There goes battery charger number 3!

pvb said:
The ammeter will typically require 12v connecting to it, in order to work, so disconnecting the sense wires won't stop it doing sometrhing if the power is connected. See this little diagram, for example...
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I guess thats a diagram for a digital ammeter which requires a power supply to operate. A simple electromechanical ammeter , be it a crude moving iron instrument , or a moving coil instrument with a shunt, merely needs a current flowing through it or its shunt.

The external circuit of course needs a power supply in order for the current to flow but that can be anything from a few mV to hundreds of volts
 
Just shows how quickly people can jump down your throat on here with insults. I re-read my post as soon as it was up and realised that the words you have quoted could be misunderstood and changed them. For clarity a small current does indeed flow but its the voltage that is indeed measured. I have not got that old, I am trying to clarify the issue for the OP not start a highly technical argument.
 
pvb said:
Simply because they tend to be standardised, commonly to produce 50mV at their rated max current.
Click to expand...

What you are talking about I believe is stuff at the bottom end of the market that goes with instruments that are not graduated or calibrated. Any good quality instrument will be calibrated to ensure that the amperage indicated is correct.
 
boatmike said:
You really are intent on having an argument rather than help the OP aren't you?
Click to expand...

If that's aimed at me, the answer is no.

If you read my posts in this thread, you'll see I've suggested possibilities and have simply corrected some of the misinformation which has been posted.
 
boatmike said:
What you are talking about I believe is stuff at the bottom end of the market that goes with instruments that are not graduated or calibrated. Any good quality instrument will be calibrated to ensure that the amperage indicated is correct.
Click to expand...

Not at all, VDO gauges aren't "bottom end of the market".
 
Has anyone solved the original problem of why the battery chargers are going "bang"?

I only know the basics of electricity so I wonder why the fuse isn't protecting the battery charger? Logically it would take a fair bit of power to blow up a battery charger so where is the power coming from?

What would happen if there was a microwave on board and the capacitor discharged into the system? I don't know that there would be enough current there but the voltage is high enough to kill a person. I can't imagine what else it would be. I suppose that is a crazy idea but without reading the 70+ comments has anyone worked it out?

NOTE Maybe enough amperage?

How to Turn a Microwave Oven Transformer into a High Amperage ...
mad-science.wonderhowto.com/.../turn-microwave-oven-transformer-into-high-ampe...
Dec 13, 2012 - In this project, you'll learn step by step how to modify a microwave oven transformer into a high-current device that can pump out 800 amps of electrical current, which is enough amperage to melt metal. If you liked the Metal Melter you saw in my previous project, here's how yo
 
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pvb said:
If that's aimed at me, the answer is no.

If you read my posts in this thread, you'll see I've suggested possibilities and have simply corrected some of the misinformation which has been posted.
Click to expand...

Oh dear no pvb! Sorry I should have made it clear that I was sniping at Richard not you and I agree that you are only trying to help. The problem here as always is that if you dare to disagree with anyone (Richard in this case) they take umbrage and start to get personal. All I said originally was that his posts were perhaps misleading. IMHO they were in suggesting that the OP had removed the shunt and left the gauge in circuit which he clearly hadn't and rabbiting on about two shunts when the OP only had one. Also when trying to make an explanation simple for the OP I was perhaps oversimplifying. When I read the original post I removed reference to current in the sensing wires as I predicted someone would point out the difference between voltage and amperage. When I said the voltage across the shunt would not change I should have said "The voltage though the shunt to main supplies would not change to any appreciable extent" I was not talking about the gauge sensor wires. It's very difficult to be so precise that misunderstandings are eliminated entirely. So sorry..... not you!
 
But I don't think they are necessarily sold as calibrated either pvb. Probably plus or minus 5% is sufficient in most cases?
 
pvb said:
The ammeter will typically require 12v connecting to it, in order to work]
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Perhaps then you would care to explain how this one will work. It only has two terminals. there is no provision to connect 12 volts or any other power supply

 
VicS said:
ITYWF what you are saying is applicable to shunts for use with modern digital meters which themselves draw a negligible current. Boatmike is, I think, talking more about shunts for electromechanical meters, eg moving coil meters. which will themselves require a significant current, maybe tens of mA to drive them and whose parameters may be rather nominal compared with those of a digital meter. Hence the need to match the shunt to the meter.
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Thank you Vic, yes correct because that is what the OP has indicated that he has.
 
coopec said:
Has anyone solved the original problem of why the battery chargers are going "bang"?

I only know the basics of electricity so I wonder why the fuse isn't protecting the battery charger? Logically it would take a fair bit of power to blow up a battery charger so where is the power coming from?

What would happen if there was a microwave on board and the capacitor discharged into the system? I don't know that there would be enough current there but the voltage is high enough to kill a person. I can't imagine what else it would be. I suppose that is a crazy idea but without reading the 70+ comments has anyone worked it out?.
Click to expand...

Thank you Coopec for bringing the thread back to the original question. The answer is No and I don't think we can tell from what we know now. It is however possible that the broken shunt could have caused it. It's only a theory at the moment but battery chargers are voltage sensing. In other words they increase charge relative to the voltage they sense at the battery. I am a bit out of my depth here because I don't know how the logic or software works on modern smart chargers but if the current flow was intermittent through a partially broken connection to the battery it possibly may have caused the problem somehow??
 
boatmike said:
Thank you Vic, yes correct because that is what the OP has indicated that he has.
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I am a similar age to you.
I remember learning how ammeters and shunts worked long before anyone ever dreamed of digital meters etc
 
Oh dear Vic! Perhaps we should keep quiet about our age.
My son has admitted that he has gone through 3 phases. In the first he thought Daddy new everything, later as a teenager Dad knew nothing, now he concedes that I seem to have learned an awful lot since then........

Regarding ammeters, I have a fully graduated plus and minus 100amp American jobbie (can't remember name but ASAP supplies sell them complete with shunt) cost about 90 quids . You can buy a VDO equivalent (at least I think they are) plus or minus 60 amp one ungraduated (Faria) from ASAP for £12. I once bought a Chinese digital one from E-Bay for £8. Lasted 6 months. I think that's the difference. The Chinkie was crap Faria probably works, but the one I have is sensitive to charge and discharge of less than 1 amp and is accurate up to 100amps. You get what you pay for I guess!
 
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boatmike said:
Oh dear Vic! Perhaps we should keep quiet about our age.
My son has admitted that he has gone through 3 phases. In the first he thought Daddy new everything, later as a teenager Dad knew nothing, now he concedes that I seem to have learned an awful lot since then........

Regarding ammeters, I have a fully graduated plus and minus 100amp American jobbie (can't remember name but ASAP supplies sell them complete with shunt) cost about 90 quids . You can buy a VDO equivalent (at least I think they are) plus or minus 60 amp one ungraduated (Faria) from ASAP for £12. I once bought a Chinese digital one from E-Bay for £8. Lasted 6 months. I think that's the difference. The Chinkie was crap Faria probably works, but the one I have is sensitive to charge and discharge of less than 1 amp and is accurate up to 100amps. You get what you pay for I guess!
Click to expand...

I don't wish to be rude but how does your post relate to the thread?

Clive
 
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