Voltage question not specific to tech

hunterdan

hunterdan

Well-Known Member
Joined
Apr 13, 2009
Location
Morganton,NC
I'm working on a marketable product. I'm trying to figure out.....Can my car battery deal with a Constant 6v parasitic drain? This thing I'm working on needs a constant 6v when car is off.
None when car is running. I have found a 12v to 6v reducer that would pwr the item from the car battery I just don't know about the constant 6v drain overnight?
If that's too much drain then I'm guessing a separate 6v battery maybe in engine compartment or trunk being charged via the alternator with maybe a voltage reducer in the charging wires?
Thanks
 
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Voltage isn't what drains the battery, its current (amperage).
You need to know how many amps your device draws.
If it is mA, you're fine.

If you don't have a proper ammeter, most multimeters have a current setting, place it inline between your device and the battery positive terminal.
 
RatLabGuy said:
Voltage isn't what drains the battery, its current (amperage).
You need to know how many amps your device draws.
If it is mA, you're fine.

If you don't have a proper ammeter, most multimeters have a current setting, place it inline between your device and the battery positive terminal.
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What he said. Most vehicles have some parasitic draw especially newer stuff. Anywhere from 50mA to 85mA or so is pretty normal. Once you get to 100mA it’s getting a little too high. My tractor currently has a 166mA draw that I haven’t been able to find yet and I had to put a disconnect on the battery terminal for now to keep it from running it down.
 
Hokie_YJ said:
What he said. Most vehicles have some parasitic draw especially newer stuff. Anywhere from 50mA to 85mA or so is pretty normal. Once you get to 100mA it’s getting a little too high. My tractor currently has a 166mA draw that I haven’t been able to find yet and I had to put a disconnect on the battery terminal for now to keep it from running it down.
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Is the starter or alternator or wiring oil soaked? I have found that oil will cause a power draw on electrical parts.
 
LT1JEEP said:
Is the starter or alternator or wiring oil soaked? I have found that oil will cause a power draw on electrical parts.
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I don’t believe so. But I honestly just haven’t had time to dig in to it much at all. I just went and bought a new battery and the disconnect. It’s relatively new Kioti (2016) and I haven’t noticed any leaks yet.
 
figure your amp draw and put a solar charger on a couple of 6 volt rechargeable batteries,
 
braxton357 said:
The dc stepdown "buck" converter will be drawing decent current even when your 6v whatever isn't on, after anywhere from 2-5 days yeah your battery would probably need a jump. Plenty of other things in vehicles are drawing milliamps for volatile memory, leds, and other cancer causing things.
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This.
If you are developing a product a pcb with a wider voltage operating range would be cheaper than any converter, resistor based or otherwise.
 
braxton357 said:
The dc stepdown "buck" converter will be drawing decent current even when your 6v whatever isn't on, after anywhere from 2-5 days yeah your battery would probably need a jump. Plenty of other things in vehicles are drawing milliamps for volatile memory, leds, and other cancer causing things.
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This. Any DC conversion = energy loss. I don't know what you're scheming but if you're designing a product, you'll need a switch that if in front of the buck converter. IOW plan to make that converter part of the device, not a separate thing.
As @Ron mentioned ideally the whole thing would be 12v. But the truth is very few electronics actually run on 12v, they pretty much always have a built in converter, its just not connected when the thing isn't "on"
 
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