I bought an used motorhome and the battery is going dead. I saw a receipt that says a radio has a parasitic draw of 500 milli amps and the brake controller 100. What’s the math in terms of starting battery life? Days or hours? I don’t mind unhooking the battery at home but don’t want a problem on the road. Lots of tech guys on the site,…thanks if anyone can answer this.
I would install a battery cut of switch .
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Parasitic draw should not drain your battery except t
For long periods of storage.(months) the disconnect pictured above is perfect for preventing that. If you are experiencing drained battery’s in weeks either your battery is weak, our your draw is excessive
500Ma is .5 amps. Does the battery even last a day? I think like 10Ma is acceptable.
Unless the radio is being left on, the parasitic draw of a automotive-type stereo isn’t going to drain a good battery. Either something is drawing significantly more juice or your battery is toast.
Thanks,…found a battery switch on amonzon to try. Agreed,…alot of draw but that was the report from Superior Ford dealership. 1/2 amp per hour at about 50 amps,…40-50 hours to drain it dowm to 50% ??? Sound right?
Just a note that my truck just got back from the shop after fixing a short in the wiring harness that fed the power driver and passenger seats. It was enough to draw the battery down overnight.
Sound right?
No, that doesn’t sound right. The only time I’ve ever had a problem with a radio drawing enough power to kill a battery is if the battery has been shot (or someone didn’t shut off the radio).
If the radio is shut off, it’s only drawing enough juice to keep the clock and memory (presets, settings).
Test your fuse panel with a multimeter meter.
It’s really easy to see what’s pulling juice and how much.
A half amp is way too much for a radio that is off
A 7″ touch screen graph pulls that much juice with the brightness at 100%
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