Engine Conversion from 12v to 24 v dc

[stefano_ita]

Hi all

I was looking for a beta marine 60 engine, base price 10.000€ + vat, with 12 V system and a 65 amp alternator.

Optional
120 amp 400 euro in stead of std alternator
175 amp 600 euro the same as up

2nd 175 amp alternator complete with pulley and belt, mounted, without voltage regulator 800 euro

Extended crankshaft for PTO 180 euro
(all the price above + 22% vat)


I asked for the same engine with just one 24 v 100 amp alternator and all the 24v system =12.000 € + vat...WTF

The question is:

Aknoledged that that price are redicolous, and a 24v 100 amp for bus cost 250 euro, what would you do for live with a 21,2 kwh pb battery pack (so about 10 kwh, max 50% DOD, included 1kw wind and 1 kw solar panels)?

Live aboard with all conforts, a/c, washing machine, induction cooking, and 24 V dc to 230 v ac inverter are far way better than 12V due the many amps involved...

Options i thought

1- Original engine with 12 V system and PTO, add 2x bus 24 v 100 amp by myself, keep light and instrument in 12 V (2x200 amp battery, 150/200watt solar panel), only domestic in 24V with 18kwh and a bit less solar panel power. (what a mess)


2-Original engine with 12 V system with optional 175 amp alt, plus 2nd 175 amp alternator, easy but 12 v to 230 v ac inverter are bad, need to keep al close, big wire, ecc


3- The expensive 24V 100 amp option with PTO and pulley and add another 100 amp bus alternator (far easier system, less complex, i'd be for this but not 100% sure )


An advice on what is better knowing that diesel don't like to run without load:

-Keep the engine running for half hour or more if needed at 1500-1700 rpm (gearbox in neutral) and get full power from the alternator

Or

- Let the engine run in idle for more time with the alternator producing less power but longer?

Thanks all
Stefano

[smac999]

do you already have a 24v house bank?


I would put in the 12v engine with small alternater to charge the engine battery and add a 24v alt to charge the house bank. get the pully / belt system for 2nd alt from them.

[stefano_ita]

No, still planning.

Space only for 6x 12v 200ah...

I'm worried if the 12v battery gets too low....but don't want to add solar or wind... Could use a 12v battery of the 24v bank as jump starter in case of emergency... Any idea?

[smac999]

if you have nothing and boat is under 70 ish feet just do all 12v.


everything else on the boat is probably 12v

[stefano_ita]

Yes you are right,

Tt's a 46 ft boat loaded like a 70's one

Meaning 3 x 3kw 230v ac inverter....I must find a way to put batteries as close as possible to engine(but in isolated area for heat) and also the inverter...maybe all connected with alluminium bar in stead of copper wire...(even alluminium has a bit more of resistence 0,26 vs 0,16, it's easier to find and to get it in large section bar)