charging system

Our Cal 39 has a 100 amp Balmar alternator on the Perkins 4-108 engine. I cannot find a shunt and am wondering if the absence of a shunt could be why we seem to take so long to recharge our 400 amp bank of golf-cart batteries. The full charge would then be going ("slower"?) through the ammeter. Last summer, I found that the dumb placement of the power and passive vents over the back of the engine panel had led to corrosion of many connections, especially the ammeter. The wire was actually so shot that it crumbled when I touched it. No wonder our batteries were down to 10.75 volts after we blissfully motored along with our fridge running-no charging! I have since installed the Link 2000 monitor, very helpful info. Now, I need to know if I should install a shunt (and what size) or re-route the wire to bypass the meter and use the Link as my ammeter. I know it is not "good" to run an un-loaded diesel for extended periods, but at what rpm should I run it to balance my needs at anchor for re-charging while minimizing damage to my engine? According to the Link I'm getting only ~6 amps at idle, but 30 or more at 1500 rpm. This is some serious time to bring back 60-100 amps! Can we run at 2000 rpm? What I didn't get to check was how many amps are happening while running at 2000 or 2500 rpm... Our biggest problem in power consumption seems to be the old fridge (AB Cold Machine) which only runs full out at a steady 6 amps, of course freezing everything unless we manually cycle it on and off. So, at idle, we are simply powering the fridge and not re-charging... Any ideas to ponder for our next trip to "Bribon"? Yes, we are thinking about solar power and wind generators, but those are topics for another time... Our Fischer-Panda 4kW generator is out of service, thanks to an undetected saltwater bath from a blown exhaust gasket. :-( Peter

C. Peter Audet wrote: > > Our Cal 39 has a 100 amp Balmar alternator on the Perkins 4-108 > engine. I cannot find a shunt and am wondering if the absence of a > shunt could be why we seem to take so long to recharge our 400 amp > bank of golf-cart batteries. The full charge would then be going > ("slower"?) through the ammeter. All ammeters contain a shunt. Now perhaps in certain very high-current situations you might need a larger shunt or the meter might be supplied with an external one, the meter has to be matched to the shunt because it's reading the little bit of current that isn't shunted and calculating the total current flow from that little bit. Chris Campbell

Peter, the ammeter itelf runs off milliamps (maybe microamps). You therefore have a massive shunt in the meter. One way to test it for "fatness" is to put your handy dandy hand held voltmeter across the ammeter while you are charging. that will tell you thage drop across the device and (by calculation) the impedance of the shunt. Hope this helps. Cheers Charlie From: Ca… [at] yahoogroups.com [mailto:Ca… [at] yahoogroups.com] On Behalf Of Chris Campbell Sent: Tuesday, September 11, 2007 9:31 AM To: Ca… [at] yahoogroups.com Subject: Re: [Cal_Boats] charging system C. Peter Audet wrote: Our Cal 39 has a 100 amp Balmar alternator on the Perkins 4-108 engine. I cannot find a shunt and am wondering if the absence of a shunt could be why we seem to take so long to recharge our 400 amp bank of golf-cart batteries. The full charge would then be going ("slower"?) through the ammeter. All ammeters contain a shunt. Now perhaps in certain very high-current situations you might need a larger shunt or the meter might be supplied with an external one, the meter has to be matched to the shunt because it's reading the little bit of current that isn't shunted and calculating the total current flow from that little bit. Chris Campbell