Powering portable AC from 18650 batteries

[spleenharvester]

We have a Fiat 500 with no aircon that is absolutely vile in the summer. Unfortunately we can't afford to part ex it for an aircon model, or splash out on the Ecoflow Wave air conditioner. However, what I do have at my disposal is three 36V 10S4P ebike batteries, each 360wh, 420wh and 500wh. My thinking was I can get this 780W 9000BTU air conditioner, parallel the batteries and power it through a 42VDC to 240VAC inverter.

I assume I will need a diode on the output of each battery to stop them backfeeding into each other. Will a large Schottky on each work or do I need an ideal diode?

Also does anyone know of a decent 42VDC to 240VAC inverter? I can only find generic models with few to no reviews...

Cheers

[eccerr0r]

the unit actually looks like it will fit one seat and actually is a ducted version so it actually could be self contained within the passenger compartment. still very unwieldy. At 780W this is just a hair over 1HP so technically ebike batteries are within normal power use oddly enough. Most likely you will need to go with mosfet rectifiers mainly for power loss, but high current schottkys would work, though you're probably best just to solder all the batteries together in parallel, the batteries will have better cycle life that way. Keeping them removable with diodes will reduce their individual lifetimes if you were still planning to use the packs as ebike batteries.

The set of all three would only last an hour of use. I suspect the duty cycle will be quite high in a hot car...

[sam_sam_sam]

I am not sure that you have enough battery power to run for very long periods of time and weather or not the compressor is designed for bouncing around in a car is another story

Do you have car junkyards if so it might make better sense to buy the hole air conditioning system and install it in your car because in this country they use one car body and it just the options that you choose make the difference now weather or not your country does the same thing is another story

If not find an alternative air conditioner system that is made to run 24 volt battery power one note about these compressors are designed differently than ones that plug into mains power supply and these compressor controllers do not seem to hold up very well

My son had bought one of coolers to have cold drinks when he was an owner operator of a semi truck driver and on this cooler I had to replace the compressor controller and it also failed in a very short time just be aware of these limitations about going down this road

[spleenharvester]

Cheers Sam. I did look into retrofitting AC but you need a load of parts from the junkyard and it could well end up being more expensive than a part-exchange for an aircon model.

I think I am just going to get a simple 12V fridge from a decent brand instead, this seems like a bit of a rabbit hole haha

[eccerr0r]

Also have to expel the hot air from any portable a/c or refrigeration unit so you will have to hang something out the window if you're not going to add in a condenser coil in the front...

[CapLeaker]

A 9000BTU air conditioner in a Fiat 500? Are you serious? Where are you going to:
A: Sit;
B: way too big air conditioner for that little car! I mean you can drive around with the windows open in the middle of the summer, the air conditioner on and still freeze you @$$ off inside the car!
C: You need a second alternator either a 24V or 48V, batteries (extra weight), inverter, or run straight 120VDC into the air conditioner.
D: I am sure that isn't street legal, having a window or house type air conditioner installed and drive around.

April fools was last month!?

[eccerr0r]

the unit actually looks like it will fit one seat and actually is a ducted version so it actually could be self contained within the passenger compartment. still very unwieldy. At 780W this is just a hair over 1HP so technically ebike batteries are within normal power use oddly enough. Most likely you will need to go with mosfet rectifiers mainly for power loss, but high current schottkys would work, though you're probably best just to solder all the batteries together in parallel, the batteries will have better cycle life that way. Keeping them removable with diodes will reduce their individual lifetimes if you were still planning to use the packs as ebike batteries.

The set of all three would only last an hour of use. I suspect the duty cycle will be quite high in a hot car...

[CapLeaker]

It be cycling on and off all the time. That costs extra power. Less cycling the better it is. Best would be no cycling at all, just an easy but constant run.

[spleenharvester]

Yeah we decided not to bother with this in the end lol. Just going to get a plain old 12V fridge and put some ice packs in it.