HOW TO: Charge your Battery and Check Drains on the Electrical System

[mark v]

First start with a Battery Charger, I prefer the Schumacher brand. Schumacher Electric; Manufacturing Battery Chargers, Portable Power Jump-Starters, Power Inverters, Welders, and Testers for Over 60 Years.

Trickle Chargers will charge a Battery but they do it so slow it may take from 2 to 12 hours to do so depending how big or small or how weak your battery is, it may even take longer.

A Battery Tender will not charge a Battery. Tenders just keep the Battery topped off at full charge, they cycle on and off to maintain the Battery's full charge. These are great for cars or Motorcycles that are not driven a lot to keep the Battery's at full charge at all times.

Never use your vehicles Alternator to charge a dead or low Battery. The alternator is not designed to power vehicle loads and recharge the battery from a very low state of charge at the same time. Forcing the alternator to produce current at its maximum rating for a long time may overheat and damage it. The alternator may get so hot that it literally melts internal connections. Always recharge any battery that is at a very low state of charge with a battery charger, before installing it in the vehicle.

Connect the Charger to the Battery before plugging Charger in, make sure both Battery terminals are clean. When Battery is done charging unplug the Charger then you can disconnect the Charger from the Battery.

A slow charge is better for a Battery than a fast charge. Unfortunately, faster is not always better when it comes to battery charging. Charging at too high a rate can overheat and damage the battery. If you are not sure how old your Battery is charge it at the slow rate. There are two battery tests that are critical: Load test and a specific gravity test that can be found in this link. Schumacher Electric | Applications & Education The voltage of a battery is useful but a faulty cell may allow a high voltage and no power.

Check battery temperature periodically during charging. If the battery case is hot to the t ouch (125 degrees F or more) stop charging immediately until the battery cools. Resume charging at a lower rate to prevent battery overheating. If the electrolyte bubbles, cut back the charge rate immediately. Bubbling indicates overcharging.

Battery Charge Table
12.6V or higher: 100% charge
12.4V - 12.6V: 75-100%
12.2V - 12.4V: 50-75%
12.0V - 12.2V: 25-50%
11.7V - 12.0V: 0-25%
11.7V or less: 0% (and probably not capable of being recharged).

If you have an electrical drain that keeps draining your Battery this may help you find out for sure.

It doesn't take much to discharge a battery - a few Milliamp's drain over time can do it. If you have a very small drain, you will not see it by measuring voltage.

You need to measure *amperage* being drawn, not voltage.

You could place your multimeter in current mode, disconnect the negative lead to your battery, then place the multimeter in series between the battery and the negative battery cable. You will then be able to see exactly how much current is being drawn. When the neg terminal is removed and then re-connected via an ammeter to the neg battery terminal the PCM will command all system monitors to function and there will be a fairly large draw. The PCM will check for expected actions and if none are received after 20 to 30 mins or so will command the sensors to go to sleep mode progressively. There will be a large drop in the amps when all systems are in sleep mode. Then you can start to remove fuses to check for abnormal current draw.

I think the monitored systems need over 200 milliamps to monitor for expected actions with nothing going on and sleep mode should have about 40 milliamps if all is ok. You cannot open doors or anything in this mode.

You can also have an Alternator diode failure which can quickly flatten a battery.

Any issues you have with this post please post it here and I will correct the sticky ASAP.

[ABE]

The post looks good, but by way of amends and to educate myself a bit better I did some testing on my 2000 Taurus 3.0 OHV wagon. The Motorcraft battery is about a year old and load tested by my dealer in December 2007 as perfect. The car had not run since noon on 8 Jan 2008 (temp +8C) and at 8:35am on 9 Jan 2008 (still +8C) I tested the battery voltage at 12.37 volts. I then took the specific gravity reading of the 6 cells and each was full of electrolyte and the reading was over 1.3 on each cell and on the top side of "good". The battery is fully charged and therefore the voltage is representative of a situation where it has been "off-charge" for many hours.

Next to the electrical drain. I opened the drivers door and left it open, after 10 minutes the lights went out. I proceeded to remove the battery neg cable and make a copper wire to fit on the battery terminal to hold the red (+) lead of my digital multi-tester. I set the digital meter on the 10Amp setting for the leads and the dial. I attached the black (-) lead to the battery cable clamp and tightened it to securely hold (ammeter setting does not differentiate + and - so any connection should be ok). The system woke up with a slight (very small white spark and little click) spark and the interior lights turned on and the meter registered 2.2 amps draw. After 10 minutes the lights went out and the draw was 1.8 amps and after 15 minutes the draw dropped to 0.240 amps (240 milleamps), after 30 minutes the draw dropped to 0.174 amps, after 32 minutes the draw dropped to 0.040 amps (40 milleamps), after 35 minutes the draw dropped to 0.020 amps and every 8 seconds spiked to .040 amps momentarily. The continuing draw of 20 milleamps with a momentary spike to 40 milleamps every 8 seconds untill 60 minutes when I terminated the test. The "theft" light blinked every 3 seconds.

Now with the driver's door open and all systems asleep the appropriate fuses can be removed to check the draw. I do not know the correct sequence, but suspect that you cannot re-connect the fuse without risking waking-up the PCM since there is a large network of monitors that are all inter-connected. It would be no fun to start that process over.

If the diode in the alternator has failed and is feeding battery to ground there will be a large draw which will produce a fat blue spark and a loud crack. This is a serious short. Battery dies in about 5 to 10 hours.

[ABE]

Everything you wanted to know about a battery:
Car and Deep Cycle Battery FAQ 7.1, Battery Manufacturers and Brand Names List, and Battery References and Information Links List

[ABE]

The typical problem is that you try to start your car and the battery is flat. But it was OK yesterday. So you get the battery charged or boosted, but it happens again. So you get it charged off the car and clean it up and when you re-connect (pos first) the neg cable there is a blue spark, a noticeable crack and then it is connected and everything seems OK, but it is not.

With all the accessories on the car switched off there should only be a small drain on the battery from the PCM and the sensors that manage the safety and operations of the car. The load should be about 2.2 amps if you have left a door open and only 0.240 amps (240 milleamps) if not and this produces a very small white spark. The 240 milleamps will drop to 20 to 40 milleamps over the next 30 mins as the sensors are put to sleep if you do nothing to the car. That rate of discharge will allow the battery to start your car after a month of sitting somewhere.

The overnight drain and blue spark show a large drain on the electrical system. The first suspect is one of the alternator's diodes which may be draining the battery to ground. Disconnect the battery and put an ammeter between the neg post on the battery and the neg cable and note the reading and disconnect. Remove the heavy battery cable from the alternator and safely insulate the connection from grounding. Remove the remaining alternator connections to isolate the alternator. Now reconnect the ammeter and note the reading, if the reading has dropped significantly replace the alternator because you have a failed diode feeding battery current to ground through the alternator.

If the ammeter is reading between 20 milliamps to about 240 milliamps the problem is solved, but keep it connected to see that after a further 30 mins it does drop to at least 40 milliamps or lower.

If the reading is higher then one of the car's electrical systems has a problem, but how to find it. Make sure all the electrical systems are switched off and the driver's door or any access to the fuse panels are open. Disconnect the neg cable from the battery and connect a digital multi-meter set to record DC amps between the neg battery terminal and the neg battery cable, secure the connections so that they stay connected (i.e. alligator clip, length of wire, etc). Record the time and the amps and wait for 35 minutes for the PCM and all sensors to go to sleep, but still monitoring. Record the time and amps.

Now you start to pull the fuses that govern the likely circuits causing the drain. However, once you pull a fuse do not put it back because that will likely wake a sensor and since all the sensors are connected with the PCM you will be back to the 2.2 amp draw due to the GEM (Generic Electronic Module) switching on the door lights, etc. So keep a record of the circuits disabled, the fuse # and size and where the fuse is now that it is somewhere safe outside the car. Do it one fuse at a time and keep checking the ammeter to note a change in reading until all the draining circuits are found and the ammeter is registering 40 milliamps or less.

Disconnect the ammeter and repair the circuit, and re-install all the fuses in their correct places as recorded earlier.

Reconnect the ammeter and verify the repair, by watching the ammeter as it shows a reducing amp draw over the 30 minutes after re-connection. If you are down to 20 to 40 milliamps the problem is fixed and you can reconnect the battery.

Hope this helps.

[mark v]

Also make sure the Battery Terminals are clean along with the Battery Cables.

A dirty battery case will attract moisture which will cause a weak short to ground, worth several milliamps.

The "old school" method is still the best. brush with a mixture of baking soda and water and a nylon brush (old paint brush is fine), Repeat until there is no "foaming". Rinse with clear water.

[mark v]

Newer (like after 2006) Fords are staring to migrate from GEM to something called the Smart Junction Box. Sort of like GEM on steroids.

The point is, it is driven by a processor and it does "wake up", "look around", possibly "exercise" some things and then go back to sleep on a "regular" basis. I can't be an more specific, but this will happen continuously.

In "theory", this current draw should be low enough and infrequent enough for a full charged battery to last 2 weeks without starting the car. After that, get out the jumpers.

[mark v]

If anyone has any useful info to add to this Sticky please PM me and I will add it asap.