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Advantages of parallel 12v battery?

Se7en

Se7en

Well-Known Member
Jun 27, 2010
4,573
223
73
Ca
What are the advantages of running two 12v car battery's in parallel with an amp behind them?

example 1: in a mobile; one being to the alt (main battery), the other parallel to the trunk with an amp?

example 2: on a base; a charger to 12v battery parallel to second battery to amp?

amp used; 4 pill (never mind the brand).

battery will not be inside room or shack, outside only in box.
battery mobile will be in battery box with vent to outside air.
 

The only advantage to paralleling two or more batteries is that the storage capacity is greater. If you use two identical batteries than the voltage is the same but the current capacity is doubled (with three batteries it's tripled, etc.).

"example 1: in a mobile; one being to the alt (main battery), the other parallel to the trunk with an amp?"

Just makes things convenient, usually not enough room under the hood for an extra battery. I'd recommend using a "battery isolator" with that set up, keeps you from ending up with a dead battery when you try to start the vehicle. The cable used to connect that trunk battery should also be huge to cut down on resistance.


"example 2: on a base; a charger to 12v battery parallel to second battery to amp?"

That charger plays the same part that the alternator on your vehicle plays, keeps things charged up. A charger can also introduce noise into the mix, so filtering it is a very good idea.

I'll stay out of the amplifier thingy, just too many variables, opinions, etc. Basically you need enough current at the design voltage to let the thing run without starving it.
- 'Doc
 
This has all been covered well for you and the only time Ive seen this done was when people are running big amplifiers like the Texas Star 1600 (Sweet Sixteen) ETC for as mentioned backup to keep the amplifier from starving for power to run it (kind of a reserve).
 
9C1Driver said:
I would dump the battery on a base idea and get a power supply.
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Agreed. A lead acid wet cell type will generate corrosive gasses and vent explosive hydrogen gas as it charges, both of which are a bad thing to have inside the house. A sealed gel cell or AGM type battery would be safer but generally offer less current delivery.
 
If you are serious about this look at a auto parts store like napa or advance auto for a battery isolator it is a device usually found on snow plow trucks and what you do is connect the lead from the alternator to the input and it has two or more outputs depending on what you buy, Anyway it will switch the charging current between batteries to charge which ever needs the current. I used to run one in my car and had a stock battery under the hood for the standard car use and the other feed from the battery isolator to a gel cell in the trunk that only fed my radio and amp. I was only running about 300 watts but had the isolator from my old plow truck and liked the idea of having two batteries just in case of a cold morning start here in Chicago. plus in a pinch you can connect the two outputs on the battery isolator to "jump" your own car should the battery under the hood go bad.
 
I've burned out the starter solenoid on a diesel car by using a tractor battery instead of its own(there was a lot of space under the hood) and a quad solenoid by using a car battery instead as the quad battery was defunct. Suffice it to say, i don't recommend giving the starter more current than it needs. If your car won't start then maybe you should change the heater plugs instead.
 
The starter, if it's operating correctly, won't draw any more current than it "needs". You could have six dozen batteries in parallel and that motor won't draw a single milliamp more than it "needs" to operate.
 
Beetle said:
The starter, if it's operating correctly, won't draw any more current than it "needs". You could have six dozen batteries in parallel and that motor won't draw a single milliamp more than it "needs" to operate.
Click to expand...


Kind of like saying "My radio only needs 10 amps so I won't put it on a 35 amp power supply because I don't want to blow it up." Heard that one before too.
 
In the long run you are better off putting the money into a power supply that will handle the load you need.
Flooded lead acid battery's are made to draw big current and then recharge quickly, deep cells are made to deliver small current drains over a period of time and recharge slowly, abuse any of them and you shorten the life of the battery.
In the mobile, if you run a big amp and draw the battery's down, you are asking the stock alt to charge a huge load and it will shorten the life of the alt.
On the base, as Captain pointed out you have out gassing and corrosion .
If you buy good quality AGM Battery`s to stop all of these problems, by the time you buy 2 of them, you could have got a power supply.
If you need THAT much power on a base station, you are better off forgetting the whole 12 volt thing, and get something with tubes.....buy the time you add it all up, you could pay for a few 3-500Z`s.........

73
Jeff
 
Beetle you took the words out of my mouth. And I'm a mechanic and am trying to figure out what a heater plug is? Are you talking about glow plugs in a diesel or spark plugs in a gas engine? Either way running a hotter number won't help a bit with starting if the power isn't there from the battery to make the spark and turn the engine over. And as far as burning up a starter solenoid by giving it too much power makes no sense to me as if this where true then jump starting a vehicle would toast the starter.
 
Look i'm not trying to be a pedant, i am just reporting my own experiences and trying to draw conclusions from them. This is not my thread and i gave my opinion and that is as much as i can say.
I was referring to glow plugs. In my country petrol cars have been in the minority for maybe a decade now as we have no petrol subsidies like the usa also most cb'ers drive diesels as many makes like vw and ford petrol efi cars are notorious for ignition interference. I am sorry for the misunderstanding if there was any. I have seen fuel vaporising heater plugs on the intake breather pipe of a john deere diesel engine so i imagine they could be adapted to a petrol if needs be.
 
BammBamm said:
Beetle you took the words out of my mouth. And I'm a mechanic and am trying to figure out what a heater plug is? Are you talking about glow plugs in a diesel or spark plugs in a gas engine? Either way running a hotter number won't help a bit with starting if the power isn't there from the battery to make the spark and turn the engine over. And as far as burning up a starter solenoid by giving it too much power makes no sense to me as if this where true then jump starting a vehicle would toast the starter.
Click to expand...

what is said in bold makes sense.

i dont need two batterys for the mobile i have a straight four x2879 now and it doesn't even phase my battery or alt. even sitting on a red light idling (automatic) i can key down for 2 minutes and the headlights do not dem or anything.
i have a brand new battery and alt. less then 1 month old.
 

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