Originally Posted by smac999
you're right, he should probably just remove the starter battery then, save weight, save fuel
, gain speed. who needs a starter battery for starting. just crank off the depleated house batteries. spiking the crap out of all the electronics which are on the same circuit.
In a properly wired system have you been able to measure this? I have not, even with an o-scope.... I've tried numerous times to capture these "spikes" and never been able to see them, in a properly wired system on a small sailboat aux engine...
I know they can exist, why I began measuring and checking for them. I also know they can cause issues in 18 wheelers and on the big Cats, Cummins, Manns etc. I work on but most all of these have dedicated start batteries from the factory. On small sailboat AX engines I've not been able to capture these "spikes".
The vast majority of my sailboat customers start and run house loads on the same bank and don't have "spiking the crap" out of their electronics issues...
I've been doing so personally for well over 25 years and also never once had an electronics failure other than by lightning
, which is "spiking the crap" out of my electronics.
Ideally a dedicated hard wired start battery is great but I am not going to suggest to my customers an upgrade that only serves to empty their wallets when I have not been able to trace down any measurable evidence that this is posing an urgent problem.
I've got one customers who regularly draws his dual 6V batteries down to 30% SOC or 70% DOD. He still has all his original Datamarine instruments, his RL series Raymarine
plotter is going on 18 years and working fine, his Ratheon 10XX radar
is well over 20, his VHF
is so old I can't even put a date on it yet he always leaves his battery switch on the house bank. I know he is due for electronics upgrades but they still work and he's on the cheaper side of the boat buck spectrum... He replaces his batteries every four years or so, because he depletes them so deeply, but they've never failed to start his motor
On another note I am replacing a $458.00 Yanmar/VDO tachometer due to a lightning
strike. Upon opening it up it is as delicate and high tech as any plotter or other piece of expensive equipment
I have done surgery on. Why are these $$$$$ tachs and other sensitive gauges not affected by being connected to the same circuit
This is a deep cycle house bank at 32F battery temp starting a 4 cyl Westerbeke
When you combine batteries in a parallel bank you also add the CA. In this case these deep cycle batteries are capable of over 2000CCA.. The start
battery on this boat is capable of about 650CCA....
Even during starting, at a 32F battery temp, air temp was colder, the deep cycle bank still stayed above 12V during the starting process....