Toyota FJ Cruiser Forum banner
  • Hey everyone! Enter your ride HERE to be a part of this month's Ride of the Month Challenge!

1 - 20 of 31 Posts

·
Premium Member
Joined
·
12 Posts
Discussion Starter · #1 ·
About 4 months ago my 16 month old Odyssey battery started losing charge. A battery charger brings it back to life, but within a couple weeks I’m back to having trouble starting the FJ. Granted my FJ does not get out of the garage a lot, but I felt the battery should hold a charge better than this. Does this sound normal?
 

·
Premium Member
Joined
·
12 Posts
Discussion Starter · #4 ·
I had front and rear bumpers installed that included additional lights. Switches were installed to control the new lights. Additionally, I had a Mean Green alternator installed. No modifications to the stock radio.
 

·
Registered
Joined
·
612 Posts
Last year, at the beginning of the pandemic, my Cruiser sat for 2 months. I discovered that my 1 year old battery had drained to the point that it would no longer hold a charge and I had to replace it. I have no aftermarket electronics so my assumption is that the FJ, in its stock form, draws quite a bit of current supplying power to the memory of various components. After researching for a "Quality" tender, I purchased a CTEK and mounted it on the wall in my garage.

I'm now in the habit of plugging in the tender each time I park my Cruiser.

Throughout the years I've owned different tenders. Some worked as advertised, some did not. CTEK products have a premium price tag but this is the best tender I've ever owned. The CTEK tender keeps my battery fully charged and I don't have to worry that it might overcharge and cook the battery as I've experienced with cheaper tenders.



IMG_7348.jpeg
 

·
Premium Member
Joined
·
4,256 Posts
I had front and rear bumpers installed that included additional lights. Switches were installed to control the new lights. Additionally, I had a Mean Green alternator installed. No modifications to the stock radio.
Any chance you have anything plugged into your OBD2? I know some of the bluetooth code readers will drain a battery if left unattended.
 
  • Like
Reactions: Winterpeg

·
Premium Member
Joined
·
12 Posts
Discussion Starter · #7 ·
No bluetooth code reader. I've had a lot of modification done to the vehicle, but only a couple involved electronic. This battery issue took more than 12 months to materialize. I'm wondering if I caught it too late and the damaged to the battery is beyond repair?
 

·
Registered
Joined
·
21 Posts
My 2010 fj that I have owned for a year would have a dead battery if set unused for a couple weeks. I started doing parasitic test and discovered that the previous owner had installed a gps tracking device under the dash. Removed it and no longer have an issue. lonslo
 

·
Admin
Joined
·
8,503 Posts
You may also want to look into an alternator voltage booster.

Dirty Parts has them I believe.... I bought mine directly from HKB Electronics.
 

·
Registered
Joined
·
522 Posts
IDK how much it would draw, but you ever go out in the garage in the middle of the night and hear the hum of a motor running under the back of your FJ? freaked me out the first time i heard it. quick google said that the EVAP system apparently feels the need to run whenever it wants. not sure how often it would run if you are parked for long periods but it will use power when it does.
 

·
Registered
Joined
·
3,791 Posts
As much money as a batteries cost today and I have two, and even if I had just one, and I was having the thing sit for a while I would really have to consider a battery tender. The price doesn't seem to bad for one.
 

·
Premium Member
Joined
·
12 Posts
Discussion Starter · #12 ·
Thanks for sharing your ideas related to my battery problem. The fix may be as simple as a battery tender. Problem is my FJ is stored in a garage built in 1932, with no electricity. Thanks again for your help.
 

·
Premium Member
Joined
·
2,992 Posts
Wow, a 1932 FJ, that battery might be old enough to replace by now (those Panasonics are good but...).

:D
 

·
Registered
Joined
·
5,200 Posts
IDK how much it would draw, but you ever go out in the garage in the middle of the night and hear the hum of a motor running under the back of your FJ? freaked me out the first time i heard it. quick google said that the EVAP system apparently feels the need to run whenever it wants. not sure how often it would run if you are parked for long periods but it will use power when it does.
The evap emissions leak test pump doesn't run "whenever it wants", it runs a maximum of once per drive cycle, and only if list of other conditions (temperature, fuel level, etc.) are met.

If you drive the vehicle and then park it for a week, the evap leak test will run once.
 

·
Registered
Joined
·
5,200 Posts
I had front and rear bumpers installed that included additional lights. Switches were installed to control the new lights. Additionally, I had a Mean Green alternator installed. No modifications to the stock radio.
You should make an actual parasitic current draw measurement with an ammeter to make absolutely sure you don't have an unknown load continuously drawing current when everything else is off.

If no parasitic load is found, I'd suspect that your typical drive drive cycle is not long, or at a high enough speed, to replace the energy drawn from the battery during each cold start. You need at least 20 minutes at moderate engine speed to recharge the battery, depending on other loads that may be on during the drive cycle.

Real-world feedback regarding people's satisfaction after installing Mean Green high-output alternators to "fix" battery charging problems indicates much disappointment ... the ih8mud forum has lots of information on the actual performance of MG alternators on multiple vehicle types.

What initially triggered your decision to ditch your Denso alternator and install the MG?

Finally, all AGM batteries will perform better, live longer, and only charge to their full capacity if the charging system voltage is boosted slightly to ~14.7V, typically by installing a diode installed in the alternator's voltage sensing line.
 

·
Premium Member
Joined
·
12 Posts
Discussion Starter · #17 ·
Thanks for the recommendation on the parasitic current draw test. I’ll definitely look into it.

The amount of drive time could be the problem. My daily drive is 4 miles each way and I only drive the FJ enough days to keep the battery charged (obviously need to rethink that decision).

Mean Green alternator was installed after reading several positive comments on this forum. It was winter, I was bord with work and looking for a distraction. Seemed like a good idea at the time. I’ll take a look at the ih8mud forum.

Which brand AGM do you lean towards?

Thanks for the feedback and info.
 

·
Registered
Joined
·
5,200 Posts
I've used Odyssey for the last 12 years or so with full satisfaction.

First 8 years were in 4Runner without a voltage boost diode, currently running in FJ with voltage boost.

I'm almost 100% certain that your 4-minute drive time 2X daily, with 2 cold starts, is the root of your battery charging problem.

Not only is this not adequate to re-charge the battery, it is hell on your engine, with the oil never getting remotely hot enough with this big V6, for a long enough period of time, to vaporize all the moisture that condenses in the crankcase.

This is a SURE FIRE recipe for engine sludge.

You can deal with the battery charging problem by plugging in a high-quality (CTEK, etc.) battery tender every night.

But to avoid premature wear, corrosion, and sludge buildup in your engine, either lengthen your commute to a minimum of 20 miles each way at moderate speed (40+ MPH), or get a cheap, "disposable" vehicle with a tiny 4-cylinder engine for this 4 mile commute, and save the FJ for worthwhile activities.

Remember, for every gallon of gasoline burned, your engine produces slightly over 1 gallon of water. Most of this water escapes through the exhaust as vapor, but some finds its way past the piston rings and into the crankcase, wh.ere it condenses into liquid water when the engine cools off

That's why most of the fluid caught in a catch can in the crankcase ventilation system piping is water, along with a much smaller amount of oil.
 

·
Admin
Joined
·
8,503 Posts
I've had my MG alternator since 2013 with no issues.... Just FYI.
 

·
Premium Member
Joined
·
987 Posts
If no parasitic load is found, I'd suspect that your typical drive drive cycle is not long, or at a high enough speed, to replace the energy drawn from the battery during each cold start. You need at least 20 minutes at moderate engine speed to recharge the battery, depending on other loads that may be on during the drive cycle.
This is exactly what happened to me this past week. I typically drive approximately 1.5 miles back and forth to the gym...and then I went for a week without driving at all. I came back to an FJ that was dead. Took her out for a nice 30 min drive mixed highway and city driving. Hopefully she is charged up now.
 
1 - 20 of 31 Posts
Top