The battery keeps draining in my van. How can I tell if it’s a bad battery or a short circuit?
manerch asked:
I disconnected the positive cable and put a multimeter between the cable and battery post and it was reading 10 volts. What should it read? Should I be testing for volts or ohms?
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I disconnected the positive cable and put a multimeter between the cable and battery post and it was reading 10 volts. What should it read? Should I be testing for volts or ohms?
February 17th, 2010 at 7:10 pm
take it to an Advanced Auto, they do free checkups of your battery for free. Jim Shorts
February 18th, 2010 at 5:31 pm
12volts start the engine and unhook a battery cable. If the engine dies its your alternator. Troy R
February 20th, 2010 at 1:30 pm
Its prolly your alternator but first just try new battery… Texas-BOY
February 21st, 2010 at 2:08 am
sounds like you have something that is still running,or pulling juice from the battery.make sure all lights ,and dash lights are off,and if you have any lights under the hood,running lighs,other items added on to your vehicle.and you should have i beleive 12 volts wilk142ray
February 21st, 2010 at 11:46 pm
It should be around 12 volts, with the car running it should be about 13 to 13.5 if not your altenator is bad, but it sounds like your battery has a dead cell. Your battery depending on brand and type should be changed every 5 years. How old is it? snowdeoracing
February 23rd, 2010 at 4:45 pm
With the introduction of on-board computers, memory radios, memory seats, and other accessories, current is required to
maintain memories when the ignition switch is in the off position. As a result of the required continuous energy supply, testing methods have changed. If we use the conventional means, inaccurate conclusions can result in condemning good parts and circuits, and wasting a lot of
diagnostic time.
TESTING FOR ELECTRICAL DRAINS
The desired test instrument is a Digital Ammeter capable of reading as low as one milliamp and up to 20 amps. Meters of a lower amp range can be used by forming a shunt using two
jumper wires connected by alligator clips. Reason: the wake-up call necessary to charge the capacitors in a full option state-of-the-art automotive electrical system can require as much as 6 amps for one minute. Many digital meters are
fused at 2 amps and therefore have withdrawal symptoms when subjected to this much current.
The shunt allows the system to properly power up the capacitors while protecting the meter from excessive current loads. Once the capacitors are charged, disconnect the shunt and read the ammeter for actual drain.
HOW MUCH IS TOO MUCH?
Some tech manuals which include a Battery Testing Section reflect acceptable current drains. Listed is a typical example of a parasitic drain (load) for a General Motors Vehicle.
EXAMPLES OF PARASITIC LOADS
Device Milliamp Draw
Voltage Regulator 1 - 2
Digital Clock 3 - 4.5
Quartz Clock 7
ECM 6.5 - 8
ETR Radio & Clock 7
Load Leveling 4
Memory Seat 3
Twilight Sentinel 3
CONVENTIONAL TESTING METHODS MAY BE ILLUSIVE
Conventional electrical drain test procedures may not identify the cause of the condition. Vehicles equipped with Electronic Control Modules can exhibit a failure mode within the ECM which can result in a high parasitic current drain on the battery. Conventional testing methods may not detect the cause. Reason: when the battery cable is disconnected, the solid state circuit which caused the excessive drain may
not re-occur once the electrical circuit continuity is restored. Cycling the ignition switch to the run position, then back to the off position may cause the electrical drain to re-occur. Caution: the ignition switch should not be turned to the
accessory, run, or start position with the ammeter installed in series with the battery terminal and battery cable as damage to the meter may result. Only turn the switch to the run position
after first installing a shunt across the ammeter.
A full option GM vehicle can experience a parasitic load of 25-35 milliamps. Remember, a milliamp is one thousandth of an amp. Twenty five thousandths of an amp is not much current.
Should you determine the current draw exceeds the allowable limit as specified by the manufacturer, it will be necessary to identify the circuit which is creating the draw. It’s best to use the process of elimination. Look for the obvious.
Check the lamp circuits (courtesy, glove box, trunk lamp, etc.) for bulbs illuminated when they shouldn’t be. For example, a glove box or trunk lamp may remain illuminated when the lid
or door is closed. To check the trunk lamp it will be necessary to get in there with it. Caution: make sure you have a helper, and most importantly, make sure he is your friend.
If the visual inspection fails to identify the drain, pull fuses, one at a time, to find the source. Remember, if the fuse box is in the glove box, the bulb will be illuminated when the door is open. Either record its draw or disconnect the bulb. Once you identify the circuit creating the draw, refer to the service manual or a wiring diagram to determine what devices are on that circuit. Disconnecting these devices one at a time should reveal the problem circuit. If pulling fuses fails to identify the drain, it may be necessary to disconnect relays one at a time. It is simply a process of elimination, isolating
circuits to identify the problem circuit. Remember, anything operated by a switch is a likely candidate in causing current drain.
Tool:
AMMETER
BATTERY
POSITIVE CABLE
NEGATIVE CABLE
JUMPER WIRES
WITH CLIPS
1. Make certain the ignition switch is in the Lock position and all electrical accessories are off and doors closed. If equipped with a hood lamp, remove the bulb or disconnect its electrical connector.
2. Fabricate two 12 gauge jumper wires equipped with alligator clips on each end. Install the jumper wires in series with the negative battery post and cable. Next, attach the recommended ammeter test leads in parallel with the jumper wires .
3. Rotate the ignition switch to the Run position. Caution: Do not rotate the ignition switch to the Start position as the test leads and ammeter will get very hot, and damage to the vehicle and wiring harness may result.
4. Rotate the ignition switch back to the Lock position. Make certain that electrical continuity between the negative battery post and cable is not interrupted. Allow a one minute wait after placing the switch in the Lock position. The wait allows the capacitors time to charge (failure to do so may result
in misdiagnosis).
5. Disconnect the alligator clips. The ammeter is now in series with the battery post and cable. Read the amp draw on the ammeter and follow the recommended test
procedure if the drain exceeds the allowable parasitic load.
PARASITIC CURRENT DRAIN
Vehicles equipped with Electronic Control Modules can exhibit a failure mode within the ECM which can result in a high parasitic current drain on the battery. The conventional testing methods may not detect the cause. Reason: when the battery cable is disconnected, the solid state circuit which caused the excessive drain may not re-occur once the electrical circuit continuity is restored. Cycling the ignition switch to the run position, then back to the off position,
may cause the electrical drain to re-occur. CAUTION: the
ignition switch should not be turned to the accessory, run, or
start position with the ammeter installed in series with the
battery post and battery cable. If you do, your ammeter can
turn into a crispy critter.
TESTING FOR ELECTRICAL DRAINS
The desired test instrument is a Digital Ammeter capable
of reading as low as one milliamp and up to 20 amps. Meters
of a lower amp range can be used by forming a shunt using
two jumper wires in parallel across the meter. Reason: the
wake-up call necessary to charge the capacitors in a full
option state-of-the-art automotive electrical system can re-
quire as much as 6 amps for one minute. Many digital meters
are fused at 2 amps and therefore have withdrawal symptoms
when subjected to this much current. The shunt allows the
system to power up the capacitors while protecting the meter
from excessive current loads. Once the capacitors are charged, disconnect the shunt and read the ammeter for actual drain.
HOW MUCH IS TOO MUCH
Some tech manuals may include a Battery Testing Section
that lists acceptable current drains. Times change … and so
do testing procedures. Coping with all the changes doesn’t have to be a drain. Years ago, we would disconnect a battery cable, make certain all electrical accessories were turned off and the doors closed; then touch the disconnected battery cable connector to the battery post while observing
for an arc. No arc — no drain.
Some technicians used voltmeters attached in series with the disconnected battery cable and battery post. This is not a valid test to determine electrical drain. Unfortunately,
some still utilize this method and thereby condemn many good parts, in addition to wasting diagnostic time. K R
February 24th, 2010 at 6:04 am
no stay with volts,and u can do is first…….hook up the neg battery cable start the van and run the poss side of the volt meter to the battery supple on the alternater and neg side of volt meter to neg on the battery see what u have on volts then take the volt meter and hook it to battery poss to poss and neg to neg ,and then u start to pull fuse if the volts go up then there is the problem ted s
February 25th, 2010 at 8:32 pm
It should be 14.5 volts. Have the charging system checked at a RELIABLE GARAGE. Some places will sell you a battery and then go through your whole system selling you an alternator and a voltage regulator just to get your money. Each of those things can be checked individually. Some auto parts places will check them for you. thomas m
February 28th, 2010 at 2:42 am
Well there are tests to determine a bad battery. First you would need a battery load tester or a gravity hydrometer. If you have neither one, simply leaving the battery disconnected to see if it keeps its charge when you get ready for a following day trip would tell the tale. A battery load test would tell the tale a lot quicker.
The multimeter should be reading 0. However, you may have connected wrong. You should have the negative disconnected and then connect your test leads between the a known good body ground and the battery post. You should have a reading of 0 on vehicles that are not computerized and do not have any keep alive components.. Any other reading such as six volts would indicate a six volt drain on the system. A 5 or 6volt drain is common for keep alive componets on radios and computers Morgan Landry
February 28th, 2010 at 5:54 am
OK..here’s an easy low tech way to find out if there is a ” draw ” on your battery. I assume you have a 12 volt test light ? Take the Negative battery terminal off….put the test light between the Negative terminal and the negative battery post ( in other words it will be between the two ) if the light comes on bright….then there is something on in your vehicle that is draining the battery. Now for the fix……disconnect the ” Dome light ” fuse…as when you have the door open the test light will be bright….if the test light goes out…or dims significantly…then the problem is in that circuit….glove box light or some other accessory light you may not readily be able to see. If you take 1 fuse out at a time until the test light dims or goes out…you eliminate the good circuits from the bad…when you remove a fuse and the light goes out…bingo…check all the things that fuse powers. I have seen Cigarette lighters short and do this also. Sorry for the long explanation…I hope I helped. JAMES M
March 1st, 2010 at 12:57 am
take it to your local parts store. most test batteries for free
–good luck alphonse v