Hey guys,

Back again, RenD fixed my previous issue with my lights, it WAS the fuse, but come to find out it was a 30A fuse, but a 10A was in it's place.
But I am not here for that thread, I've run into another issue. I got a new engine put in along with w new battery (proper amperage draw for the engine this time). Haven't driven it all that much, had good clean strong starts in this harsh cold winter. But today, I came out to my truck battery drained. After putting jumpers to it from my F150, fired right up, stayed constant charged. But as soon as I remove the jumper cables, the truck dies in about 5 minutes because the battery is drained. But, my jumper cables have a display that shows me my Voltage level, and it was at 12V!!!! I assumed I am not getting proper amperage. I am still troubleshooting alternator, but I never had this issue before. Going to check the Battery live saver fuses as well. COuld use any other advice from any one else that's had this issue in their ranger or mazda. Thanks

 

Car/'truck batteries use these voltages
12.8-13.0 volts when brand new
12.5 volts at 3 years old
12.3 volts at 5 to 6 years old and this means its at 50% capacity, so time to shop for battery sales

12.2 volts or lower is a done battery, or drained

These batteries last 5 to 7 years and their chemicals are used up

Test battery voltage

Start engine
Voltage at battery with running engine should be MINIMUM 13.5 volts, 13.8 to 14.8 volt is normal
If lower than 13.5v then alternator is bad or wiring for it is

Engine off key off
Alternator has a larger wire on a stub/nut connection, this is called B+
Use alternators metal case as ground and test voltage on B+, should be "Battery Voltage", you just tested it,so if it was 12.3v then thats what B+ should be
If its not then you have blown fusible links

If B+ tests OK then unplug the 3 wire connector on alternator and test the Yellow wire on that connector, should see Battery Voltage
If not then blown fusible link

If Yellow wire is OK then test Green wire, should be 0 volts
Turn on the key
Retest green wire, should be Battery Volts minus 0.1 or 0.2volts
If not then check fuse 11 in cab fuse box, 7.5amp, replace with another fuse if you are not sure
Retest green wire for battery volts, key ON
This green wire is the ON/OFF switch for alternator, also the Battery Light, so if you haven't noticed Battery Light coming on with key on, then start with this fuse 11, its blown