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NASA bm2.
Jun 22, 2020 15:25:03 GMT
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Post by ianali on Jun 22, 2020 15:25:03 GMT
Finally got around to fitting this battery meter. I acquired it second hand a while back. It works fine. However, it came with a shorter cable than a new one, only around 3 metres, new ones being 5 metres. I’ve wired it in ok but could do with it being maybe a metre longer to make the cable run neater. Can I simply extend with similar wiring or is the wire gauge critical to how the meter reads?
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Post by Telemachus on Jun 22, 2020 17:24:26 GMT
No it won’t much matter as long as it’s something fairly similar. The yellow and white wires are the wires sensing voltage across the shunt and pass virtually no current, hence no voltage drop on a long run of cable. As per the manual, even though the black and white wires both originate from the same point (battery negative) it is essential to keep them separate all the way to the meter because the white wire is sensing a very small voltage, whilst the black wire is passing the current required to run the device and hence will introduce slight, but significant, voltage drop.
Not having seen the cable in the flesh, I presume it isn’t a screened cable? If it is, you should extend with screened cable at least for the yellow and white wires.
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NASA bm2.
Jun 22, 2020 17:35:56 GMT
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Post by ianali on Jun 22, 2020 17:35:56 GMT
No it won’t much matter as long as it’s something fairly similar. The yellow and white wires are the wires sensing voltage across the shunt and pass virtually no current, hence no voltage drop on a long run of cable. As per the manual, even though the black and white wires both originate from the same point (battery negative) it is essential to keep them separate all the way to the meter because the white wire is sensing a very small voltage, whilst the black wire is passing the current required to run the device and hence will introduce slight, but significant, voltage drop. Not having seen the cable in the flesh, I presume it isn’t a screened cable? If it is, you should extend with screened cable at least for the yellow and white wires. Thank you very much. No the cable isn’t screened. |
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Post by peterboat on Jun 23, 2020 11:31:05 GMT
I have just pulled out my instructions and it shows all cables running together, mine was supplied with short wires on the meter and multi wire length of yellow black white and red. I googled and same instructions on tinternet
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NASA bm2.
Jun 23, 2020 14:12:45 GMT
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Post by ianali on Jun 23, 2020 14:12:45 GMT
I have just pulled out my instructions and it shows all cables running together, mine was supplied with short wires on the meter and multi wire length of yellow black white and red. I googled and same instructions on tinternet Thanks for taking the time to look. Mine came as you describe but with a shorter main cable, this is what I am going to extend. I like the readout, but I think it would be easy to become obsessed with watching the amps in and out... |
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Post by peterboat on Jun 23, 2020 16:07:29 GMT
I have just pulled out my instructions and it shows all cables running together, mine was supplied with short wires on the meter and multi wire length of yellow black white and red. I googled and same instructions on tinternet Thanks for taking the time to look. Mine came as you describe but with a shorter main cable, this is what I am going to extend. I like the readout, but I think it would be easy to become obsessed with watching the amps in and out... You do!! mine is on absorb or float so is putting in 5 amps ish from solar, fridge freezer and other bits running so it never drops to zero. The red display when you press the button is very good |
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Post by ianali on Aug 18, 2020 8:25:44 GMT
After years of managing with just a voltmeter to keep me informed of my batteries needs, I now have this BM2. It’s interesting to see how many amps various equipment use. Have been pleasantly surprised how little the inverter and fridge use. Tv not to bad either. Stereo likes electric, but it’s quite a powerful unit, we like our sounds so worth it. All in all it’s better to be able to see what’s happening I guess. Saying all this I’m not sure it will extend my batteries lives. As Peter said though, it’s a pretty red light.
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