I purchased a 1991 Contest 35s sailboat at the end of last season, and she's now on the hard, and being refit for this coming season. Which includes an electrical refit. Currently, all 3 Group 31 batteries are housed in an open top fiberglass battery box with straps, (factory installed), under the aft-berth. She has the factory DC panel, and an added 120v shoreside system, with a 30amp inlet and a separate single main AC breaker, (which isn't a double pole breaker). Her electrical inventory includes;
- Starter Battery - West Marine Seagel Deep Cycle Gel 97
- House Bank - 2 Deka Dominator (8G31DTM) in parallel
- Perko 1-2-All Battery Switch
- Amptech 125/108 High Performance Alternator
- Heart Interface incharger 3 stage Alternator Regulator (84-2006-00)
- Guest Charge Pro 5/5 10amp Charger
- 2 - 80 Watt MBF80 Solar Panels
- Xantrex C12 12 amp Solar Charge Controller
I can appreciate the logic in working backwards from accurate calculations of how much electricity needs to be consumed, and designing an electrical system to support that consumption. However, there are a number of electronic upgrades that I want to add in the future, such as air/heat, water maker, television (DC), upgraded entertainment system (Fusion MS-AV700i), and updated nav electronics, but initially this refit will focus on upgrading the electrical foundation of the boat. I've been trying to identify the components I should consider upgrading, (mostly after reading threads here), but I still have some questions.
A house bank of 3 AGM Group 31 batteries fits in the existing battery box, and can provide 375ah. If I could make the box deeper, I could accommodate 3 Group 30HTs for a total of 450ah, but the original box would probably need to be cut out, and a custom box built. This may force me to go with the 3 Group 31 375ah house bank, then house a single AGM Group 31 100ah starter battery close by, in it's own battery box or tray. With the switch to AGMs, I thought that I should upgrade the engine with a serpentine belt kit, and a higher output alternator with regulator, (150amp+), as well as upgrade the charger. I also wanted to upgrade the panel to a combined AC/DC, Blue Sea Systems 360 panel, and add a Blue Sea Systems Dual Circuit Plus Battery Switch with an Automatic Charging Relay.
The current system appears to provide AC power to only the water heater and the 2 AC outlets on the boat, but only when the boat is plugged in. As part of this refit, I do want to add a couple more AC outlets, but I also want to add DC USB charging outlets for charging tablets and phones, (and in the near future for laptops, too
). I also want to add DC electronics where it makes sense, such as the JVC DC TV when I get to that project. Even though I'm trying to design a system that minimizes the need, I believe I will need AC power underway. Which means adding an inverter to this system. At this point I'm curious about a few things;
- Is adding a serpentine belt kit, (and alternator), a better choice than simply adding a higher output marine alternator, (or keeping the existing one)?
- Are high output marine alternators from Electromaax, and Sterling Power, good ones to consider for this application, (since they price out less than Balmar)?
- Is it sensible to combine inverter and charger by installing something like the ProMariner TruePower CombiPS for this application?
Any other suggestions, corrections, etc., are welcome as always.