Van of enormous power Mk 4

[Stinsy]

Looking at DC side today and I'd need some serious cables to run a 1kW inverter.

Had a look and the 3way fridge runs at 125W consumption in 230Vac mode. 3kWh per day if no solar..

Well I'm not going to be specifying the system to run at that as I won't have physical battery space to meet the capacity req'd. Even on a 10hr sun Med day I'd be needing 1.75kWh.

I guess the spec will be dropped back to somewhere around a 700W inverter. TBH I could probably get away with 600W. I'll see what the cable calc says.

Edit- the cable calc says 25mm sq @ 600W and 35mm sq @ 750W. Both at 4mtr 1 way runs.

Massaging the figures to 750W inverter 3.5mtr run (one way) and 12.8V squeaks me through the door at 25mmsq cable.

https://www.fabhabs.com/dc-cable-sizing-calculator

I'm pretty happy with that. I can run the fridge up on gas to get cool and then maintain off the LB. I'll have a dig in about and see how it's wired to the 240V ehu and install a manual selector switch for offgrid.

Does anyone have experience on a decent inverter manufacturer? I'll go for 750W since the cable will support that size. At this size I can run a 500W electric heater (not for long), but at least if push comes to shove and we've run out of gas on a Winter time away we can knock the edge off until refilled.

Don't forget the fridge won't run constantly. It'll probably only run for 15 mins in any hour unless you put a load of warm beers in there or leave the door open.

[Joeboy]

Looking at DC side today and I'd need some serious cables to run a 1kW inverter.

Had a look and the 3way fridge runs at 125W consumption in 230Vac mode. 3kWh per day if no solar..

Well I'm not going to be specifying the system to run at that as I won't have physical battery space to meet the capacity req'd. Even on a 10hr sun Med day I'd be needing 1.75kWh.

I guess the spec will be dropped back to somewhere around a 700W inverter. TBH I could probably get away with 600W. I'll see what the cable calc says.

Edit- the cable calc says 25mm sq @ 600W and 35mm sq @ 750W. Both at 4mtr 1 way runs.

Massaging the figures to 750W inverter 3.5mtr run (one way) and 12.8V squeaks me through the door at 25mmsq cable.

https://www.fabhabs.com/dc-cable-sizing-calculator

I'm pretty happy with that. I can run the fridge up on gas to get cool and then maintain off the LB. I'll have a dig in about and see how it's wired to the 240V ehu and install a manual selector switch for offgrid.

Does anyone have experience on a decent inverter manufacturer? I'll go for 750W since the cable will support that size. At this size I can run a 500W electric heater (not for long), but at least if push comes to shove and we've run out of gas on a Winter time away we can knock the edge off until refilled.

Don't forget the fridge won't run constantly. It'll probably only run for 15 mins in any hour unless you put a load of warm beers in there or leave the door open.

Aye, and tbh I'm unlikely to ever be seriously impinging on the inverter capabilities. I think I'm going to treat myself and go for the Victron 12V/800W pure sine wave inverter. I have had a look around this morning and there's only about £20 difference and 200W between Victron offerings and Chinese units.

I did see a unit on Amazon US, had great orientation connectivity & usb ports but can't find it with a UK voltage spec.


At least with the Victron gear I'll have app access to data, although I'm a fool.for a brightly coloured lcd screen.

Now away to work out the difference between Phoenix & V.E direct inverters...

Edit- Still unsure of the difference between phoenix & V.E. defo need to.buy a Bluetooth dongle too for apps comms. That's another 50 Euro on top.

So that's 300 Euro for a unit that can output a consistent 650W at 25degs and speak to my phone app, has one 230V output and no usb unless I pay out again. That would be me up to about £360 to have usb too and 1 230V socket.

This 1kW unit is £160 off Amazon AND it has a bright colourful screen.

[Joeboy]

The Amazon unit had a £30 voucher on it so £130 was the cost. It's meant for 100 to 120Ah battery so I'll have to adjust my expectations (learn).what's what on the gauge once I upgrade order from Colin.

The Victron add ons were too much for me to swallow so it's bright screen time when I open the utility door.

There is a 16ft cabled remote screen too but I'm not fancying drilling holes just for that.



Ah well, in for a penny...
This does come with Bluetooth built in.



Running total
£165 Bifacial 195W panels 2 of
£34 DC isolator, cable entry & Y's
£130 1kW inverter
£67 MPPT Charge controller
£396

I can get this all fitted in between other tasks and test it on the current 100Ah LA LB.

To hit 800W load at 3.5mtrs 1 way cable length I'd need 35mm sq cables. I'll make up a cable out of PV cable see if I can get the run length down to 25mm sq territory. I'd shift the inverter closer to the battery or vise versa but tbh it's a hassle I could live without and I'd rather that all will be mounted in the utility cupboard with the DC cables going forward to engine bay under van.

Edit- just checked and a 3mtr run drops in at 25mm sq whereas a 3.5mtr run is 35mm sq. Most of the run will be under the van and exposed to air as well as 99% of the time we'll be running a few hundred W's so I think I'll risk the 25mm sq over distance

Aliexpress freaked me out with the insane low pricing and huge lies of power outputs. Instead I went to the security of Amazon Warranty. Old Jeff B eh? Some shopkeeper that.

[AGT]

Plastic kopex is cheap and good for additional protection for cables fixed underside of vehicles.

[richbee]

240v inverters & wiring seems to be where things get expensive if you want high power levels.
I guess you don't want to either, replace the fridge with a 12v one - or go for 24v battery setup to allow easier wiring for the inverter?

I was surprised, when looking at 1kw or 2kW inverters, how relatively low power outputs they would maintain for a serious period of time.
I was wondering if it was sensible to aim for gas-free cooking in van 2 with an induction hob, but decided that probably by the time I add more solar, bigger mppt, more batteries, bigger inverter & associated wiring etc etc, the cost would get prohibitive....

[Andy]

I presume there is a reason you are running 4m to the inverter and not putting the inverter in with the batteries and running the 230V wiring from there.

[Joeboy]

I presume there is a reason you are running 4m to the inverter and not putting the inverter in with the batteries and running the 230V wiring from there.

"I'd shift the inverter closer to the battery or vise versa but tbh it's a hassle I could live without and I'd rather that all will be mounted in the utility cupboard with the DC cables going forward to engine bay under van."

The inverter needs to be inside the monocoque. The existing LB wiring is already in the engine bay. Simpler to just pay for a longer run cable size.

[Joeboy]

240v inverters & wiring seems to be where things get expensive if you want high power levels.
I guess you don't want to either, replace the fridge with a 12v one - or go for 24v battery setup to allow easier wiring for the inverter?

I was surprised, when looking at 1kw or 2kW inverters, how relatively low power outputs they would maintain for a serious period of time.
I was wondering if it was sensible to aim for gas-free cooking in van 2 with an induction hob, but decided that probably by the time I add more solar, bigger mppt, more batteries, bigger inverter & associated wiring etc etc, the cost would get prohibitive....

You are right, I don't want to replace the fridge as its working fine, it's a 3 way absorption unit and I already have 12V function for temp maintaining with engine running, the fast cool down of the gas side, and the ehu. Adding the extra offgrid capability to run alongside the ehu gives me a wide choice of scenarios covered. I hope to pull it down to temp with ehu at home or on gas when away for longer then maintain with the LB/solar.

I also noticed the huge step up in price as we go up the power scale.for inverters & cables. My old van had a 500W inverter and it would alarm sometimes depending on what I was doing. Now I run a travel kettle, small oven and will likely look into a single plate induction hob if I can find a 500W capable unit.

I'll run some tests once the 1kW inverter unit is in and report back on when it stalls. Hoping for a reliable 800W out of it.

Truth is though that gas is much easier on a day to day basis in an RV. When No1 and I were away to Braemar in Jan it was great doing a fry up on gas with the extra space and washing the dishes on water heated off the ehu.

I reckon I'll be about £600 all in to have the PV choice in the van. I'm OK with that cost as I know it will reduce our gas consumption a lot. I'd be interested if you ever price up a bigger system Richbee? If even just to know how scary it can get. The other option that shows up sometimes on secondhand sites is utility van rip outs of inverters etc?

Thanks for the conduit tip.AGT, I'll look into it.

[Joeboy]

Well that's the buying fun out of the way. A question for any van owners or knowledgable folk. As I have an existing LB set up in the van I shouldn't need any extra control or relays?

Or do I?

My thinking is
The solar controller takes care of battery charge so as not to.overcharge whether as LA or lifepo4 (I choose setting in app) and the 12.8V of the potential lifepo4 is close enough in V rating to a LA. 14.4V or so off the alternator shouldn't cause a problem as the onboard bms will kick in if need be.

Anything else I'm missing?

Edit- interesting guide. I'll have a good look around the van and see what was fitted.

https://www.12voltplanet.co.uk/split-ch ... X6Ku6ewUnc

[Stinsy]

Well that's the buying fun out of the way. A question for any van owners or knowledgable folk. As I have an existing LB set up in the van I shouldn't need any extra control or relays?

Or do I?

My thinking is
The solar controller takes care of battery charge so as not to.overcharge whether as LA or lifepo4 (I choose setting in app) and the 12.8V of the potential lifepo4 is close enough in V rating to a LA. 14.4V or so off the alternator shouldn't cause a problem as the onboard bms will kick in if need be.

Anything else I'm missing?

Edit- interesting guide. I'll have a good look around the van and see what was fitted.

https://www.12voltplanet.co.uk/split-ch ... X6Ku6ewUnc

How are the systems setup at the moment?

Basically there are 3 options:
- Completely separate. Easiest way to do things but you lose the opportunity to charge the leisure battery from the alternator or the starter from the solar.
- Always connected. Basically the same as having a bigger starter battery. You risk draining the starter battery with the house loads.
- some sort of smart connection/disconnection. Traditionally this is a timer relay so the two systems are connected once the ignition has been on for 5-mins (or whatever) and disconnects the moment the ignition is turned off. Other people have a switch on the dash controlling a relay but this is open to human error.