Dead Battery (3x in 2mths) - 30A BAT Fuse has 500mA draw - what next?

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Your battery terminals are also perfectly clean and tight right? Often I find bad batt connections where the high current will flow for starting etc, but the connection is bad enough that no charging takes place.
AimCOtaco - thanks for the suggestion. Not sure the best/recommended way to clean the terminals but I used brake cleaner (sprayed onto a cloth) and sandpaper to clean everything up and then used dielectric grease on all the contact points. I did this for the positive/negative posts, cable clamps, bolt threads, nuts, etc including the starter and alternator connections that come off the positive cable.

I can't say this resolved the problem yet, but I can say that the voltage readings went up by about .14V. I was getting as low as 13.33V at low speeds and idling around town on the battery mole b/f and now I hadn't seen it go below 13.47. In general from the same lunch trip I've been taking 2x/wk for the past few weeks, I used to see 13.3-13.6 and I'm now at more like 13.5-13.8 most of the time.

I'll remain cautiously optimistic and in the meantime I've got cables and a multimeter in my toolbag :-(

I've got a big family trip this weekend in the LX - I toyed with the idea of bringing the starter contacts, alternator brushes, and picking up this set of tools for road trips moving forward (Professional Mechanic's Tool Set - 301 Piece)...


'Yota terminals are good but lack range in my opinion so after a few cycles they don't tighten very well, have used brass shim stock to improve the tension on occasion.

Can you elaborate on this? What do you mean by toyota's cables lacking range? Just want to understand more.

Thanks again!
 
Not saying the cables are lacking range but the terminal clamp it's self. After being really tight a few times it seems that the clamp bolt runs out of range. I have seen them where the clamp bolt was as tight as possible, no threads left, but you could still pull the terminal off of the battery by hand. I have on occasion used a little brass or copper sheet metal to wrap the battery terminal (effectively making it larger) and then the OEM clamp holds better, this method is for helping folks out in a parking lot, not how I run my stuff. I'm the go to at work for car trouble and a jump start often leads to me diagnosing poor terminal conditions.

I don't think you need to haul the brushes and contacts for the current situation but nice to have in general. I do recommend carrying long heavy jumper cables as they work best on trails or divided highways to get you running and off fast! And of course tools, lots and lots of tools, can never have enough tools!

Sounds like you did a good job improving contact on your whole system and are seeing the voltage jump to confirm it. Sure hope you're fixed! I really need to upgrade the ground side of my set up soon to avoid a similar situation.

Abrasion followed by dielectric grease and tight fittings are the way to go for terminal up keep.

Happy Crusin',
 
Figured I'd post an update - been almost 2 months with a two week period I didn't drive at all mixed in there and the rest of the time following my typical weekends only driving and no issues since the terminal cleaning so I think it's fair to say that dirty terminals/posts was my issue allowing enough current for startup but not enough for charging until I cleaned it up.

For future reference, I typically get 14V-14.1V when I first start up, as low as 13.4V when I'm idling after warmed up, and 13.6-13.8 while driving at speed.
 
I've owned my LX for about 8 months now and have had to replace the (acdelco) battery twice and recharged once. Luckily under warranty.
It's the battery the PO had in it, and it was fairly new.
I really haven't driven it that much, once every 5 weeks due to my 80 parked behind it in driveway. Have wondered if the blinking security light on center dash is much of a drain?
 
I've owned my LX for about 8 months now and have had to replace the (acdelco) battery twice and recharged once. Luckily under warranty.
It's the battery the PO had in it, and it was fairly new.
I really haven't driven it that much, once every 5 weeks due to my 80 parked behind it in driveway. Have wondered if the blinking security light on center dash is much of a drain?

Quickest/easiest way to get a good starting point on your situation is to take your car to a shop or parts store and have them do their starting/charging system test. If you're comfortable with a multimeter you can do some of your own testing as well to get an idea of what's going on. I'd say with 2 batteries and 1 recharge (and sounds like PO replaced the battery recently) you have a problem that needs to be fixed and replacing the battery is just masking it. Let us know what you find.
 
I hate to have to post to this thread again, it's 4 months later and a dead battery this morning.
Try to unlock car - no dice. Try other key - no dice. Unlock manually and try to start - lights dim and no juice, no click nothing. Suspect a dead battery.

Facts:
1) Voltage was 5.4V !!! :-(
2) I check for draw and find .247 draw.
3) I start pulling fuses and ... removing short pin or removing 30A BAT fuse - either one takes the draw down to something significantly lower between .09 and .127.

2 times ago after a recharge the battery lasted 2 months. Back in May when I cleaned up terminals, now I got 4 months out of it. Not sure what to conclude - parasitic draw, still a bad connection somewhere, alternator not putting out enough juice to fully charge, not driving enough to fully charge, or starter drawing more amps than it should. I had what I thought was good data from before that indicated draw was high initially due to anti theft system, that starter was fine and not drawing too much amps, that alternator was outputting within spec range.

While driving the voltages on are up there at 13.9V while warming up and down to 13.3 while idling and up to 13.5/13.6 while driving. As before, my driving habits are pretty much just weekends for this vehicle but often a few hours of driving over the course of the weekend.

Just wanted to post the update and see if anyone has other ideas.

For now, I was going to replace the battery with a new one and start monitoring the battery voltage weekly to see if weekly I'm losing charge and not regaining it during the course of my driving. Not sure whether I have a draw I haven't identified, a short circuit, bad battery, or bad alternator.

Not sure if I should just replace the Alternator as a precautionary measure. Don't believe the starter has anything to do with what I'm seeing. I think I've explained away the seemingly high draw last time around - boiled down to antitheft drawing high initially and then going down. Each time I pull a fuse and reconnect or pull battery terminal to test draw, it spikes... I didn't verify that it goes back down to 50mA as before but no time for that right now.
 
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Is there a chance you stressed the battery by many full discharges earlier when you had a bad connection at the post? That could have killed the battery - or at least greatly shorted its life.

I had one of those spiral-cell batteries earlier. Supposed to be really good. It would discharge if I did not drive the vehicle every week. Now I use a group 49 battery. Never had a single problem. 4 weeks between starts, no problem.
 
It sure is possible - in fact I was hoping it's the battery b/c at least that would explain things and I'd be ok with a new battery. The reason I'm doubtful on the AGM battery being bad is that I recharged it and part of the recharge mode is that it does some sort of test and I believe it passed. I don't know how meaningful that is though. I guess I can take the battery in to a shop to have them do some real tests on it?

In the meantime, I plan to monitor the state of charge of my new lead acid more frequently than I did before. Fingers crossed that the it was combination of AGM plus infrequent driving that led to the multiple drains but I guess I'll see.
 
FYI. I did not measure my drain recently, but I suspect my brake controller (for trailer, Teconsah) is my biggest drain at the moment. It is connected directly to the battery - via a fuse as per the instructions. After I installed it, I noticed my battery was draining a lot faster.
 
...
4) current draw is ~500 mA
5) draw went down to ~10mA when BAT fuse was pulled (or when short pin A is pulled but looks like BAT is downstream of short pin A)
...
the BAT fuse comes off the short pin (and other things come off short pin too) so that should mean the BAT 30A fuse is the real issue and whatever comes after BAT 30A fuse must be causing the draw.
Art

...
The Dome, ECU-B2 and RADIO fuses come off that (each 10A). I pulled each and it looks like the ECU-B2 fuse is the source of the draw.

Great - but the ECU-B2 is the anti theft system and I don't know what's normal draw since it is one of the few things that should be drawing current even when the car is off.

If all the above makes sense, would love tips on how to troubleshoot the ECU-B2 current draw.

OK - I am going back to the theory that I have a parasitic draw.

I am new to wiring diagrams, and while it's true that ECU-B2 powers the anti-theft, that's not the ONLY thing it powers. ECU-B2 powers a TON of other components and that makes it more difficult for me to troubleshoot...

Current flows from ECU-B2 to the following (other) Systems:
AHC and AVS
AC Front
AC Rear
Automatic Light Control
Center Diff Lock
Comb Meter
Cruiser Control
Door Lock and Theft Deterrent
ECT and AT Indicator
Engine Control
Engine Immobilizer System
Front Wiper and Washer
Headlight
Interior Light
Key Reminder
Lexus Nav and Rear View Monitor
Light Auto Turn Off System
Moon Roof
Muyltiplex Comm System
Power Seat
Power Tilt and Power Telescopic
Power Window
Rear Wiper and Washer
Remote Control Mirror
SSeat Belt Warning
VSC
Wireless Door Lock Control

...

So I'm a bit overwhelmed - what do I do next? pulling fuses until the draw goes down was easy. Do I need to start check wiring to each and every component (i.e. taking apart the interior to get to the wiring for each)?
Or is there an easy way I can identify the source of the draw from the Junction Box itself?

Sorry if it's a stupid question - I don't want to tear into everything if I can just figure out from the J/B which of the 27 systems is the source of the draw.
 
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Are you leaving the key in the ignition switch overnight or for days at a time? I was a longtime Sequoia owner before up-grading to a LC and this was known to run the battery down.
 
phippsj said:
Are you leaving the key in the ignition switch overnight or for days at a time? I was a longtime Sequoia owner before up-grading to a LC and this was known to run the battery down.

nope - never. i do not leave my keys in ignition excep when driving.

Sent from my iPhone using IH8MUD
 
Only aftermarket items are Vaistech Modules for satellite radio and ipod.

Where are you getting power for the Vais? Is your iPod always plugged in?
I have an issue with battery drained if it sits for a couple of weeks. Don't have a Vais, but a different brand with iPod always plugged in and wondering now if that is my problem. Might kick into charge iPod, and when voltage gets low not kick out.
 
Skidoo said:
Where are you getting power for the Vais? Is your iPod always plugged in?
I have an issue with battery drained if it sits for a couple of weeks. Don't have a Vais, but a different brand with iPod always plugged in and wondering now if that is my problem. Might kick into charge iPod, and when voltage gets low not kick out.

Ipod is always plugged in. I was pretty sure when car is off it isn't powered but can't say 100%.

Saw my new battery was at 12.3v this afternoon after driving ~1hr in morning yesterday and ~1hr in evening yesterday. have a family trip this weekend so sucked it up and brought it to stealership - i'm hoping they identify the problem ... but have that feeling i'm gonna pay 195 for them to tell me something stupid like everythings fine or i need a new battery :(
yep - i'm cynical. but the service rep just tried to tell me that even though i went through two new batteries in pat 6 months, the problem could be that my batteries were not lexus batteries and therefore it might die in 3-6 months. oh and 195 was no joke - that's just to do basic diagnostics.

Sent from my iPhone using IH8MUD
 
An ipod can take around 500mA when charging. Does not seem like this issue is too common and we both have it and both have adapters modules with iPods plugged in. Just saying, might be something to look into. I will be looking into mine.
 
Well - the other week I took it to the dealership to have them check it out because I had noticed that on a weekend my battery started full (~12.7) and a few days later it was down to 11.9V... Also, my left turn signal was blinking double fast sometimes and then other times went back to normal so I thought maybe there was a short or something ~$270 later they told me I don't have a parasitic draw, that it was only drawing ~34mA which is normal, and that I just needed a new turn signal lamp even though it was intermittently double fast. I wasn't able to speak to the Tech firsthand...

Anyhow - this past weekend, I wanted to spend more time looking at the draw b/c I knew I had seen high current but wasn't sure what was normal, what the pattern was, or which circuit it traced to. I narrowed it down to the Radio Fuse in the passenger side j/b based on initial review of current with and without it.

Not having a data logging multimeter and not wanting to sit there for an hour and a half recording readings, I used a video camera and recorded three scenarios:
1) car locked for 25 minutes.
2) car locked for 20 minutes with the radio fuse removed
3) car unlocked for 35 minutes

What I found was that when the car was locked, I would see a pattern of about 20 seconds worth of 500mA draw followed by about a minute of 32mA draw for a period of 20 minutes. After 20 minutes, it stayed at a solid ~30mA... Seems quite acceptable and normal to me.

When the car was locked with radio fuse removed, I saw a ~300mA draw for about 10 seconds and then down to a solid 26mA solid... So clearly all the activity above is tied to something in the Radio fuse.

When the car was unlocked (radio fuse in place), for the first 15 minutes it was ~600mA draw solid, then dropped to ~130mA draw solid for another 15 minutes and then down to 27mA draw solid.

Based on what I see above, there does not seem to be a parasitic draw. After driving around on the weekends, I've checked and my battery has been ~12.7+ so it seems like the alternator is doing it's job well enough. I'm still monitoring my battery to see if it goes down in voltage over a few days after I know it was at full charge. Still stumped so far. I have seen that my alternator fluctuates significantly sometimes when certain things are running - for example when AHC kicks in the alternator output drops to < 13V, also oddly when I hold my driver side window up buttons in the up position the alternator output drops to ~12.8V if I hold em up for a few seconds. Have no idea what that means. My alternator's output since I've watched in the past few months has never put out more than 14.2V and that's only for the first few minutes after startup and when the temps are 50s right now (vs. 13.8 high when the temps were higher). Most of the time I'm in the low 13's - like 13.3 or 13.5, not much higher than that while driving and while idling always around 13.3 after warmup.

Still monitoring, not sure what to conclude:
- Don't think I have a parasitic drain unless it's intermittent or only certain conditions
- don't think it's the battery (been through a few)
- don't think it's starter related
- perhaps a weak alternator?
- could there be a link to the intermittent double fast blinking and the battery drain? I don't think so, just throwin it out there.

Also, I did some basic voltage drop tests to make sure at the terminals and grounds that I have good connections.
saga continues...
 
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the only issue I see here it's your alt charging low .. I feel nervous each time my V it's under 14.0V and that happen a lot with my old alt ( well mine was really old compared to yours ) so I swap to Tundra alt ( dunno if it's an option for you guys ) and problem solved ..
 
At 14V you are probably referring to a running engine. After a week of not using the vehicke, my battery measures 11.89V - I just checked it. I know it will start just fine. Even after a few more weeks of not using it and the voltage drops more, it will start.
 
As for the higher mA draw initially, one question. I notice when I get out of my truck after parking and turning the engine off, removing the key, locking, etc, there seems to be a light fan noise coming from the fuel filler cap area. After a period of time it goes away, or if you open the filler cap it goes away.

1) does anyone know what this is
2) could it be the culprit for the initially higher reading that then drops?
 

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