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Discussion Starter #1
1995 Camry 4 cyl, 2.2 liter:

I finally got into a battery drain problem on my 95 Camry. After about 3-4 days parked without starting, my known-good battery drops from 12.6 VDC to 10.5 VDC or less, and usually won't crank since it's weak. Battery was replaced. Alternator charges at battery and alternator output around 14.6 VDC. My VOM shows an amp drain of 27 milliamps in system, all switches confirmed off, doors closed, etc. When removing Fuse 5 (Dome, audio system, interior lights, trunk light) from engine compartment, drain drops to virtually zero. Disconnected radio and drain drops to 18 milliamps. I have also disconnected the alternator, and am waiting maybe 3-4 days for any big drops as before (day 2 battery voltage still holding at 12.6 VDC). Questions:
1. Is 27 milliamps a standard, expected drain (some YouTube car repair gurus say Yes, some No)?
And therefore, am I chasing an unrelated false issue?
2. Considering 2 different batteries test good, charge good, and apparently holding resting voltage
normally with the radio and alternator disconnected....can an alternator output 14.6 VDC to
the battery but in some way drain it at rest?
3. My radio sound functions operate properly, except the digital display has stopped working. Is this
a hint?
4. No other fuse removals cause the amp-drain to zero out. Can the parasitic drain still be coming
from elsewhere?
 

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leaving your headlights in the 'auto' position can drain that much if not more. also. a burglar alarm system will drain around 50ma. the other always on stuff like the clock in your radio, the door unlock computer (listening for you to ask to unlock the doors), the memory of the radio stations and other switch settings around the cabin that the ecm/bcm/pcm's need to stay awake and listening for inputs will also do some draining.

figure out how many amps your starter is pulling. it might be way over 120a or so, indicating you need a new starter or rebuild.

and do a loaded voltage drop test on the grounds, when in use, to see if there is any more than .2 volts dc across the ends of the individual cables to see if you have a bad cable and/or grounding point.
tony
 

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'00 4 Cyl. Auto Camry LE
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For that kind of draw, in that time frame - I'd suspect the dome lamp, sunvisor vanity lamp(s), or trunk lamp, being left on .. if here.
 

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27mA is totally fine, and would definitely not drain the battery in 3 days. You battery has 50-70a reserve capacity, and 27mA will only draw 27mA x 24hr = 0.65A in a day. It would take a month or two to drain a good battery at that rate.
10mA for the radio is right on the money. That's what they draw in my experience, esp aftermarket ones.
How exactly are you measuring your drain?
 

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'93 LE Wagon V6 '94 LE I4
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Consider a bad diode in the alternator that allows a current drain back through the alternator when the car is off. Not sure if this applies to Denso alternators but it was a known issue in early '90s Crapillacs.
 

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Discussion Starter #8
Drain is being measured in series between battery negative post and negative cable, with a 1 ohm, 10 W resistor....measurement across resistor (Per Scotty Kilmer on Youtube) Note: third day of having radio and alternator disconnected from system, battery holding steady at 12.6 vdc....no drain at all. Tomorrow if batt voltage still steady will reconnect radio, which is what I've been suspicious of due to its display malfunction.
 

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that way of measuring might not get you an exact battery drain unless you're using a very close tolerance resistor but it's close anyways. you can also plug your ma meter right in the path making sure you have it set higher than the expected drain.
anyway, sounds like it's what you suspected to begin with.
tony
 

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Drain is being measured in series between battery negative post and negative cable, with a 1 ohm, 10 W resistor....measurement across resistor (Per Scotty Kilmer on Youtube) Note: third day of having radio and alternator disconnected from system, battery holding steady at 12.6 vdc....no drain at all. Tomorrow if batt voltage still steady will reconnect radio, which is what I've been suspicious of due to its display malfunction.
Well, then it's either you're making an error in your measuring, or the battery is on it's last leg (though I doubt this). Look at the math in my last post - it's just not possible to drain a good battery with that drain in that time frame.


For example: a run of the mill 36R battery (what the Camry uses) has 130amp reserve capacity:
https://www.autozone.com/batteries-starting-and-charging/battery/duralast-battery-36r-dl-group-size-36r-650-cca/298368_348924_25698


Using this calculator:
https://www.powerstream.com/battery-run-time-calculator.htm


130A capacity, with even 0.05A (50mA) capacity will take 2600 hours to drain, or 108 days, or 3.5 months.
In order to drain the battery in 3 days (72hr), you would need 1.8 amp draw. Even if your battery is half dead at 65amps, you'd still need near a 1 amp draw to kill it, 30 times higher than what you're reporting. It just doesn't add up.

Hope this helps.
 

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Discussion Starter #11
Well, now I'm stumped. With alternator disconnected, radio reconnected...drains to about 11 vdc in 2-3 days. Recharged battery to full charge, reconnected another Toyota factory radio and in 1 day battery drained to 10.5 vdc. A strange symptom even with the different Toyota radio is that this 2nd radio's digital display also does not work. I measure 2 12 volt lines at the radio connector, so I think I have the correct voltages. If the display requires 5 vdc, I'm not measuring it anywhere on the 2 radio connectors. The radio plays normally and picks up stations. Could a shorted antenna wire cause this? Either the radio circuit is causing this drain, or I'm chasing my tail and the problem is elsewhere. Again, the "drain" measured in series with the battery is only 27 milliamps, .027 amps. I'm stumped.
 

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'00 4 Cyl. Auto Camry LE
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a shorted power antenna circuit (motor) could certainly be one possible cause of that current draw.

re: radio display - that is controlled by the lamp Dimmer control (Rheostat) - and should vary intensity as other lighting (gauge cluster / heater control / rear window defogger / AT shift console lamp) in the circuit, when working as expected.
 

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Discussion Starter #15
a shorted power antenna circuit (motor) could certainly be one possible cause of that current draw.

re: radio display - that is controlled by the lamp Dimmer control (Rheostat) - and should vary intensity as other lighting (gauge cluster / heater control / rear window defogger / AT shift console lamp) in the circuit, when working as expected.
Thanks, but the car does not have an antenna motor. The displays on both radios do not display any digital characters. One radio's backlight comes on but no characters. The other radio powers up with audible stations but absolutely nothing displayed.
 

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Discussion Starter #16
Well, then it's either you're making an error in your measuring, or the battery is on it's last leg (though I doubt this). Look at the math in my last post - it's just not possible to drain a good battery with that drain in that time frame.


For example: a run of the mill 36R battery (what the Camry uses) has 130amp reserve capacity:
https://www.autozone.com/batteries-starting-and-charging/battery/duralast-battery-36r-dl-group-size-36r-650-cca/298368_348924_25698


Using this calculator:
https://www.powerstream.com/battery-run-time-calculator.htm


130A capacity, with even 0.05A (50mA) capacity will take 2600 hours to drain, or 108 days, or 3.5 months.
In order to drain the battery in 3 days (72hr), you would need 1.8 amp draw. Even if your battery is half dead at 65amps, you'd still need near a 1 amp draw to kill it, 30 times higher than what you're reporting. It just doesn't add up.

Hope this helps.
Thanks much. Stumped here. Something, somewhere is draining the damn battery. The battery was bench tested at AutoZone as good. Cleaned all contacts plus chassis ground. About ready to sell a good driving vehicle at a big reduction. No problem if the car is run everyday. More than 2 or 3 days it's back to the 10.5 VDC.
 

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Something's not adding up here. Can you explain in great detail *exactly* how you're measuring the drain?
 

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Discussion Starter #18
Battery negative cable disconnected, 1 ohm, 10W resistor in series between negative battery terminal and negative cable connector. Measurement taken across each side of resistor in amps scale.
 

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Ditch the resistor, if your meter can measure amps. With the negative cable disconnected, attach one lead to the battery negative terminal, and the other to the cable. But watch this vid completely before doing anything...

 

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'00 4 Cyl. Auto Camry LE
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Thanks, but the car does not have an antenna motor. The displays on both radios do not display any digital characters. One radio's backlight comes on but no characters. The other radio powers up with audible stations but absolutely nothing displayed.

Understood. * The only other component in the circuit that has a servo/motor which would possibly cause that level of power draw that I can see (aside from lighting draw / a suspected wiring short) are the Power Mirrors - which are fed from / branched off the CIG/RADIO fuse, from the schematics I have here. * To isolate: disconnect the connector from the Power Mirror control.


re: no display - sure, it's possible to have (2) radio units w/ bad display circuitry. Unlikely, but possible. I would be Q/A'ing / confirming the other lighting controlled by the Rheostat (see previous post), and voltage testing the (G)reen wire in the radio harness connector, against a known good ground, for voltage range of (0v) to (12v), depending on the position of the Rheostat control. If voltage range is as expected: next test would be to for a poor (or bad) ground in the radio circuit, if here.


The CIG/RADIO fuse circuit has several circuit branches post-fuse: it is energized with Ignition switch (Key On) operation, therefore it is used to power / control those circuits that should only be active, w/ Key On operation. Above is not meant to divert you from any other diagnostics you may be pursuing in the thread - just to help you understand the circuit, which may help you target the source of the power draw.
 
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