Two Battery Banks

[brulaz]

Want to add more battery capacity.

Have two 6V golf carts non-AGM US2000 connected to a 390W solar with mppt. Two more US2000 on the tongue would be too much weight. Maybe one 12V on the tongue would be ok, but even better, tongue weight-wise, would be a couple of AGMs inside closer to trailer axle.

However I do it, these new batteries would be quite different from the originals and probably should be charged and used separately from the 2 golf carts. Also it would be nice to equalize some batteries at higher voltages, while using others at more reasonable voltages for loads.

So, I've talked myself into two switched battery banks. But how best to do it? Was thinking of two switches (like Blue Sea 6007 ).

One switch would connect the charging wire (from the mppt) to bank 1 or 2 (or both). The other would connect the load wire (from the WFCO 12DC distribution centre) to bank 1 or 2 (or both).

So when the charge switch is set to bank 1, I would set the load switch to bank 2, and vica-versa. And basically switch from one bank to other once one gets charged and/or the other is 50% depleted.

For storage, once both banks are fully charged, maybe I could set the load switch to off, and the charge switch to both. Hopefully "floating" both banks at once?

Is this sort of how two battery banks are managed?

[mena661]

brulaz wrote:
(Too bad the trailer doesn't run on 24V)

2oldman is using a 24V inverter and a DC-DC converter for the house loads.

[westend]

In the upper right corner is the manual circuit breaker, above the controller.

[brulaz]

westend wrote:
It depends on the controller for sequence of power to the controller from batteries and from the modules. I think some of the cheaper controllers don't like the modules connected with no power from battery. A switch on both solar and battery would be easiest.

In the two bank configuration, I used three dual bank switches, one from the solar controller, one from the converter, and one to the inverter. I used a single pole manual circuit breaker between the module and the controller.

So, instead of a single bank switch to all loads, including an inverter, you switch the inverter separately from the DC loads/converter. Certainly gives you more flexibility. Run the inverter off one bank and the DC loads off the other. Nice.

But I wasn't planning on installing an inverter. A while back we started wondering how much hassle it would be to power the microwave. Turns out it would be a lot of hassle, $$$, and monster 1/0 cables to the battery banks. (Too bad the trailer doesn't run on 24V)

So, for now I'm putting an inverter into the "wait-and-see" category. I can situate the xtra bank to minimize cable runs to the switches and the other bank, and design the layout so that if in the future we decide to add an inverter, I can just replace the cables with 1/0, add a 2000W inverter between the banks, add another bank switch and be good to go. We'll see if that ever happens.

Oh, and the Rogue mppt likes you to disconnect the solar panels first. That tells it to go into rest mode and put down a log entry. Then you can disconnect from the batteries. If you disconnect from the batteries when it's not in rest, there will be no log entry and you loose that accumulated info for the day. No big deal really ...

[Carb_Cleaner]

I think I follow all this.
Memory being what it is - fleeting - subscriptions are your friends.

[westend]

It depends on the controller for sequence of power to the controller from batteries and from the modules. I think some of the cheaper controllers don't like the modules connected with no power from battery. A switch on both solar and battery would be easiest.

In the two bank configuration, I used three dual bank switches, one from the solar controller, one from the converter, and one to the inverter. I used a single pole manual circuit breaker between the module and the controller.

[pianotuna]

Hi,

I routinely disconnect my Blue Sky 3024di from the battery bank, but never disconnect from the solar side.

None of my switches are make before break. They are all spst.

[brulaz]

full_mosey wrote:
? about using one of these battery switchers with a solar controller.

My two controllers specify that the batteries are connected first and then the solar panels. The connections on one are actually numbered:

1. Battery -
2. Battery +
3. Solar -
4. Solar +

It is my understanding that the solar controller is powered by the battery. Disconnecting the battery should follow disconnecting the solar controller(reverse order of installation).

When operating the battery selector switch in a break before make mode, doesen't there exist a time when no battery is connected to the solar controller. Wouldn't you want a break switch on the controller before switching battery banks?

HTH;
John

The Blue Sea switches I linked to are "make before break".
Dunno about the NAPA switches PianoTuna referred to.
My mppt controler is like yours, so "make before break" is good to have.

[full_mosey]

? about using one of these battery switchers with a solar controller.

My two controllers specify that the batteries are connected first and then the solar panels. The connections on one are actually numbered:

1. Battery -
2. Battery +
3. Solar -
4. Solar +

It is my understanding that the solar controller is powered by the battery. Disconnecting the battery should follow disconnecting the solar controller(reverse order of installation).

When operating the battery selector switch in a break before make mode, doesen't there exist a time when no battery is connected to the solar controller. Wouldn't you want a break switch on the controller before switching battery banks?

HTH;
John

[pianotuna]

Hi,

I used much simpler and cheaper switches from Napa auto. They are 100 amp continuous and 1000 amps contacting.

I have switches for solar and switches to control the charging path from the alternator.

I did not bother to switch the OEM converter, but it is a simple matter to have both the Napa auto switches in the on position which allows it to service both banks.

[Son_of_Norway]

I have 3 battery banks so I can go for a couple of days without having to run the generator. The first is a set of golf carts, the other 2 are AGM's. Both of the AGM battery banks are controlled by relays that work automatically. When the batteries are being discharged the relays are open and I have all of the capacity of the three banks available. When 120 volt AC is present the relays close and the three banks are isolated from each other. The AGM banks have their own AGM charger that works automatically. The golf carts are charged by the house converter. Let me know if you have any questions about how to set it up.

Miles

[12thgenusa]

That's exactly how I did it using that very switch. My batteries are identical but I wanted the capability of equalizing two while powering systems with two. Other than that both switches are always set to "both".