If my car's battery is dead, will it CHARGE it so it can start?
1171804
No, it will not charge the dead battery. This device gets its power from car battery so it could charge your other electronic devices like cellphones, tablets, etc. If your car battery is dead you need to jumpstart it or get battery charger.
2125609
No offense, but you are making a common experimental error. It sounds like you are saying your car started because you put this charger on it for an hour. That is an invalid conclusion. You don't really know the charger was the reason the car started. To determine if that was the case, you'd need to charge the battery fully, then leave the lights on for the same period of time as before, then turn them off, immediately try and fail to start the car as you did before, and finally leave the car alone for the same hour you said you put the charger on the car. Then, try to start the car. This would be a true and valid A-B experiment. I'm betting the car would start in this second scenario. Anytime a lead-acid battery is run down to the point where it won't start a car, if you shut off the battery drain and let the battery rest for a while, the battery will usually recover and be able to start the car.
2265493
Yes, just be sure it is turned on. It will charge whether turned on or off.
1555953
It depends in how good the signal is. If it's spotty, the battery won't last. You can get a charger for your car. It uses a regular mini USB cable.
2208399
Maybe not. We left our battery uncharged all winter long for two winters and it was fine the next spring when we plugged it back into the car. We just recently bought a new battery because the old battery that originally came with the car finally died.
1275389
No, this (G750) unit is only going to charge smaller batteries. Notice all the comments about jetskis, lawnmowers, etc. A dead car battery needs a more powerful charger and, if you actually want to start up the car, a boost capability. But as you suggest, it will keep a stored car battery from going dead.
284649
Yes..it will charge it. Takes a while if battery is drawn down all the way.
1356012
Yes, it will keep your battery fully chrged however it is NOT waterproof so keep it under the hood, or somewhere dry...If the battery is almost dead, (under 3 volts), the charger will NOT recognize it and won't charge.
229972
No... but if you are talking about a battery that had the lights left on overnight and 'dead' it will not charge if it is below (I think 2 volts) some minimum voltage left in the battery. It IS very frustrating because the older 'not so smart' chargers would at least try to charge a dead battery where these smart ones won't work at all. I faked one out once by connecting a small motorcycle battery to my dead car battery and fooled the 'smart charger' to start working and then put the motorcycle battery back. Battery was fine after about 6-8 hours of charging.
168688
Make sure it is charged up and then connect the cables on each side just like you would jumper cables. If I remember right, you turn the switch on the back to "on" and then start your car. Works great!!
1656958
I would say yes as long as the battery isn't totally drained. The battery needs to be charged because it's a maintainer to keep a battery fully charged all the time! I think it's to small to charge a totally dead battery. The battery tender only puts out 1.5 volts and a regular battery charger puts out 12 volts to charge a totally dead battery.
1900946
No. you have a built in charger in your unit and it will top charge the battery in case it is a little bit discharged.
1070018
Good question! You can charge using the car's battery for power, but the ignition key will need to be in the "accessory" position (engine not running). However, the mfg. recommends you start the engine every few few hours to charge the car's battery up again. If the car's battery drains down to 10.5 volts (12 volts is full charge), the Energizer will shut itself off. Hope this helps.Bill R.
1275386
So my question I guess would be is -- if I left my lights on and car battery died overnight, could I just hook this thing up and within a few minutes, startup my car?
2259136
It will take several hours to charge enough to start the car. If the battery is in poor condition, and the voltage output of the battery is below 2 volts DC, the charger will not charge the battery at all and just shows a floating charge. This is covered in the instructions. It may be time to replace your battery altogether.
1958030
I wouldn't. When your car isn't running it doesn't charge and I would think there's a possibility it might discharge. You can get a good, full charge by plugging it into a USB port on your computer for about 3-4 hours and the charge should last about a month
632958
Wei, the battery arrived charged, but I would still recommend throwing it on a charger for a bit- mine was at 11.8V, which is certainly enough to start most cars, but may cause issues with newer, more electronically controlled cars. Also, it will reduce the load on a starter which likely has been already strained starting on the previous, dying or dead battery- Mark W.