It Begins: Converting Cal 2-27 to Electric Propulsion!

[nimblemotors]

Interesting there is a commercial product with integrated separate 12v chargers for 48volts. This is possible because of the isolated outputs from the power supplies. One could even do 8 six volt chargers. I see mpja.com has a 16amp 9v power supply on sale for $10ea (9 Volt Power Supply, 16.7A, Switching, Meanwell | MPJA.COM) that is only $60 for 128amps! What AC power is available at your dock?
Might need some work to cutoff the charging, limit the amps, and maybe get the volts low enough for 6 volts batteries.

[GrowleyMonster]

Originally Posted by nimblemotors

Interesting there is a commercial product with integrated separate 12v chargers for 48volts. This is possible because of the isolated outputs from the power supplies. One could even do 8 six volt chargers. I see mpja.com has a 16amp 9v power supply on sale for $10ea (9 Volt Power Supply, 16.7A, Switching, Meanwell | MPJA.COM) that is only $60 for 128amps! What AC power is available at your dock?
Might need some work to cutoff the charging, limit the amps, and maybe get the volts low enough for 6 volts batteries.

Yeah I actually am considering separate chargers for each battery. Also thinking about a variac and an isolation transformer for manually managing the batts, and having a small float charger on automatic. The nice thing about the variac, of course, is the voltage is continuously variable and can easily accommodate any future increases in bank voltage. The modular aspect of separate chargers has advantages, too. A single battery on its last legs could be singled out for an equalizing charge, for instance. I think I could handle building a 6v processor controlled PWM charger, for that matter. Or 8 of them, and a spare. Anyway I am dead broke now and need to go back to work for a few months before I can play, so plenty of time to consider my options.

[mcarling]

Originally Posted by Finnigan

They are US Battery 305XC lead acid batteries the maker estimates 700 cycles to 80% or 10 years they are used in electric lifts and floor scrubbers and are resonably priced for there size The L16 420ah batteries needed a 40 amp charger so I went with the 310ah The thing that got the most bang so far was the 3:1 reduction and 18X15 prop I hardly ever use more than 30 or 40% during an outing its just nice to have it there if I need them The next project is a Honda gen set for chargeing when I cant get to shore power I have 660ah @ 12vdc with 250 watts of solar for the house

I would consider combining the propulsion and domestic battery banks into one 48V bank exceeding 20KWh and using a DC-DC converter to provide 12V as needed. Then the solar capacity could be used to charge the 48V bank.

[GrowleyMonster]

Originally Posted by mcarling

I would consider combining the propulsion and domestic battery banks into one 48V bank exceeding 20KWh and using a DC-DC converter to provide 12V as needed. Then the solar capacity could be used to charge the 48V bank.

Exactly. Except I really like redundancy. Rather have 2 48v banks. Stuff happens.

I'll probably end up with a single smallish 12v emergency batt installed high and dry somewhere, charged with its own dedicated 10w panel, so I got emergency VHF and cell charging, too, but normal 12v house loads will eventually all be supplied from a DC/DC converter. I will also be converting interior lighting to 48v, and replacing the inverter with a 48v one. I don't want to be occupied with the care and feeding of banks of 2 different voltages.

[mcarling]

If you have two 48V battery banks, then having a separate DC-DC converter for each 48V bank would provide redundant 12V DC power for your VHF and all other 12V devices without any need for a 12V battery or a separate solar panel and 12V solar charger.

[Finnigan]

I like haveing the drive seperate from the house If I make any changes down the road I will probably go with 2 smaller 1 drive & 1 house 48 volt banks and use the house bank as a backup for the drive if needed

[GrowleyMonster]

A couple more observations.

Cheap digital volt meters are not always as accurate as you might expect. And even a half volt can represent 10% of state of charge. When using a cheap meter for monitoring battery state of charge, it is important to first verify state of charge by checking specific gravity, so you get a baseline voltage correction for the meter. I tried 3 meters and the voltage was all over the place. And make sure all connections are nice and tight.

The rule of thumb is to measure resting voltage, after letting batteries sit for 6 hours after charging or discharging. But I found that with my bank a reasonably accurate resting voltage can be found after resting for only an hour. From the 1 hour measurement to the 6 hour measurement, I only see a difference of about .1 volt. Good for me, since I wont always have the luxury of letting the batteries, sit idle for 6 hours when I want to find how much juice I have in the bank.

For modest discharge rates, down to 50% and at a draw of 20 amps or less, I can apply a simple correction while discharging, and the resulting SOC calculation will be close enough for me. At greater rates of discharge, the correction is not quite as linear. And of course the base correction is somewhat different for different current draws, too, so it is good to initially pick just a couple of different power levels to run at, during trials and then during normal operation.

At low speeds, a moderate headwind can make a tremendous difference in your range.

[sony2000]

You will need to almost double the pitch of the prop. Either 12",13", or 14" is needed. I suggest the cheapest folding prop. This is where I'm at and still testing.

[Boatyarddog]

Your not going to get much distance traveling on this system.
About 4 or 5 hrs on a full speed run, good for around the bay or coming into port.


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[Boatyarddog]

Your also going to have to be sure your balancing those batteries low and in the center of the boat.
They are heavy, like 130lbs each, smaller batteries will not have much capacity.
I recommend AGM. High charge rates.


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[GrowleyMonster]

Originally Posted by Boatyarddog

Your not going to get much distance traveling on this system.
About 4 or 5 hrs on a full speed run, good for around the bay or coming into port.


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Much less than that, actually, at full speed. But who wants to go fast, anyway? It makes the trip over too soon.

I will be adding another bank, though.

[GrowleyMonster]

Originally Posted by Boatyarddog

Your also going to have to be sure your balancing those batteries low and in the center of the boat.
They are heavy, like 130lbs each, smaller batteries will not have much capacity.
I recommend AGM. High charge rates.


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They are as low as they can go, on the centerline. GC2, 85 lbs each, 8 of them at present, in series.

AGM too expensive for me. Got these from Sams for $85/ea. Best bang for the buck. If I had the money I would splurge on LiFePO4.

[GrowleyMonster]

Originally Posted by sony2000

You will need to almost double the pitch of the prop. Either 12",13", or 14" is needed. I suggest the cheapest folding prop. This is where I'm at and still testing.

I don't want to go bigger than 12" due to clearance issues. I will probably try a 12x10 fixed 3 blade this year. Should be about right with this motor and the 2:1 gearbox. I seem to be slightly underpropped at present, with the reduction gear.

[Fog Bank]

Originally Posted by GrowleyMonster

I don't want to go bigger than 12" due to clearance issues. I will probably try a 12x10 fixed 3 blade this year. Should be about right with this motor and the 2:1 gearbox. I seem to be slightly underpropped at present, with the reduction gear.

Overall, how are you liking the the new drive so far?

[Boatyarddog]

Originally Posted by GrowleyMonster

Much less than that, actually, at full speed. But who wants to go fast, anyway? It makes the trip over too soon.



I will be adding another bank, though.

I was talking more about distance, however a bit of a headwind ,or current plays into your travel plans.
Love the quiet propulsion!


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