Charging 12v 7ah batteries

I have a permenant shack and I recently got a used car radio from a junk yard and installed it so I can have some tunes. I went to Fleet farm and perchased 3 12v/7ah batteries that i will wire in parallel so I can use all 3 at once to power up the radio…and I will have a spare batt incase my Marcum batttery runs out of juice.

What you you guys think the best way will be to charge those 3 batteries after a day (12 hours) of use? My hope is that after a long day of running the radio I will be able to charge the batteries over night and have them fully charged in the morning.

Thanks for any help.

You are probably going to be quite disappointed. Those three batteries will only be able to power that car stereo for around 3-5 hours. They are 7 amp(hr) batteries wired in parallel giving you 12 volts and 21 amp/hr of use. I did some digging and found that most general car stereo decks are using between 5 and 7 amps. So you’ll only get 3-5 hours of runtime.

So you probably spent $75 on those 3 batteries. It may be in your best interest to pick up a 12 volt group 27 battery (car battery) these batteries have around 100 amp(hrs) and will power a 7 amp stereo for about 13 hrs.

I would use any float charger that could do 2 amps, I have a couple automatic chargers that do 2 amps and they do a great job charging the batteries.

Your best bet is a car or deep cycle batt. Like Matt said size 27 would have been about the same price and lasted over twice as long. Maybe u can return??? Not sure on their batt policy.

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You are probably going to be quite disappointed. Those three batteries will only be able to power that car stereo for around 3-5 hours. They are 7 amp(hr) batteries wired in parallel giving you 12 volts and 21 amp/hr of use. I did some digging and found that most general car stereo decks are using between 5 and 7 amps. So you’ll only get 3-5 hours of runtime.

So you probably spent $75 on those 3 batteries. It may be in your best interest to pick up a 12 volt group 27 battery (car battery) these batteries have around 100 amp(hrs) and will power a 7 amp stereo for about 13 hrs.

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Matt,

The batteries that I bought were on sale for $10 a piece, so i only put $30 into the purchase. As far as run time, i used my fully charged Vexilar battery last year and it ran the radio about 4 hours. The radio is only powering 1 speaker, I’m sure if i was using more speakers it would lower the run time on one battery. I was hoping that 3 batteries would run the radio atleast 10 hours?

I have tried little AA batt powered radios in the shack but i can only get one radio station and lots of static. With an antenna on the tin roof making a large ground plane, i can get tons of stations that come in crystal clear.

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I would use any float charger that could do 2 amps, I have a couple automatic chargers that do 2 amps and they do a great job charging the batteries.

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Nick

This is what I was thinking too. I have a little .5ah charger that would take forever to charge those 3 batteries. I also have a regular car charger that I believe is 15ah and I think thats too much. I think that I will have to find a charger that will do about 2ah and I will be set. Thanks.