pontoon rebuild 3 battery question

[dirtleg]

ok so I'm trying to understand how to set up my batteries, i have an 80# thrust 24 volt trolling motor, 25 amp amplifier, fish finder, phone charger, nav and stern lights, and a set of head lights. not all running at the same time, but I will be trolling and music and occasionally trolling music and lights. never really more than 6-7 hours. I was given this diagram but it looks like the trolling motor is wired for 12v

I have also seen this diagram by silvertip which seems to show 3 batteries like I will have

and finally I have my own diagram. please someone just tell me exactly how you would set it up so that I don't drain my evinrude 1977 55hp cranking battery.

 

[Silvertip]

Re: pontoon rebuild 3 battery question

ok so I'm trying to understand how to set up my batteries, i have an 80# thrust 24 volt trolling motor, 25 amp amplifier, fish finder, phone charger, nav and stern lights, and a set of head lights. not all running at the same time, but I will be trolling and music and occasionally trolling music and lights. never really more than 6-7 hours. I was given this diagram but it looks like the trolling motor is wired for 12v

I have also seen this diagram by silvertip which seems to show 3 batteries like I will have

and finally I have my own diagram. please someone just tell me exactly how you would set it up so that I don't drain my evinrude 1977 55hp cranking battery.

Not my diagrams

 

[Silvertip]

Re: pontoon rebuild 3 battery question

#1: You cannot charge a 24 volt system from the engines 12 volt system without some sort of transfer switch that switches the troller batteries from series to parallel. And when doing that, you would not be able to run the troller. Not a practical application.

Recommendation: Install a two bank on-board charger dedicated to the troller batteries and plug in at the dock for charging. chances are the engine alternator does ot have enough output to keep up with that system anyway.

#2: You have a bunch of audio gear (25 amp draw you indicate but are you sure about that), lights, etc that amounts to a heavy electrical load. Running that from the starting battery would leave you dead in the water after 6 - 7 hours. Running it off either of the troller batteries seriously reduces the troller run time. I have no solution for this other than to lose the high power stereo or add another house battery.

If you are getting the impression that there is a shortage of power both from a battery and alternator standpoint you would be correct. But then we have no idea what the alternator output actually is since we don't know what powers this boat.

 

[dirtleg]

Re: pontoon rebuild 3 battery question

my apologies, I understood from the sticky that the middle diagram was from you, no offense intended. I really appreciate your input, in fact I have been hoping you would look at my thread. powering my boat is a 1977 55 hp evinrude which I understand from another post on a different thread that my motor has really low output, maybe 6 amps at WOT. we don't usually run everything night fishing is occasional and the headlights only get run when we come in at dark. what would be optimum would be to be able to troll with the fish finder and music for 5-6 hours. if we fish at night we use the lights and music and fishfinder and we would probably be polling instead of trolling just due to hidden logs and such. we mainly troll when red drum fishing off oyster bars a cedar key. If I need to add a 4th battery that would be fine. I would really like to know how you would set it up if you were me. I'm buying wire tomorrow, i believe I need 16 ga for accessories and 6 ga for my trolling motor supply lines. I would like to set the entire system up so that I can plug it into an extension cord an charge it while off the water.

below are the specs from my amp, I don't run it to really play loud music, but rather to avoid a cd/radio. we just plug the ipod into the amp and play the speakers that way. I was thinking 25 amps because that is the fuse size on the amp but now i'm thinking that that is way up on the top end of it's usage. below is the specs for the amp.

MTX Thunder 4122 - amplifier specifications
General
Product Type Amplifier
Recommended Use Car
Width 8.0 in
Depth 9.8 in
Height 2.1 in
Audio System
Response Bandwidth 20 - 20000 Hz
Signal-To-Noise Ratio 100.0 dB
Max Output Power / Channel Qty 50 Watts x 2
Continuous Power / Channel Qty 30 Watts x 2
Amplifier Output 2-channel
High Level Inputs Yes
Crossover 2-way active crossover
Crossover Slope 18.0 dB/octave
Low Pass Frequencies 85 Hz
High Pass Frequencies 85 Hz
Amplifier Output Details 80.0 Watt - 4.0 Ohm - THD 1.0 % - 12.5V DC - 2.0 channel(s) , 60.0 Watt - 4.0 Ohm - THD 1.0 % - 14.4V DC - 2.0 channel(s) , 30.0 Watt - 4.0 Ohm - THD 1.0 % - 12.5V DC - 2.0 channel(s) , 120.0 Watt - 2.0 Ohm - 14.4V DC - 2.0 channel(s) , 200.0 Watt - 2.0 Ohm - 12.5V DC - 1.0 channel(s) , 50.0 Watt - 4.0 Ohm - 14.4V DC - 1.0 channel(s)
Additional Features Input level controls
Connections
Connector Type 1.0 x Speakers output ( RCA phono x 2 ) , 1.0 x Audio line-in ( Screw-type ) , Speakers input ( RCA phono x 2 ) , DC power input ( Screw-type ) , Audio line-out
Manufacturer Warranty
Service & Support 3 years warranty
Service & Support Details Limited warranty - Parts and labor - 3 years

 

[dirtleg]

Re: pontoon rebuild 3 battery question

In doing a bit of research I came across this formula for calculating amps used by an amplifier on crutchfield.com.

To calculate the current draw of an amplifier, multiply the number of channels by the RMS watts per channel (a 2 channel amp rated at 300 watts RMS per channel would be 600 watts). Double it to account for amplifier inefficiency (600 watts X 2 = 1200 watts), then divide by the average output Voltage of an alternator, 13.8 volts (1200 divided by 13.8 = 87 amps). Since the average music signal requires about 1/3rd of the average power in a test tone, divide by 3 (87 amps divided by 3 = 29 amps). The result is the amplifier's approximate average current draw.

A quick way to ballpark an amplifier's current draw is to divide the total fuse value of the amp by two. For amplifiers with multiple fuses, the rating of all fuses provided with the amp must be added together. This will likely produce a significantly higher estimate than using the proper formula. Although inaccurate, this will err on the side of safety.


by applying this math to my amp I come up with 2 channels at 30 watts, is 60 watts x2 is 120 watts, divided by 13.8 is 8.69, divided by three is 2.8 amp per hour I think, now at the same time I don't have an alternator on my boat except on my engine which is only capable of 6 amps at wot so if I exclude the alternator part of the equation, I get 40 amps per hour. so if that is correct how long will that last on a 12v deep cycle battery?

 

[dirtleg]

Re: pontoon rebuild 3 battery question

what gauge cable should be used when connecting two batteries for series or terminal connections?