T-Pain Is On A Boat: Re: [Electric Boats] Re: battery bank upgrade

Saturday, August 28, 2010

Re: [Electric Boats] Re: battery bank upgrade

If a relay is a big heavy power switching unit it is called a contactor instead of relay. Normally they are built such that a magnetic field is made by an electromagnet which pulls the contacts together. That field is there until you want to open it. The field takes power. A latching contactor closes with a pulse of power and stays connected until an unlatching pulse is applied. The period in between no coil current is used - it is held closed without powering the electromagnet.
Field effect transistors have been used to switch power instead of a mechanical device.

http://en.wikipedia.org/wiki/MOSFET
http://www.allaboutcircuits.com/vol_3/chpt_5/2.html scroll down
http://en.wikipedia.org/wiki/Solid_state_relay

http://archive.chipcenter.com/circuitcellar/november00/c1100rp56.htm

http://home.cogeco.ca/~rpaisley4/SSRelays.html

Kirk

From: acsarfkram <acsarfkram@yahoo.com>
To: electricboats@yahoogroups.com
Sent: Sat, August 28, 2010 1:49:58 PM
Subject: [Electric Boats] Re: battery bank upgrade

Hi Kirk,

Can you explain what you are talking about? Latching contactors, FET's, RDSon?

Thanks,
Mark
Santa Cruz

--- In electricboats@yahoogroups.com, Kirk McLoren <kirkmcloren@...> wrote:
>
> latching contactors save a lot of coil current.
> There are some FETs with really low resistance drain to source on (RDSon) as
> well. They can be easily paralleled which you cannot do with mechanical stuff.
>
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> ________________________________
> From: Eric <ewdysar@...>
> To: electricboats@yahoogroups.com
> Sent: Sat, August 28, 2010 10:59:24 AM
> Subject: [Electric Boats] Re: battery bank upgrade
>
>
> Brian,
>
> You will need separate chargers for your AGMs and Lithium banks. The batteries
> have significantly different charging needs. Elcon chargers have different
> charging profiles available for the common LiFePO4 battery brands on the market.
> Be sure to confirm that any charger that you are considering has lithium
> specific profiles available. I spent a couple of months trying to get a
> properly configured charger from Delta Q, but the factory finally said that they
> would not release their lithium profiles unless I had bought ALL of my storage
> equipment, including batteries and BMS through one of their distributors.
>
>
> But I agree with you, there is no sense in throwing away perfectly servicable
> equipment when you can transition slowly from one technology to the other. If I
> were to set up both banks, I would put contactors on both the positive and
> negative leads from each battery bank so that they can be completely isolated
> from the other and the drive system. With the chargers wired to the battery
> sides of the contactors, each bank can be charged independently. One bank can
> be "activated" to the drive , while the other is being charged. One drawback
> that I could see is the need for separate instrumentation to track the current
> in and out of each pack, if you are so inclined. But this configuration should
> work fairly well.
>
> Fair winds,
> Eric
>
> --- In electricboats@yahoogroups.com, "Brian Holt" <drmsudo@> wrote:
> >
> > Eric- thanks again. I am thinking of one add on bank of LI then I will be able
> >to continue to use the current agm batteries I have with the charger. The
> >future will hopefully hold a much better system. This way I continue to get the
> >$ out of my current design and expand it with the new. Do you know about the
> >charger that will work with my Honda 2k? Thanks.
> > Brian
> >
>