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Post by smileypete on Nov 14, 2016 11:46:26 GMT
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Post by Deleted on Nov 14, 2016 11:53:32 GMT
I'll be interested to hear how you get on with them, do you have an independent way to check the accuracy?
Top Cat
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Post by Telemachus on Nov 14, 2016 13:19:10 GMT
I recall that PaulC bought a few of these (well, not necessarily that exact model) and none of them worked properly. However, perhaps he was just unlucky!
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Post by smileypete on Nov 14, 2016 13:39:39 GMT
I'll be interested to hear how you get on with them, do you have an independent way to check the accuracy? Top Cat Dunno, I'm not buying one myself as I've got far too many bits n pieces like that already, I really want to get rid of some not the opposite! For a decent panel voltmeter the 5 digit ones are hard to beat, they have a super accurate IC for doing the conversion: www.ebay.co.uk/itm/Red-0-36-LED-5-Digit-DC-0-33-000V-Digital-Voltmeter-Voltage-Meter-Car-Panel-/181938068489The spec of the ammeters in the links is pretty good which makes me hopeful that they share the same design, it's a pity they don't show the back of it. Even if not, the less accurate meters include a preset adjuster for calibration. ETA: Nick n Tony seem to have much more time than me, maybe they could buy one and try it out for the greater good!
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Post by smileypete on Nov 14, 2016 13:45:02 GMT
I recall that PaulC bought a few of these (well, not necessarily that exact model) and none of them worked properly. However, perhaps he was just unlucky! I think he bought a few of the ones that are supposed to read current in both directions and need an isolated supply, I could never get him to say which ones they were or what the problem was! The ones that read current in one direction don't need an isolated supply which makes them much easier to use. A few years ago I bought a 33V/3A version of these type combo meter when they first came out and it's been pretty good, the voltmeter seems spot on at least: www.aliexpress.com/item/40pcs-lot-DC-0-33V3A-Red-Red-dual-LED-display-Color-4-bit-Car-voltage/32247930581.html
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Post by Deleted on Nov 14, 2016 19:21:04 GMT
Something I learned the hard way with tools probably applies to instrumentation too
DONT BUY CHEAP
T C
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Post by tonyqj on Nov 14, 2016 19:24:05 GMT
Well for the sake of a tenner I ordered a couple of those in the OP so I'll let you know what I find after they've turned up and I have time to do something with them. Must buy a shunt now
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Post by Clinton Cool on Nov 14, 2016 21:58:47 GMT
I already have an ammeter for when I'm charging with my genny, the amp display on my battery charger. I also have one on my Tracer solar meter. I quite fancy having one for if and when I charge the leisure battery with my boat engine. Would one of these do the job, how would I wire it?
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Post by tonyqj on Nov 14, 2016 23:12:52 GMT
I already have an ammeter for when I'm charging with my genny, the amp display on my battery charger. I also have one on my Tracer solar meter. I quite fancy having one for if and when I charge the leisure battery with my boat engine. Would one of these do the job, how would I wire it? Should do. It would go in the batt -ve feed.
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Post by smileypete on Nov 15, 2016 10:19:05 GMT
I already have an ammeter for when I'm charging with my genny, the amp display on my battery charger. I also have one on my Tracer solar meter. I quite fancy having one for if and when I charge the leisure battery with my boat engine. Would one of these do the job, how would I wire it? On these the shunt must go in the leisure batt negative return, between the leisure batt negative post and EVERYTHING else. There's a little diagram in the 4th pic of the Ebay ad but it's not very clear. According to the ad it does come with a shunt which is nice. Having said all that if you've just bought a Trojan batt I'd get hold of a hydrometer for reading SG (acid strength), and check the SG after a FULL charge at least weekly. If the SG is declining over time the first priority will be to sort out a way of doing an EQ charge, and improving the batt charging. Another alternative for current measurement is a handheld clamp ammeter which can read DC amps, these can be had from about £25 on Ebay, one model is the Mastech MS2108A: www.ebay.co.uk/itm/Mastech-MS2108A-Auto-Range-DC-AC-Digital-Clamp-Meter-Multimeter-Voltage-Tester-/262394484215Maybe I could do a FAQ at the weekend for installing a shunt ammeter, if there's demand for it.
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Post by tonyqj on Nov 15, 2016 10:23:41 GMT
Maybe I could do a FAQ at the weekend for installing a shunt ammeter, if there's demand for it. Sounds like a good idea. You could explain the differences between the types and why it matters.
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Post by smileypete on Nov 15, 2016 10:25:13 GMT
Something I learned the hard way with tools probably applies to instrumentation too DONT BUY CHEAP It's easy enough to check one out before installing. Some years ago you could have said don't spend less than £800 on a laptop, but a decent lappie can be had for a lot less these days. Even with tools a reasonably decent branded impact driver can be had 'cheaply' these days. I s'pose to avoid any risk one could buy the usual £100+ boat batt monitors from a chandler and stick with that.
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Post by smileypete on Nov 15, 2016 10:32:50 GMT
Maybe I could do a FAQ at the weekend for installing a shunt ammeter, if there's demand for it. Sounds like a good idea. You could explain the differences between the types and why it matters. All I'll explain is how to install a shunt in the negative battery feed for those meters that require it. The instructions for the meter will tell what to connect where and must be followed, I could add some pointers on how best to make these connections as well. Some meters allow a shunt in the positive feed but I'm not keen on these, there's more chance of shorting the shunt which is at +12V to the hull plus the shunt sensor wires need fusing really.
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Post by canaldweller on Dec 18, 2016 11:51:06 GMT
Sounds like a good idea. You could explain the differences between the types and why it matters. All I'll explain is how to install a shunt in the negative battery feed for those meters that require it. The instructions for the meter will tell what to connect where and must be followed, I could add some pointers on how best to make these connections as well. Some meters allow a shunt in the positive feed but I'm not keen on these, there's more chance of shorting the shunt which is at +12V to the hull plus the shunt sensor wires need fusing really. Just replying to your post in the courier thread. Thanks for this: www.amazon.co.uk/DC-DC-Converter-Isolated-Module-10-16V/dp/B008P880QUPresumably it goes between my ammeter and my domestic batteries. Is this correct?
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Post by smileypete on Dec 18, 2016 18:10:28 GMT
All I'll explain is how to install a shunt in the negative battery feed for those meters that require it. The instructions for the meter will tell what to connect where and must be followed, I could add some pointers on how best to make these connections as well. Some meters allow a shunt in the positive feed but I'm not keen on these, there's more chance of shorting the shunt which is at +12V to the hull plus the shunt sensor wires need fusing really. Just replying to your post in the courier thread. Thanks for this: www.amazon.co.uk/DC-DC-Converter-Isolated-Module-10-16V/dp/B008P880QUPresumably it goes between my ammeter and my domestic batteries. Is this correct? That's right. Maybe order a spare if like me you're good at blowing things up. Bear in mind it'll likely come from china, so take a while... To connect to it, what might work well is some 'stackable header' www.ebay.co.uk/itm/2-x-8-Pin-Arduino-Stackable-Header-/262341198271With a bit of luck you might be able to cable tie some small 3 amp terminal block 'back to back' and bend the long pins to get them directly into the block. I do think it would be prudent to protect any small gauge wires plus the converter itself with a small value fuse in the positive feed towards the battery end. A good tip for connecting smallish wires or fine stranded wires into a terminal block is to use bootlace ferrules. www.ebay.co.uk/sch/i.html?_nkw=bootlace+ferrulesI don't think the electrical gods will strike you down if you squish the ferrules on with pliers or they're a little oversized.
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