My car battery died last Monday and it’s been a week; I’m trying to get it to charge using a noco genius portable battery charger but nothing comes on in my car, no sound lights or anything. Will I have to wait 24 hrs for it to fully charge or will I need a new battery? Bought it from auto zone. 
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How long had you left it connected before trying the lights? That charger is only capable of delivering 1 amp, so it will take a while before the battery has any significant charge in it.– HandyHowieJul 29, 2021 at 10:16
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Have you cleaned your battery terminals and the connectors that bolt onto the terminals? If not, it is worth doing.– HandyHowieJul 29, 2021 at 10:17
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I let it there for about 5 hrs till it started raining. There’s still no lights or anything came on. I did notice corrosion yesterday that I scraped off with a knife but am going to clean with baking soda and water.– Jada LaceyJul 29, 2021 at 10:23
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So basically it will need a 24 hour charge then?– Jada LaceyJul 29, 2021 at 10:23
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After 5 hours, I would have expected that you should see your dash lights come on. It does sound like there may be a bad connection somewhere.– HandyHowieJul 29, 2021 at 11:20
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3 Answers
Most battery chargers today are smart enough to not apply a charge to something which it doesn't see as a 12v battery. If the voltage on the battery is too low, this may be what's at issue. The reason for this is safety so you aren't trying to charge a 9v battery to 12v, which would cause issues to the battery as well as could cause problems with the charger.
To overcome this, I will put a good 12v source battery in parallel with my weakened battery to provide that source voltage the charger needs. I have several small 12v batteries which I've changed out from different sources (ie: garage door opener battery backup) sitting around for just this purpose. Once attached to the battery to be recharged, the charger will see the 12v source and charge it along with the weak battery. Once both batteries are up to par, the charger will go into maintenance mode. I have found this method works well for charging depleted AGM batteries as well.
answered Jul 31, 2021 at 12:46
A depleted or nearly depleted battery should be totally recharged and tested. The battery should not be used while the charger is hooked up. Charge your battery following the instructions to the charger. If the charger is working the battery should then have a full charge. Then you can get the battery tested to determine if it needs replaced. If it needs replaced you need to confirm the cause of bad battery. Was it old and worn out, or has the charging system failed. When installing a new battery all cables need to be checked and cleaned. Then check the charging system.
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That week before it died I took it up to autozone and they tested it out and said both the battery and alternator were good Jul 29, 2021 at 9:59
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The failure happened after testing. The procedure should still be the same. But given the circumstances I would concentrate on checking cables and connections. It would also be a good idea to charge the battery with the battery cables disconnected. Then when the battery, charging system and cables are all confirmed good and there are still problems, a parasitic draw test can be done. Although I think that you may find the problem with the cables and connections, to accurately diagnose, these steps should be taken.– JupiterJul 29, 2021 at 13:27
1-Finding corrosion on battery connections can create poor electrical connections. Being aware of using baking soda, water and a toothbrush will dissolve dried battery acid immediately by bubbling up. Rinse with plain water then coat with grease, petroleum jelly or battery spray treatment to minimize future corrosion. Don't let the baking soda/water solution into battery cells as this neutralizes battery acid, effectively killing each cell inadvertently with spilled bs/water.
2-Your charger is only outputting 1 amp according to specs found online, basically a trickle charger that's mainly used for topping off a partially discharged battery and can be left permanently connected for long term battery storage without overcharging it. To use it for charging a dead battery may require minimum of 24 hrs or more. Battery chargers outputting 10-20 amps then drop output automatically are more suited for recharging a dead battery. With an Autozone battery tested as sound, you may be able to ask them to recharge it and return later in the day or next day. Call ahead and ask. If your dead battery is discharged below 10 volts, your low amperage charger simply takes longer and may not even charge.
