- First Name
- Elliot
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- 2019 Sahara
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- #1
....it sounds like the stuff that serves as preamble to a comic's punch line.
A lot of posts on the board have correctly suggested that the only true test--the gold standard if you will--of vehicle battery testing is the load test, not how many volts some meter registers when connected to an ICE (internal combustion engine) vehicle's battery terminals (although low voltage readings in such a meter would rule in a problem, it's just that adequate voltage readings can't rule out a problem.)
Why?
Voltage registers how much charge is in a battery, not that battery's ability to deliver energy. That energy, which will cover below, and measure in watts, is a product of both voltage and current...and we measure current in amperes or amps for short.
You'll pardon my limited analogy, that I offer with no disrespect, but I could provide vast amounts of glucose (volts or charge) to an elderly (old or defective battery) person, and verify its presence in their blood stream with a blood test (the volt meter,) but it doesn't mean that such levels will find them able to compete in a marathon (watts.)
(The analogy was not attempting to equate our finest generation with defect. Anything but.)
On the other side of the spectrum, as mentioned prior, the glucose test (or voltage) isn't worthless, just limited in diagnostic value. A battery with low voltage, like an elderly person (old/defective battery) deprived of calories for days, certainly isn't likely to win any strength competitions either--it's just that loading them up with energy isn't likely to produce any metal winning performances.
If you prefer this analogy: voltage is the speed of the marchers in a parade.
Current, on the other hand, again, measured in amps, is the width of the parade marchers.
The speed and width of the parade, voltage and amps, multiplied together is watts. It is watts that make appliances work.
That static electricity shock you got rubbing against the carpet in a dry room....probably 1000s of volts, but next to no amps (current) and therefore next to no watts, and thankfully, no way lethal given the low amperage and watts.
Much of the European standard for electricity is 220 Volts, not the 110 Volts found in North America. More volts, all else equal is more watts. More volts means watts can be delivered with lower amps. Lower amps requires thinner cable, and conductive metals are expensive. On the other hand, more volts, all else equal, can be more dangerous.
Another analogy. Food is electrical current. Envision a bunch of cars loaded with food from Costco runs, sitting in the Costo parking low but with no gasoline (volts). That's high amperage but low voltage: we can't send that energy in the form of food in cars, when those cars can't travel, to where it is needed. This is the analogy the volt tester can detect.
Now envision that same bunch of cars have just had their gasoline tanks topped off from that very Costo's gasoline station and are ready to deliver food (current), but we haven't yet visited the store to load up on food. That's high voltage low amperage. You can drive those cars to hungry people, but have nothing to offer them in the way of calories. This is the analogy that proves the volt tester unable to detect.
With all these analogies, and I've offered several because none is perfect, a load tester tests both voltage and amperage. It tests not only ability for the battery to delivery its power (the Costco cars full of food and gasoline) , but accept a recharge (from the alternator). This is the essence of what a good ICE vehiicle battery has to do.
~~~~~~~~~~~
When you load test the batteries in your dual AGM battery JL they must first be electrically isolated. If you don't disconnect them, any load or voltage tester generates a composite reading where one battery could be, say, helping the other and masking an individual battery's inability to delivery charge.
Two black factory cables can be found at the main battery's negative terminal. One of those cables can be traced to the passenger's side panel under the hood. That cable is the body ground connection and should be left alone. It's connected presence allows many vehicle appliances to complete a circuit with the battery by using the very vehicle's electrically conductive body to connect to the battery's negative terminal via this cable.
The other factory cable on the main battery's negative cable is the one that, to load test each battery independently, needs to be temporarily disconnect. It is this cable whose other end is connected to the ESS battery's negative terminal. When disconnecting this cable make sure it doesn't come into contact with other parts of the vehicle.
With this cable disconnected, placing the leads of a load tester on the main battery's terminals will load test (only) the main battery. Moving only the negative lead of the load tester thereafter on to the end of the dangling cable will test (only) the ESS battery.
It may seem odd that the load tester's positive end remains on the main battery to test the ESS battery. Rest assured, the only completed circuit the load tester sees here is to the ESS battery.
Don't forget to reconnect that cable you just disconnected back on to the main battery's negative terminal.
A lot of posts on the board have correctly suggested that the only true test--the gold standard if you will--of vehicle battery testing is the load test, not how many volts some meter registers when connected to an ICE (internal combustion engine) vehicle's battery terminals (although low voltage readings in such a meter would rule in a problem, it's just that adequate voltage readings can't rule out a problem.)
Why?
Voltage registers how much charge is in a battery, not that battery's ability to deliver energy. That energy, which will cover below, and measure in watts, is a product of both voltage and current...and we measure current in amperes or amps for short.
You'll pardon my limited analogy, that I offer with no disrespect, but I could provide vast amounts of glucose (volts or charge) to an elderly (old or defective battery) person, and verify its presence in their blood stream with a blood test (the volt meter,) but it doesn't mean that such levels will find them able to compete in a marathon (watts.)
(The analogy was not attempting to equate our finest generation with defect. Anything but.)
On the other side of the spectrum, as mentioned prior, the glucose test (or voltage) isn't worthless, just limited in diagnostic value. A battery with low voltage, like an elderly person (old/defective battery) deprived of calories for days, certainly isn't likely to win any strength competitions either--it's just that loading them up with energy isn't likely to produce any metal winning performances.
If you prefer this analogy: voltage is the speed of the marchers in a parade.
Current, on the other hand, again, measured in amps, is the width of the parade marchers.
The speed and width of the parade, voltage and amps, multiplied together is watts. It is watts that make appliances work.
That static electricity shock you got rubbing against the carpet in a dry room....probably 1000s of volts, but next to no amps (current) and therefore next to no watts, and thankfully, no way lethal given the low amperage and watts.
Much of the European standard for electricity is 220 Volts, not the 110 Volts found in North America. More volts, all else equal is more watts. More volts means watts can be delivered with lower amps. Lower amps requires thinner cable, and conductive metals are expensive. On the other hand, more volts, all else equal, can be more dangerous.
Another analogy. Food is electrical current. Envision a bunch of cars loaded with food from Costco runs, sitting in the Costo parking low but with no gasoline (volts). That's high amperage but low voltage: we can't send that energy in the form of food in cars, when those cars can't travel, to where it is needed. This is the analogy the volt tester can detect.
Now envision that same bunch of cars have just had their gasoline tanks topped off from that very Costo's gasoline station and are ready to deliver food (current), but we haven't yet visited the store to load up on food. That's high voltage low amperage. You can drive those cars to hungry people, but have nothing to offer them in the way of calories. This is the analogy that proves the volt tester unable to detect.
With all these analogies, and I've offered several because none is perfect, a load tester tests both voltage and amperage. It tests not only ability for the battery to delivery its power (the Costco cars full of food and gasoline) , but accept a recharge (from the alternator). This is the essence of what a good ICE vehiicle battery has to do.
~~~~~~~~~~~
When you load test the batteries in your dual AGM battery JL they must first be electrically isolated. If you don't disconnect them, any load or voltage tester generates a composite reading where one battery could be, say, helping the other and masking an individual battery's inability to delivery charge.
Two black factory cables can be found at the main battery's negative terminal. One of those cables can be traced to the passenger's side panel under the hood. That cable is the body ground connection and should be left alone. It's connected presence allows many vehicle appliances to complete a circuit with the battery by using the very vehicle's electrically conductive body to connect to the battery's negative terminal via this cable.
The other factory cable on the main battery's negative cable is the one that, to load test each battery independently, needs to be temporarily disconnect. It is this cable whose other end is connected to the ESS battery's negative terminal. When disconnecting this cable make sure it doesn't come into contact with other parts of the vehicle.
With this cable disconnected, placing the leads of a load tester on the main battery's terminals will load test (only) the main battery. Moving only the negative lead of the load tester thereafter on to the end of the dangling cable will test (only) the ESS battery.
It may seem odd that the load tester's positive end remains on the main battery to test the ESS battery. Rest assured, the only completed circuit the load tester sees here is to the ESS battery.
Don't forget to reconnect that cable you just disconnected back on to the main battery's negative terminal.
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