Fuse Tap Orientation

watch7ower

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#1
Hi all,

I've gone up and down the Internet on this and not really found a definitive answer, so... fuse taps!

Is there a specific way they need to be inserted? I've seen conflicting things where people say yes or no or "it doesn't really matter...", etc. Any help on this?!
 

Nigel

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#3
Even if he reads all the way to the end of that, he wont find the answer :D

The best advice is that if it is for a dashcam and you are tapping a 10 amp or greater fuse then it really doesn't matter since the power taken is so small compared to what is available. If it is for a parking mode backup battery such as the Celllink Neo then neither way is good since they can take a lot of power, you should install a dedicated cable and fuse direct from either the battery or engine compartment fusebox ~100A link/fuse.
 

M8TJT

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#4
Even if he reads all the way to the end of that, he wont find the answer.
Yes he will, Post 4 explains it.
Yes it does matter, otherwise the extra current is drawn through the original fuse and might blow it. Not the result required. But what Nigel said in his second sentence is correct, but not 'best practice'.
Look at the thread pointed to above, but don't bother wading all through it, Post #4 explains it all.
Take out the original fuse and check which side still has 12V on it. then as per post #4 there.
 
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Nigel

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#5
Yes he will, Post 4 explains it.
Yes it does matter, otherwise the extra current is drawn through the original fuse and might blow it. Not the result required. But what Nigel said in his second sentence is correct, but not 'best practice'.
Look at the thread pointed to above, but don't bother wading all through it, Post #4 explains it all.
Take out the original fuse and check which side still has 12V on it. then as per post #4 there.
Wrong, OP needs to read through the full thread before they can make a decision on who is correct, post #4 is just one point of view, and also happens to be the one that makes least technical sense!
 

M8TJT

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#6
But there is only one correct point of view. The original circuit and the add on circuit should be separately fused. Period.
If the fuses are effectively wired in series, a gross overload in the add in circuit could also blow the donor fuse and thus kill that circuit as well. Not a desirable outcome, which could have serious consequences depending on which circuit the donor fuse is protecting.
And it's basic electronic principles that any circuit shoul have it's own fuse. That's why there is so bloody many of them in a car.
Although I do agree with your second sentence in post 3 that, providing the donor fuse is much larger than the add in fuse, it is unlikely to cause problems (but still not the safest or correct way to do add in fuses).
I rest my case.
 
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#7
Hi all,

A genuine many thanks for your responses. I didn't have a multimeter to hand so I went about testing it all a different way... my car's (Ford Focus Mk. II) passenger fuse box has some empty fuse slots but they can't be used as there are no metal prongs in these slots to accommodate a fuse (if this is always the case, feel free to laugh at me!)

Instead I used the slot for 'audio modules battery supply' (permanent live and powers the radio) and did the following:

- Removed the original 15A fuse from the slot.
- Connected the fuse tap with the dashcams 2A fuse in the top slot of the fuse tap as normal and no fuse in the bottom slot, then checked to see which orientation would supply power to the dashcam.

As expected, only one of the two orientations supplied power to the camera--so which is the right way to connect the fuse tap when I put the original 15A fuse into the bottom slot of the fuse tap?

1) The direction in which power was supplied to the camera
or
2) The direction in which no power was supplied to it?

Many thanks.
 

M8TJT

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#8
Great tip bud. Never would have thought of that as I have a multimeter.

The answer to your question to satisfy my rantings above despite Nigel's comments is: 1) The way around that supplies 12V to the camera with the 15A fuse NOT fitted.

Then of course, having established which 'way round' this is, refit the 15A fuse to the 'lower' slot to power the original circuitry.
 
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#9
Thanks very much! All done now, glad I have a way of testing if need be again. On to a different issue now where I've gone to the car to find the camera in a restarting loop with a flat battery... Nextbase support say it's likely the SD card but I am using one they specifically recommended to me (https://www.amazon.co.uk/gp/B00V5Q1K3O) -- hope this is resolved soon too!

Thanks again.
 

M8TJT

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#10
Flat NB battery or flat car battery?
Are you using the NB hardwire kit as I believe this is meant to stop car battery flattening by switching off the cam when the battery gets down to about 11.8V (I think)
 
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#11
Flatt NB battery, the device boots up then dies and boots up again! Disconnecting it from the powered mount won't allow it to turn on at all so I have to connect it to my PC and let it fully charge for 2 hours. Using the NB hardwire kit to a permanent live fuse.

Not sure what I am doing wrong... NB Support ruled out the memory card being the issue. I do want to use parking mode but should I have it wired on a permanent live or switched?

My understanding is that permanent live would let the device charge until the cut-off is met whereas switched would only let the device charge while the engine is running (so if not driven enough it would need periodic charges via PC?)
 

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#12
Charging via PC, especially USB2, isn't the best as the voltage is low. Ideally you need a wall socket with USB or a mobile phone 'brick' that can supply ~2a
 

M8TJT

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#13
My understanding is that permanent live would let the device charge until the cut-off is met
That's why I asked which battery.
Charging via PC, especially USB2, isn't the best as the voltage is low. Ideally you need a wall socket with USB or a mobile phone 'brick' that can supply ~2a
A USB3 socket should provide enough @0.9A, but USB2 can only supply 0.5A will charge it eventually. It's the available current that is limited on USB, not low voltage.
 
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