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Is there anyway to get a "smart" charger to charge a dead SLA battery?

Is there anyway to get a "smart" charger to charge a dead SLA battery?

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  #1  
Old 06-09-20, 08:24 PM
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Is there anyway to get a "smart" charger to charge a dead SLA battery?

I have a little project planned.
I am making a toolbox into a boombox out of an unused car stereo .
I do not have any of the major parts yet, basically so far I only have the toolbox and a few SLA batteries that I though were good but I guess I let them sit a little too long.
So my stupid so called "smart" charger does not even attempt to charge them.

It is a ChromeBattery Xtend 6 step 4.2A probably not the best one of these out there but it is all I have (for now).

I have 1 18AH 12V SLA that measures only 7.08V So I think that one is a lost cause unless there is a way to revive it but I don't think so

I also have 2x 7.2AH 12V one was at 12.13V and the other one was 11.95V.

The 12.13 one charged fine but the other one the charger said it was a motorcycle battery and took about 3 hours and then switched to the car symbol (higher current I guess). It did fully charge it though it just took awhile

So my question is there a way to get it to charge the 18AH one or is it a lost cause.

Also I am going to put a heavy duty switch on the red ignition (Key on/off) switch.

How much current does the radio need when the switch is (key out engine not running) off when just the yellow wire is connected to the battery.

Also how does battery wiring work? I know if you wire them in series you get twice the voltage (24V with 2x 12V) which I don not want to do as that would instantly fry the radio (and that would be the end of my project)

If I wire them in parallel I get twice the capacity but still 12V? So if I wire both of those 12V batteries in parallel I would get 12V 14.4AH? or am I wrong?

I obviously want a decent running time. I probably will use mostly in the house (for that I have a heavy duty power supply for) but I want it to be portable at the same time (not simultaneously of course).

Thank You and good job if you got this far

 
  #2  
Old 06-09-20, 08:46 PM
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Do you have a regular car battery charger..... like a 2A/10A model ?
Charge it on the 2A setting for a day.

0.03 amps, or 30 milliamps would be a nominal memory hold current for an indash stereo.
 
  #3  
Old 06-09-20, 08:57 PM
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Unfortunately I don't have regular auto battery charger.

Can I use a laptop style power supply as I do have several laptop style ones from 15VDC all of the way to 24VDC

I also have a power mobility chair charger A24030-9C




 
  #4  
Old 06-09-20, 09:45 PM
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You can try connecting your 7V battery to a car battery in parallel.
If you run the engine, it will charge at a higher current, but just connecting them in parallel should bring the charge up as well.

Another thing you can try is connecting your good battery and 7V in parallel. That will have same effect as charging with car battery. You can connect your smart charger at the same time.

Lead acid and SLA are very forgiving and you can charge it with very simple power supply. I used to charge the SLA battery with a bench power supply set at 15V, but when charging at high voltage like this you have to monitor the current. When the current drops, cut back on the voltage to around 12.5~13V to trickle charge. (This is essentially when smart charger is doing).

How much current does the radio need when the switch is (key out engine not running) off when just the yellow wire is connected to the battery.
It differs from radio to radio, but shouldn't be much. a few hundreds of mA at most. If you don't need to keep radio settings or clock settings, there is no need to connect stay on wire. For playing a simple CD, tape, or MP3 files, you can just switch both stay on and power wire off.

Also how does battery wiring work?
You are correct that voltage doubles when connected in series and capacity doubles when connected in parallel.
However, if one of your batteries are bad (ie shorted cell), it may drain a good battery down as well and eventually kill it as well.
 
  #5  
Old 06-09-20, 09:45 PM
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A "smart" charger needs to see a minimum voltage before charging.
Your mobility charger is 24v.
Unfortunately 15v is too high and will cook the battery. You need something closer to 13.8v max.
 
  #6  
Old 06-10-20, 11:30 AM
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Will a 14VDC power supply work or will the extra .2V be an issue. It is a switching power supply that was for a Samsung monitor that died
 
  #7  
Old 06-10-20, 11:39 AM
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Try it. Put it on charge for an hour. If the battery gets hot.... stop charging. After an hour.... check the voltage. If it has come back up..... switch over to the smart charger.
 
  #8  
Old 06-10-20, 03:30 PM
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Yeah. Try 14v. It make take several days to desulphate. Note though that SLA donít like high charge voltages when they are healthy. The gel will overheat and harden up.
 
  #9  
Old 06-11-20, 01:24 PM
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I found this on the Facebook Marketplace for $20, I did not buy it yet, as I want to know if this would be of any use for my project & batteries.

I also have come to dislike that "Smart" charger that I should of never bought.

I am posting a picture from the listing in case you do not want to click on a Facebook link (I can understand why some people hate social networks).

It looks old enough (or just very used and dirty?) and it also says manual battery charger but I don't know if it is a good one.

I still did not try the 14VDC adapter yet (I have to find it first) but I will post the outcome of that when I do.


 
  #10  
Old 06-12-20, 08:31 PM
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OK that 18AH battery is unfortunately not salvageable.

I had it on the 14VDC power supply for 2HRS and the voltage only went up to 11.75V and dropped fast as soon as I removed the charger (Surface charge I assume?)

I was given a Razor scooter that had 2 brand new 5AH 12V SLA batteries installed (the problem was the electric motor not bad batteries)

So I am going to wire them in parallel for 10AH @ 12VDC

I want to wire a switch so I can power it via the batteries (and also charge them) or power it via external 12VDC power supply hopefully using the same power connector.

What type of switch would I need to accomplish that task? (I assume Double Pole Double Throw DPDT)

How would the switch wiring be done?

I want one with an off position.

Also how much current can a standard (5.5MM x 2.1MM) round DC power jack handle?

I got the radio yesterday and it says 6A (the specs on the user manual have a different power rating probably because the same manual is shared between multiple stereos) max power draw (I assume with four speakers being driven but I am only going to be using two)


 
  #11  
Old 06-12-20, 08:51 PM
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You're using a car stereo as a portable radio.... like a boom box. Based on two speakers and low to moderate sound level....... the current draw should be around 2A or less. The louder the volume.... it uses more current. The CD will also use slightly more power.

A 12v power supply and a 12v charger are different things.
 
  #12  
Old 06-12-20, 09:08 PM
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Yes I know there is a difference I was asking if I could wire a switch so I could power it using a 12 power supply and also charge it using that "smart" charger but using the same power input jack. I just need to know if that is possible and I do know that the radio would have to off when charging the batteries
 
 

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