what V reading do you get after shutdown?
does anyone know if Lead Acid batteries have been redeveloped to have 1 V more than older L-A , batts. there has been so much new battery technology in past few years?
14V+ all the time ,when running, i wonder if that will keep 12.9/13 overnight?
i’m going back to the dealer i bought from , and measure his new Batteries, on shelf NOT on charge, its a brand i never heard of , NO place where they are made on them, he said a new company! HMM?
Sounds like a parasitic draw.
Here’s some steps on how to find it. I’m lazy and didn’t read the whole thread.
Step 1: Prepare for Test
You should have a fully charged battery before starting – voltage would be around 12.6V for a good one. Be sure to close all doors, turn off the radio and disconnect accessories, such as smartphones and add-on GPS devices. Even a key in the ignition can have systems waking up on newer cars that will initiate draw.
Step 2: Disconnect the Battery
Pop the hood and disconnect the negative cable from the negative battery terminal. It is always best to do a parasitic draw test from the negative side so there is no chance of accidentally shorting should you test from the positive side.
Step 3: Connect the Multimeter
Plug the black probe into the common ( COM ) jack input of the multimeter and the red probe into the amps (usually A) jack input. Then connect the red probe to the previously disconnected negative cable of the car loom, and the black able onto the battery terminal.
Note : in order to test for current, the multimeter must be connected in series with the circuit as it needs to gauge electron flow, so to speak. Voltage, on the other hand, is measured in parallel.
Step 4: Give the Car Time to Sleep
Modern car systems may ‘wake up’ when you connect a multimeter in such a fashion as it picks up the power of its batteries. So wait a few minutes before conducting the draw test.
CAUTION : when connected, avoid starting the engine or even turning on the headlights as this will likely blow a fuse in the multimeter. Vehicle batteries put out a lot of amps due to being low voltage.
Step 5: Reading the Meter
Newer, auto ranging multimeters will automatically select the correct range of a signal they pick up. On manual ranging meters, you will need to select a range, usually either 2A or 200mA. If you get ‘OL’ on the screen, it means over limit and you should select a higher range.
If you see a reading of around 50mA and above on a standard car, it generally means something is drawing power and you likely have parasitic draw. Just note that if you have a big, modern, luxury car its added computerized systems will likely increase the natural current draw. In this instance, the threshold might be 100mA.
It is now time to see what is causing the draw. The tried and tested method is to start pulling fuses to see which circuit is the culprit.
Step 6: Pulling Fuses
Locate the fuse panel(s) and start pulling out fuses one after the other, taking notice of any drop in the reading on the multimeter. If there is no joy with the fuses, start removing the relays. For those fuse boxes that are inside the vehicle, a tip is to lay the meter on the windshield facedown so you can see the display.
Step 7: Narrowing Down
When the display drops to a nominal mA draw, note the fuse/relay position number and check the vehicle’s manual. There is often more than one circuit on a given fuse, so you would then need to eliminate each one, such as remove a bulb or unplug a heater.
Step 8: Repair and Reconnect
When the meter drops down to 25mA or less after removing the offending fuse, bulb or unplugging a circuit, you likely have your culprit. Repair the fault/replace the item and run another test to be sure. If you’re confident there are no other faults, reconnect the battery.
Alternator fault? : if you’ve gone through all fuses and relays (and checked for other fuse boxes), oftentimes the alternator can be at fault. One of the diodes may have shorted out and caused current to drain back to the battery. Test it with the multimeter before and after unplugging.
Mark i’m kinda lazy also, i will read your info , when i more awake, its alot to digest and understand!
thanks from ron
Noooo such thing as too many ground paths!
It can be a pain to keep pulling fuses and then checking back at the battery for the current draw. Especially if the current draw is related to the boot being open, which has happened to me once. Easiest thing to do is to pull the fuse and then use the meter across the contacts where the fuse was. Bonus points if you make a fake fuse that plugs into your meter leads.
The trick with the boot if the battery is in there is to trigger the latch so that the ECU reads it as closed.
I was caught out by the extra circuitry in the XJR-S that will energise a relay for the auto aerial shutdown mode. Difficulty to trace with boot open or closed, unless you check at the fuse panel
Trying to locate a parasitic draw is a PITA – big time. Parasitic draw by definition is any draw on the battery greater than 25ma. My definition of a parasitic draw falls in the category of a draw greater than 50ma. Of course while the
car is parked, keys out of the ignition, Everything secure, nothing left on, lights off, doors closed.
Good idea about fuse lead.
must be me explaining my CARS problem!
with cables off not connected, when i 1st installed new battery, it measured
12 .95 VOLTS battery was over a month old just setting on shelf,WHY?, after driving and parking overnight battery measures 12.65, if i charge it 2amps, for 10 minutes, it will come up to 12.90+ V ,my car starts better and runs better, everything reacts BETTER! for me i need 12.95/13.00 volts after shutdown!
question is why??
If you haven’t done so, maybe checking under the bonnet may provide a better answer to your question “Why”
Check the voltage under the bonnet at the the positive lead on bulkhead or at the coil? it should be somewhere between .5 and 1 volt less than what the battery reads, if Get back to us on what the reading is under the bonnet.
I would worry about too much charge…just like people that get a boost from something…and they burn out too.
I concur. Like the coveted factory radio… on my Series III (XJ6) from an over charge condition from the alternator, and my XJ-S won’t start after a surge from a battery charger. The battery was dead, so I disconnected the battery cable and threw a battery charger on it. I didn’t get the cable securely out of the way, and it fell and arched here and there against the car. I didn’t notice it right way cause I always secure the charger leads before I plug it in. The car is up on the lift out of the way.
I climbed down off the lift and plugged in the battery charger. I discovered it when I turned off the light in the garage, turned around to notice the boot light flickering. I thought, “well that’s odd.” having a clueless moment, then it dawned on me "OH SH…TTT!!! Ran over other side of the garage and unplugged the charger. climbed back up on the lift securied the cable out of the way, and charged the battery. Went to start the Blue XJ-S, only to discover it was too late… I didn’t get to it time, it was just enough to cook something. Now My XJ-S won’t start. 
Three years later, I still haven’t looked into that yet - I’m pretty disgusted with myself.
Oh, Ya, another project. 
well finally got what i’m lookin for!
pic of voltage after a 10 day,in unheated garage 55/60F , no run of motor,!
12.97 volts at battery, no neg connected, close enough to 13V.
spins over fine all is good!
its the battery i bought that gets higher volts as temperature goes down,(to a certain point)!
new technology in lead acid batteries, in past 5/7years, along with the Lithium R&D!
engines when cold need a little volt boost, to make starting and running easier, after startup alternator takes care as it supposed to ,14.4, and down to 13.4 when battery is up to normal!!and a hotter spark when cranking, ,i have a relay that puts full battery into coil when cranking
So what battery did you buy?
Durn a few years ago, I thought I had a genius level idea!! some place or another, I got a box off odds and ends patch cords. I adopted two of them to fit my VOM on one end and the other two a socket designed for a 12 v draw from the cigar lighter. Yipee, I could read volts in real time, differing loads and rpms. Exonerated my alternator and convicted my battery.
Over the years, a ,lot of them, I’ve learned that a charger beats the alternator in getting a battery up to a full 100 percent. My Schumacher smart charger is a great device…
Yes measure the acidity PH level with a hydrometer.
I forgot the desired number for full charge, but 1160 rings a bell. I may have one hanging on the section in my shopfr unusual devices…
In my college days, I worked at a full service station. we used teotool to measure and evaluate batteries. The hydrometer and a volt meter that had two progs to stick into each cell. Six volt batteries were te ones used then. Not uncommon to fid one of the tnree cerlls dead… We also ahd a “gang” charger, that was sued to charge several batteries in slow charge mode. The “hot shot” charger came later and was used for 'quickie" needs… Boss did not like it…
Carl
Time ; East Penn batteries, model DEKA!
great company, ahead of the curve on technology!
ron
Hmmmmm just looking and they show 3 different deka batteries. Did you get it at a local dealer, or order online?
a new line from my local auto store, they just took it on , AGAIN a family owned store, like east penn!
Trumps bringing small business back to USA!
Are Exide, Johnson controls and Optima “off shore” outfits?
Local family operated parts emporium featuring made in USA stuff is great…
Carl
Ae, as DJT had anything todo with it!!!
Carl
