Standard practice is to charge the battery without disconnecting it. In fact, a few manufacturers have purposely built in a trick that can lock up some computers if the battery is disconnected, including simply to replace it. Some models won't come out of "park", and on others, if the engine even starts, it won't rise above idle speed. Those have to be dragged out of the shop and hauled to the dealer to have the computers unlocked or reprogrammed.
Here's links to some related articles you might find of interest:
https://www.2carpros.com/articles/how-to-charge-your-car-battery
https://www.2carpros.com/articles/everything-goes-dead-when-engine-is-cranked
https://www.2carpros.com/articles/how-a-car-battery-works
https://www.2carpros.com/articles/how-to-jump-start-car-battery-using-jumper-cables
https://www.2carpros.com/articles/how-to-replace-a-car-battery
Be sure to have the charger turned off when you connect and remove the charger's cables. That will prevent causing a small spark. Batteries give off explosive hydrogen gas, so we want to not cause sparks near them. Once connected, set the charger to a low rate. For a typical small portable charger, that could be as low as 2 amps, but six to 20 amps is more common. Standard car batteries will be near fully-charged after two to three hours, or at least more than enough to start the engine. The newer-style "AGM" batteries can take two to three days to fully charge, but even those will be charged enough to start the engine after charging for a few hours.
Unless you're really in a hurry, avoid charging a battery at a fast rate as some wheeled chargers can do. Unlike with the charging system in your car, home chargers put out a pulsing voltage that switches on and off up to 120 times per second. That pulsing current vibrates the plates and increases how fast the lead flakes off of them. That flaking occurs naturally in all batteries and can't be avoided, but it commonly takes up to five years or more before that causes the battery to fail. Fast charging makes that inevitable failure occur sooner.
That faster charge rate is accomplished by raising the voltage the charger develops. If you're worried about damaging computer modules, that is another reason to avoid those higher charging rates.
You didn't mention why the battery needs to be recharged, so allow me to just add a few quick observations. If the vehicle has been sitting a long time, the battery is going to run down due to all the computers' memory circuits drawing a little current. Unless specified differently by the manufacturer, the industry standard is that "ignition off draw", or IOD current must not exceed 35 milliamps. (0.035 amps). At that rate a good, fully-charged battery will still be able to crank the engine fast enough to start after sitting for three weeks. They'll commonly go longer as in four to six weeks, but that isn't guaranteed. When a battery sits longer than that, it could become totally discharged. As long as it doesn't freeze, it can be recharged, but be aware it can take up to about 15 minutes before that battery STARTS to take a charge. It can take that long before the acid becomes conductive. That's when the electrons first begin to get stored in the plates. If your charger has a current meter on it, you might see the charging current stay near 0 amps for that first 15 minutes, then it will slowly increase. Try to keep it from going over 15 to 20 amps at that point. Once the charging current drops back down to around five amps after a few hours, the battery can be considered fully-charged.
A vehicle as new as yours likely came with the newer AGM, (absorbed glass mat) battery. Those take a lot longer to fully charge, but that makes them susceptible to running down over weeks or months if you do a lot of short-trip driving. I often drive my truck only five miles at a time, twice per day. When I don't include a few longer road trips, I have to use a small charger overnight about once per month. That would not be necessary for the older, standard lead / acid batteries because they will fully charge during those short trips.
If none of these things apply, yet you need to recharge the battery often, you might want to test the charging system on your vehicle. There's three parts to this test. Two of them require a professional load tester. You'll need to visit a mechanic to have that done. The tests take just a couple of minutes. You can start the testing yourself by measuring the battery's voltage, first with the engine off, then with it running. With it off, you should find the battery's voltage is close to 12.6 volts. That shows it is good and fully charged. If you find it's closer to 12.2 volts, it is good, but fully discharged. If you've never used a voltmeter before, here's a link to an article that shows how it's done:
https://www.2carpros.com/articles/how-to-use-a-voltmeter
They're using an "auto-ranging" meter here which is an expensive option. If you have a standard voltmeter, I can help you set it up, if necessary.
With the engine running, you should find the battery's voltage is between 13.75 to 14.75 volts. If it is low, the battery will not charge completely. If it is too high, it will tend to boil the water out of the cells. Remember, this is just the first of three tests. If this one passes, it only means it is okay to continue with the rest of the tests, and those require the professional load tester. This article shows that charging test:
https://www.2carpros.com/articles/how-to-check-a-car-alternator
One more comment of value. When a battery is disconnected for any reason, then reconnected, it is quite common for multiple fuses to blow. There's typically a fuse box under the hood and another one or two inside the vehicle. Those fuses blow due to the rush of current that charges the computers' memory circuits when the battery is reconnected. All that's needed is to identify the blown fuses and replace them. This can also happen sometimes when connecting jumper cables. Connecting the battery's cables or jumper cables backward will also cause many fuses to blow. Computers have protection for that built in that causes the fuses to blow, thereby protecting them. Here again, most of the time all that's needed is to connect the cables correctly, (positive to positive, negative to negative), then replace the blown fuses.
Let me know if you have other questions.
SPONSORED LINKS
Friday, January 20th, 2023 AT 11:28 AM
