question

ronr avatar image
ronr asked

Disconnecting battery and MPPT

I have a camper with 160W PV, Victron MPPT and two 6 volt batteries in series.

During the initial installation of the controller, Victron instructions make it quite clear to attach the battery connections before attaching the PV connections.

Now that the system is up and running, when it comes to routine maintenance for such things as installing new batteries or working on something that requires the batteries to be disconnected, can I now just turn the controller off with the Victron app?

In other words, can I just leave the connections to the controller hooked up and turn off the controller? I ask because my controller is mounted where disconnecting the wires is a hassle.

MPPT SmartSolar
2 |3000
Toggle Comment visibility. Current Visibility: Viewable by all users

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

2 Answers
lehrling avatar image
lehrling answered ·

I would say yes, turn controller off.

But, it is recommended to have breakers on both sides of the panel. Switchable DC breakers such as those from MidNite Solar are perfect for this. These breakers can be mounted in their Baby Box.

https://www.midnitesolar.com/productPhoto.php?product_ID=183&productCatName=Breakers&productCat_ID=16&sortOrder=18&act=p


https://www.midnitesolar.com/productPhoto.php?product_ID=79&productCatName=Breakers&productCat_ID=16&sortOrder=1&act=p

1 comment
2 |3000
Toggle Comment visibility. Current Visibility: Viewable by all users

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

ronr avatar image ronr commented ·

Thank you.

0 Likes 0 ·
siletzspey avatar image
siletzspey answered ·

As discussed here last year (somewhere), with the introduction of LiFePO4 and BMS's that suddenly disconnect, charger vendors like Victron have beefed up their chargers so they don't burn out as easily on disconnects.

Even so, disconnects are arguably hard on chargers, and because no charger can react fast enough, potentially damaging voltage fluctuations (spikes) could hit your DC devices. I personally shut down the cells and charger first, before disconnecting the charger from the batteries.

Also, the FIRST charger to battery connect is so the charger can sense your battery setup and auto-set 12V or 24V for you, before any solar power comes in. Without 12V or 24V being set first, the charger won't know what to do with incoming solar power.

--tg

1 comment
2 |3000
Toggle Comment visibility. Current Visibility: Viewable by all users

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

ronr avatar image ronr commented ·

Thanks for the info. Especially good to understand the underlying reasoning. Thank you.

0 Likes 0 ·