Mobile Barista at wits end!

[Seb217]

All I want to do is sell coffee!!! ... yet I have found myself stressing about power supply!

I have a mobile coffee van. I'm done with using generators and so are many event/festival organisers who are now banning petrol/diesel from their sites. In an ideal world I would like a battery fed inverter to power all the equipment that I can't run on LPG.

I would like to achieve 1.5kW of power - I actually currently need 1.2kW of power (not all continuous) but want the extra to future proof against any further equipment that I may want to put on the van in the future.

I need to be able to have power for approx. 10hrs per day. I have sufficient space (but not endless amounts of) to house the batteries and inverter.

As all the equipment that requires power is plugged in to sockets on the walls of the van, can I plug the ‘hook up’ plug into the inverter?

I understand everything there is to know about coffee (and it's more of a science than many people may think) but I know nothing about power. Is there anyone that can please please help.

 

[Seb217]

You've not heard of a cafetiere then?

Personally, I'd rather have a nice cup of tea!

There are no words LOL
I sell tea too - herbal ones LOL

 

[Seb217]

WOW! Thank you so much for your extensive and very interesting and informative reply! It really is very very much appreciated!! Whilst I couldn't fathom most of the maths (without a lot more coffee), I'm coming to the conclusion that batteries aren't feasible.

I am struggling to find the Yuasa GC200 batteries for sale online.

Out of interest I looked up Li-ion ones and almost choked on my coffee!! LOL

 

[ferg]

How are you heating the water for the coffee?

 

[Seb217]

How are you heating the water for the coffee?

In the coffee machine - it has a 14L boiler heated by LPG - only 350w needed to run pump.

 

[ferg]

all becomes clear. Thanks.

 

[Charlie_]

We know a guy on here who can instantly boil water for free...
He’s definitely worth a shout!

You will need a pair of spoons

 

[littlespark]

We know a guy on here who can instantly boil water for free...
He’s definitely worth a shout!

You will need a pair of spoons

Problem with that is it’s perpetual. You can’t turn it off once it’s on.
That’s a lot of coffee to be drinking.


I would think that any event these days would offer a power socket for any exhibitor or caterer that required it.
If they are the ones that say you can’t use generators, they have to supply an alternative.

 

[Seb217]

Problem with that is it’s perpetual. You can’t turn it off once it’s on.
That’s a lot of coffee to be drinking.


I would think that any event these days would offer a power socket for any exhibitor or caterer that required it.
If they are the ones that say you can’t use generators, they have to supply an alternative.

Sadly it really doesn't work like that :-(

 

[Lucien Nunes]

I would run far far away from a 6v system. A 24 volt would be much better

I don't think anyone was suggesting using 6V, only building the battery out of 6V blocks.

I wonder if there is any way that you could make me understand why? The explanation will need to be very very basic

The lower the voltage, the higher the current required for a certain power (they are inversely proportional, half the voltage requires twice the current etc.). The higher the current, the greater the voltage drop in the resistance of the cables, isolator, inverter electronics etc. But at the same time, there's less voltage available to be dropped, e.g. 0.6V drop represents 10% loss at 6V, but only 5% at 12V and 2.5% at 24V.

The result is that for a given wiring setup, the losses decrease as the inverse square of the voltage. For a given wiring system handling a given wattage, doubling the voltage reduces the loss by a factor of four. Put another way, to achieve the same loss level, at 6V the wiring and accessories need to be 16 times as heavy as for 24V, meaning a lot of copper! FWIW there aren't 6V inverters, but even a 12V system requires four times the cable size and four times as many transistors in the inverter, etc, to achieve the same efficiency as a 24V equivalent. At low powers, this makes little difference. At the power levels you require, even 24V is copper-heavy and 48V would be better, although this tends to increase the cost and size of batteries because of the greater number of individual cells. I expect the happy medium would be 24V.

I am struggling to find the Yuasa GC200 batteries for sale online.

I just pulled the type number out of the Yuasa catalogue at random because it had nice round numbers. Their suggested application was automatic guided factory vehicles. There are hundreds similar.

 

[Seb217]

I don't think anyone was suggesting using 6V, only building the battery out of 6V blocks.


The lower the voltage, the higher the current required for a certain power (they are inversely proportional, half the voltage requires twice the current etc.). The higher the current, the greater the voltage drop in the resistance of the cables, isolator, inverter electronics etc. But at the same time, there's less voltage available to be dropped, e.g. 0.6V drop represents 10% loss at 6V, but only 5% at 12V and 2.5% at 24V.

The result is that for a given wiring setup, the losses decrease as the inverse square of the voltage. For a given wiring system handling a given wattage, doubling the voltage reduces the loss by a factor of four. Put another way, to achieve the same loss level, at 6V the wiring and accessories need to be 16 times as heavy as for 24V, meaning a lot of copper! FWIW there aren't 6V inverters, but even a 12V system requires four times the cable size and four times as many transistors in the inverter, etc, to achieve the same efficiency as a 24V equivalent. At low powers, this makes little difference. At the power levels you require, even 24V is copper-heavy and 48V would be better, although this tends to increase the cost and size of batteries because of the greater number of individual cells. I expect the happy medium would be 24V.



I just pulled the type number out of the Yuasa catalogue at random because it had nice round numbers. Their suggested application was automatic guided factory vehicles. There are hundreds similar.

Thank you once again for the lengthy and detailed reply and understandable explanations

No pressure, but if you had my set up, what would you have? (I trust and respect your advice/opinion)

 

[mattg4321]

I suspect you are going to end up back where you started with a portable petrol inverter generator like everyone else.

IMO there is no sensible alternative other than power being supplied by the site.

 

[Lucien Nunes]

if you had my set up, what would you have?

A Showmans steam road loco. Loads of hot water available free from the injector spill, up to 30 kilowatts of leccy from the dynamo, handy puffs of steam from the water gauge blowdown for frothing milk, enough grunt to pull a dozen vending trailers and a unique atmosphere and selling point. You could italianise the name to make it seem more authentically coffee-related. 'Avelino e Portio - caffè cilindrico direttamente dal motore'.

 

[Seb217]

A Showmans steam road loco. Loads of hot water available free from the injector spill, up to 30 kilowatts of leccy from the dynamo, handy puffs of steam from the water gauge blowdown for frothing milk, enough grunt to pull a dozen vending trailers and a unique atmosphere and selling point. You could italianise the name to make it seem more authentically coffee-related. 'Avelino e Portio - caffè cilindrico direttamente dal motore'.

... and if I can't find one of those on eBay?

 

[Lucien Nunes]

LPG Honda?

Or Nuclear. We haven't done a feasibility study on that yet. Compact, silent and long-lasting... RTGs work in space probes so they might work for you.

 

[ruston]

I had a nuclear scan a few weeks ago it is harmless too. takes about five hours to get into the system though , so you might have a bit of a queue.