I bought battery charger since I ran into this issue last yr but never thought about charging it daily, yeah I only drive once a week and it’s a short trip. When you think about it these batteries are ancient tech if the cars don’t get driven almost daily battery cell will break. I also jumped this battery a dozen times that probably made it worse.

 

Since Covid, I haven't been driving much. I always let it run for 15 minutes once a week to keep it charged, if I don't drive it.

 

With a battery maintainer (commonly referred to as battery tender) you can leave them plugged in for as long as you like.
They will charge the battery up and then go into "float" where they cycle to keep the battery topped up.
Battery Tender is actually a brand, recognized by their green and black case with yellow writing, that is popular to use as a battery maintainer.
There are also battery chargers that are used strictly for charging batteries...and have no maintainer function.
And there are combo units that will do both...charge at varying rates when you need to charge a battery, and can also be a maintainer to keep a charged battery full.
Whatever brand/model you're using to maintain the battery, just confirm it's set properly for what you need it to do.

 

I have this unit since last yr I only used it to charge battery does this top off “float” battery? I left it plugged in and it simply turns off once it reaches 100%.

Amazon

Amazon

 

I drive at least once a week and it seems like it’s not enough and battery eventually dies after a few months. Maybe because mine is IS350 with 6 cylinders harder to start?

 

Something is not right. How long do you drive it? Seems something is draining the battery.

 

I only drive short local trip maybe 20-30 minutes total. I got new battery in Aug 2019 and just got another one yesterday. I was worried my Android screen might be draining battery but other owners don't seem to have same issue.

 

It mentions a "maintain" feature in the product description...but they don't really give too many details about it. I'm skeptical if it really "maintains" the battery. Seems to be a little loose with the language.

Here is a well known brand for simply maintaining the battery charge:
If you think something may be drawing on your battery, a battery draw test would be the only way to confirm. You will need a multimeter to do the draw test.
There are several Youtube videos on how to do it, personally I would recommend this one: ...with the caveat that I would use the Negative battery terminal, not the Positive terminal like in the video. The result will be the same with no chance of anything going wrong.

 

A bit too complex for me to do this test, looks like I have to take out each fuse and see the current draw including alternator. I just bought another battery charger that can top off. Spending too much money on battery related stuff. $80 on Schumacher charger, $99 for supercap jumper, another battery charger for $85. I could have gone with cheaper one you show but some reviews are not so good.

 

For the video posted above, once you check the battery draw and it's normal, you stop there...no need to pull fuses or anything complicated. Only if you have an excessive draw do you start pulling fuses.
Even though there is no repair manual spec for battery draw, it should be about 30mA for our vehicles...give or take a couple mAs.
In the video the meter showed 0.02A, which is 20mA...really it could have been 21 to 29mA, but the meter only had two decimal places...so our car if you got 0.02 or 0.03 you would be fine.

Ironically I just finished fixing a battery draw issue on my buddies 2006 Z4 M Roadster...it was 0.33A, or 330mA...battery would die in about 3 days...like dead dead.

 

Just a word of caution on the plastic cased Deltran Battery Tender models, a member of another forum I participate in had one melt down and almost burn down his house. I’ve had a metal cased one connected to my other car for almost every day for 6 years with no issue, just barely warm to the touch.
A very popular brand is CTECH, which is rebranded by high end car makers and sold for much higher prices than the CTECH labeled models. Ones I’ve seen recommended are the MUS 4.3 and MXS 5.0, e.g.: CTEK - 40-206 MXS 5.0 Fully Automatic 4.3 amp Battery Charger and Maintainer 12V (40-206)

 

Good to know...I also have a metal cased one that I use on my bike for the last 10 years. The thing has fallen so many times, my gawd, but still works like a charm and never misses a beat.
It probably about twice the price of the one I linked above.
CTEK is also a well known brand along with the Noco Genius line of products.
You have to figure in every line of products there is going to be a dud somewhere that's not reflective of the quality in the rest of the products.

 

CTEK MXS 5 is the one I just bought looks like a good choice, it's not cheap but better than starting fire. It's same model used in BMW dealers they actually slap their logo but it's made by CTEK. Is it ok to keep eyelets connected to battery and just leave in engine bay it's easier to connect and disconnect? Not sure cables can handle long term heat from engine.

 

It's ok to leave the eyelets connected. Considering where the IS battery is, it would be easy to just tuck the eyelet away between the battery and firewall.

 

I'm stumped! I couldn't start my car again, I had the new CTEK charged battery to full yesterday this morning when I fired up engine won't turn completely and dropped off midway. Second start it takes longer to turn the engine and I was able to start. I'm starting to suspect it's something else since I already ruled out battery. This is starting to irritate me, I'm going to let CTEK charge the battery again. I also measure current draw it was only 3mA when everything was off, but I'm not sure whether Android screen might be waking up middle of the night and drawing power.