What voltage should a car battery be under load,car battery change in dubai 050,weight of a 12 volt car battery - New On 2016

02.01.2016
You accidentally left the lights on or some other accessory that pulls power from the battery even when the ignition key is off.
There is a key off parasitic electrical drain on the battery because a relay is sticking, a module is not shutting down (going into "sleep mode"), or there is a shorted diode in the alternator. The first things you want to check are the battery and the output of the charging system (alternator). After charging the battery or jump starting the car, connect the voltmeter to the battery the same as before and not the charging voltage. After the battery has been recharged, the battery should also be tested to see if it is capable of holding a charge. The average service life of a wet cell lead-acid car battery is only about four to five years, and can be as little as three years in really hot climates (like Arizona and Florida).
If your car battery is less than six years old and tests okay, and the charging system is working normally, your battery may be running down because of a key-off current drain (also called "parasitic battery drain").
When you turn the ignition off, switch the lights off and remove the key from the ignition switch (or the smart key fob from the vehicle), the electrical load on the battery should drop to almost nothing. Many modules have internal timers that either turn off the module to put it into a "sleep mode," or power down the module to a "standby mode" to reduce the parasitic power drain on the battery after a predetermined length of time when the key is turned off.
WARNING: When disconnecting or replacing a car battery on a late mode vehicle, you should always maintain voltage to the vehicle's electrical system to preserve learned module settings.
As a rule, the parasitic drain on most late model vehicles should be less than 50 milliamps one hour after the vehicle has been shut off and left undisturbed. Keep in mind, though, that opening a door, the trunk or turning anything on can wake up various modules and start the timer countdown all over again. Check for Voltage Drop: Use a digital volt meter to measure voltage drop across individual fuses with the key off. Use an ammeter with an amp probe to measure key-off current flow at the battery: Connect an inductive amp probe to your ammeter or digital multimeter, then clamp the probe around one of the battery cables.
Use an ammeter to measure key-off current flow at the battery: This method requires disconnecting one of the battery cables and connecting the ammeter in series between the battery and cable so any current flow will pass through the meter. Causes of excessive current drain from a car battery include things like lights that remain on (trunk and hood lights, interior lights, brake lights, etc.) and also relays that may be stuck on, or modules that are not going to sleep or powering down.
A fuel pump relay that sticks on may keep the fuel pump running after the engine is shut off.
An accessory such as a DVD player, game console or cell phone charger left plugged into a rear seat power receptacle may be pulling power from the battery. If the key-off current reading is above specifications (typically, more than 50 mA one hour after the vehicle has been shut off), the current drain is too high.
Once you've found the circuit that is causing the excessive current drain, check the relay, switch, module or other components in the circuit and replace as needed. BMW recalled 2004 to 2010 BMW 5 Series and 6 Series cars for a faulty battery-cable connection in the trunk. I put together the following chart which indicates the state-of-charge (percent) as it relates to battery voltage or specific gravity.
How I determined the voltage values: I researched as many battery manufacturers that I could find regarding their own published SOC data.


Note: Voltage measurements are only approximate to determine SOC, and measuring battery voltage is NOT the most accurate way to do this (there are variables under varying circumstances). Note: For longer battery life, batteries should remain in the green zone (40% or more SOC).
Note: The 100% voltage is NOT the recommended charging voltage (which will be higher, and multi-stage). If the gravity of each cell stays relatively the same (usually all in the green) does that mean that I don’t need to equalize that battery? The reason I ask is: I have 90 watts of harbor freight panels, run thru a sunsaver controller that charges 2 wally world deep cycle batteries and the gravity has almost never been below the green level, and I never really have had to add much water. My other set up has about 750 watts of poly panels, run through a xantrex 30 amp charge controller charging a trojan 12 volt golf cart battery. I guess my question is do I need to do this since the wally world batteries always seem to be in good shape as per hydrometer readings? I built an off-grid system for my home and have expanded and maintained it myself over the years, so that is my knowledge base. Also, NEVER combine different types, or age, or widely differing state of charge of your batteries when charging.
Thanks Carl, and as you insinuated, there are variables, including temperature compensation measurements and others. Saw this as I was looking for a SG to SOC chart and thought I would make a couple of comments. A bolt that connects the battery cables in the trunk may come loose, creating increased electric resistance and an overheated cable connection. Or better use another browser which respects html and css standards - Mozilla Firefox, Opera, Google Chrome, Safari etc. Voltages and Specific Gravity are listed for a 6-volt or 12-volt battery, and battery banks of 24 and 48 volts. Some were slightly different from each-other with regards to their SOC values, however I averaged all of them together to come up with a chart which represents what I believe to be a good general indication. A more accurate method is to measure the specific gravity of each cell within the battery, however for many batteries this is difficult or impossible (AGM batteries, for example). Occasional dips into the yellow may not be harmful, but continual discharges to those levels will shorten battery life considerably.
Just thought it might be helpful to add that one tool I’ve found useful is the little floating balls thing for checking individual cell status in lead acid batteries. I mainly use this system for 12 volt water pumps,a few LED’s and cfl lights and occasionally power tools. My immediate thought about the differences in your two battery banks is that the wally world batteries are newer, or less heavily used than the Trojan.
I do off grid solar for a living, 25 years now and I sent a customer the link to this chart to give him an extra tool to keep tabs of his system.
Measuring and knowing the SOC of a battery or battery bank is useful when applying towards alternative energy, or any other situation where you need to know its condition.
Many (most) alt-energy systems incorporate a DC-shunt which keeps track of SOC by monitoring the current flow in and out of the battery or battery bank, which is a very accurate way to track state-of-charge.


To be somewhat accurate, the battery should be in that condition for an hour or two before taking a measurement, while for a more accurate measurement you should wait 6 hours up to 24 hours. Generally speaking, the less you discharge the battery before recharge, the longer the battery will last. The Trojan sounds like it is getting old, and needs more frequent watering and equalizing to keep it functioning. The one thing I would disagree with somewhat from your well written article is concerning the accuracy of state of charge meters. Most alternative-energy systems are designed to keep the battery bank at least 50% or higher.
When batteries are in series they do not necessarily charge at the same rate and can become imbalanced.
In addition, there may be a burning or melting odor, smoke, and possibly a fire in the trunk.
It is set to equalize every 30 days, however sometimes I have to do it more than that, to bring them all back to green. The plates may have become heavily sulfated enough that the equalize mode can’t get it all off into solution. The equalizing charge ups the charging voltages in order to get enough voltage to the lesser charged batteries in the series chain. I combine the batteries whenever we lose power for more than a few hours so we can run TVs, fans DVD player and lights etc. The standard meter for years has been the Tri-Metric meter but I finally gave up on using them because they arent very accurate unless fine-tuned beyond the level most homeowners are capable of understanding.
Yes it will over charge the higher charged batteries, which is why the equalizing charge is only applied for a short time, however if the system uses a single battery equalization is not required and can be detrimental. You should probably start saving your shekels for a new battery because that one is not going to live much longer. It doesnt help that the manual makes little sense to the layman or that the meter cant read battery voltage and often keeps compounding small errors into bigger ones.
It would be wise to buy a desulfator unit for your batteries in order to reverse sulfation of the plates after long periods of less than 100% charge.
The meters that you can get that take their info from the inverter or in the case of Midnite Solar from the charge controller are more accurate because they temperature compensate but they need fine-tuning as well. Just yesterday a customer called because his inverter shut down at 23 volts, a definite low battery but the SOC meter claimed he was at 81% full.
I sent him a link to your chart and told him to call Magnum tech support to learn to tweak the meter.



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Comments What voltage should a car battery be under load

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