24V Electrical Concept

Assumptions

• 24V 400AH LFP
• 24V Fridge and Freezer
• 24V Water Pump (Shurflo makes them)
• Multiplus 24/3000/70 ($1,284)
• 24V Alternator
• 2+ 24/12-25 Orion DC-DC Converters (2*75$) or 1 480W 24V to 12V for ($38) (see 48V concept).
• Smart Solar 150/45 ($450)

Open [or now closed] Questions

• Does REC BMS that supports 24V also support Victron? Yes
• Does Wakespeed 500 support 24V? Yes according to Nation's? Yes according to Nations and Wakespeed manual.
• Availability of 24V alternator for 2021 Transit: According to a 10-27-2020 discussion with Nations, the only 24V alternator available that is compatible with the 2020 Transit is the 55XP-WS500 serious which is $3299.95. Not verified: Compatibility with 2021 3.5 Ecoboost, Price of 2nd alternator bracket, and whether price includes wakespeed 500. According to a 12-11-2020 email with Adam Nations, they can do a 24V alternator capable of 150A (would like to see power curve) that will fit an Ecoboost. Also if desired, and perhaps as a place holder until the 2^nd alternator is installed and integrated, I could run an orton-system that could provide an additional 50A or so off the factory alternator (perhaps with an automatic transfer switch with normal shore power with aux contacts and a thermal based contact to adjust Multiplus current limit when powered in orton-mode).

Benefits

• MPPT is 3 kg and 4393750 mm^3 and ~$450 for 24V vs 4.5 kg and 6563160 mm^3 and $700 for 12V

• Alternator line temperature rise will be 1/4 of 12V for equivalent wire.

Other Notes

• I don't think the latching relay approach is worth the complexity. GigaVac makes contactors in the MX line that have 24V high efficiency coils (GigaVAc MX14,MX64,MX15 - NO, I=400A, P_{coil_48V_listed}=2.0W, P_contact@400A=60W, R_{contact_max}=0.375ohm). TYCO has a nice option as well: TYCO makes an attractive option - KILOVAC EV200: P_{coil_24V_listed}=1.7W, P_{contact_typ@400A}=32W, R_{contact_typ@200A}=0.2mOhm.

Similar/Equavalent Wire Comparisons:

12v to 24v Equivalent Voltage Drop % and Equal Loss for the Same Transmitted Power

V=IR. Because I has decreased by 1/2 and Vsource has increased by 2, to achive the same fraction of Vsource/Vdrop, Vdrop must also double. This implies R must increase by a factor of 4.

P = R*I². I has decreased by a factor of 1/2, thus I² has decreased by a factor of 1/4. This implies R must increase by a factor of 4.

4/0 becomes 2 AWG

2 AWG becomes 8 AWG

8 AWG becomes 14 AWG

12v to 24v Equivalent Ampacity for Same Power

4/0 becomes 2 AWG

2 AWG becomes 6 AWG

8 AWG becomes 14 AWG