Re: [Electric Boats] Which Amperage?

I responded off line.

Steve Spence
Renewable energy and self sufficiency
http://www.green-trust.org
http://arduinotronics.blogspot.com/

On 10/18/2010 08:01 PM, Daniel Michaels wrote:
>
>
> Steve, I could use some help getting a few things. I need a 12v aux
> thermostat for a Colman fridge.and a simple solar panel to keep one 12v
> battery charged (not using much elec). Until I can get the larger panels.
>
> Dan
>
> --- On *Sat, 10/16/10, Steve Spence /<steve@green-trust.org>/* wrote:
>
>
> From: Steve Spence <steve@green-trust.org>
> Subject: Re: [Electric Boats] Which Amperage?
> To: electricboats@yahoogroups.com
> Date: Saturday, October 16, 2010, 6:40 PM
>
> 65ah * 61 = 3965ah (@12v. multiply 61 * 4 (244 batteries) for 48v)
>
> this would power a 200 amp load for 10 hours or so.
>
> http://www.green-trust.org/peukert/
>
> Steve Spence
> Renewable energy and self sufficiency
> http://www.green-trust.org
> http://arduinotronics.blogspot.com/
>
>
>
> On 10/16/2010 07:20 PM, Kirk Mason wrote:
> >
> >
> > So, when a motor manufacturer says his 48 volt motor is capable of
> > handling up to 200 amps, to provide that kind of amperage from the
> kind
> > of batteries described here, one would need 16 of them?
> >
> > --- On *Sat, 10/16/10, Dave /<dasilvor@rarius.co.uk
> </mc/compose?to=dasilvor@rarius.co.uk>>/* wrote:
> >
> >
> > From: Dave <dasilvor@rarius.co.uk
> </mc/compose?to=dasilvor@rarius.co.uk>>
> > Subject: Re: [Electric Boats] Which Amperage?
> > To: electricboats@yahoogroups.com
> </mc/compose?to=electricboats@yahoogroups.com>
> > Date: Saturday, October 16, 2010, 1:35 PM
> >
> > Well spotted Carel, I didn't see the other half of the
> question. :-)
> >
> > The use of the higher voltage set up reduces the size of the
> wiring
> > required. If you are going to draw 260amps your wiring will
> have to be
> > much heavier than if you are drawing 65. I would think though that
> > Carels final option would be the most useful. 16 batteries, in
> a 4 by 4
> > block.
> >
> > Cheers
> > Dave
> >
> >
> >
> > On 16/10/2010 13:47, Carel Ruysink wrote:
> > > Dave is correct.
> > >
> > > For the second part of your question;
> > > If you have 4 batteries 12V/65Ah in series you get a battery of
> > 48V/65Ah.
> > > If you have 4 batteries 12V/65Ah parallel you get a battery of
> > 12V/260Ah.
> > > If you want 48V/260Ah you need 16 batteries, ie. 4 rows of 4
> > batteries.
> > >
> > > If you discharge at a higher rate than C10 (or C20 as some
> > manufacturers use) than are the usefull amps less or
> discharging at
> > a lower rate it will be more (peukert effect).
> > > Do not use more than 50% of the rated Ah or you will ruin your
> > batteries in no time.
> > >
> > > Carel.
> > >
> > > ----- Original Message -----
> > > From: Dave
> > > To: electricboats@yahoogroups.com
> </mc/compose?to=electricboats@yahoogroups.com>
> >
> <http://us.mc545.mail.yahoo.com/mc/compose?to=electricboats@yahoogroups.com>
> > > Sent: Saturday, October 16, 2010 2:27 PM
> > > Subject: Re: [Electric Boats] Which Amperage?
> > >
> > >
> > >
> > > What the figures mean is that the maximum amps you can safely
> > drag out
> > > of the battery for cranking an engine over (etc) is 950amps.
> > Below a
> > > certain temperature (no idea what that will be, but the
> > manufacturer
> > > will provide that info) that figure drops to 750amps. The
> final
> > figures
> > > is how long you can draw a certain number of amps before the
> > battery is
> > > flat. This last figure is usually calculated at a ten
> hour rate
> > (C10),
> > > so theoretically you can draw six and a half amps for ten
> hours
> > on a
> > > fully charged battery. As soon as you increase the discharge
> > rate, you
> > > lose capacity. So if drawing thirteen amps, it will probably
> > only last
> > > four hours instead of the expected five.
> > >
> > > I hope this helps.
> > >
> > > Cheers
> > > Dave
> > >
> > > PS.. I've been lurking for a while so thought I ought to
> start
> > > chipping in. I used to race electric model boats, so am
> > facinated by the
> > > idea of having a boat with electric propulsion. My long term
> > goal it to
> > > have a narrowboat on the UK canals using an electric drive
> > perhaps in
> > > the same configuration as a diesel electric train to
> improve fuel
> > > consumption.
> > >
> > > On 16/10/2010 13:12, Kirk Mason wrote:
> > > > My 12-volt Optima AGM batteries have three Amp
> ratings: 950
> > cranking amps; 750 cold cranking amps; and 65 amp hours.
> > > >
> > > > When it comes to relating that to motor specs, to
> which do I
> > refer?
> > > >
> > > > Say I have four of them wired in series for 48 volts. Does
> > that mean my battery pack has 260 amp hours?
> > > >
> > > > Is that what manufacturers mean when they say their
> motor is
> > rated for 48 volts and 200 amps?
> > > >
> > > > Thanks,
> > > >
> > > > Kirk
> > > >
> > > >
> > > >
> > >
> > >
> > >
> >
> >
> > ------------------------------------
> >
> > Yahoo! Groups Links
> >
> >
> >
> > electricboats-fullfeatured@yahoogroups.com
> </mc/compose?to=electricboats-fullfeatured@yahoogroups.com>
> >
> <http://us.mc545.mail.yahoo.com/mc/compose?to=electricboats-fullfeatured@yahoogroups.com>
> >
> >
> >
> >
>
>
> ------------------------------------
>
> Yahoo! Groups Links
>
>
> electricboats-fullfeatured@yahoogroups.com
> </mc/compose?to=electricboats-fullfeatured@yahoogroups.com>
>
>
>
>

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