

Safety feature...

Put the battery on an old school charger for a couple of hours. This will bring the voltage up or over the threshold (~3v IIRC) to use the smart charger.

Caution: Jumping and driving may stress your alternator, they have been "weight reduced" so many times, many dont have the capability to run the car and charge a fully discharged battery.

quote:

Originally posted by a1abdj:
This is one of the reasons that I like the old school chargers. Doesn't matter what condition the battery is in, it will run a charge to it. Today's smart chargers don't like to do that.

What I have done is taken another battery, run a set of jumper cables to it, and then hook the charger up to the dead battery to get it to run. On occasion it will catch on that you're attempting to trick it and shut off, so you may need to restart it a few times.

Yup.

I've run into this problem and ended up having to hook a dead battery up to a regular old "dumb" charger in order to get a little voltage on her before the "smart" charger would recognize it and start charging it on its own.

Thanks guys. So, jump and drive is out. Sounds like a CTEK is advocated here? One that will charge and maintain?

Be extra careful about polarity because a battery that is totally dead can be charged up backwards (not that I know anyone who worked on a car lot as a kid and has ever done that).

Cars back in the 60's might survive that, but I'm sure modern cars would then fail the smoke test.

Depending on the age of the battery, you might just buy a new one.
Then buy a CTEK for future use.
When you get the charger get one of these too.
https://smartercharger.com/col...riant=18737430626404

If it only took two or three weeks to completely die, it's likely time for a new battery...wouldn't hurt to have your alternator checked also

quote:

Originally posted by PeteF:
Put the battery on an old school charger for a couple of hours. This will bring the voltage up or over the threshold (~3v IIRC) to use the smart charger.

This.

Go get a new battery and quit dicing around with the old one.
If you do manage to get the old one working the question is for how long?

Bob

Good decision. But what is a CTEC? The photo didn’t help my understanding.

quote:

Originally posted by Cassandra:
Good decision. But what is a CTEC? The photo didn’t help my understanding.

Battery charger.
https://smartercharger.com/

I checked my files. Battery is about due at 2.5 years old. Typical time to replace. Off to buy a new battery today.

Supposedly, there is a way to use a 9V battery to trick the battery tender into kicking on.

2.5 years is not an old battery.
You should still have some warranty life left on it. Most batteries now have a pro-rate warranty fro something like 60 months, depending on brand and how much you paid.

I'm with Bob on this one. If you get it charged up it may seem to be OK for awhile but let me warn you...it is just waiting for the worst time, the worst place, and the worst weather to smite you. Get a new battery!

for my car, I've been replacing batteries every 2-3 years. Usually get some pro-rated price on the new battery. but the last round, the warranty was only 2 years. but i think the warranty is longer for new purchases again. all Costco.

You get what you pay for.

Bob