Tell me about car battery chargers

Factual Questions
1

Background: I have a 1999 Chevy Tahoe. About 6 months ago it was stolen. I got it back a month later but the person who stole it cut into the electrical system to rig up a heavy duty stereo system. I disconnected all that stuff. I now find if I don’t start my truck within three days the battery goes dead. I’m guessing there is a small drain some where.

It has a new battery in it.

My question: I’m looking for a small, inexpensive charger to keep on the battery while it’s parked in the garage. I was thinking I should get a trickle charger (because that’s what I’ve heard in the past) but I’ve read on the internet not to waste my time with them. So for what I’m trying to accomplish (keeping my battery charged), what type of battery charger do I need?
ETA: I know I need to fix the root problem but don’t really have the smarts to fix it or the money to pay someone.

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2

I think what you want is a float or maintenance charger. I see from my link below that they are also called tenders. Many regular battery chargers go into float mode when the charge is complete.

3

A charger will help but won’t solve the underlying problem. I believe the best solution in the long run would be to find the leak and fix it. Any semi-competent car shop can do that.

With a multimeter and a few minutes to spare you can even do it yourself: How To Perform a Parasitic Draw Test - EricTheCarGuy - YouTube

4

I got a maintenance charger at my local Honda equipment dealer for $30. it works great to keep my generator battery charged. I would guess it would work for you too.

5

How about disconnecting the battery when you’re not using it? You’ll still need to disconnect the charger every time you leave, right?

6

Too many computers and other electronics that need constant current. The transmission might have to learn its shift points every day.

The truck’s anti-theft gizmo wouldn’t work, and worst of all, the open-sesame key fob would be useless. What means this word, key?

7

Ah, I was hoping the car didn’t depend that much on electricity. Transmissions adapt shift points to drivers?

8

Here’s one example:

And the radio probably would lose its station settings.

Edit: Screwed up the link. It’s here: Diagnose Automatic Transmission

9

Wow, I didn’t know that. That’s useful if you change gear ratios, I guess. Maybe they should use non volatile memory though.

10

Thanks for that link. I don’t know if I could manage that test myself but I know people who probably could. The info towards the end on parasitic draws was especially helpful in that it pointed me to possible culprits.

Still looking for info on chargers in the mean time.

Thanks everyone.

11

FWIW, a floater/ tender is what you want. I have several cars and don’t always drive them enough to keep a good charge on the batteries. Due to computer stuff I don’t disconnect my cables. The floater/tender won’t overcharge your battery like a trickle charger can. I have never had good experiences with Schumacher brand. You may want to buy a charger you can use to charge a flat battery if the Tahoe is your only vehicle. They aren’t that much more expensive.

Try Amazon. Car part stores mark them up ridiculously.

12

The link wasn’t for helping with testing, it was to demonstrate the float or tender charger principle. Here, $19 at Walmart.

13

And that one is what started my hatred against all chargers branded Schumacher. It’s a saga no one wants to hear, but there are others around that price range. Also, for the OP’s Tahoe year, you might be fine disconnecting the battery when not in use.