battery switch

System · March 2008

I have an aging battery bank of 16 6v 220ah agm 8x2 48v..(Golf cart)
I d like to set up another of the same but , use a selector switch to not have the new be dragged down by the old , but get as much life out of the old as I can. Will the switch except 4/0 cable, and most of all is this practical

mike95490 · March 2008

Re: battery switch

I'd build up the new bank, and keep it on float charge, until you can't stand looking at the old bank. Or just swap cables from 1 bank to the other, keep the idle bank on float, who knows, maybe after a week on float, the old ones may recover a bit. (how old are they?)

The common battery switches are for boats, http://www.cgedwards.com/Perko/pko13.html (several listed, scroll down to really HD ones)
are rated 250A cont, so that size wire should fit

example: Blue Sea 9002e e-Series Battery Switch:
3/8"-16 tin-plated copper studs for maximum conductivity and corrosion resistance, accepts 3/8" and M10 ring terminals - 7/8" (22.22mm) stud length to accept multiple cable terminals
So that one takes ring terminals.

Most boating switches are "make-before-break" so that would connect the 2 banks briefly, for some fun.

crewzer · March 2008

Re: battery switch

Here's a link to a "1 + 2" battery switch available from NAWS, this site's sponsor: http://store.solar-electric.com/basw1300amp.html

Link to specs: http://bluesea.com/category/1/products/9001e

Here's a really heavy duty model: http://bluesea.com/category/1/products/3002

NOTE: These switches are rated for 48 VDC max. It's not completely clear to me if that's "48 VDC absolute", or "48 VDC nominal", although I suspect they're intended for the typical marine system voltages of 12 VDC, 24 VDC, and 32 VDC. This may be an issue considering that your "48 V" nominal battery bank will regularly see charging voltages in the 59 V range (ref 77 F), and EQ voltages of 62 V or so. The make/break spark across the switch contacts at these elevated DC voltages might be a problem. References to "12 V" and "24 V" battery systems in documents like this one lead me to believe that the 48 VDC rating is absolute and should not be exceeded. It's probably worth contacting Blue Sea and requesting clarification.

HTH,
Jim / crewzer

SolarJohn · March 2008

Re: battery switch

philter wrote: »

I have an aging battery bank of 16 6v 220ah agm 8x2 48v..(Golf cart)
I d like to set up another of the same but , use a selector switch to not have the new be dragged down by the old , but get as much life out of the old as I can. Will the switch except 4/0 cable, and most of all is this practical

I'm getting ready to replace my battery bank, and I like the idea of a switch. My old batteries are still in good shape, and only two years old. They are Marine deep cycle batteries from Sams, 105ah each, and I have four of them in parallel. I'm going to buy 3 - 12v floor-machine batteries (8C12 I think is the number).

I see some advantages of using a switch:

1. I can easily connect the old batteries to the charge controller once in a while to maintain the charge.
2. When the power fails I can connect the old bank in parallel with my new battery bank, giving me more ah's when I need it most. I realize that this is not an ideal situation, but I can't imagine why this would be harmful to the new batteries. I'm going to avoid deeply discharging them.

Except for emergencies, I'll isolate the old batteries from the new. Does anyone see anything bad about this scenario?

John

System2 · April 2008

Re: battery switch

The Bluesea item recommended by Crewzer [Here's a really heavy duty model: http://bluesea.com/category/1/products/3002] is a great product.

I bought it from NAWS. You can use it to alternate between banks and, also, to switch off the batteries, hence using it as a "quick disconnect". It is very easy to install. (If I was able to install it, anybody can!)

Amilkar.

System2 · April 2008

Re: battery switch

Thanx for all the info. I m going after the bluesea HD .

battery switch

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