[Electric Boats] Re: Skeptical wife has question about SolidNav

 

Hi Denny,

A question on charging a 48V bank of four 12V batteries with four separate chargers: I suppose that is OK only if the chargers outputs are isolated from ground. OK?

/KGB

--- In electricboats@yahoogroups.com, "dennis wolfe" <dwolfe@...> wrote:
>
> John,
> The reason that 48 volts is a popular voltage is that it takes a certain power to push your boat. Power = volts times amps. Double the voltage, cut the amps in half. Resistance losses in the motor vary with the square of the current so a 24v motor at 100 amps is less efficient than a 48v motor at 50 amps. Also, the size of the components generally goes with the amperage, not the voltage so a higher voltage, lower amperage system can have smaller wire, smaller controller, etc.
>
> 12v systems are not used, except for the smallest trolling motors, because the current would be so high to get the required power.
>
> Charging a 24, 36 or 48v system is simple. If you do not want to get a high voltage charger you can use multiple 12v chargers; one for each 12v battery or pair of 6v batteries.
>
> You will want at least (4) 60 - 70# 12v batteries to get enough energy storage to have a practical range under power. (8) 65# 6v batteries would be even better. Starting with one 12v battery with the thought to add more later is not a practical option. 48v motors, chargers and controllers are readily available.
>
> I believe Compac has tried a few EPower pod drives from Kevin Plank. He is now out of business. You would be better off with an "inboard" electric motor or a Torqeedo outboard on a transom bracket.
>
> The electric system, including a decent bank of AGM batteries, should cost around the same as a diesel. The diesel will have more power to push the boat into adverse weather, have much greater range, be annoyingly noisy and require some periodic maintenance. If you can live with the range and max power limitations of electric drive and can recharge from shore power conveniently, electric may be for you. Cruising along in a flat calm at 5 kts in silence is sweet. A well engineered system with AGM batteries requires no more maintenance than your cell phone - just plug it in at night.
>
> You should try to get a ride in an electric boat before committing to diesel.
>
> Denny
>
>

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