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- W WA
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- 2024 CX-5 Premium
The fuse exists to protect the multimeter from damage if the current is too high. The fuse gets blown when the current being measured exceeds the maximum current that the multimeter can handle.
Battery Dead .5~1.0V voltage drop normal?
- Thread starter StylingSequ
- Start date
I guess my question is should the amps be high enough to blow the multimeter's fuse even though it was set to 10A range? If so, what kind of multimeter should I buy that can handle the load?
This was with the car resting, and all of the car's electronics off. I did have key fob in my pocket. Although I didn't open the door, I'm hoping the proximity didn't set off the electronics.
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- CX-5 Sport 16.5 6M
Measuring amps can be difficult. Usually what they do is make a circuit to 'siphon' a small amount of current proportional to the full current (via a shunt) and measure that.
Your problem is pretty weird. Any current draw will sap the battery, so the exact amount of amperage isn't huge.
Your problem is pretty weird. Any current draw will sap the battery, so the exact amount of amperage isn't huge.
Is it possible that the proximity of the key fob triggered the electronics, so the amp spiked above 10A?
I guess I should have used a clamp meter (don't have one) to first make sure the amp is low enough?
Yep, I definitely used the 10A socket this time. I also checked the 10A fuse afterward and it's blown. The 200mA fuse is still good.
I was also extra careful not to accidentally connect the positive and negative terminal.
Would the key fob possibly trigger the electronics? If the parasitic draw was already 4-5A, I'm wondering if something else turned on, it sent the amps over 10A.
I'm wondering if the front-end work that the body shop did 1-2 months earlier caused this parasitic draw. Or if another component of the car is at fault. There is a slew of other posts by Mazda CX-5 owners experiencing the same thing. They keep going through several batteries and just deal with it.
However, I have a feeling that my battery is going to go dead faster. I only drive this car every 2-3 days, so I'm guessing it won't last.
Yep, it's more like 10 min there and 10 min back. I'm guessing that's why the battery keeps dying. And because it keeps dying, I'm guessing it may have damaged the battery.
N7turbo
2023 CX-5 2.5T ... 2024 MX-5 RF GT
I keep one of these at the ready and charge cars and bikes with it.
https://www.amazon.com (commissions earned)
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- CX-5 Sport 16.5 6M
Some of those have a cig lighter plug so you can just plug into a live 12v port without lifting the hood.
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- CX5 GT
btw you are good candidate for EV with such short drives.
with such drives a normal battery doesnt have a chance to charge fully.
Conrad 16.5
Banned
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- 2016.5 CX-5 GT AWD titanium/black 2016 Miata Club ST MT white
The only way for the fuse to blow is to draw too much current. 4.4a ain't gonna do it so that means that you did something else to make it happen.
Even if you accidently pressed one of the fob buttons while measuring the current, I don't believe that the current is going to blast up past 10a because of this.
I suggest that you have someone with a greater understanding of car electronics take a look at your CX.
N7turbo
2023 CX-5 2.5T ... 2024 MX-5 RF GT
I haven't measured the Mazda, but the Mercedes I posted an example of would hit 20-30 amps when you unlock the doors with the fob. All the systems wake up, the headlights turn on, and the fuel pump is primed.
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I realize that I don't need to measure the current from the battery anymore. I know the current is about 5A and something spikes it over 10A. I just have to measure the millivolts from each of the fuses. I'll do that once the batch of new fuses comes in the mail.
You definitely make sense. Once I get the batch of new fuses for the multimeter, I'm going to try to isolate which fuse the draw is coming from. I'm going to commit only an hour or so to this. Anything more, the car is going to go to the dealer, even if I have to pay for a car under warranty.
I know it could be a number of things but I wonder if the draw has anything to do with the keyless remote entry. A third of the time, the car doors won't lock when I walk away. (My mother-in-law has the same car and this doesn't happen with her car, so it's not in my head.) I wonder if the car's electronics stay on for the same reason the doors remain unlocked and there is a continual amp draw.
Thanks for the advice.
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- W WA
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- 2024 CX-5 Premium
I'm not clear on what you mean by "measure millivolts from each of the fuses". Did you mean milliamps?
It would probably be easier and quicker to measure total current draw at the battery and start pulling fuses one by one to see which one is responsible for the bulk of the parasitic draw. I suggest getting a clamp style meter so you won't have to be concerned with blowing more fuses. Available on Amazon for $30 or less, be sure to get one that measures DC as well as AC current.
I haven't tried it yet but I read that instead of putting the multimeter in series with the battery's negative terminal, I can read the amount of voltage directly going across each of the fuses. The voltage would be small so it would be in millivolts, and I could use a chart to calculate the number of corresponding amps.
I agree that it might be easier to measure at the battery but I don't have a clamp meter. I was going to buy one until I realized that I could just measure the millivolts across the fuse.
Btw, are the clamp meters from China for $30 fine? I was looking at the Milwaukee ones in the $110 price range and I was reluctant to shell this out when I'm only going to use it once.
N7turbo
2023 CX-5 2.5T ... 2024 MX-5 RF GT
You should measure fuses without pulling them; this prevents waking up the computer systems.
I suppose a clamp meter could work if you're in the 5 amp range, as that much power is above the noise level. However, it won't be as accurate as the direct connection.
Here is the best bang for the buck I could find.
https://www.amazon.com (commissions earned)
However, most people won't need more than https://www.amazon.com (commissions earned) for household tasks.
I like having both around because the 12V setting on the Innova is handy, and I use the Southwire clamp meter for other things.
I also used the Southwire on this car but there wasn't a benefit over the cheap Innova for this. And the clamp meter wouldn't work because the current draw was too low to pick out from the noise.
Of course, you don't need to do this anymore because you already determined you have a current draw. So you must now find the fuse/circuit that's live. If you want to measure each fuse without having to wait 10+ minutes between each one, don't pull them—just measure with the probe.
Good point about not pulling the fuses. I'll just place the probes across each fuse to get the millivolts.
I have https://www.amazon.com (commissions earned). As basic as they come. I ended up blowing the fuses, but new fuses cost half the price of a new multimeter so I ended up just getting a new meter. But then the fuse blew again!
I thought about getting a used clamp meter from Facebook for $60 but it gets dicey. I've been burned before.
I love those Jorgensen clamps you have. I would love to have them but they seem a bit out of my price range because I don't know if I'd use them that much. But I'd love to have them because they look so handy.
