Other pages on this site recite that a lead acid battery which is common to most all mobile equipment today is simply a reliable source for dc electrical energy. D.C electrical energy has a direction it travels within a conductor. A conductor is any path or conduit electrical energy can travel within. The energy from the battery is useless unless there is some type of mechanical device that is manufactured to use the electricity. Lack of batteries can prevent a mobile piece of equipment to be started or used, a lead acid battery that is bad simply has lost capacity or ability to hold volume of current.

A large number of problems can be made to happen when a battery or charging system is not working properly.



The digital meters reading voltage use two decimals out ( 12.59), the 5 is tenths and the 9 is hundredths. Most people wouldn't even think that's needed but that is not the case.

This is the most common reading on the dc voltage scale for a good battery and electrical system. This is really close to what your battery will want to read for you to know it's ok and normal. You will notice the .59 and that's a key number you will be paying attention to when testing your battery.


An important fact regarding batteries is that they are made up of what is called cells. These cells are amazing to me because the rule of thumb is that each cell in a conventional lead acid or paste battery will be able to produce 2.2 Volts dc when in operation. It does not matter if the cell is as big as the Hana Hotel or as small as a Macadamia Nut, it will still only produce 2.2 Vdc (Volts direct current) and that figure of 2.2 is used as a base figure to calculate the state of a battery. A state of high charge is not normal 13.07 and a state of low charge 10.5 is also not normal for a battery that is in usage.


A solar system battery looks like any other lead acid or paste battery however "the battery" is only the outside case and "the cell" is a component of the battery. The solar battery is way larger than a 12 volt auto battery but with one cell produces approximately 2.2 Vdc. The cell is like a storage tank of water and the more water stored the more capacity (Current = I ) so the larger the cell the larger the volume of electricity that can be stored. If you had something that operated off of 2 volts it could be powered for a long time compared to a smaller cell but the voltage in the battery is simply used to produce a magnetic field both to start a vehicle and also to re charge the battery. So voltage is directly proportional to the strength of the magnetic field produced from any coil, starter motor, alternator or generator. 


A normally used voltage is said to be 12 Vdc in most all mobile equipment and that means your battery needs to have a minimum of 6 cells added together to make a total of 13.2 Vdc in a perfect scenario of a new battery. A new battery charged 100% of it's rated capacity should read 13.18 to 13.22 without being attached to anything which is called a no load test. When the meter reads 11.88 with no load it is less than 40% charged and if the meter reaches down past 2.2 volts from 100% or 11.2 Vdc to 10.18 it means the battery is bad because of one cell is not working. That is how come the few hundredths of the volt are very important to a system using 12 volts as a base to operate properly.


How a lead acid battery looses it's ability to produce current or electrical volume is when the plates in the cell have absorbed the water (H2O) in the electrolyte solution originally filled into the cell. As water is absorbed by the plate a proportional loss in capacity is noticed and making the volt meter read lower than 12.2 Vdc with no load applied. The specific gravity test on the battery will tell you the condition of the electrolyte and add water is the point if needed. If you re fill a battery with acid once it has been filled in origin you can be sure you will be purchasing a new one to replace the one you just ruined by filling it with electrolyte, use water only.


There are several ways these cells go bad before the battery gets old and used up, one method to kill the battery and cause it to lose capacity is to overheat it, the exact number in heat is 118F to 120F and the plates start to soften inside and absorb the water from the electrolyte. When a battery in this condition is used to start an engine the starter cranks over the engine a few times and then you can hear the starter slow down and if the engine fails to start quickly you are looking for a jump start.

Here is a battery damaged by heat and loss of capacity, the voltage reading shows one cell is bad. I could just put this in the equipment and jump start the engine and it will run fine because my charging system will keep it going. What this would end up doing is cause a constant charge into the battery while running and the cell temperature will go higher and to the point you smell an acid smell in your equipment. This overheats all components and you will eventually need to replace the alternator, battery, starter. Running a vehicle with a low battery is going to kill the electrical system.


When you ask someone to give you a jump always make sure to let the vehicle charging the dead battery to charge it up for no less than 3 minutes up to 5 minutes. Trying to start your car immediately after hooking up the jumper cables will start a failure on the other cars charging system that could take several months to surface.


If you are giving a jump to someone never let the person try to start their car before you have left the car running and charging for 3 to 5 minutes or you will cause a situation in the regulator chip inside the alternator. This situation is caused by a surge and back EMF (voltage) into the running equipment's regulator chip within a modern alternator system as well as a computer controlled engine. This surge causes a substrate failure not evident right away, how it develops is like a rust on metal where pits are formed and then later the entire component is rusted internally. A regulator chip has a silicone wafer inside called a substrate and the surge puts small microscopic pits onto it's micro surface, after a couple months of operation you will be driving along and find the voltmeter needle is higher than normal. Then you smell an acid smell, look at your battery and it's all corroded on top and see that the water is a little low in some cells. After you fill it up and drive longer it will work fine until you notice the light going brighter and dimmer, and when you look at the voltmeter as the equipment is running, you will see the voltages fluctuating in the tenths decimal point. This is hardly noticeable until one day you go out to start your equipment and no start due to the battery has lost it's capacity from jump starting a piece of equipment when the operator was in a hurry to get going and didn't wait until the dead battery being jumped had enough charge to normalize the vehicles electrical systems. Be aware when jumping others cars, now days because I have seen damages caused that cost hundreds to the electrical parts damaged.

In the pictures above the "FUZZ" on the cable in the far left picture is a result of heat. It is that simple heat, when a system is operating and using as much electricity as it can there is a voltage drop that is signaled in hundredth's of a volt within the alternator voltage regulator chip and the alternator charges to maintain a specific voltage within the battery. To get this voltage the alternator needs to produce current, a volume in number just like the fuel tank. For example the tank holds fuel to run the engine, there needs to be some way to get the fuel to burn in the engine so you add volume which is pints, quarts, or gallons whatever size your engine is and requires to run. In an electrical system the gallons are the volume of current (I) and to fill the electrical tank the volume needs to fill it. The current is made up of electrons and they are compressible just like air. Your battery is rated in a capacity or ampere rating. One ampere in one second is equal to 6.25 billion/billion electrons past one point in one second, a point I am trying to relay is that electrons are negatively charged energy and flow towards a more positive charge area.


The D.C electrical energy is electrons flowing towards a more positive environment. As these energy units (electrons) flow within a conduit (wire) they go in one specific direction and as they end up stored and used they also travel in one direction. The more flow in amperes to the battery the more heat is produced within the cells of the battery. 

Most all batteries are vented meaning the individual cells are vented by a hollow passage leading outwards the battery and into the local atmosphere. This is due to a charging battery produces a by product not intended for usage. The product is a gas, hydrogen (H) a very flammable gas and when you smell the acid smell it is highly concentrated with the hydrogen atom. I have personally had three battery accidents whereas the battery blew up into small pieces throwing acid in my eyes. When a battery is under heavy charge (high volume) quickly it produces hydrogen gas and acid you can smell and you will notice bubbles inside the battery in the electrolyte. As soon as you hook up a battery jumper cable a spark ignites the hydrogen air mixture and the battery explodes like a hydrogen bomb, scary at the least and that's why when servicing a battery always have water and soap handy to wash you eyes out. many people have been seriously injured by a battery they didn't understand could injure them for life. Always use eye protection when working with a lead acid battery.


As the alternator keeps up the volume on the current to build the voltage in the battery heat is a result. A good example is how a large volume of fluid is flowing within a conduit (tube) and then a restriction is applied (valve) and heat is a result where the "pressure drop" or change in volume after the restriction is building.  

This restriction to flow of the electron and called resistance produces heat, this heat allows the fluid within the battery to gas at a rate that pushes it out of the poor sealed battery posts to the battery cover. Even though most all batteries have this failed method of sealing gas within the charging battery this battery was my example and clearly seen is the retailer. There are very few battery manufacturers so no matter where you buy one they are very similar to one another and leak gas vapors out of the vent passage and through the seal on the battery cover where the posts of the cells come out to put a cable on. This causes the FUZZ as noted and will keep going until you seal the area with some epoxy. I chose this Loctite picture 3 from left because it was 3 bucks at the Lowes store. Sealing this area will prevent the FUZZ.


Picture 2 shows a locally available brass brush (redneck toothbrush) to clean the acid/gas erosion of the metal (FUZZ) from the battery cable terminal end and the post and base to cover areas. Picture four from left is the exact metal to plastic failure point and the glue tip is on the seal area. The next pictures show the repair is complete and we will use this as an example of how to eliminate the FUZZ for good.

IMPORTANT; is to not operate your equipment with a bad battery, expect to spend more in component replacement, when the source of power is low things overheat.


Think of it this way, mechanical energy from you to move a rock and the voltage in a dc battery. If you weigh 100 lbs. and try to push a rock 50 pounds it would seem easy and that would represent a good battery and electrical system. So we will say the rock on a scale of one to twelve is a 12 and very little heat will develop in the 100 lb. person from pushing the rock like the battery at 12.59 volts dc.


The 100 lb. person would be a 12 in strength to easily and efficiently move the 50 lb. rock. Now lets say the persons energy is depleting as they are pushing the 50 lb. rock and now the 100 person is at a level 6 exactly half the strength due to the continued pushing of the rock. The 100 lb. person has now developed heat due to the resistance of the 50 lb. rock to push. Voltage is the strength or electrical pressure (E) as compared to the strength of the 100 lb. person. Finally the 100 lb. person will reduce to the strength that equally matches the resistance to push the rock, and neither will move however the 100 lb. person is gaining heat with no movement of the rock. Finally the system dies after heat is built up and no movement happens and all energy of the 100 lb. person is depleted. That is as close to a low battery and system destined to fail as I can think of right now. Purchase a cheap 20 dollar meter and prevent 100's of dollars you would have spent in parts and figuring out your problem if you didn't have a DVOM.

Picture one here is a very good no load voltage reading on a John Deere Battery in a John Deere D-120 lawn tractor. This unit had been setting for 24 hours with the hour meter in the dash running and pulling surface charge as well as current from this battery. John Deere and Caterpillar batteries are very good batteries and these batteries read a higher no load voltage than most other batteries I have tested. They are a little more expensive but if you want to make sure your electrical components stay in good shape you will want to use only the best batteries available.


In picture 2 there shows a load with the starter rotating the engine and the voltage 8.95 Vdc which is perfect as a mechanic views it. As you are doing this test it is good to look into the cells of the battery, a battery that is bad with one cell out will bubble (off gas) in that cells electrolyte. The load tests of the past to tell the actual capacity in amperage of the battery being tested always required the load to be applied in a carbon pile until the battery reached a 9 Vdc potential in voltage and then the load would be decreased to maintain the 9 Vdc potential for 15 seconds. The amperage read at that time on the meter was considered the capacity of that battery in it's present state. That amperage would be around 165 amp hours on a good equipment battery, I have measured them up to 200 amps but that's quite a bit of current and develops heat quickly. Now the batteries are rated in cold crank (CC) amps which is simply how many amps can be drawn out of the battery for 15 seconds.


In picture 3 it shows a voltage of 13.23 after the engine starts and is at a low idle, as seen the voltage immediately went up when the engine started. This is a sign to the mechanic that the charging system is working and as the engine idle is increased the voltage will rise also. This mower has a good battery and charging system that is shown in the pictures.

The You Tube video link below demonstrates how to test a 12 volt battery using a digital meter like the one pictured above.