Starter data needed...in-depth stats...calling electrical gurus
11-30-2016, 11:24 PM
#16
Electron Wrangler
Lifetime Rennlist
Member
Lifetime Rennlist
Member
Jim great offer! I'd also be interested in seeing this data.
I like almost every Blue Sea Systems product I see. I have several of their HD battery switches - they are quite wonderful products - works of art and supremely functional too, this shunt looks very nicely made.
Alan
I like almost every Blue Sea Systems product I see. I have several of their HD battery switches - they are quite wonderful products - works of art and supremely functional too, this shunt looks very nicely made.
Alan
11-30-2016, 11:34 PM
#17
Rennlist Member
Alan,
Blue Sea is a good company, in Bellingham WA just north of us. Lots of cool stuff, website is here: http://www.bluesea.com
Blue Sea is a good company, in Bellingham WA just north of us. Lots of cool stuff, website is here: http://www.bluesea.com
12-01-2016, 01:56 AM
#18
Rennlist Member
Thread Starter
Carl,
I've got a Fluke clamp-on DC ammeter which I believe is good for 600A, and a recording digital scope. I've done the measurement you want, DC amps on the ground strap while cranking, but didn't save the data. If you can give me a few days I can do that again and post the data.
Offshore sailboats have serious energy-management needs and are usually fitted with high-current shunts to keep track of things, including the starting bank.
A typical one is here, 50mV output for a 500A load: http://www.westmarine.com/buy/blue-s...shunt--3827151
A "calibrated" piece of wire would also do for a shunt-- all you need is the resistance per foot for whatever wire you use for a ground strap. Or, for a factory strap (in good condition) just measure the voltage drop while doing the current test above, which tells you the resistance.
I've got a Fluke clamp-on DC ammeter which I believe is good for 600A, and a recording digital scope. I've done the measurement you want, DC amps on the ground strap while cranking, but didn't save the data. If you can give me a few days I can do that again and post the data.
Offshore sailboats have serious energy-management needs and are usually fitted with high-current shunts to keep track of things, including the starting bank.
A typical one is here, 50mV output for a 500A load: http://www.westmarine.com/buy/blue-s...shunt--3827151
A "calibrated" piece of wire would also do for a shunt-- all you need is the resistance per foot for whatever wire you use for a ground strap. Or, for a factory strap (in good condition) just measure the voltage drop while doing the current test above, which tells you the resistance.
That would be extremely helpful, and very much appreciated. I was just looking at the Fluke 88V but they are very expensive, even used on Ebay. I will hold off on the purchase for now, and eagerly await your results. Getting this data from a stock 928 is great. Thank you for offering to do this!
Cheers!
Carl
12-01-2016, 10:17 AM
#19
Electron Wrangler
Lifetime Rennlist
Member
Lifetime Rennlist
Member
Clearly the data will vary depending on the ambient temperature and likely somewhat on the engine configuration. e.g. between an S4, GT and GTS I'd expect there will be some differences due to rotational mass, compression etc. I'd also expect esp. wrt earlier cars that there may also be a difference in how well primed the fuel pump is before cranking (primary effect on cranking duration - where later cars may be worse).
Alan
Alan
12-13-2016, 10:58 AM
#20
Rennlist Member
Thread Starter
I agree, the later cars would theoretically (and practically) have a higher draw. Designing the unit based on those measurements should leave plenty of margin for earlier cars.
Jim,
Did you get a chance to take those measurements?
Cheers!
Carl
Jim,
Did you get a chance to take those measurements?
Cheers!
Carl