Hi Mike
Its murder isn't it
I bought the engine brand new which was a major cost
not far off a brand new hyundai at the time
at 156 hours on the clock it has had a series of problems
At least the lift pump was free , but the labour for finding the fault wasn't or the cost of pulling her out or the charge for being up on the hard for a few weeks while the experts scratched there heads
They did fit it for free in the end which was good but of course the anti fouling had gone hard after being out of the water so long so I had to redo that as well
If I was doing it again I would go electric
oh well all is easy with hindsight
I think I could have bought a mars motor for the price of the noise deadening I have stuffed in the boat just so I can talk to passengers
The worse thing is that I only coughed up so much money for the motor as I had 2 small kids at the time and my wife is on crutches
So the idea of a small motor boat (fantail launch) with a dodgy engine was impossible
Yet I seem to have ended up that way
The engine still occasionally blows air out of the water intake
I can think of a few reasons for this
None are good
I think I will try and sell the dam thing back to the supplier within the next 12 months and go electric
The saving should be back on track to do this by then so we will see what the motor does next!
The only thing I can say in its defence is that it has all ways got us home
even if it was smoking so much one day I could not see the dock!
Nick
On Tue, Apr 19, 2011 at 11:22 AM, Mike <biankablog@verizon.net> wrote:
--- On Tue, 4/19/11, Nicholas Luker <nickluker@gmail.com> wrote:
From: Nicholas Luker <nickluker@gmail.com>
Subject: Re: [Electric Boats] LiFe battery
To: electricboats@yahoogroups.com
Date: Tuesday, April 19, 2011, 12:39 AM
Well according to Jack rickards testing you can punish these cells pretty heavily and he thinks the manufacturers claims are very conservativeBut he does stress 2 points heavilyDont overcharge themDont over discharge thembut he does test one down to 1.6 volts at 400 amp loadIt does kill it but its nice to now that if it was an emergency like running for shelter with a cyclone up your back side that these cells will give there allBut you would be replacing them the next day!So it would be an extreme event to do thisdriving the cell down to 1.6 volts by pulling 400 amps out of it meets my definition of extremesurely though 5000 cycles would ,for most people be more than they could do in a lifetime of leisure boatingSo a battery pack would be a once off purchase that should last the life of the ownerThis is a much better deal than a diesel engineI am amazed at the money my diesel engine has cost me and the amount of grief it has given me and my wallet (well credit card actually)It must have esp as every time I think about replacing it with electric it plays up and sucks up the little I had started putting away to go toward replacing itNick
On Wed, Apr 6, 2011 at 6:04 PM, Eric <ewdysar@yahoo.com> wrote:
John,
What you're suggesting is kind of like driving your car way past empty on the gauge, until there is less than a cup of gas in the tank before you think about looking for a gas station.
You can interpret the graphs any way you like. However, the spec sheet clearly states that the batteries should deliver greater than 3000 cycles at 0.5C if kept above 80% DoD, and 5000 cycles if kept above 70% DoD.
I take most manufacturer claims with a grain of salt, the specs also show that the cells can take an impulse load of 20C (1800A for the 90Ah cells) without damage. That seems a bit optimistic to me, but might be true. Personally, I try to look at these specs conservatively. I'm setting my expectations to getting only 1500 cycles for my pack if kept above 80%, though they will probably die of old age long before then.
You do need to be careful with lithium though. A single event of discharging a cell to less than 2.5V can ruin it completely. The difference between 2.8V and 2.5V is less than 2% of the rating or less than 1.8Ah for these cells. That can happen pretty fast in real life.
BTW, The batteries that I suggested significantly exceed the performance of your original battery at the weight that you wanted. I'm surprised that you're willing to risk this kind of investement for such a small percentage more range. If you want more range, buy bigger cells like 160Ah that would still be lighter than your original set up. But like I said before, if you buy them, you can treat them any way you like.
Fair winds,
Eric
Marina del Rey, CA> Eric--
>
> When I looked at the discharge curve in the link provided below, the LFP battery doesn't fall to the recommended cutoff voltage of 2.8V at a discharge rate of less than 1C until more than 100% capacity is reached.
>
> Since I would be operating at 30 amps (0.33C for the 90AH battery), shouldn't I be able to discharge beyond 80% without damaging the battery, provided I stop prior to reaching 2.8V?
>
> John Casperson
>
> --- In electricboats@yahoogroups.com, "Eric" <ewdysar@> wrote:
> >
> > Here's a quick comparison that I recently wrote: "As a practical comparison, the 160Ah 48V lithium battery bank in my recently converted 1964 Cheoy Lee Bermuda 30 ketch is 60% lighter, 50% smaller and cost 50% more than an high quality 200Ah 48V AGM battery bank that would deliver a similar range under normal 4-5kt operation."
> >
> > So here's what I would do if I was aiming for the performance equivalent of your battery. I have no idea what the Ah capacity of your battery is, so I'll have to focus on the weight.
> >
> > Thundersky 90Ah LiFeYPO4 3.2V cells weigh 7.05 pounds, so 4 cells with strapping would be right around 30 pounds. The cells cost $112.50 a piece for a total cost of $450 dollars. Her's a vendor that sells them. http://currentevtech.com/Lithium-Batteries/Thundersky/Thundersky-90ah-cell-p23.html
> >
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