1998 Mazda B2500 Battery Dead
#1
1998 Mazda B2500 Battery Dead
Okay it is a dead battery every time the truck is not driven for one or two weeks. Battery manuf. date is 10/20. Walmart Everstart model. From reading several hours on the forum what I think I know is...
This truck should draw 30-70ma 30-45 min after shut off when Battery Saver Relay engages to shut everything down except the radio memory and clock. I just learned about the 30-45 min BSR delay last night from reading on here.
Before I knew about the Battery Saver Relay delay I was seeing 0.34A current draw through the negative terminal with the ignition off. I found that fuse #26, when removed, brought the at rest current draw to 0.04A. I am going to test the draw again today after the 30-45 off time as I just learned of this aspect last night..
The question I have right now is.... I have measured the battery voltage before and after being disconnected from the car overnight.
Battery negative terminal disconnected in the evening read... 12.75V
The next morning it read... 12.69V. A 0.06V difference.
Is this 0.06V enough to be causing the dead battery issue?
Thank you
This truck should draw 30-70ma 30-45 min after shut off when Battery Saver Relay engages to shut everything down except the radio memory and clock. I just learned about the 30-45 min BSR delay last night from reading on here.
Before I knew about the Battery Saver Relay delay I was seeing 0.34A current draw through the negative terminal with the ignition off. I found that fuse #26, when removed, brought the at rest current draw to 0.04A. I am going to test the draw again today after the 30-45 off time as I just learned of this aspect last night..
The question I have right now is.... I have measured the battery voltage before and after being disconnected from the car overnight.
Battery negative terminal disconnected in the evening read... 12.75V
The next morning it read... 12.69V. A 0.06V difference.
Is this 0.06V enough to be causing the dead battery issue?
Thank you
#2
RF Veteran
iTrader: (1)
The battery should have no voltage drop at all when disconnected, but you may have had a residual higher voltage when first tested
If engine had not been run for at least 4 hours prior to disconnection and the 12.75v reading then yes, battery is self draining
When a battery is charged, by the alternator in this case, it takes 3 to 4 hours for voltage to drop to its average, cools down internally
After sitting for 4 hours these are the average voltages for car batteries
12.8v is a new battery
12.5v is a 3 year old battery
12.3v is a 5/6 year old battery
So 12.75v for just less than 1 year old battery looks OK, but so is 12.69v, since average is 0.1volt drop per year
If you can let battery sit longer, disconnected, and test it every day, that would be a better test, it should stabilize and NOT drop after that
If engine had not been run for at least 4 hours prior to disconnection and the 12.75v reading then yes, battery is self draining
When a battery is charged, by the alternator in this case, it takes 3 to 4 hours for voltage to drop to its average, cools down internally
After sitting for 4 hours these are the average voltages for car batteries
12.8v is a new battery
12.5v is a 3 year old battery
12.3v is a 5/6 year old battery
So 12.75v for just less than 1 year old battery looks OK, but so is 12.69v, since average is 0.1volt drop per year
If you can let battery sit longer, disconnected, and test it every day, that would be a better test, it should stabilize and NOT drop after that
#3
#4
#5
RF Veteran
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#7
#8
RF Veteran
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#9
RonD,
From your response it sounds like the GEM and BSR are likely functioning correctly.
I will set it to a "Milliamp Scale" and see it I can improve on the reading.
The meter is a Fluke 77 from the early 80's so I am unsure of the accuracy.
At the current level of definition it is difficult to tell whether the at rest measurment is in the desired 30-70mA range.
Thank you
From your response it sounds like the GEM and BSR are likely functioning correctly.
I will set it to a "Milliamp Scale" and see it I can improve on the reading.
The meter is a Fluke 77 from the early 80's so I am unsure of the accuracy.
At the current level of definition it is difficult to tell whether the at rest measurment is in the desired 30-70mA range.
Thank you
#10
RF Veteran
iTrader: (1)
0.1amp is 100mA so isn't much of an amp draw but a bit more than expected, 30-70mA
0.1amp draw would take 1,400 hours(60 days) to drain 280AH battery down to 50%
Assuming 400CCA car battery which is 280AH rating, which is on the low side for car battery, 500+ CCA is what it usually is, which is 350AH rating
50% is about when a car battery can no longer turn over an engine
CCA X 0.7 = AH
0.1amp draw would take 1,400 hours(60 days) to drain 280AH battery down to 50%
Assuming 400CCA car battery which is 280AH rating, which is on the low side for car battery, 500+ CCA is what it usually is, which is 350AH rating
50% is about when a car battery can no longer turn over an engine
CCA X 0.7 = AH
#12
#13
Ok after further reading...
The radio in this particular vehicle is connected to an "always hot" power source because it can be turned on when the truck is not running and the key is not in the ignition. It appears to be a stock radio so... maybe someone wanted to have the option to play the radio with the key removed?...
Found the below while searching and reading on Ranger-Forums...
"Fuse 20 powers the radio, key on power, the yellow/black wire, this is the one you use for new radios power source"
So I am thinking to look at the wiring and see if I can ascertain where the power is coming from currently and reconnect it to the proper Fuse 20 power source. This seems like the thing to do since the radio is coming on all by itself when left unattended and Fuse 20 would not allow this to happen.
The radio in this particular vehicle is connected to an "always hot" power source because it can be turned on when the truck is not running and the key is not in the ignition. It appears to be a stock radio so... maybe someone wanted to have the option to play the radio with the key removed?...
Found the below while searching and reading on Ranger-Forums...
"Fuse 20 powers the radio, key on power, the yellow/black wire, this is the one you use for new radios power source"
So I am thinking to look at the wiring and see if I can ascertain where the power is coming from currently and reconnect it to the proper Fuse 20 power source. This seems like the thing to do since the radio is coming on all by itself when left unattended and Fuse 20 would not allow this to happen.
#14
RF Veteran
iTrader: (1)
No, unless someone has monkeyed with the wiring the radio part doesn't have any power until key is in ACC or RUN(on) positions
The Radio, like the Computer and Keyless entry system, DOES HAVE full time power to hold Clock time and Radio presets, this is just a .01/.02amp draw
If your radio can be turned on without key being in and turned to ACC or RUN then wiring has been altered
The Radio, like the Computer and Keyless entry system, DOES HAVE full time power to hold Clock time and Radio presets, this is just a .01/.02amp draw
If your radio can be turned on without key being in and turned to ACC or RUN then wiring has been altered
#16
OK well... yesterday the car truck was driven to my daughter's house and turned off.
The radio did not power up when attempted immediately after powering the truck off.
An hour later after pressure washing her deck the radio powered up with the car off and key removed from the ignition.
Any thoughts? Maybe the Battery Saver Relay somehow... ???
The radio did not power up when attempted immediately after powering the truck off.
An hour later after pressure washing her deck the radio powered up with the car off and key removed from the ignition.
Any thoughts? Maybe the Battery Saver Relay somehow... ???
#17
RF Veteran
iTrader: (1)
The stock Radio has no power with key off
The clock and memory have power but not the radio
So either the radio's internal circuit is bad or the wiring is
1998 Radio wiring here: https://www.therangerstation.com/tec...dio_Wiring.pdf
Fuse 28 causes Radio Audio to MUTE when starting the engine, just FYI
Fuse 29 holds clock and presets
Fuse 20 allows radio to activate when powered up by the key in ACC or RUN
The clock and memory have power but not the radio
So either the radio's internal circuit is bad or the wiring is
1998 Radio wiring here: https://www.therangerstation.com/tec...dio_Wiring.pdf
Fuse 28 causes Radio Audio to MUTE when starting the engine, just FYI
Fuse 29 holds clock and presets
Fuse 20 allows radio to activate when powered up by the key in ACC or RUN
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