Looking for any feedback and advice on my ideas on upgrading the electrical system on my yacht.
Currently I have 2x110Ah FLA house bank and 1x110Ah SLA engine start bank. Connected through a 1-2-both isolator.
Charging sources are the alternator, plus a Marlec PWM charge controller. Originally was configured for a 30w PV plus a wind turbine. The turbine died and I have temporarily added a 100w PV which goes through the Marlec. However in the long term I will use that input for a towed generator.
Next year we plan to start living aboard the full time and cruising, heading for the tropics. We don't expect to use shore power often if at all, and we really do not want to rely on the engine for charging.
So here's my plan for the upgrade:
- install another three PV panels (100+300+300), bringing the total to about 830w
- install an Epever 60A MPPT charge controller linked to the four large panels (leave the small one on the old controller)
- use the MPPT to charge a 4S bank of LFP cells, probably 200-280Ah.
- connect the LFP cells via a low voltage cutoff device to the high-current but non-critical loads, e.g. fridge, inverter, laptop charger.
- as and when necessary, use a B2B charger to transfer power from one bank to the other. Ideally I would trickle charge the lead-acids most days to get them to 100% SOC and thus prolong their lives.
The LFP bank could be drawing up to 250A (mostly through the inverter) so the low-voltage protection has to be beefy, and this is probably going to be my biggest headache. I would use a Victron battery protector but they max out at 220A. Or perhaps I could find an inverter with a built in low voltage disconnect.
I'd appreciate any feedback at all on my ideas.
(One other thing- I could actually go 24v on the new lithium system, which helps on the max current draw but at the risk of overcomplicating things. It also means I can't in future swap loads from one bank to another. All in all a solution that I don't really want to pursue unless I have to).
Currently I have 2x110Ah FLA house bank and 1x110Ah SLA engine start bank. Connected through a 1-2-both isolator.
Charging sources are the alternator, plus a Marlec PWM charge controller. Originally was configured for a 30w PV plus a wind turbine. The turbine died and I have temporarily added a 100w PV which goes through the Marlec. However in the long term I will use that input for a towed generator.
Next year we plan to start living aboard the full time and cruising, heading for the tropics. We don't expect to use shore power often if at all, and we really do not want to rely on the engine for charging.
So here's my plan for the upgrade:
- install another three PV panels (100+300+300), bringing the total to about 830w
- install an Epever 60A MPPT charge controller linked to the four large panels (leave the small one on the old controller)
- use the MPPT to charge a 4S bank of LFP cells, probably 200-280Ah.
- connect the LFP cells via a low voltage cutoff device to the high-current but non-critical loads, e.g. fridge, inverter, laptop charger.
- as and when necessary, use a B2B charger to transfer power from one bank to the other. Ideally I would trickle charge the lead-acids most days to get them to 100% SOC and thus prolong their lives.
The LFP bank could be drawing up to 250A (mostly through the inverter) so the low-voltage protection has to be beefy, and this is probably going to be my biggest headache. I would use a Victron battery protector but they max out at 220A. Or perhaps I could find an inverter with a built in low voltage disconnect.
I'd appreciate any feedback at all on my ideas.
(One other thing- I could actually go 24v on the new lithium system, which helps on the max current draw but at the risk of overcomplicating things. It also means I can't in future swap loads from one bank to another. All in all a solution that I don't really want to pursue unless I have to).
