Battery issue?
#23
Registered
I'm having an issue with batteries. Twin 500 efi's and brand new batteries that are fully charged. Battery voltage is 12.7 volts. I put a volt meter directly on each battery and when the engine cranks the voltage drops to between 9 and 10 volts. Stop cranking and the voltage is right back to 12.7 volts. The same thing is happening on both motors.
Those EFIs don't need some specialty 1000 cca starting battery and your deep cycles should do fine.
Last edited by NightHawk; 05-23-2017 at 03:47 AM.
#24
wrong.
It doesn't mean you should take the chance.
Your saving grace has been your on board charger. A fully charged deep cycle battery will start an engine but it is not ideal. At what point does a
standard deep cycle battery not start a high compression/high horsepower engine? I don't know. Ask Mercury or one of the pro engine builders.
Now that your on board charger is not performing you are experiencing what most of us that have tried these things have found out. Your engines
alternator will not fully charge a deep cycle or dual purpose battery when just tooling around in the boat going to the beach, bar, or your GF's dock.
These batteries need many hours on the charger to get a proper charge.
Dual purpose batteries would be a better alternative for you.
The best scenario is what I described before.
Replace your on board charger and use it every day and you will probably be O.K.
Do things the way I first described and you will be O.K.
I have used all three types of batteries on my boats and found that using 1 starting battery and 1 deep cycle is the best way.(single engine)
I also remove my batteries and take them home to be put on the charger on a regular schedule.
#25
Registered
HP500EFI Specifications
Propshaft Horsepower: 470/350
Displacement (Liter/CID): 8.2/502
Cylinders: V-8
Bore (in/mm): 4.47/113
Stroke (in/mm): 4.00/102
Compression Ratio: 8.75:1
Fuel Requirements: 87 Posted Octane (R+M)/2
Full Throttle RPM Range: 4800-5200
Ignition Type: Digital
Alternator (amps/watts): 60/847
Not exactly 'high compression'. That shouldn't require anything more than an average 600 CCA battery. Although I agree, the dual purpose AGM batteries made today are the best choice for almost everyone.
#26
Registered
iTrader: (3)
If I'm not mistaken these are the specs for the OP's engine;
HP500EFI Specifications
Propshaft Horsepower: 470/350
Displacement (Liter/CID): 8.2/502
Cylinders: V-8
Bore (in/mm): 4.47/113
Stroke (in/mm): 4.00/102
Compression Ratio: 8.75:1
Fuel Requirements: 87 Posted Octane (R+M)/2
Full Throttle RPM Range: 4800-5200
Ignition Type: Digital
Alternator (amps/watts): 60/847
Not exactly 'high compression'. That shouldn't require anything more than an average 600 CCA battery. Although I agree, the dual purpose AGM batteries made today are the best choice for almost everyone.
HP500EFI Specifications
Propshaft Horsepower: 470/350
Displacement (Liter/CID): 8.2/502
Cylinders: V-8
Bore (in/mm): 4.47/113
Stroke (in/mm): 4.00/102
Compression Ratio: 8.75:1
Fuel Requirements: 87 Posted Octane (R+M)/2
Full Throttle RPM Range: 4800-5200
Ignition Type: Digital
Alternator (amps/watts): 60/847
Not exactly 'high compression'. That shouldn't require anything more than an average 600 CCA battery. Although I agree, the dual purpose AGM batteries made today are the best choice for almost everyone.
#27
Registered
iTrader: (1)
#28
Platinum Member
Platinum Member
iTrader: (6)
I think Chris means hair dryer's lol
#30
Platinum Member
Platinum Member
iTrader: (6)