Carel Kolesky
New member
What size battery should one use for river boat with single 30hp outboard,fish finder and nav lights?Best way to keep it charged?
Boat battery
- Thread starter Carel Kolesky
- Start date
Limpopoking
Sealiner
I have a 45Ah battery on my little river boat. That's considered small, but I have never run out of battery power on a day on the water. I now have a 20Hp motor that has an alternator but previously I had a 30Hp Yammy with no alternator and I just charged my battery from the wall socket when I got home after an outing.
It's like everything in life, it's all compromise. I'd say you would not want anything less than 45Ah which will cost you R? or you could get a 105Ah that will last twice as long and cost you 2xR?
I'd also go with a Deep Cycle. Even though you are not supposed to crank an engine on a deep cycle battery, something as small as a 30hp motor will not do any damage. The deep cycle will just last a lot longer, with the ability to take more charging cycles. Get a good quality smart charger. ALWAYS KEEP YOUR BATTERY CHARGED.
Replace your globes with LEDs. Happy boating
It's like everything in life, it's all compromise. I'd say you would not want anything less than 45Ah which will cost you R? or you could get a 105Ah that will last twice as long and cost you 2xR?
I'd also go with a Deep Cycle. Even though you are not supposed to crank an engine on a deep cycle battery, something as small as a 30hp motor will not do any damage. The deep cycle will just last a lot longer, with the ability to take more charging cycles. Get a good quality smart charger. ALWAYS KEEP YOUR BATTERY CHARGED.
Replace your globes with LEDs. Happy boating
Carel Kolesky
New member
Thank you!
willem wikkel spies
Moderator
the correct battery is indeed necessary!
because 2 stroke engines don't have altenators, they use coils and rectifiers to charge a battery!
what this means is, the higher the motor revs, the higher the charging voltage is!
but the lower the amps!
so in essence you need a lead battery which will absorb the high voltage inputs!
the wrong battery will not last long.
so do your homework on them, the batteries normally state for leisure, which means for 2 stroke engines.
if its a 4 stroke engine which has a alternator, the charging voltage is normally regulated not to go above 14,50 volts dc!
because 2 stroke engines don't have altenators, they use coils and rectifiers to charge a battery!
what this means is, the higher the motor revs, the higher the charging voltage is!
but the lower the amps!
so in essence you need a lead battery which will absorb the high voltage inputs!
the wrong battery will not last long.
so do your homework on them, the batteries normally state for leisure, which means for 2 stroke engines.
if its a 4 stroke engine which has a alternator, the charging voltage is normally regulated not to go above 14,50 volts dc!
That is interesting.
I have an old 2 stroke and have often wondered how much charge my battery is getting from those coils. I see on my fishfinder that the voltage sometimes gets very high. (around 16 volts). I have often wondered what the actual power output is (amps vs voltage). Ant idea?
I have an old 2 stroke and have often wondered how much charge my battery is getting from those coils. I see on my fishfinder that the voltage sometimes gets very high. (around 16 volts). I have often wondered what the actual power output is (amps vs voltage). Ant idea?
Slimy Salamander
New member
DP wrote:
You will need a clamp meter capable of measuring DC, in other words a clamp meter that has a Hall effect sensor in the clamp and not the transformer type. You then need to connect a battery that requires a charge and hopefully still be able to start the engine. You then connect the clamp meter over the positive wire and take your current (amp) measurements at various RPM’s. That should give you a rough output curve of the charging current when you plot it in a graph. Don’t use a fullly charged battery for this.
Btw, I’ve never measured altinator/coil output current before, but in theory my technique above should give you a fairly good idea of what your altinator/coil is outputting on an empty battery. And before anyone tells me that an altinator outputs AC, just member that the rectifier “converts†it to DC.
You will need a clamp meter capable of measuring DC, in other words a clamp meter that has a Hall effect sensor in the clamp and not the transformer type. You then need to connect a battery that requires a charge and hopefully still be able to start the engine. You then connect the clamp meter over the positive wire and take your current (amp) measurements at various RPM’s. That should give you a rough output curve of the charging current when you plot it in a graph. Don’t use a fullly charged battery for this.
Btw, I’ve never measured altinator/coil output current before, but in theory my technique above should give you a fairly good idea of what your altinator/coil is outputting on an empty battery. And before anyone tells me that an altinator outputs AC, just member that the rectifier “converts†it to DC.
willem wikkel spies
Moderator
the higher the revolutions the less the amps will be.
higher rpm means higher voltage but less amps.
lower rpm's is the opposite.
in any case, the lower the amps used to charge a battery, the better the charge will be!
thus the slower.....the better
higher rpm means higher voltage but less amps.
lower rpm's is the opposite.
in any case, the lower the amps used to charge a battery, the better the charge will be!
thus the slower.....the better
willem wikkel spies
Moderator
MichaelK wrote:
need to disagree here;
Depending on age of the motor.
that will ultimately be the deciding factor.
a proper lead battery, like the "leisure type" can withstand the high voltage low current charging cycles.
im not sure, if im proven wrong......then I will have learned something more
deep cycles don't like too high voltage charging.
see this:
https://www.glen-l.com/phpBB2/viewtopic.php?t=9686
need to disagree here;
Depending on age of the motor.
that will ultimately be the deciding factor.
a proper lead battery, like the "leisure type" can withstand the high voltage low current charging cycles.
im not sure, if im proven wrong......then I will have learned something more
deep cycles don't like too high voltage charging.
see this:
https://www.glen-l.com/phpBB2/viewtopic.php?t=9686