Best way to swap batteries hooked to a charge controller?

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pioneerMan
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Best way to swap batteries hooked to a charge controller?

Post by pioneerMan »

The instructions warn that I should NEVER, EVER hook up solar panels to the charge controller without having a battery connected. Okay, got it. But what if I'm charging a single 12 volt battery at a time, and want to swap it out for another battery that needs charging? I'm going to have to disconnect the solar panel wires going to the controller FIRST, before I can then swap in another battery, right? What a inconvenient pain! Why can't modern charge controllers be designed to deal with the incoming solar power until the controller senses that a battery has been hooked up?

Let the discussion begin!
raysun
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Re: Best way to swap batteries hooked to a charge controller?

Post by raysun »

Charge Controllers need a battery connected in order to have a voltage reference and a current sink, two electrical properties essential to their design. Hooking up PV panels without those necessary elements is like driving off the mountain in a truck with no breaks. Putting the right pedal to the metal is all well and good. Putting the left pedal to the metal will have one singing with the angels in no time.

That one is confronted with the drudgery of disconnecting the PV wiring from the charge controller in order to replace the battery is a sure and certain sign the system is missing an extremely important safety element - a PV array disconnect. There should be an appropriately sized circuit breaker on the PV+ lead between the panel array and the charge controller PV+ input.

Save yourself a good deal of hassle, and burning down your equipment shed, and install something like this on each charge controller: https://www.solar-electric.com/midnite- ... eaker.html
Last edited by raysun on Mon May 03, 2021 5:44 pm, edited 1 time in total.
provo
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Re: Best way to swap batteries hooked to a charge controller?

Post by provo »

pioneerMan wrote: Mon May 03, 2021 4:52 pm
I'm going to have to disconnect the solar panel wires going to the controller FIRST, before I can then swap in another battery, right? What a inconvenient pain!
Most systems (and maybe yours, too :grin: ) have a breaker between the panels and the charge controller input, and another breaker between the charge controller output and the rest of the system (including the batteries.)

If you don't have a PV In breaker, you might want to add one.

Ooops, raysun beat me by 2 minutes -- oh well, no harm in you hearing it twice!
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Greg T Fordan
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Re: Best way to swap batteries hooked to a charge controller?

Post by Greg T Fordan »

pioneerMan wrote: Mon May 03, 2021 4:52 pm Let the discussion begin!
Not much material for discussion. All you need is some kind of disconnect means between the PV array and the charge controller, as raysun and provo said.
Greg T Fordan
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Re: Best way to swap batteries hooked to a charge controller?

Post by pss »

How to change out your batteries: First, disconnect your panels from the charge controller. This is by breaker or DC disconnect switch. Input to charge controller should read zero volts. Next, disconnect batteries from inverter. Do this by turning your battery bank switch to the OFF position. If you only have one bank of batteries, then the inverter will need to be shut down first. If you have multiple banks, the inverter can run on the other banks while you change out the disconnected bank.

Your battery bank should now have no current input from the charge controller and not be connected to any other power source like inverter or other bank. It will be safe to disconnect the wiring from the terminals and remove each battery and install replacements. If your system does not have individually switched battery banks, a DC disconnect switch for the panels or beakers for the battery banks and panels and charge controllers to de-energize in place, then ask yourself why? Ask who designed and installed the system. Then ask questions on how to do it right.
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