Strange issue - no power

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If you want to know for sure what circuit is consuming it, that would be the next step.
 
And if it's simply the security system and keyless entry? I'm saying 50mA is not out of the norm for a Toyota/Lexus vehicle.
 
If vehicle doesn't have power issues, then yes.

If vehicle has a battery that keeps going flat I would want to verify that the circuits that should be pulling power are the ones actually pulling power.

It could be a charging issue, but I would still want to verify. I plan on doing this with my truck as soon as its back from head gasket repair.
 
I'm gonna go stare at my multimeter for a fair bit while I consume a bev and...contemplate... That's my normal M.O. and why I'm the freaking slowest mechanic on earth. But I'll probably screw something else up. I'd like to fully charge the battery and see what happens. I've been getting reports of the Lexus Enform/Touchscreen flicking off, and then rebooting during normal driving. Wondering if that's just a low voltage situation? I've also put the Beatsonic Carplay/Android Auto unit in there two years ago. IH8AutoElectrical...
 
I have the exact voltage modifier in both trucks.
 
@re_guderian, your parasitic draw test looks good. 50 mA is the Lexus spec, so you can rule out a parasitic draw. That being said, your battery terminals do look corroded (white powder substance), which could be causing an intermittent connection issue that might lead to some of the symptoms you have experienced. I would clean the battery terminals and the cable ends with spray-on terminal cleaner (CRC makes it in a can) and install some felt pads on the terminals (a few bucks from any auto parts store). You can also add some terminal grease/protector on the assembled terminals too if you want (multiple options at the parts store).

In regards to the voltage booster you DO need one for a AGM battery. I didn't get one for years and upon checking my Odyssey AGM realized it was under charged. Get the VB Pro Texas Slim, which has a "high" +1.0 volt and "low" +0.5 volt setting and run it on low. The high setting can fry light bulbs and other things.

Lastly, I would also suggest picking up a battery tester (device that checks CCA), which are about $40 online or at Harbor Freight. I'd then check up on the battery regularly to see how it is doing and if it is degrading. That will help you know if the problem is "fixed" or if it is something else that will rear it's head again in the future.
 
Rednexus said:
@re_guderian, your parasitic draw test looks good. 50 mA is the Lexus spec, so you can rule out a parasitic draw. That being said, your battery terminals do look corroded (white powder substance), which could be causing an intermittent connection issue that might lead to some of the symptoms you have experienced. I would clean the battery terminals and the cable ends with spray-on terminal cleaner (CRC makes it in a can) and install some felt pads on the terminals (a few bucks from any auto parts store). You can also add some terminal grease/protector on the assembled terminals too if you want (multiple options at the parts store).

In regards to the voltage booster you DO need one for a AGM battery. I didn't get one for years and upon checking my Odyssey AGM realized it was under charged. Get the VB Pro Texas Slim, which has a "high" +1.0 volt and "low" +0.5 volt setting and run it on low. The high setting can fry light bulbs and other things.

Lastly, I would also suggest picking up a battery tester (device that checks CCA), which are about $40 online or at Harbor Freight. I'd then check up on the battery regularly to see how it is doing and if it is degrading. That will help you know if the problem is "fixed" or if it is something else that will rear it's head again in the future.
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Perfect information, thanks! I ordered the VB Pro for the GX 460, hope it comes soon. I really do think this would explain the symptoms, just constantly on the ragged edge of being charged. I cleaned up the negative terminal. I have those SDHQ battery terminals. While nice to attach accessories to, they really aren't worth the outrageous price, if you ask me...
 
Got the Voltage Booster Pro in the mail today, and installed no problem. As advertised, it raised by idle voltage from 13.6 V to 14.1 V on the low setting, again at idle speed with lights off. Is that sufficient to maintain the AGM battery? Literature said they like 14.5V - 14.8V to maintain the AGM battery, but not over 15V. Will the higher RPM charge voltage fall into this range on the low setting of the VBPro?
 
re_guderian said:
Got the Voltage Booster Pro in the mail today, and installed no problem. As advertised, it raised by idle voltage from 13.6 V to 14.1 V on the low setting, again at idle speed with lights off. Is that sufficient to maintain the AGM battery? Literature said they like 14.5V - 14.8V to maintain the AGM battery, but not over 15V. Will the higher RPM charge voltage fall into this range on the low setting of the VBPro?
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Should have two modes. A higher charging mode for winter and a lower charging mode for aummer
 
re_guderian said:
Got the Voltage Booster Pro in the mail today, and installed no problem. As advertised, it raised by idle voltage from 13.6 V to 14.1 V on the low setting, again at idle speed with lights off. Is that sufficient to maintain the AGM battery? Literature said they like 14.5V - 14.8V to maintain the AGM battery, but not over 15V. Will the higher RPM charge voltage fall into this range on the low setting of the VBPro?
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Your voltage seems kind of low. I don't know the exact Lexus spec off the top of my head, but I'm pretty sure you should have over 14V at idle (after starting the engine) without the voltage booster. Odyssey says their batteries need 14.2-14.5 volts. You should check what your battery manufacturer recommends. I'd also recommend checking a GX460 FSM and confirming what the voltage spec actually for your rig.

I am wondering if you alternator is getting weak, which would certainly explain the string of dead AGM batteries.
 
Rednexus said:
Your voltage seems kind of low. I don't know the exact Lexus spec off the top of my head, but I'm pretty sure you should have over 14V at idle (after starting the engine) without the voltage booster. Odyssey says their batteries need 14.2-14.5 volts. You should check what your battery manufacturer recommends. I'd also recommend checking a GX460 FSM and confirming what the voltage spec actually for your rig.

I am wondering if you alternator is getting weak, which would certainly explain the string of dead AGM batteries.
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Thanks, I'll check. The alternator is less than 2 years old. 205k miles on rig.
 
re_guderian said:
Got the Voltage Booster Pro in the mail today, and installed no problem. As advertised, it raised by idle voltage from 13.6 V to 14.1 V on the low setting, again at idle speed with lights off. Is that sufficient to maintain the AGM battery? Literature said they like 14.5V - 14.8V to maintain the AGM battery, but not over 15V. Will the higher RPM charge voltage fall into this range on the low setting of the VBPro?
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I've had one one in my rig for a couple years now.
So far it's been great, reading anywhere from 14.4 to 14.9 VDC on my OBDLink when I'm driving.
I just keep mine on "high" all the time, even though we don't get cold weather here.
 
r2m said:
I've had one one in my rig for a couple years now.
So far it's been great, reading anywhere from 14.4 to 14.9 VDC on my OBDLink when I'm driving.
I just keep mine on "high" all the time, even though we don't get cold weather here.
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"High" on my rig bumps it to over 15 volts at idle, which fried my rear LED dome light bulb :). I have an aftermarket DC Power Engineering alternator in mine, which may be the reason for that. It will get up to about 14.7 volts on startup, with it on the "low" setting. It then settles down to 14.1-14.4V under normal driving.
 
I'll have to drive around and see. Is the OBDLink reading I get sufficiently accurate through the obd port to estimate battery voltage?
 
re_guderian said:
I'll have to drive around and see. Is the OBDLink reading I get sufficiently accurate through the obd port to estimate battery voltage?
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I'd suggest a USB charger that plugs into the cigarette lighter that reads voltage. I have put a hard-wired USB charge port (Toyota switch-sized) in my rig that always does that. The USB chargers are pretty inexpensive on Amazon. And you get a charger :).
 
re_guderian said:
On OBDLink I saw 14.3-14.4 while driving around tonight. Setting on low. Good enough?
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That would work for an Odyssey, but I'm not sure about your particular brand. I'd check battery state of health in a few months and see how it's doing.
 
Rednexus said:
"High" on my rig bumps it to over 15 volts at idle, which fried my rear LED dome light bulb :). I have an aftermarket DC Power Engineering alternator in mine, which may be the reason for that. It will get up to about 14.7 volts on startup, with it on the "low" setting. It then settles down to 14.1-14.4V under normal driving.
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I have a 240 amp Tucson Alternator in mine also, but have never seen over 15 volts. Maybe your alternator is more efficient??
 
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