Mobile coffee power problem.

[curbside coffee]

Thanks for the info. Could anyone tell me the benefit of going 48v instead of 12v?
Thanks.

 

[brianmoooore]

Size of cables, currents flowing through them and voltage drop as a percentage, are all reduced to a quarter.
It's the same reason that electricity is distributed around the country at such high voltages. (400,000 volts for the big pylons)

 

[pc1966]

What @brianmoooore said.

To get 3kW at 12V you need 250A (plus a bit more for conversion losses) and that is seriously thick cables and all of the issues that go with it. At 48V you are looking at 62.5A which is big, but within the cable size seen domestically (probably 16mm would do, depending on length and so voltage drop).

 

[curbside coffee]

I've been looking at hybrid All-in-one inverters, specifically the eco-worthy 3000w 24v pure sine wave inverter. QQ.
Could I wire my car alternator to this device without a b2b charger? (would it also be possible to add a small generator to boost the battery's?)
Would my 200w solar panels even register as input?
Could I run 4x12v battery's in parallel and series?

 

[marconi]

Pc1996 #13 has told you that the provision of 3kW at 240V from a 12V battery is not impossible but to be avoided because of the very high current drawn from the battery which will rapidly discharge it and the need for very short very thick cables to carry this large current at 12V. You would need a special battery to cope regularly with such prolonged high current otherwise its life will be rapidly consumed . My suggestion should have been clearer but I did give my car’s inverter and the knife grinder as an examples. Using you car battery perhaps supplemented by the engine generator is workable for up to about 500W for very short periods - the knife grinder example I gave or as in my car up to 150W for phones, lap top power supplies, tv, small fridge cool box maybe for a few hours but longer with engine running.

If one discharged the battery at a higher rate than the charging rate by the engine then over time it will become flatter and maybe then unable to start the engine nor run the car electrics satisfactorily.

As davesparks said gas is the answer for high power heating. Time to bite the bullet methinks.

Storing electricity at low voltages in batteries is demanding chemistry. And expensive per kWh stored. I did a solar off grid with gennie back up which had a 24V battery ( 4 x 12 V) each of 200Ah. Total Ah is 2 x 200 = 400Ah which is theoretically 400 x 24 = 4.8kWh.

They were agm batteries. To maximise their life they are never completely discharged over a 24 hour period. On demanding days they are 50% discharged. Thus they only reslly are used to store and then deliver 2.4kWh

We get this performance by supplying an equivalent low average power over a 24 hour period of 2.4/24 = 0.1kWh every hour or 100 Watts. This is a discharge current of 100/25/2 = 2 A through each of the 4 batteries - trivial for a 200Ah battery.

We this set up the batteries are never flat , quickly recharged by solar or gennie and their life is maximised ( 1800 cycles of charge discharge). Total cost of 4 batteries £1800 if I remember correctly with about £300 of cabling and sundries including a locked safe enclosure for them.

 

[marconi]

Pc1996 #13 has told you that the provision of 3kW at 240V from a 12V battery is not impossible but to be avoided because of the very high current drawn from the battery which will rapidly discharge it and the need for very short very thick cables to carry this large current at 12V. You would need a special battery to cope regularly with such prolonged high current otherwise its life will be rapidly consumed . My suggestion should have been clearer but I did give my car’s inverter and the knife grinder as an examples. Using you car battery perhaps supplemented by the engine generator is workable for up to about 500W for very short periods - the knife grinder example I gave or as in my car up to 150W for phones, lap top power supplies, tv, small fridge cool box maybe for a few hours but longer with engine running.

If one discharged the battery at a higher rate than the charging rate by the engine then over time it will become flatter and maybe then unable to start the engine nor run the car electrics satisfactorily.

As davesparks said gas is the answer for high power heating. Time to bite the bullet methinks.

Storing electricity at low voltages in batteries is demanding chemistry. And expensive per kWh stored. I did a solar off grid with gennie back up which had a 24V battery ( 4 x 12 V) each of 200Ah. Total Ah is 2 x 200 = 400Ah which is theoretically 400 x 24 = 4.8kWh.

They were agm batteries. To maximise their life they are never completely discharged over a 24 hour period. On demanding days they are 50% discharged. Thus they only reslly are used to store and then deliver 2.4kWh

We get this performance by supplying an equivalent low average power over a 24 hour period of 2.4/24 = 0.1kWh every hour or 100 Watts. This is a discharge current of 100/25/2 = 2 A through each of the 4 batteries - trivial for a 200Ah battery.

We this set up the batteries are never flat , quickly recharged by solar or gennie and their life is maximised ( 1800 cycles of charge discharge). Total cost of 4 batteries £1800 if I remember correctly with about £300 of cabling and sundries including a locked safe enclosure for them.

Correction of my sums in bold below-

Storing electricity at low voltages in batteries is demanding chemistry. And expensive per kWh stored. I did a solar off grid with gennie back up which had a 24V battery ( 4 x 12 V) each of 200Ah. Total Ah is 2 x 200 = 400Ah which is theoretically 400 x 24 = 9.6kWh of stored electricity.

They were agm batteries. To maximise their life they are never completely discharged over a 24 hour period. On demanding days they are 50% discharged. Thus they only really are used to store and then deliver 4.8kWh.

We get this performance by supplying an equivalent low average power over a 24 hour period of 4.8/24 = 0.2kWh every hour or 200 Watts. This is a discharge current of 200/25/2 = 4 A through each of the 4 batteries - trivial for a 200Ah battery.

 

[curbside coffee]

Thanks again for the info. it looks like I'll have to bite the bullet n invest in a lpg system.
Unless.. I can adapt my current coffee machine? to run on lpg? like.. could i "install" a lpg heating element on my machines 8l boiler? cutting down the initial 10 min heating time!
Or at least insulate the boiler so it gets up to temp quicker?!

 

[davesparks]

Unless.. I can adapt my current coffee machine? to run on lpg? like.. could i "install" a lpg heating element on my machines 8l boiler? cutting down the initial 10 min heating time!

If this is possible then it will probably cost more to do safely than it would to buy an LPG machine.

Or at least insulate the boiler so it gets up to temp quicker?!

Insulation won't noticeably decrease the time it takes to heat up the water, you still need to input the same amount of energy to raise the temperature. You can't cheat the laws of of physics!