question

kiwi avatar image
kiwi asked

Unusual system sizing help request.

I'd appreciate the help of the community to give me some direction in designing a system.

  • I have a storage shed that is off grid. It is used to store a four vehicles that get infrequent use.
  • Each vehicle has a battery system, and three of them are different voltages, 18v, 24v and 12v.
  • Each vehicle has a dedicated mains charger.

What I'd like to achieve is a cost effective means of charging and maintaining the vehicle batteries. There is no need for any other power i.e. if it were possible, a stable mains supply during day light hours would be sufficient.

About 1Kw of mains power would be sufficient and allow for charging batteries with some diversity (i.e. not all chargers running 'bulk' charge at the same time) as well as maintaining them.

My initial thought was a solar panel of around 280W, ( which should be more than sufficient to run all chargers in trickle mode) MPPT controller and a small ish battery to supplement solar when demand is greater than the PV panels are producing.

I'm struggling to figure out what size of system battery would be needed, given that no power is needed during the night, and if there was a day without mains (while the system battery recharged?) it wouldn't be the end of the world.

Any help, guidance, or pearls of wisdom greatly received :-)

system design
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
solardude avatar image
solardude answered ·

I have never used one, but on paper the EasySolar 12V/1600 sounds like exactly what you need.

If you go with lead acid batteries, 2 deep cycle 6V 225Ah batteries should be good. You can always add 2 more later if you need.

If you go with Lifepo4 batteries, a single 12V 100Ah should be enough. It’s roughly the equivalent usable power of (2) 6V 225Ah lead acid batteries.

Should be able to find a 280-300 W panel for cheap. Might even want 2 of them. The EasySolar can handle up to 700W.

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.

kiwi avatar image kiwi commented ·

Thanks @solardude

I think the EasySolar product has way more features and capacity than I'll make use of, but it's given me a steer in the right direction :-)

0 Likes 0 ·
kai avatar image
kai answered ·

Batteries will typically have a recommended charging current. If you have no other constraints, match the battery recommended charging current to the typical charging current from your chargers.

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.

Related Resources

Additional resources still need to be added for this topic