Battery charger for electric motor

[Jeannietheboat]

For the one who asked the boat is a morgan 35. So the reason I said I was gonna run the system on 72 volt is the conclusion I end up by talking with one of the thunderstruck representant. Obviously running on 48v would be the cheapest option to do but with a 11900 lbs of hull displacement and maybe another 2000 lbs of stuff aboard. You get to about 14000 lbs to push.

I was also thinking on getting a dc-dc inverter so I will be able to use a 12 v battery charger , wich is cheaper. And I will also have my 12v battery bank with a bigger amp/h rating. Do you think it would work ?

[StuM]

Originally Posted by Jeannietheboat

For the one who asked the boat is a morgan 35. So the reason I said I was gonna run the system on 72 volt is the conclusion I end up by talking with one of the thunderstruck representant. Obviously running on 48v would be the cheapest option to do but with a 11900 lbs of hull displacement and maybe another 2000 lbs of stuff aboard. You get to about 14000 lbs to push.

I was also thinking on getting a dc-dc inverter so I will be able to use a 12 v battery charger , wich is cheaper. And I will also have my 12v battery bank with a bigger amp/h rating. Do you think it would work ?

No such thing as a DC-DC "inverter". Presumably you mean a DC-DC "converter" which is a totally different thing. Is the converter going to go between the charger and a 48/72V battery bank, or between a 12V batter bank and the motor? If the former, you will be able to slowly charge your batteries. If you are thinking about the latter, forget it. No 12-48 converter will handle anywhere near the power demands of your motor. You will be lucky to find anything rated at much more than 1KW.

The problem is still going to be the number of Amps at 48 or 72 volts that you can generate with a battery charger. (You need to divide the rated Amperage of the charger by 4 or 6 to figure out how many Amps will be going into the battery bank.) It will take many hours of charging per hour of run time.

How much bigger an Amp hour rating are you talking about - and where will you fit the extra batteries?

I think it will probably work for getting your boat in and out of a marina in good weather, but that's about it.

[smac999]

Originally Posted by barnakiel

I have found online only one 72V charger unit that only remotely matches the specs. It delivers 100A (while up to 200A is required) and it clearly states not to be used in hybrid electric application. This one is 1500 freedom units inexpensive. Does not look all that splash-proof either ...

So where are those 72V 200A chargers that can be run off an onboard genset while charging batteries for a huge electric motor that is being run at the same time
b.

A 72v 200a charger would take a 15kw+ gen to run and he has a 5kw...

[smac999]

What size are your 12v batteries?

Ie if they are group 27. You will have 80ah at 72v. And your motor would last less one hour from batteries. (You can only use half the capacity. So 40ah, and with such high current makes it much worse) In fact you'd probably only get 15-30mins because of a .6 c rate.

I wouldn't do this with less then 200ah because of the draw. This gets you down to a .25c draw. That would be 12 group 31s. 12 golf carts would be better.

With a 72v 50-60a charger you might keep up and you'd be maxing the gen out. (Nothing else could run off the gen)

If your house charger is only 4a you also need to throw that out and get a new house charger.

How big is your house bank?

[Jorgen Moller]

Don't consider the DC up-converter! The charger can't "see: the batteries and can't apply the charge profile for the chosen batteries. For a boat of the size you are planning the installation for don't go below 200Ah usable capacity, and for your own safety don't mess with a voltage higher than 48V nominal. Fully charged the voltage will be close to 60V depending on the battery type, enough to give you heart filibrations which can kill you in a damp environment if the current goes between you hands across the chest. This could quite easily happen if you have to fix a problem or change the main fuse in bad weather.

Spend the money on a proper enclosed charger programmed to the profile of your batteries. A good one would be the Eicon EL-PFC-2000+. It will match both a reasonable battery bank and your genset, as well as a 30A dock stand.

Dropping the Perkins and selecting electric propulsion sounds like you can't afford a new 55Hp diesel, but installing the electric system will cost you easily more than $12-18K depending on your own effort, and the quality of the overall system. Without proper instrumentation and knowledge of the limits of your installation, you can get yourself in trouble. Don't use the serial batteries for other use, i.e. don't put loads on part of the chain, as the whole chains capacity is no higher than the weakest battery. Keep them balanced and in good health.

[Scout 30]

Originally Posted by barnakiel

I have found online only one 72V charger unit that only remotely matches the specs. It delivers 100A (while up to 200A is required) and it clearly states not to be used in hybrid electric application. This one is 1500 freedom units inexpensive. Does not look all that splash-proof either ...

So where are those 72V 200A chargers that can be run off an onboard genset while charging batteries for a huge electric motor that is being run at the same time?

I think someone has not done their pre-project research or else my broadband is so narrow tonight. Which may as well be.

So pls someone bring me up to speeds.

Cheers,
b.

The Elco site has chargers that work for their systems.

[Scout 30]

Here's an article from WoodenBoat about a repower of a classic. They ended up with a 96 volt motor & Elcon configured a charger to match it. The article says they will adjust their chargers to a specific voltage at no additional "charge".

Re-Powering a 1910 Yacht with Electric - Elco Motor Yachts

[Scout 30]

Here's story of an electric repower of the 100 year old SS BigWin with a great video attached.

Electric Re-power - Elco Motor Yachts

[valhalla360]

Another question: What is the goal in switching to electric?

It may help us direct you in the right direction.

[mitiempo]

Originally Posted by valhalla360

Another question: What is the goal in switching to electric?

It may help us direct you in the right direction.

An illogical goal in my opinion. Slower speed, less range, and probably more expense than a diesel installation if done properly.