pilotfish Posted August 23, 2019 Share Posted August 23, 2019 Hi All, long time since I have been active on the forum So I have a question for the more electronically enabled minds out there - I need to upgrade the power on a decades old yacht that will be cruising oceans without regular access to shore power. Referring to the attached line diagram you will see that there is 1.15kWp of solar which will charge a 48v 4.8kWh Lithium bank via MPPT (there are 2 heavy loads - a windlass to raise/lower the anchor (1.2kW) and an RO water-maker (1.2kW) - these will both be 48v in order to limit high currents otherwise required). There is also a 72v 60amp alternator which will be connected to the MPPT PV input via a C/O disconnecting PV when the motor is running. Question 1 - any concerns having a 72v automotive alternator as PV input to an MPPT charge controller? Additionally there will be a 12v 2.4kWh lithium bank that is to be charged via a 2nd MPPT with the 48v bank as input source. The 12v bank is for critical loads (navigation, communication, bilge pumps etc), so it will be quite convenient to have the 48v bank as primary source keeping the 12v bank fully topped until the 48v bank fails - the 12v bank therefore acting as a "reserve tank". I see no problem using a the 48v bank as power source for the 2nd MPPT unless anyone is able to advise otherwise. To further complicate matters there is a 24v engine-start bank which can no longer be charged by the engine alternator as this is now 72v! so I would like to charge this bank using another charge controller with the 48v bank as source (only active when ignition switch is on). Question 2 - any issues with connecting the PV input of 2 separate MPPT to a single battery bank. If yes would a PWM charge controller for the 24v bank be an option? Early draft of Line Diagram attached - thanks for looking Bella Luna Power.pdf Quote Link to comment Share on other sites More sharing options...
Youda Posted August 23, 2019 Share Posted August 23, 2019 (edited) 12V 24V 48V 72V.... It's not a boat anymore...rather a floating RadioShack, I would say Edited August 23, 2019 by Youda Quote Link to comment Share on other sites More sharing options...
pilotfish Posted August 23, 2019 Author Share Posted August 23, 2019 I like to keep my options open You left out 220v from MPPT/Inverter #1, and 110v from MPPT/Inverter #2!!! Quote Link to comment Share on other sites More sharing options...
pilotfish Posted August 23, 2019 Author Share Posted August 23, 2019 ...not without reason tho. The 48v is for the 48v windlass and water-maker, and because it makes a great main battery, The 72v alternator is needed to be able to charge the 48v main battery, The 12v is because all critical systems nav/comm/bilge/etc run on 12v and would cost R100'sK to change, The 24v starter battery is because grunt needed to start the 120hp Perkins, The 220v is for RSA/Europe shore power and charging when available, The 110v is for USA shore power and charging when available. As for "Radio Shack", there is VHF for short range comms, HF/SSB for long range comms and weather, AIS, GPS, Epirb, Radar, Sonar, FM radio and not to forget Wifi - so fair comment I guess Quote Link to comment Share on other sites More sharing options...
Jaco De Jongh Posted August 23, 2019 Share Posted August 23, 2019 6 hours ago, pilotfish said: Additionally there will be a 12v 2.4kWh lithium bank that is to be charged via a 2nd MPPT with the 48v bank as input source. 6 hours ago, pilotfish said: any issues with connecting the PV input of 2 separate MPPT to a single battery bank. What equipment are you referring to? If its Victron, your plans will work. The Victrom MPPT's works fine with the 48Volt as Source and will limit the power in to its power out rating, so it will never take more from the bank that what it can give out. I am running a 12volt buss through my house that use to charged from the 48Volt bank using a Victron Mppt. If you are referring to another brand, I am not sure how other Mppt's will handle this. Youda 1 Quote Link to comment Share on other sites More sharing options...
pilotfish Posted August 23, 2019 Author Share Posted August 23, 2019 1 hour ago, Jaco de Jongh said: What equipment are you referring to? MPPT#1 will be a WRND 48v/30amp and MPPT#2 will be a WRND 12v/40amp. I have used a couple of WRND units in the field for charge only applications (no inverter requirements) and have had no comeback issues - I was able to order with conformal coating and adjust voltages to suit my lithium charge profile which swayed my decision to go with these units (and they are pretty cost effective which didnt hurt either). Quote Link to comment Share on other sites More sharing options...
___ Posted August 24, 2019 Share Posted August 24, 2019 12 hours ago, pilotfish said: have had no comeback issues I was pretty appalled at the quality of an earlier unit I took apart some years ago, but of course things do evolve and get better, so I reserve judgement on the newer models Quote Link to comment Share on other sites More sharing options...
pilotfish Posted August 24, 2019 Author Share Posted August 24, 2019 2 hours ago, plonkster said: I was pretty appalled at the quality of an earlier unit I took apart some years ago I think it is time for you to do that again and let us know! Quote Link to comment Share on other sites More sharing options...
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