2kw Inverter + 4 GC2 6v batteries = wiring???

[DiskDoctr]

I now have 4- 6volt GC2 215 batteries, PD9270 converter charger, and and a ProSine 1800 watt inverter (2800 watt surge) and want to start wiring.

I have a quantity of 2 AWG wire on a spool, a supply of tin clad copper wire ends in various sizes, and a heavy terminal "hammer spike crimper thing"

I would like to add a battery turn off and shunt to measure amps and also be able to measure voltage/charge remaining.

So here's the setup.

1. Four batteries in a row, long sides against each other. Call them A, B, C, D. A&B pair #1, C&D pair #2

2. Two 2 AWG cables for each section to allow higher amps. Ex. two 2 AWG cables between battery A(-) and B(+), and two 2 AWG cables between battery C(-) and D(+), and two 2 AWG cables between B(-) and C(+) to make two sets of series then paralleled together to get 12v "super battery" LOL

3. Two 2 AWG cables from D(-) to one end of shunt and then two 2 AWG cables from other end of shunt to inverter (switch, then (-)) and PD9270 (-)

4. Two 2 AWG cables from A(+) to inverter (+) and PD9270(+)

5. 120v AC line to distribution box (30 amp transfer switch?) and PD9270

It's a little foggy, so I'll stop there and ask for input 😉

Wire size, wiring diagram, etc.

Caveat, the PS1800 has built in transfer switch, but I prefer not to use it. Want to keep a separate circuit and/or transfer switch at the 30 amp 120v incoming cable for pedestal/generator.

Help? 😉

[DiskDoctr]

time2roll wrote:

DiskDoctr wrote:
Looks like I should get some copper bus bars, too?

For what? Have you run out of places to connect something?

Maybe not. I was picturing the shunt connector in my diagram, I think.

I can probably wait on that, too

[time2roll]

DiskDoctr wrote:
Looks like I should get some copper bus bars, too?

For what? Have you run out of places to connect something?

[DiskDoctr]

All good advice, thanks!

Looks like I'll wait on the shunt, but use a bolt to bond the cables at the point where a shut will be- once I find one 😉

I just ordered 20ft of 4/0 cable. I have to work out the length of cables and ends I need and will get them installed and made up while I'm there.

Looks like I should get some copper bus bars, too?

According to this table, a 1/4" x 1" should handle 400a. I hear 12vdc usually has a bit of derating because of the DC heating, but since 400a is the SURGE rating and the column I checked was the lowest temperature rise, it should be fine, right?



from this site: Copper bus bar selection

[BFL13]

You don't even need a shunt and monitor for RVing. A voltmeter will show when the batteries need recharging. The idiot light monitor is just a crude voltmeter and will tell you when to recharge too.

You could get your set up going with what you have and get a monitor later sometime.

[time2roll]

DiskDoctr wrote:
So if it surges over 200a, the shunt will burn out, or just max out?

any shunt should only be run max about 80 percent of rating or it heats up and distorts the readings. Yes it will burn open like a fuse at some point such as short circuit.
Don't ask how I know 😉

[BFL13]

DiskDoctr wrote:

BFL13 wrote:
If he were getting a Trimetric, AFAIK the choices are 100 or 500 and he needs more than 100. However, he is looking at other monitors.

Didn't you have a thread about a Poor man's Trimetric a while back? What ever became of that?

It was an eBay gizmo. Mine was too fragile for me and broke, but others here have had some luck with theirs.

It also got complicated where some of the gizmos only read amps into or out of the battery but not both ways, like a Tri, so you have to be careful what you are buying or get two one-way jobs I guess. There is something about their AH counters having a limit? Forget--Mr Wizard has some info on that ISTR.

There were 100a or 200a versions of the one I got ISTR. The Tri choices also relate to voltage decimal point readings, where the 500 shows one and the 100 shows two on the display IIRC. Don't know about the gizmo ones for that. The Tri with one decimal point voltage is ok for government work, but sometimes you want two so out comes the multi-meter.

I needed more than 100 to show inverter amp draws, but also for charging amps. I charge at up to 155 amps at times. (Same as guys with those big inverter/chargers that are eg, 3000w/150a.)

EDIT--on where to use double #2, you need high ampacity from any buss so it will carry the total amps of all the incoming "branches" to the buss. Same with the shunt to battery--it carries the total amps of everything going into the outer end of the shunt.

If it is a pos buss, you fuse each branch wire before the buss according to its individual ampacity, then fuse the fat wire from the buss with a big fuse for that fat wire.

[DiskDoctr]

Here is the voltage drop and wire gauge sizes recommended by Xantrex per watt of their inverters. I thought it might be helpful to have this chart in the thread, too.



At 2000 watts it shows 2 AWG wire has over twice the drop as 4/0, so two #2 wires should be close to 4/0, which agrees with time2roll's earlier comment about it.

Also, since it looks like #2 AWG is plenty for the 9270, a substantial savings can be had by using a single #2 wire everywhere except the leads from the battery bank to the inverter.

Does that sound correct?

[DiskDoctr]

MrWizard wrote:
you don;t need a 500amp shunt

a 200amp shunt will be find

150amps for 1800w

200a = 2400w

So if it surges over 200a, the shunt will burn out, or just max out?

[DiskDoctr]

BFL13 wrote:
If he were getting a Trimetric, AFAIK the choices are 100 or 500 and he needs more than 100. However, he is looking at other monitors.

Didn't you have a thread about a Poor man's Trimetric a while back? What ever became of that?

[DiskDoctr]

MrWizard wrote:
much better

Thanks! I updated the graphic and it retroactively updated the previous posts and the quote, so it looks odd that you say it will short but is now fine, LOL. Maybe you can edit your post to drop the pic so future readers can learn from this thread and not get confused?

I guess now we won't know what "critical mass" of a 4 battery bank really is, nor the melting temp of a Keystone tongue :E LOL.

Some things we are better off not knowing 😉

[BFL13]

If he were getting a Trimetric, AFAIK the choices are 100 or 500 and he needs more than 100. However, he is looking at other monitors.

[MrWizard]

you don;t need a 500amp shunt

a 200amp shunt will be find

150amps for 1800w

200a = 2400w

[MrWizard]

much better

[DiskDoctr]

MrWizard wrote:
disckDoctor your wiring diagram is wrong you have a dead short on all your batteries

there are ONLY (4) interconnect wires used/needed
only one positive to negative connection in each pair
(2) batteries side by side positive to neg
is going to blow up

Good catch, thanks!!!

How about this one?

[DiskDoctr]

time2roll wrote:
I would skip the NC Relay and pull power for the converter from the Shore input of the TS30.

Just add a fuse same as the prewired GP TS-30

Ahhhh! Now I get it...

Move the Converter/charger's power supply to the same terminal blocks in the transfer switch as the shoreline input cable. So it would only be powered if the shoreline cable/generator supplies power.

The inverter would still be "on" by getting 12vdc from the batteries, but its 120v output would be switched OFF by the presence of the shore/generator power.

I think that is okay. I can either turn off the inverter with its switch, or leave it running, since it won't have any load and the camper will have 120v supply from shore/generator providing charge to the batteries through the converter/charger- so no draining of batteries.

Sound about right?

Thanks!