Atomvoyager
New Member
- Joined
- Sep 5, 2021
- Messages
- 14
(Update - new here and didn't see the Marine section. I reposted this there but don't see how to delete this one. Maybe the Admin can do that.)
I'm installing 220w of 12v solar on a boat with 200AH of 12v lithiums for house and 100AH AGM for engine. I want the two banks completely isolated for simplicity and fail-safety, not using a 1-2-off-Both switch because in Both position it could cause problems with different battery chemistries. I'll have two separate on/off switches instead. I plan to have the engine alternator output to the AGM with a Renogy 40A battery to battery charger to charge the Lithium bank when engine is on. That way the engine alternator is protected from a BMS cutout failure.
All other charge sources (MPPT solar controller and stand alone 10A mains battery charger) will go only to the lithiums, as well as all loads other than engine starter (switch panel and stand-alone 1000W pure sine wave inverter).
My question is what is the best way in this layout to solar charge the AGM to deal with self-discharge and ensure it is always topped for engine starting? I see the following options:
1. Install a dual output Lithium compatible MPPT to both banks. The only one I found so far is the expensive and big Xantrex 30A #710-3024-01. Together with the remote display it's $245 and is overkill at 30A. A 20A version that's less expensive and smaller size would be more appropriate. Does anyone know of another option in lithium dual output MPPT?
2. Perhaps I could run the MPPT instead to the AGM bank and and have a separate switch to energize the battery to battery charger but that seems inefficient.
3. Or use a second battery to battery charger from lithiums to AGM. Again that seems inefficient.
4. Another option is to use my existing Epever MPPT to lithiums only and ignore the problem and make sure to start the engine at least once a month to ensure it stays charged. In the rare event it became too discharged to start the engine then the wires from solar, shore charger, or lithiums could be transferred and used to start the engine. That seems least desirable and troublesome if the boat was left unattended for several months and the AGM self-discharged.
5. Or plug in a 5-10A shore power charger into the invertor to charge the AGM from the Lithium. Probably very inefficient but doable on those rare times it's needed.
We're setting up the boat for live aboard mainly on the hook and only occasionally in the marina with shore power. I'm familiar with solar and 12v marine wiring but have no experience in mixed battery banks so would appreciate any recommendations.
I'm installing 220w of 12v solar on a boat with 200AH of 12v lithiums for house and 100AH AGM for engine. I want the two banks completely isolated for simplicity and fail-safety, not using a 1-2-off-Both switch because in Both position it could cause problems with different battery chemistries. I'll have two separate on/off switches instead. I plan to have the engine alternator output to the AGM with a Renogy 40A battery to battery charger to charge the Lithium bank when engine is on. That way the engine alternator is protected from a BMS cutout failure.
All other charge sources (MPPT solar controller and stand alone 10A mains battery charger) will go only to the lithiums, as well as all loads other than engine starter (switch panel and stand-alone 1000W pure sine wave inverter).
My question is what is the best way in this layout to solar charge the AGM to deal with self-discharge and ensure it is always topped for engine starting? I see the following options:
1. Install a dual output Lithium compatible MPPT to both banks. The only one I found so far is the expensive and big Xantrex 30A #710-3024-01. Together with the remote display it's $245 and is overkill at 30A. A 20A version that's less expensive and smaller size would be more appropriate. Does anyone know of another option in lithium dual output MPPT?
2. Perhaps I could run the MPPT instead to the AGM bank and and have a separate switch to energize the battery to battery charger but that seems inefficient.
3. Or use a second battery to battery charger from lithiums to AGM. Again that seems inefficient.
4. Another option is to use my existing Epever MPPT to lithiums only and ignore the problem and make sure to start the engine at least once a month to ensure it stays charged. In the rare event it became too discharged to start the engine then the wires from solar, shore charger, or lithiums could be transferred and used to start the engine. That seems least desirable and troublesome if the boat was left unattended for several months and the AGM self-discharged.
5. Or plug in a 5-10A shore power charger into the invertor to charge the AGM from the Lithium. Probably very inefficient but doable on those rare times it's needed.
We're setting up the boat for live aboard mainly on the hook and only occasionally in the marina with shore power. I'm familiar with solar and 12v marine wiring but have no experience in mixed battery banks so would appreciate any recommendations.
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