Where to connect an ammeter?

[Toadusmodus]

Trying to figure out the wiring in the Cerb so that I can fit an ammeter and monitor battery charge rate etc. I can see the wire from the alternator to the big fuse, from the fuse it heads towards the starter but I cant see exactly where it goes,and re-appears near the starter and heads towards the battery.

Does anyone know where the positive lead goes between the big fuse and batter, and also where I should connect the ammeter leads to get the correct reading?

Joe

[ridds]

Any of those cables will do. I'd go between teh battery and the starter as the alt lead feeds back through this I think. You can also monitor how much it draws when cranking too.

Lead runs from Alt to Starter to Battery.

[GreenV8S]

ridds said:

Any of those cables will do. I'd go between teh battery and the starter as the alt lead feeds back through this I think. You can also monitor how much it draws when cranking too.

One possible disadvantage is that the starter motor will draw far more current than any normal automotive ammeter will be able to deal with, so you would need to check whether your meter will cope with 500-600 Amps.

[Toadusmodus]

ridds said:

Any of those cables will do. I'd go between teh battery and the starter as the alt lead feeds back through this I think. You can also monitor how much it draws when cranking too.

Lead runs from Alt to Starter to Battery.

Cheers matey, will give it a go. Expect pics of a burning Cerb engine bay in the next few days!

[Steve_T]

I'd suggest a hall effect clamp meter to read the current. I found something that might be useful here:

http://web4.lem.com/hq/en/component/option,com_cat...

I think bosch are doing one that fits to the battery as a future product.

Steve.

[ridds]

GreenV8S said:

ridds said:

Any of those cables will do. I'd go between teh battery and the starter as the alt lead feeds back through this I think. You can also monitor how much it draws when cranking too.

One possible disadvantage is that the starter motor will draw far more current than any normal automotive ammeter will be able to deal with, so you would need to check whether your meter will cope with 500-600 Amps.

Good point. Also depends what it would do to it. Must (I guess) would just full scale and nt give a reading. I suppose there is a chance of burning it out though. Hall effect should be ok for this though.

[Toadusmodus]

Well, I am going to be connecting one of these http://cgi.ebay.com/20-V-100-A-DC-Blue-LED-Solar-P...

via one of these

http://cgi.ebay.co.uk/SHUNT-for-DC-100A-75mV-Curre...

Where should I install the shunt do you reckon??

[GreenV8S]

ridds said:

Good point. Also depends what it would do to it. Must (I guess) would just full scale and nt give a reading. I suppose there is a chance of burning it out though. Hall effect should be ok for this though.

Most direct measuring ammeters I think will just go 'phut' and stop working, but if you're lucky it will blow a fuse (so it stop working but without the 'phut'). I think you would be better putting the ammeter at a point that avoids the starter current.

[ridds]

Defo, not between the battery and Starter then.

[Toadusmodus]

GreenV8S said:

ridds said:

Good point. Also depends what it would do to it. Must (I guess) would just full scale and nt give a reading. I suppose there is a chance of burning it out though. Hall effect should be ok for this though.

Most direct measuring ammeters I think will just go 'phut' and stop working, but if you're lucky it will blow a fuse (so it stop working but without the 'phut'). I think you would be better putting the ammeter at a point that avoids the starter current.

Any suggestions on where to place the shunt then? This is all a bit beyond me, maybe I will just connect up the volt meter side of things!

[ridds]

Probably your best bet. You could put it inline before or after the 100amp fuse near the starter. This will avoid the starting current and teh 100amp fuse should protect it.

Is there any real raeason why you want to see current? Just curious?

[Steve_T]

Here's a link to what I was talking about: http://www.bosch.co.jp/en/press/rbjp-051020-13.asp

[Toadusmodus]

ridds said:

Probably your best bet. You could put it inline before or after the 100amp fuse near the starter. This will avoid the starting current and teh 100amp fuse should protect it.

Is there any real raeason why you want to see current? Just curious?

I was under the impression that just measuring voltage wont really tell me if the alternator is providing enough current to charge the battery, and seeing as I have the funky instrument that can give me volts and amps, thought might as well fit it.

[ridds]

I thought that providing your alternator kicks out between 13v and 14v when running above about 1500 revs/min then all is well and good.

I know very few people that use Ammeters to check batterys health. Providing the battery is recieving a voltage that should create the reaction within the battery to store that energy. A real test for a batteries ability is to "Drop Test" it (search out battery drop tester) as this shows the batteries ability to provide the large current required when starting.