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senormechanico · 07-12-2011, 14:45

Thanks for that.
I think my HiPower prismatics installation meets all your paramaters.
They're clamped with nylock nuts, installed inside a companionway closed staircase, and haven't got any heat issues.
A MiniBMS system is installed with them, and I've made sure they are pre equalized.
My adjustable alternator single stage regulator is turned all the way down.
It puts out 14.2 volts at that point into a fully charged bank regardless of RPM.
At that point, the BMS shunting LED's light up dimly, with a 3.6 individual cell voltage.
The solar array feeds a BlueSky MPPT controller with a programmable remote panel.
I've currently set the bulk to 14.0 volts and float to 13.8.
Batteries are coupled with flat, silver plated links, and the + and - battery leads have new, clamped and soldered ends.
So far, so good, but there's not enough solar around here since the battery installation to really test that part.

**s/v Jedi** · 07-12-2011, 15:09

It sounds strange, but the silver plating is not enough in a marine environment. Spray it all with a good corrosion inhibitor. A transparant one keeps it looking good.

cheers,
Nick.

senormechanico · 07-12-2011, 19:46

Thanks Nick.
Good idea, I'll do it tomorrow!

deckofficer · 07-12-2011, 21:11

Can I do better than $1.22 per amp/hour?

sytaniwha · 07-12-2011, 22:12

Hi deckofficer,

I don't know what the pricing is where you are so can't add much price info. However, remember that you need considerably fewer Ahr of LiFePO4 than of lead-acid (I reckon it's a factor of 2) to achieve the same usable capacity, so if you're doing a price comparison with lead acid you need to take that into account.

I'm based in Malaysia at the moment, and we had our LiFePO4 cells air shipped directly from CALB in China. Landed and on the boat, they cost US$1.37 per Ahr.

In this part of the world it worked out to be almost identical to what I had paid for an equivalent Trojan wet cell system 3-4 years ago in Thailand.

I hope this helps.

Cheers,
Paul.

deckofficer · 07-12-2011, 23:36

Paul,

Not even counting the increase in DOD ranges, the price is low enough that it meets other chemistries when you factor in cycle life. The best golf cart flooded batteries can be cycled 500 times (as you mentioned at a shorter DOD) before the drop to 80% capacity. 2 volt AGM bateries are good for 800 cycles, whereas the blue LiFePO4 go 2000 cycles. Crunching the numbers adjusting for the cycles comes to this,

Cost per a/hr based on 3.2 volt cells

LiFePO4 $1.22 USD
Golf cart $0.87 ~ $1.30
AGM 2 volt $1.37

Needless to say, I'll be going the LiFePO4 route for both house batteries and propulsion. Diesel/hybrid will be my re-power of choice. I have a background in EVs, designed and built 2, bought one. I have a perfect 12 Kw cont., 30 Kw peak, 96 volt brushless PM motor and can get more for $700 a copy at Motor "Motenergy" ME0913 Brushless PMSM BLDC

My plans are for a 400 a/hr, 96 volt house and propulsion bank and (2) inverters stacked and tapping 48 volt strings. The inverters as best as I can tell, will pull each string equally, and I will use either a DC/DC for 12 volts or a 75 amp switching power supply run off the inverters. The inverters have a wide range of charge profiles that can supply 60 amps at charging voltage. With 2 inverters that is about 7000+ watts draw from the generator, which at a speed of 5 kts should float right across the batteries. If any increase in speed is needed, then the draw would come from both the genset and batteries. Since you folks have "been there done that", any critiques?

sytaniwha · 08-12-2011, 00:26

Bob,

Actually, I haven't been to where you're going i.e. electric propulsion.

I looked at that when we repowered our 30 year old yacht 3 years ago, but I couldn't find any viable motors (we need at least 15kW cont & up to 40kW peak), and it all seemed too hard and too expensive, so we threw another diesel in.

If I was to do it now, I think I'd be able to run something along the lines of what you are thinking, with a separate genset driving the electric motor through a buffer of batteries. In my view it offers the best of all worlds: the huge advantages of an electric motor, the ability to get out of anchorages & marinas on electrics only, but the solidity of being able to run on genset when long distance powering.

We are only using our LiFePO4's for house bank application, which is really low charge and discharge rates. I think they're a real paradigm shift in that application. However I really can't comment in a practical way on what you're doing - no real world experience. I think you have a heap more experience than I, given your EV background.

Theoretically what you describe sounds fine to me.

What I can say is: make sure that the electrics are all good for the marine environment (esp the motor). I am continually amazed by how much gear just rusts away in a few weeks or months (e.g. a pair of well made high end Tyco crimpers I bought showed significant rust after just 2 weeks on the boat). The marine environment is nasty

Sorry I can't offer anything more constructive. But do keep us posted - I'd love to hear progress reports from you.

Cheers,
Paul.

deckofficer · 08-12-2011, 01:12

I am enamored with the idea of regenerative charging while under sail. A prop like the Max prop when in astern propulsion, will change its pitch and will not feather as it will in forward propulsion after slipping out a gear into neutral. With this direction of pitch there is a huge potential for regenerative energy. I have friends that run a separate prop shaft just for charging. I appreciate the warning about the marine environment, being a deck officer in the merchant Marine I never really dealt directly with that, the deck hands and bosun handle that. So I am concerned the motor that has worked ideally for me in over the road installations might just get eaten alive in a marine environment. What I have done for my trap inverted vee antenna is I've potted the coil and capacitor in a resin. Since what I consider to be a perfect motor for this installation is a brushless design, wouldn't a liberal spraying of WD-40 keep corrosion at bay?

sytaniwha · 08-12-2011, 03:31

Bob,

I doubt that a liberal spray of WD-40 will be enough, but it depends on the boat. If you're running the motor in a bilge area like a traditional engine room, then there's a high likelihood of significant corrosion.

I think the key is the materials that the motor casing, etc, is made of. Also, regular use seems to significantly help reduce corrosion.

Maybe something like this might help:

YachtsOfStuff.com - Spray-On Rubber Coating, Clear, Conformal, Electronic Protection, Corrosion Inhibitor

I've never used it, but if it does what it claims it could be very useful.

Of course, regular coats of paint on motor casings, etc, are one of the most common ways of fighting corrosion on small yachts.

And even if it doesn't work out, the motor is really good value, so it's worth a try.

Cheers,
Paul.

deckofficer · 08-12-2011, 10:16

That motor is 1/2 the price of a Lemco and offers more power.

T1 Terry · 08-12-2011, 12:59

Hi Bob,
What controller are you using with this BLDC motor? Any reason for BLDC and controller over DC and simple contactors?

T1 Terry

Target9000 · 08-12-2011, 13:07

Not to bust anyone's bubble, but these threads drift enough as is. This is a thread about using LiFePO4 for house banks. Can you take the discussion on propulsion use and motors into another thread. There are several of them already started.

deckofficer · 08-12-2011, 13:56

Quote:

Originally Posted by Target9000

Not to bust anyone's bubble, but these threads drift enough as is. This is a thread about using LiFePO4 for house banks. Can you take the discussion on propulsion use and motors into another thread. There are several of them already started.

I agree 100%, I'm bad. This is the best thread ever on LiFePO4 for house batteries. I'll start a new thread over on engines and propulsion systems. It will be titled "propulsion motors".