Dead battery

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xlx

xlx

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Oct 24, 2017
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Columbus, OHIO/TLCA #26516
Need some help diagnosing a dead battery issue. This one is on my FJC. It was my daily driver until I got my GX three months ago. I never had any issues with it until I parked it in the garage for the winter. It sat for about 2 months without being started. When I went to start it it needed a jump. I let run but eventually the battery died. I just wrote it off as an old battery. I got a brand new Optima red top and it was starting fine until today. The battery is only a few weeks old and was dead. We had a cold snap but the vehicle has been in the garage the whole time. What would cause a new battery to discharge without being driven? It jump started fine and is on the battery charger now. Something is draining the battery. It has not been driven in 3 months. Any help would be appreciated. Thanks.
 
Last time it happened to the wife someone had left a map light on in the back. I've also noticed the vanity mirrors on these GX's are a potential drain. It has been particularly cold here in Ohio these past couple of weeks, and batteries not being tended do grow weak in the cold. I keep a $.99 battery/alternator tester handy that I picked up at Harbor Freight. Pop it in the 12v outlet and get battery health at a glance, then start the engine and see what the alternator is up to.
 
That stinks and can be a pain to chase down. You might have had that parasitic drain for while but it wasn’t noticeable because you were regularly driving the FJ. Is it stock or modded? I used to have the same issue w/ my 4Runner when it was parked for extended periods. I eventually installed a cutoff switch at the battery.
 
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Thanks for the replies. It is a 100% stock FJC. It's actually a model that was build for the Canadian market and came with a heavy duty alternator and block heater plug. When I was driving it daily, I never had any issues with it. When I parked it for the winter, I even turned off the radio, heater, dome lights, etc..The old battery did test bad, so I just got a new one. Didn't expect to have any more issues. I put it on the battery charger for an hour and it fired up. I guess I'll have to start it everyday just to keep the juices flowing. In the back of my mind I'll always have that nagging doubt that something is draining the battery.
 
There are several multi-meter tests that can be done to test the alt., bat. but then you start down the rabbit hole of pulling a fuse and testing, pulling a fuse and test.... too much for me to list but if you search "parasitic battery drain testing" there are several DIY articles.
How many miles on the FJ? Is there a possibility that the alt. could be on its way out. Mine have always gone rather quickly but thought I'd ask. I'd start w/ the simple stuff first though. Check all wiring and grounding points at the battery, test the battery for amp draw, test the alternator. Hopefully you can isolate it there.
 
I'm at 95,600 on the clock. Thanks for the info. I'll get some time this weekend to dig into it.
 
When I switched my FJ Cruiser from daily driver to occasional usage, I had a very similar issue. After a few months the yellow top was dead and no longer took a charge. I put in a new battery and within a couple of weeks it could no longer start the engine. I chased down wires, unplugged fuses, checked the alternator, pulled my hair out thinking I did something wrong and it turned out... Batteries drain a little all the time, just they way they work ( If you really want to learn about lead acid batteries google off-grid battery systems and you'll find out about the chemistry behind it ). Cold increases the drain rate a little more. Although it is just a little, it is occurring all the time and it adds up if the truck is not turned over in order for the alternator to bring it back to full.

I solved the problem with a little trickle charger designed to be left on all the time when storing a car. I keep an eye on the charger and most of the time when I check the battery shows full. Every once in awhile when I check it shows it is topping off the battery to bring it back to 100%. I've now had my FJ Cruiser on a trickle charger for the last year or so and it starts every time and the battery rates good on a tester.

If you didn't change anything by adding a new light or pump or something that runs off the battery and didn't leave a dome light or something else on it is probably just the natural behavior of batteries. If the battery doesn't charge up when driving that is different but if you are storing your truck in the garage for weeks or months and not turning it over every few days a trickle charger may be the answer for you like it was for me.

Hope that helps and good luck.
 
lgrt said:
When I switched my FJ Cruiser from daily driver to occasional usage, I had a very similar issue. After a few months the yellow top was dead and no longer took a charge. I put in a new battery and within a couple of weeks it could no longer start the engine. I chased down wires, unplugged fuses, checked the alternator, pulled my hair out thinking I did something wrong and it turned out... Batteries drain a little all the time, just they way they work ( If you really want to learn about lead acid batteries google off-grid battery systems and you'll find out about the chemistry behind it ). Cold increases the drain rate a little more. Although it is just a little, it is occurring all the time and it adds up if the truck is not turned over in order for the alternator to bring it back to full.

I solved the problem with a little trickle charger designed to be left on all the time when storing a car. I keep an eye on the charger and most of the time when I check the battery shows full. Every once in awhile when I check it shows it is topping off the battery to bring it back to 100%. I've now had my FJ Cruiser on a trickle charger for the last year or so and it starts every time and the battery rates good on a tester.

If you didn't change anything by adding a new light or pump or something that runs off the battery and didn't leave a dome light or something else on it is probably just the natural behavior of batteries. If the battery doesn't charge up when driving that is different but if you are storing your truck in the garage for weeks or months and not turning it over every few days a trickle charger may be the answer for you like it was for me.

Hope that helps and good luck.
Click to expand...

Thank you very much for that info. I'm going to get a trickle charger and keep it plugged in and start it up a little more often. It was below zero for a few days here in OH so that probably help drain the battery. I just need to get it out on the trail. Thanks
 
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The stock FJC and GX have an intermittent .5A draw and a static ~150mA draw when off. The .5A is part of the security system (so if a door gets pulled on, locked actuated, etc) it will stay at .5A for 30-60 seconds every time. The static 150mA draw is security and other systems maintaining volatile memory, etc. If you left a 150mA across 2 months = 60 days =1440 hours = 216,000mAh (@150mA) = 216AH of load, which is well over your 20-60AH battery. A tender is the answer, or disconnect the battery.
 
Thanks for the technical explanation. I was worried I was going to track down an electrical problem. That also explains why my old Jeep fired right up after months of sitting. Something to be said for the good old days of manual key unlock and window cranks. My grandson asked me what that thing on the door was. He was looking for the window button. I had to show him how to roll down the window. Anyhow, thanks for all the help. It's on the battery tender now.
 
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