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safely connecting a battery bank

Posted: Wed Dec 06, 2017 5:26 pm
by Megunticook
Just getting ready to put my grid-tie with battery backup system in service (inspector coming Friday!).

I have 8 6 volt lead acid batteries wired in series (Rolls Surette S-550). I've wired them together and the cables to the inverter are wired at the inverter, but I held off on connecting those to the bank. I have some experience dealing with vehicle batteries but have never handled a bank with this kind of power. What's the safe procedure for making those final connections? With the battery breakers open, and a careful check inside the GSLC to make sure I didn't leave any tools inside or cross up any wiring, my plan was to connect the positive cables to the battery first, then connect the negative cables last. Will be wearing gloves and goggles. Is this the correct way to proceed?

And when disconnecting, always disconnect the negative first?

Thanks for any advice.

Re: safely connecting a battery bank

Posted: Wed Dec 06, 2017 10:55 pm
by JRHill
If you have to ask this question then you should probably hire a tradesman.

Re: safely connecting a battery bank

Posted: Thu Dec 07, 2017 7:36 am
by Megunticook
Whether or not I hire a tradesman to make the initial connection, it's important for me to know how to properly connect and disconnect the battery bank because there may be situations down the road where that needs to be done and a tradesman is not available.

I probably should've hired a company to install my whole system (I did get proposals from several but because of availability issues and a looming net metering deadline, I ended up doing the entire install myself), but the process of learning how it's done and doing it has given me all kinds of important knowledge that will help me maintain everything well and keep things safe.

I respect the danger of electricity and am trying to educate myself on the safest methods to perform important tasks like disconnecting the battery bank.

So...back to the original question. Breakers open, positive cables first, then negative cables?

Re: safely connecting a battery bank

Posted: Thu Dec 07, 2017 9:18 am
by JRHill
Once the loads are shut down and the the breaker is opened, it the negative first, then the positive. Formally, it doesn't matter which cable is removed 1st on a negative ground system but depending on the enclosure or other metal items around, once the neg is removed there'll be no shorting hazard except between the battery terminals.

Re: safely connecting a battery bank

Posted: Thu Dec 07, 2017 9:23 am
by Mike Curran
That's how I would do it. I installed my entire system myself also. As long as your battery->inverter breaker(s) are open you should be okay.

When I added more PV and an FM80 last year I powered down my system, opened the battery breakers and disconnected the positive cable at the battery, making sure it was secured away from the terminal before I started working inside the PSDC enclosure. FYI

Re: safely connecting a battery bank

Posted: Mon Jan 22, 2018 3:04 pm
by spirit
I'm not a professional installer, but I can tell you how I did this. I obtained a DC switch of sufficient amperage rating for my system from a marine supplier (an adequate DC breaker could probably also be used). I installed the DC switch (in the off or open position) in the positive line between my battery bank and inverter. Then, I made sure that the AC supply to the inverter was off and the AC load from the inverter was off (to make sure there was no supply to or load on the inverter). Then I first turned the DC switch to on, then turned on the AC supply to the inverter (breaker), then turned on the AC load from the inverter (breaker). Finally, I wrote up and printed the correct disconnect and connect sequence and posted that near my system. Disconnect: AC load, then AC supply, then DC. Connect: DC, then AC supply, then AC load. Hope this helps.

Re: safely connecting a battery bank

Posted: Tue Jan 23, 2018 7:38 am
by tallgirl
JRHill wrote:If you have to ask this question then you should probably hire a tradesman.
This needs to be pinned at the top of a LOT of forums.