Hunter 37 — Chesapeake Bay Weekend Cruiser
sailboat · 12V system · Annapolis, MD
Weekend cruiser out of Annapolis. 200Ah LiFePO4 bank replacing the original flooded bank. Anchors out 2 nights most weekends, club dock midweek. 300W rooftop solar + alternator handles weekend turnaround.
Daily load
1,634 Wh
Daily Ah
136 Ah
Battery
400 Ah LiFePO4
Solar
600 W
Load budget
| Load | Watts | Qty | Hrs/Day | Wh/Day |
|---|---|---|---|---|
| 12V Marine Fridge | 45 | 1 | 16 | 720 |
| Anchor LightCRITICAL | 10 | 1 | 10 | 100 |
| Tricolor Masthead LightCRITICAL | 12 | 1 | 10 | 120 |
| VHF Radio (Standby)CRITICAL | 5 | 1 | 24 | 120 |
| Chartplotter | 25 | 1 | 4 | 100 |
| Navigation LightsCRITICAL | 15 | 1 | 6 | 90 |
| LED Cabin Light | 5 | 4 | 4 | 80 |
| Phone Charger | 10 | 1 | 3 | 30 |
| Freshwater Pump | 60 | 1 | 0.5 | 30 |
| Bilge PumpCRITICAL | 30 | 1 | 0.3 | 9 |
| Stereo / Speakers | 25 | 1 | 3 | 75 |
| Laptop | 60 | 1 | 2 | 120 |
| Depth Sounder | 10 | 1 | 4 | 40 |
Battery bank
2 × 200Ah in parallel
Your daily consumption is 136Ah. With 2 days of autonomy, you need 272Ah of usable capacity. LiFePO4 (Lithium Iron Phosphate) batteries should only be discharged to 80% depth of discharge, so you need 340Ah of total capacity. We recommend a 400Ah bank (2 × 200Ah in parallel), giving you 320Ah of usable capacity — enough for 2 days without any charging.
Solar array
3 × 200W panels · 63A charge controller
Your daily consumption is 1634Wh. With 4.2 peak sun hours, a 75% system efficiency factor, and LiFePO4 (Lithium Iron Phosphate) round-trip efficiency of 96%, you need 540W of solar panels. We recommend 3 × 200W panels (600W total). This array will produce approximately 158Ah per day at 12V. You'll need a charge controller rated for at least 63A. MPPT recommended — higher efficiency at this array size.
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