Ammeter wiring

[JohnR]

Why does the current to my battery from the generator pass down 5mm wire until it reaches the ammeter when it passes through 0.4mm wire. Does this make sense or have I got it wired incorrectly?

 

[Dave_Snelson]

Are you sure thats how it is wired? 'Cos if it is, then its wrong. Usually what happens is that charging from the genny is taken care of with ordinary wire, while the feed out of the battery for services such the starter motor are on big thick stuff.

 

[ChrisP]

Should use the 5mm all the way otherwise the smaller wire will burn when carrying the full alternator current.

 

[boatone]

Souinds like the ammeter is being fed via a shunt as it should be. Feeding full current load thru the ammeter used to be fairly common but not good practice to do it these days.
Strikes me your question is a bit lacking in detailed info to get reliable replies.

TonyR
boatone@boatsontheweb.com

 

[ChrisP]

4 or 5mm cable is quite normal if as mentioned earlier the ammeter is not wired via a shunt. The cables need to be capable of carrying full current (usually about 30-60 amps). The cables to the starter would normally be around 45 - 70 square mms. In the many years that I have been messing with boats I have only found one boat that uses shunts for the ammeters and that needless to say was the Riva but I will admit that I haven't worked on many of the newer range of Princesses. Sunseekers and the like.

 

[ccscott49]

Most boats these days dont fit ammeters, as they dont really tell jyou much, tell you whats going into or oput of batteries, but dont tell you whats in the batteries, which is more important. They stopped putting ammeters in cars years ago, for the above reasons.

 

[JohnR]

This is shore-based wiring. The 5 or 6 mm cable runs from a wind geny to a terminal block which also accepts feed from a 12v Honda, when needed, then between the terminal block and the pair of batteries there is the ammeter on its .4mm 'ish wire, so the current flows 5mm, 0.4mm, 10mm battery connections.

OK if I do away with the ammeter how do I know current is flowing and how much (can't see the wind geny from where the batteries are). I can tell 'ow much there is in the batteries by looking at the lights.

 

[BarryD]

Correction CC - bigger cars with large current draws still get ammeters. My daily drive (couple of years old) has heated everything and what isn't heated is powered - sometimes both. Cause of this the ammeter is quite handy to see what the draw / re-charge status is. My other car funnily enough is 29 years old and has an ammeter too - but that's 'cos it was posh and sporty in those days. I think I'd swap them both for something useful like an oil temperature gauge.

 

[ccscott49]

Take out the ammeter, put a voltmeter across the battery, when the genny is charging, the voltage will be approx 14 volts, when it isnt it will drop to 12+ volts if the battery is ok and lower than 12 if it isnt. First man in the world to have voltmeter eyes apart from superman that is!

 

[JohnR]

My garden tractor has one, if pointing to the right there is some sort of charge, if to the left, turn off the headlights.

 

[JohnR]

All my batteries are lucky to get above 10.5v. From now on I will racially discriminate against ammeters. I am just off to find an unlocked car with a voltmeter on the dashboard.

 

[BarryH]

Ah ha Oil temp gauge!! it must be an old Leyland group car, for get that and fit an oil pressure gauge. if the pressure drops the oils hot (and the water temp is thru the roof) or your up s*@t creek and in trouble

 

[jfm]

Nah, oil temp guages common as muck

(Some) current BMWs, VWs and fords have oil temp guages

 

[BarryH]

Re: Nah, oil temp guages common as muck

Well all i can say that with modern oils, what a waste of time, and any way as an ex Merc trained spanner monkey its a waste of dash space

 

[Guest]

Well if an amateur did the wiring and you've got a problem, you better get a professional to do it again.

Send blank sheque to marina and say "please fix this".

 

[ccscott49]

Torch batteries are unlikely to get above 10.5!

 

[ccscott49]

Re: Nah, oil temp guages common as muck

A Merc is a waste of dash space! Any prestige car used as a taxi!!? Cant be very prestigous! tee hee, Jags for ever!

 

[boatone]

Are you serious about the 10.5volts............?
If you are you need help...mucho help.......

TonyR
boatone@boatsontheweb.com

 

[BarryD]

It\'s got an oil pressure gauge!

I want a temperature guage as the old car is a Stag v8 and these have a history of running a bit hot. One of my cars of many years ago had a diff oil temperature gauge - now that is rare. Went like stink though.

 

[JohnR]

10.5 v is sheer luxury. End of next week I shall get to the cottage (miles from anywhere in the Borders) and the batteries will be flat, I don't understand that, I did charge them up 3 years ago, I shall plug the Honda in and there will be light. Then I will discover that someone has nicked the flagpole which I put the wind genny on. I hope the mice haven't eaten all the candles. I don't need help I am quite capable of banging my head against the (wet) stone walls on my own.