Portable aircon and power supply

[leopardchaser]

Hello all.  Tvan newbie here, thanks for this great resource.  I have a 2024 build Firetail Mk5. I don't really understand vehicle electrics that well.  200Ah lithium and 2000W inverter in the Tvan

I would like to run a Cybertake S1 or S2 pro portable aircon on those really hot nights.
https://cybertake.com.au/products/s1-pro 
Its 48V, uses max 550W at initial peak and 100-150W when running on Eco mode.  Supplied with a 240V adapter. A 12V to 48V booster with Anderson plug is available to run off a battery without using the inverter. So it would seem the current is about 12A max and 3A in Eco if my maths is correct..

My questions are:

- Can I use the cigarette socket above the Redarc panel to run this via the booster? What's the max current the cig socket can safely manage?

- Has anyone retro-fitted a 50A rated Anderson plug in their van?  How did you do this?

- Running off the inverter would be the easy option, but any idea of the relative power loss doing this, compared with using the 12-48V booster?  Is there much difference in efficiency?

Thanks in advance

Paul

[robstevens]

As a rule, only use cigarette lighter sockets for a max of 10Amps as this is all they are designed for.

I'd Install a separate Andersen plug instead, with a 50Amp fuse, direct to the battery - keeping the leads as short as possible to minimize current losses...

Just had a look at their website... as you have a 12volt system, and the air conditioner (S1 or S2) uses 550 watts which translates to 45 Amps at 12 volts - so that's fine but if you have a 200Ah lithium battery, it will last under 5 hours from full to empty... just saying! Your calculations of 12 Amps is for a 48volt system. You have a 12 volt system so multiply the amps needed at your battery by four!

[leopardchaser]

As a rule, only use cigarette lighter sockets for a max of 10Amps as this is all they are designed for.

I'd Install a separate Andersen plug instead, with a 50Amp fuse, direct to the battery - keeping the leads as short as possible to minimize current losses...

Just had a look at their website... as you have a 12volt system, and the air conditioner (S1 or S2) uses 550 watts which translates to 45 Amps at 12 volts - so that's fine but if you have a 200Ah lithium battery, it will last under 5 hours from full to empty... just saying! Your calculations of 12 Amps is for a 48volt system. You have a 12 volt system so multiply the amps needed at your battery by four!

Thanks for that. So I need a 50a Anderson..
However, the device only draws 100-150W in eco mode. So I should be able to get 8h at 150W easily?

[luke]

It'll run fine, but the challenge isn't usage, it's putting the energy back in.

• Yes. Use a 50A Anderson.
  Yes there are other ways to do it, and yes you don't actually need the full 50A throughput, but the start-up current exceeds a cig-plug rating.
  Andersons are also common, robust, and give you flexibility in the future.
  
  • As suggested, wire it separately with its own fuse. I prefer a 'MIDI' fuse, but a Maxi will also work.
• Yes — assuming ~150W in Eco mode, you should get ~13–14 hours.
  Caveat: This is effectively a one-shot (or two ~7-hour sessions). Without a lot of solar or driving, you'll be going backwards each day.
• Start to add 'accessories' (like a fridge), and the numbers only get worse.
• Adding an extra anderson
  Assuming the MK5 is similar to the MK4, the batteries are commonned in the drivers side battery box.
  Just add an extra cable there for your fuse, and run the cable to wherever you need. (I'd avoid taking the electrical panel apart if possible)
• The MK4's already had an anderson on the outside next to the 240V inlet, so you could repurpose that.
  I added an extra anderson internal to the drivers side hatch, but that means you'd need to leave the hatch open.

High-level explanation
(Averaged numbers)

Lithium basics

• Voltage
  Lithium runs at a higher voltage, so I'll assume ~13.5V
  (NOTE. This is optimistic, especially if you're draining the battery down to 20%)
• Discharge Floor
  You can safely discharge lithium's further than lead-acid, but how much depends on the make / model, and lifespan may be affected.
  I'll assume a 20% floor (Maximum of 80% usable power)
• Capacity
  Based on the above, this gives you ~2,160 WH to use.
  200Ah × 13.5V × 0.8 ≈ 2,160Wh

Usage

• I'll assume worst case Eco draw of 150W
• Runtime
  With nothing else running, that's ~14 hours max
  2,160Wh / 150W ≈ 14 hours
• Any other loads reduce this (e.g. a fridge can average 20–60W per hour)
  
  • As this is for summer use, we'll assume a worst case of the fridge at ~60w per hour, which reduces the max Eco time from 14 hours down to ~10 hours

Recovery
(this is the real limitation)

• 8 hours of Eco use = ~1,200Wh of power you need to replace
• Solar:
  (Both assume no other loads, good solar orientation, and realistic averages for VIC summer (but do not account for shade, overcast, etc))
  (Assumes peak VIC summer output of up to x5-x6 solar output per day (vs. x~3 in winter))
  
  • Using the Standard 120W solar
    ~550-700Wh/day will require ~1.5-2 days to recover 8h Eco use
  • Just adding a fridge (no other loads), this is now ~2.5–3 days to recover
  • If you've got the 200W solar upgrade
    ~900-1,200Wh/day → ~Just over 1 day to recover 8h Eco use
  • Adding a fridge (no other loads), this is now ~1.5–2 days to recover
• Alternator charging:
  Assuming the 40A Redarc BC-DC charger, set to max current and with appropriate cabling, alternator, etc.
  1,200Wh / 540W ≈ 2–3 hours of driving
• Adding a fridge (no other loads), this is now ~3-3.5 hours to recover

I'm sick, so probably worth sanity checking the numbers above, but as mentioned, what ever you take out you need to put back in . . . .

[luke]

I can understand why you want the aircon, but by comparison the Caframo Sirocco fans only use ~1.4W on low, up to ~4.2W on high.

Table taken from manual Sirocco

Fan Speed	Current Draw (Amps) – 12 Volt	Current Draw (Amps) – 24 Volt	RPM (12 & 24 Volt)
Low	0.12	0.06	1100 ±100
Medium	0.22	0.11	1400 ±100
High	0.35	0.21	1700 ±100

And double the numbers again for His and hers 

[leopardchaser]

Wow thanks for the detailed response. Very useful.