Instruments - Volt/ ammeter

[Bro]

Anyone tried these?:-

 

http://www.ebay.co.uk/itm/170865112831?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649#ht_5968wt_1187

 

(Ebay item number 170865112831).

[Chris Pink]

Green? Blue is far more stylish.

 

Yes, I've got something similar. Works. Not particularly accurate but doesn't need to be.

 

Don't forget to buy the shunt. And a switch.

[NB Willawaw]

It always puzzles me why nobody in the UK buys these in volume and sells them.

 

There are always lots of companies in China and Hong Kong selling them, but nobody seems to want to act as their UK agent.

 

There is a big price gap if you need a high current digital ammeter between these and the next UK supported equivalent which is over £100.

[twinpot]

Ive got the volts only one and its very good and quite accurate,but i got it from a uk seller,if you do order that one don't forget to order the shunt if you want to measure amps.

[Chalky]

Fine of a bench unit in your workshop (I've got one in my home made power supply). The boards are not coated so it'll get severely upset by damp. It's also not designed for the temperature range you see in a boat so don't be surprised if it doesn't make it through the winter (the chip will either crack or it'll loose a bond wire due to thermal expansion & contraction). The power supply won't be designed to cope with the transients and voltage range you'll see (there's debate on the forum if these exist. Having worked with 12V systems for 20+ years I know they do).

 

To install it you'll need a couple of switches, a mounting panel, some cable, fuses and fuse holder, shunt and something to protect the shunt from inadvertent contact. You'll also need to allow cooling for the shunt (be worth checking if its continuously rated for the current they quote). By the time you've gone through all the effort of setting it up (costing your time) and testing it it could be easier to buy something like a Nasa BM-1.

[NB Willawaw]

Yes thats what I suspected might be behind it.

 

I won't supply them to boaters - if they want to buy one themselves, then its up to them.

 

I'm more concerned about fires with the high current shunts.

 

Fine of a bench unit in your workshop (I've got one in my home made power supply). The boards are not coated so it'll get severely upset by damp. It's also not designed for the temperature range you see in a boat so don't be surprised if it doesn't make it through the winter (the chip will either crack or it'll loose a bond wire due to thermal expansion & contraction). The power supply won't be designed to cope with the transients and voltage range you'll see (there's debate on the forum if these exist. Having worked with 12V systems for 20+ years I know they do).

 

To install it you'll need a couple of switches, a mounting panel, some cable, fuses and fuse holder, shunt and something to protect the shunt from inadvertent contact. You'll also need to allow cooling for the shunt (be worth checking if its continuously rated for the current they quote). By the time you've gone through all the effort of setting it up (costing your time) and testing it it could be easier to buy something like a Nasa BM-1.

Edited June 28, 2012 by NB Willawaw

[Troyboy]

Don't forget that if you do decide to buy you might get the item seized by HMRC and a VAT charge made on it .

Via ebay I purchased a part for my Thetford toilet from the USA . Customs intercepted that and on top of the £5-44 VAT the Royal Mail wanted £8 admin fee . I must admit thats the first time I have been 'caught ' if thats the right term but something to bear in mind when buying items from abroad .

[Gibbo]

The power supply won't be designed to cope with the transients and voltage range you'll see (there's debate on the forum if these exist. Having worked with 12V systems for 20+ years I know they do).

 

You'll still hear "But my TV has been fine so they can't exist"

 

By the time you've gone through all the effort of setting it up (costing your time) and testing it it could be easier to buy something like a Nasa BM-1.

 

They don't survive the voltage spikes either

 

But for the price, I really can't argue with them.

[Bro]

Don't forget that if you do decide to buy you might get the item seized by HMRC and a VAT charge made on it .

Via ebay I purchased a part for my Thetford toilet from the USA . Customs intercepted that and on top of the £5-44 VAT the Royal Mail wanted £8 admin fee . I must admit thats the first time I have been 'caught ' if thats the right term but something to bear in mind when buying items from abroad .

 

 

I got same treatment when I bought parts from USA for a trike. Reckon Customs and Post Office are generally tightening up to get as much revenue as possible.

 

You'll still hear "But my TV has been fine so they can't exist"

 

 

 

They don't survive the voltage spikes either

 

But for the price, I really can't argue with them.

 

Thanks to all for comments.

 

For similar price they do 200v and 200A unit (all with shunt). Would the 200V stand up better to 'spikes'? Also, regarding affect of dampness, if the instrument were positioned inside a dry cabin would that not be OK.

 

Is shunt fire a serious issue and if so what precautions should we take when installing?

 

Finally, I only ever run my 12V TV when the engine is not running. So far so good!

[smileypete]

Anyone tried these?:-

 

http://www.ebay.co.uk/itm/170865112831?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649#ht_5968wt_1187

 

(Ebay item number 170865112831).

If there's enough panel space, why not fit a separate voltmeter and ammeter? Saves switching between them.

 

Maybe just start off with the voltmeter initially, doesn't need a shunt, just a low value fuse in the red/positive cable at the battery end to protect the connecting cable.

 

http://www.ebay.co.uk/itm/220972587327

 

At £3.20 it's not the end of the world if it gets zapped or leaked on Duty is chargeable for stuff declared over £18 IIRC so no problems there.

 

With these voltmeters/ammeters the thing to check is whether it needs a separate supply to power the meter, the ones that don't (including the one above) are much easier to deal with.

 

As for heat/fire I think the 200A Ebay meters are better in this regard than the 100A NASA BM-1 as the shunt will dissipate less heat at a given current, and is probably bigger too so will run less hot.

 

cheers, Pete.

~smpt~

[Gibbo]

For similar price they do 200v and 200A unit (all with shunt). Would the 200V stand up better to 'spikes'? Also, regarding affect of dampness, if the instrument were positioned inside a dry cabin would that not be OK.

 

It's not the shunt that's the issue, it's the internal power supply to the actual device. It dies under the usual test for vehicle electrical systems.

 

Is shunt fire a serious issue and if so what precautions should we take when installing?

 

It's possible, but I really wouldn't lose sleep over it. It's one of the most unlikely problems to ever rear its head. But is is still possible.

[Chalky]

 

Also, regarding affect of dampness, if the instrument were positioned inside a dry cabin would that not be OK.

 

 

You'll get a number of effects. the damp will cause the analogue electronics to drift affecting accuracy. It'll help encourage tin whiskers which will eventually short something out and it'll also affect the digital circuitry by shorting out pins etc. The effects can be subtle and don't always happen. Electronics designed for the job will be conformally coated (special varnish) to stop these problems.

 

You'll also find problems with the LCD in low temperatures. As they cool down the response speed slows until they stop altogether. Some will recover as they warm up (automotive grade), the rest can be permanently damaged.

 

They're a great module for some applications, just not necessarily in a boat. If you can accept a bit of hastle then give it a try, just don't expect it to be as reliable as something which costs more but is designed for the job. The extended temperature ranges and environmental and circuit protection fitted to quality kit cost more, but are there to ensure that the device is more robust and reliable.

[Arthur Brown]

The duty and VAT issue is real, sometimes small parcels escape notice but both duty and VAT are due on import.

 

On the issue of importing a bulk, First there is the duty and VAT to pay THEN there is the compliance testing and certification to arrange and if/when it fails there is the waste electronics to dispose of. Trade importing from China is not for the faint hearted.

 

Yes I have a friend who imported a whole cotainer full from China and had to dispose of the lot because they simply didn't work, and there is simply NO warranty when buying from China, you pay first then get what they send you whatever.

[Gibbo]

there is simply NO warranty when buying from China, you pay first then get what they send you whatever.

 

You tried it too then?