T-Pain Is On A Boat: Re: [Electric Boats] Re: Generator run time?

Monday, March 21, 2011

Re: [Electric Boats] Re: Generator run time?

Solar/wind/regen trickle top up above 85%down to 50% is from here to there if i motor all the way with a half to spare if I want to stay out? Who runs the fuel tank dry when they go out sailing? I want more than I'll ever use but enough to use more if I need it/want it? It's a big boat and I don't want to get stuck for the sake of a few batteries? Cause they arrive next week and it's too late now? I could so I did? There are a few random answers. Thanks for the number crunching.

I am looking for a smart marine electrician / Mentor in the Bay area? Any recommendations?

Sent from my iPad

On Mar 21, 2011, at 20:30, "Tom" <boat_works@yahoo.com> wrote:

If you charge 85% and only discharge to 50%, you are using 35% of 540AH, which is 189AH.

Dividing 189AH by your 28A charge rate means you'll spend about 6.75 hrs charging, depending on your charging profile and BMS activity.

But why do you want to use only 50% of the available capacity?
Quality LiFePo4 cells are rated at >3000 charge-discharge cycles at 70% DOD. That's a lot of money to spend just to get 189AH.

-Tom

--- In electricboats@yahoogroups.com, Pitt Bolinate <boombolinate@...> wrote:
>
> Sorry I would have said drained max1/2 charge charge time up to 85% perhaps?
>
> Sent from my iPad
>
> On Mar 20, 2011, at 20:51, "Tom" <boat_works@...> wrote:
>
> >
> >
> > Hi Pitt,
> > We can't answer the time to recharge question without knowing how deeply the cells were discharged. You mentioned charging to 80-85%, but how far do you plan to discharge them?
> >
> > I have 180AH of CALB cells aboard, I only discharge to 70% DOD, so I have 126 AH available, if I fully charged them. But I don't. LiFePo4 doesn't take well to being overcharged or over-discharged, so I prefer to quit charging before they are near max capacity. This means I have paid for capacity that I never use, but it also means I never operate an expensive battery bank near the ragged edge.
> >
> > The EU2000i is only rated at 1600W continuous, I doubt you'd be able to run the Elcon 2000+ from this generator for more than half an hour before it complains.
> >
> > But let's say you discharge your bank to 70% DOD. You have 378AH available, it you fully charged them. The Elcon 2000+ is rated at 28A output when operating at 115V. 378AH divided by 28A equals 13.5 hours.
> >
> > Performance when powered by the Honda 3KW should be the same.
> >
> > It may take a bit longer if you have configured your charger and BMS (if any) to run CC-CV.
> >
> > In my case I charge with an Elcon 1500 at 22-20A and shunt current from the first cells to reach 3.4V until the other cells have caught up. This balancing only takes 15 minutes or less.
> >
> > By measuring cell voltage and counting AH consumed and AH replaced I know when to quit charging. I don't like the charge profile (much too high voltage for my taste) of the Elcon 1500, so I manually terminate the charge before it completes the CC stage, which is about the same time the BMS says "we're done".
> >
> > The ELcon and BMS has been working reliably for nine months now, but I still like to be around to keep an eye on the charge process. Not a problem for me, since my shop is about 50 yards from the boat.````````````````````````````````````````````````````````````````````````
> > -Tom
> >
> > --- In electricboats@yahoogroups.com, "Pitt" <boombolinate@> wrote:
> > >
> > > If I have a lifepo4 battery bank 48V x 540 AH an Elcon 2000 charger. How long would it take to charge the batteries with
> > >
> > > A~ shore power hook up?
> > > B~ Honda 2000i to 80-85% ?
> > > C~ Honda 3000Is to 80-85% ?
> > >
> > > There are people here who seem to gobble up the math for the these questions. That makes it possible for people like me to even consider going electric. Thanks guys.
> > >
> >
> >
>