Car Battery Question

Yes, I know; we discussed this in several threads over the years...

Here's the De-limon: My wife bought a Ford Fusion Hybrid 2 years ago and we love the car. There is one issue with it. Well, like all new over engineered cares there is more than one but this is the latest big one: If it is left and not run for 3 weeks the 12volt regular car battery that actually runs the car's systems , not the electric engine, will go totally dead to the point it can't be recharged. My question is what is the best automatic trickle charger out there... that will keep the battery charged but not over charge it? I'm still trying to determine how many amps the car's system pulls while it is turned off. My first test showed .3 but then I realized that was with the trunk light on... this is where the battery is located*. I have a good amp meter and when I tried to check in the front under the engine hood (no light there) and with the trunk closed I'm only getting .01 amps as a drain. Twice a year we take off for close to 3 weeks using a different vehicle. (The Ford Flex with the $6,000 transmission in it) and so I need to fix this problem... this is the second time I've had to replace a battery and this latest one is less than a year old. I supposed I could have taken it in and gotten a replacement under warranty that I'm sure I still had but it is really not the batteries or manufacturer of the batteries fault.

Good trickle charger that won't over charge the battery is what I need that I can leave hooked up for 3 weeks or possibly put on a timer?

*Oh one of the interesting designs of this car is like I said the battery is in the trunk and the only way to open the trunk is electrically with either the remote fob or pushing a button on the dash and so when the battery is completely dead you technically can't get the trunk open. You can because the hood is not electric but mechanical and then you hook 12 volts up to two connections beside the engines and that will allow you to open the trunk and dig the battery out of the side which is strapped in tighter that a NASA astronaut getting ready to take off.

As posted above...sorry it's sideways.
We've had good luck with both of these, longer history with the Battery tender brand, I've got 4 of them hooked on cars with conventional
lead acid batteries and no issues. Leave them on all winter. They make a variety of chargers but the one in the box is what we sell.
Been selling the Optimate 3 for a few years now and I've got one plugged into my forklift and one on the John Deere tractor, leave the
tractor on in the winter and the fork truck almost always....so far so good.
If it matters the Optimate is made in China and the Deltran which used to be made here comes out of Vietnam now. Not sure
about their other various models.

I have three of these. Two in my barn on automobiles in the winter and one in my basement on my backup sump pump. They work great and I've never had a problem with them. I purchased mine thru Amazon.

Battery Tender.

There really isn't anything wrong with your car. There are so many processors with a "keep alive memory " they just draw that much that about 3 is all they can do without running.

I am surprised that you can't bring that battery back to life though.

This is the BEST, that you asked for, Sir.
It also has a desufater mode that will bring "dead" batteries back to life.

I believe that I would try to find what is draining the battery. If anyone bought that car and went on a vacation, parked at long term at the airport, you would expect it to start when you returned. What does the dealer say?

Quite a few regular chargers will drop back to maintenance output when a battery is fully charged. I keep one on by Jeep.

Without the least hesitation, I recommend Battery Tender/Battery Tender Jr. I have 6 of them. All will charge a battery if needed, and then maintain it at .5 amp, which will not boil a battery no matter how long it is left on. Mine are all over 6 years old. Never had to replace one. Never had a bad battery. One battery is on my shelf hooked up- I use it one time a year as backup during my out-west hunting trip. 7 year old Interstate still at full charge. Now, for a jump starter, NOCO has my vote.

Fox Mike said:

I believe that I would try to find what is draining the battery. If anyone bought that car and went on a vacation, parked at long term at the airport, you would expect it to start when you returned. What does the dealer say?

Click to expand...

New cars have a stated maximum draw. Unlike years ago, there is an acceptable limit and your stated situation can be too long. I don't remember the spec, but it is about three weeks of no use. It also varies by vehicle. We dealt with it a lot on our test vehicles. (retired auto engineer)

85 milliamps

Battery Tender. Have two on two vehicles and leave them on all winter (6 months or so). Never had a problem with either of them.

Good or bad, I've been satisfied with 'STANLEY' branded(no idea who makes them) trickle chargers. I had two that were at least 5-6 years old but one was lost in the 11/2/22 fire while the other still works as expected. During winter months, I rotate a trickle charger between dump truck, 5 tractors, a skid loader, and mini-excavator with each getting a couple days charge every month so basically, the charger is in use full time. I've never had a problem with overcharging.
After losing one STANLEY, I replaced it with a SCHUMAKER that so far has worked fine. With so many(approximately 30 for our entire operation) batteries in use(many of them seasonally), it's important to keep them in good condition. Even with good maintenance, I've already spent almost $700 on replacement batteries this year.

Battery Tender
Noco Genius

Both of them work great.

I am no expert but I'm pretty sure your car ain't supposed to do that.

For vehicles that will be parked outside look at one of these:

If parked inside near a window this could also work.

I am not a Solar Expert but I understand a good charge system has a charge controller?

My wife's car was having the same problem and I installed a NOCO Genius Gen 5x1 and the problem went away. One nice feature is that you can select the type of battery that your vehicle uses. When she's not been using the car for a while I just pop the hood and plug it in but if we were going on vacation I plug it in before we leave and just leave it. It will only charge when the battery needs it.
** I installed it permanently under the hood **

If you are worried about over charging, power the charger with a chrismas tree timer for one hour a day.

Literally every single charger/maintainer these days will automatically shut off once it reaches capacity. It's almost impossible for a tender to overcharge.

Hybrids have a bunch of computers that are kept alive by the 12 volt battery. Most of them also have a small water pump and a heater to keep the batteries at a proper temp. If the engine doesn't start for a few weeks, the battery dies.
The early Prius hybrids would randomly start the engine to avoid this problem, but that caused bigger problems, so they stopped doing that.
A 7 watt solar panel connected directly to the 12 volt battery with alligator clips will keep it alive as long as it's in sunlight. They don't work in the garage. Can't plug the panel into the accessory socket, (formerly known as cigarette lighter socket) because it turns off with the "ignition".