Advice on buying generator please

[ice man]

Hi

I am looking at purchasing and running a drinks cooling machine to run on no mains electric what so ever!



The company that sells the machine have advised the following

Frequency: 50Hz Rated current: 5.5A Rated input: 800W



This machine is a liquid to liquid based (water and anti freeze bath) heat exchange and only runs when liquid is passing though it. And will only operate when I open the tap and fill a glass up from it so it will not be running most of the time



The two option I am considering is buying a generator inverter and battery and charging the battery up as required. Or just running the generator when it is in operation. So what do you think?



Thanks

 

[ice man]

I designed a system to power 20 odd catering vans, each with chest freezer, 2 tall larder fridges, lighting and payment system using solar power Mar-Oct - and on peak solar days in summer a 1kW hand hot water heater. Other times a Honda engined 3.4kVA LPG generator with automatic voltage regulator provides van power during opening hours and charges the batteries for overnight use.

This is the robust 3kW inverter which has a very high peak power capability (9kW), pure sinewave and 'sleep' mode when load drops below 75W and wake up when load rises above this figure which conserves battery power.

12V solar panels charging kits for caravans, motorhomes, boats, yachts, marine - https://www.photonicuniverse.com/en/catalog/full/164-3000W-24V-low-frequency-pure-sine-wave-off-grid-inverter-peak-power-9000W.html

Batteries are Advanced Gel Matrix by Victron:

12V solar panels charging kits for caravans, motorhomes, boats, yachts, marine - https://www.photonicuniverse.com/en/catalog/full/470-200Ah-12V-Gel-deep-cycle-battery-for-motorhomes-caravans-boats-and-off-grid-power-systems.html

Either 6 x 200Ah or 4 x 300Ah, wired in strings of 2 batteries in series to give 24V and these then connected in parallel. The theoretical power available from fully charged to batteries 'flat' is 12 x 1200 = 14.4kWh but this is not achieved nor relied upon. Instead the batteries are never discharged more than 50% to preserve their life; thus about 7kWh is the working amount of electrical energy available.

7kWh would run an 800W cooler constantly for 7000/800 = about 9 hours.

Did you use all of that set up to power all of the vans at once?

 

[marconi]

No, poor writing. Each van had an installation since the fleet of them is dispersed around England. I tried to persuade my client/BIL to use Honda inverter generators but he continued with the conventional Honda GX engined frame generators because he and his team knew them so well and had a maintenance and repair set-up for them already. It is the engine which fails not the alternator. My BIL changes engines and sets them up to start and run correctly.

Generators are attractive items to 'certain' folk and are easily stolen unless solidly chained to something immovable or built in to the structure. Overnight or when unattended, if not built in to the structure behind a very strong locked door (obviously when shut down) or if left chained up outside they will soon disappear.

 

[ice man]

No, poor writing. Each van had an installation since the fleet of them is dispersed around England.

Surly you are not tell me each van had 6X £350 vorth of batteries and a £500 invertor to run a couple of houes hold fridges?

 

[ice man]

The company that sells the machine have advised the following

Frequency: 50Hz Rated current: 5.5A Rated input: 800W

This is the robust 3kW inverter which has a very high peak power capability (9kW), pure sinewave and 'sleep' mode when load drops below 75W and wake up when load rises above this figure which conserves battery power.

Surly not in my case is it not?

 

[ice man]

...........error post

 

[marconi]

Yes. If food is kept in a fridge or freezer to be sold to the general public then those fridges and freezers must always have electricity to maintain their correct temperature. It is not satisfactory to rely on their insulation. This applies to my clients business and is a condition of his licence to operate on the sites he trades at.

We tried electric-start Honda frame generators triggered to start by a separate thermostat inside the fridges and freezers but they did not start reliably and had to be exposed to the possibility of theft in order to run. The modifications to do this to the van were unacceptable we decided after doing one van.

When I did the analysis, it is more economic too because the generators consume less gas, break down less frequently and have a longer life. Two other benefits are the van is quieter more of the time and produces less CO2. The staff, mainly women, also like not having to start and stop and regularly checking the gennie.

As I finished with in one of my earlier posts I am not suggesting this is your solution but rather something similar and at a smaller scale. For example you said it only operates at the weekend whereas my solution is every hour, every day all year.

 

[marconi]

The first vans used a 2kW (6kW peak) inverter without problem. We upped the power to 3kW because we wanted to have the spare capacity to run other equipment which so far has not happened. The marginal increase in cost was small.

I have most likely taken you down a rabbit hole and your solution will be much simpler and cheaper. I did suggest you contact Tom and an electrician who does off-grid installations. Or you can just buy a generator after seeking advice on kVA from the supplier. It is difficult to advise you on kVA without knowing more about the beer cooler refrigeration system so we tend to say anywhere between 5-10 times the running power for generator kVA and buy one with an automatic voltage regulator AVR. It becomes a little more complicated if you have several motors supplied by the same generator but you indicate you only have one to start.

 

[pc1966]

Surly you are not tell me each van had 6X £350 vorth of batteries and a £500 invertor to run a couple of houes hold fridges?

It really is a design aspect. You and whoever is doing the electrical design side have to work out what the load is:

• Peak demand as fridge(s) kick in as that sets the inverter size)
• Average between charging based on the insulation quality, throughput of drinks bring cooled, and any other loads (e.g. LED lights, payment system, etc) as that sets the battery size.

If you can charge from mains overnight then it might be worth spending more on batteries and not on a generator.

If you simply have to have a generator (e.g. parked in the middle of nowhere for days on end, etc) then you might decide on smaller and cheaper batteries and a charge pattern of running the genny a couple of times per day (ideally electronically controlled starting so staff don't need to worry about it). But then you have the issues of safe ventilation for CO poisoning risk, fire hazards if near dry long grass or similar, any permits/permission or restrictions for handling/storing fuel (near arable land, rivers, etc), the risk of theft, ongoing maintenance costs for the generator's engine, etc.

 

[marconi]

It really is a design aspect. You and whoever is doing the electrical design side have to work out what the load is:

• Peak demand as fridge(s) kick in as that sets the inverter size)
• Average between charging based on the insulation quality, throughput of drinks bring cooled, and any other loads (e.g. LED lights, payment system, etc) as that sets the battery size.

If you can charge from mains overnight then it might be worth spending more on batteries and not on a generator.

If you simply have to have a generator (e.g. parked in the middle of nowhere for days on end, etc) then you might decide on smaller and cheaper batteries and a charge pattern of running the genny a couple of times per day (ideally electronically controlled starting so staff don't need to worry about it). But then you have the issues of safe ventilation for CO poisoning risk, fire hazards if near dry long grass or similar, any permits/permission or restrictions for handling/storing fuel (near arable land, rivers, etc), the risk of theft, ongoing maintenance costs for the generator's engine, etc.

Nicely put.

 

[ice man]

Yes. If food is kept in a fridge or freezer to be sold to the general public then those fridges and freezers must always have electricity to maintain their correct temperature. It is not satisfactory to rely on their insulation. This applies to my clients business and is a condition of his licence to operate on the sites he trades at.

Did you or him ever consider consider cooling down with ice every day?

We tried electric-start Honda frame generators triggered to start by a separate thermostat inside the fridges and freezers but they did not start reliably and had to be exposed to the possibility of theft in order to run. The modifications to do this to the van were unacceptable we decided after doing one van.

When I did the analysis, it is more economic too because the generators consume less gas, break down less frequently and have a longer life. Two other benefits are the van is quieter more of the time and produces less CO2. The staff, mainly women, also like not having to start and stop and regularly checking the gennie.

So did you not bother with generators for the rest of the fleet in the end; where by you charged the batteries up from mains from a building?

I have most likely taken you down a rabbit hole and your solution will be much simpler and cheaper. I did suggest you contact Tom and an electrician who does off-grid installations. Or you can just buy a generator after seeking advice on kVA from the supplier. It is difficult to advise you on kVA without knowing more about the beer cooler refrigeration system so we tend to say anywhere between 5-10 times the running power for generator kVA and buy one with an automatic voltage regulator AVR. It becomes a little more complicated if you have several motors supplied by the same generator but you indicate you only have one to start.

I have looked online again for other beer chiller as I was not happy with the tecnical speck I was given for the chiller I was quoted for. Have a look at this one
BRW36H Series Water Cooled Range Base - https://www.booth-dispensers.co.uk/Catalogue/Products/Brewery-Equipment/Beer-Coolers/BRW36H-Series-Water-Cooled-Range-Base-2
Its about the closest I could find to my needs. there is the option on that page to download a manual but you have to email the company to get it (so have done so)

You said on this project for you customer you installed fridges for him. Are these domestic type fridges? The reason I ask is I was adviced not to use fridges as they do not oporate well when in transit. The gases need to settle first and can take up to 24hrs. I was also told that they only consume a lot of power when they start up from warm and cool the contence of the fridge down. But once cool they use very little power keeping them cool at all

 

[ice man]

Either 6 x 200Ah or 4 x 300Ah, wired in strings of 2 batteries in series to give 24V and these then connected in parallel. The theoretical power available from fully charged to batteries 'flat' is 12 x 1200 = 14.4kWh but this is not achieved nor relied upon. Instead the batteries are never discharged more than 50% to preserve their life; thus about 7kWh is the working amount of electrical energy available.

I was always on the idea that batteries should by fully charged and then fully discharged to flat and fully charge again to increase there life spam. Is this then wrong? or dose it depend on the type of battery?
Thanks

 

[marconi]

Taking your questions in order:

1. My client has 20 or so vans at 20 or so locations. He would have to build 20 ice making systems and then transport the ice blocks each day of the year. It is however a very good idea to keep the freezers filled up with frozen goods and if they cannot be done with produce then frozen blocks can fill in the gaps. He keeps his freezers over half full.

2. I was not clear enough. Each van still has a generator to cover the winter months and some prolonged periods during the year when sunshine alone is not enough to keep the the batteries sufficiently charged. The batteries must have by the end of working day enough power to maintain the refrigeration overnight and on some sites from close of play Saturday to opening up Monday morning. All his fridges and freezers have max and min thermometers inside them to check the food has been kept safely frozen or chilled. Before going on site the fridges and freezers are brought to the required temperatire either from solar of mains. It depends on the time of year they first arrive on site after refurbishment or from start up.

3. He was not allowed access to the site‘s power supply, not even from lamp standards nearby. He had to be completely off grid.

4. I repeat, in order for him to obtain a licence to operate and liability insurance The fridges and freezers have to have power available constantly for them to run as demanded by their thermostats. He previously operated using gennies running during the day and reliant upon the freezer or fridge insulation keeping contents cold enough when the van was closed for business. Alas, another licence holder, using the same scheme sold some burgers which had been defrosted while the gennie was shut down overnight in hot summer period and then refrozen when the genie was running again next day, and then cooked. the punter who ate them was very poorly afterwards.

5. I will read the product spec you provided tomorrow.

6. My client buys domestic fridges and they are changed for new every couple of years. He buys LEC and the ones capable of being placed in a warm environment - fridges and freezers have environmental classes to suit where they are used in the world. This should be taken into account also for one placed in a warm garage or conservatory.

7. Yes, one should allow some time for the gas to settle before powering up after significant motion of them. My client allows a few hours not 24 hours.

8. Yes, Fs and Fs need time and energy to cool their contents to the point that they are thermostatically regulated in temperature. Opening the door or lid of course will demand some energy during normal operation and placing products inside which need cooling. Every time the motor starts to run the compressor there is a brief surge in power/current drawn to quickly accelerate the mechanical components to running speed. When running the power/current is that necessary to run the refrigeration. Think about you having to quickly run up to speed a children’s roundabout and the compare that to with what is required from you to keep it at that speed. The same physics applies.

9. Batteries- a vast subject. You get what you pay for and their life and degradation of capacity t9 store energy over time depends much on how they are charged over time and depth of discharg and what temperature they operate in and what temperature the heating effect of the current which flows in them causes. Too much to cover right now. I specified top end victron brand batteries. Two years on the first few vans are still performing well on their original batteries.

 

[ice man]

4. I repeat, in order for him to obtain a licence to operate and liability insurance The fridges and freezers have to have power available constantly for them to run as demanded by their thermostats. He previously operated using gennies running during the day and reliant upon the freezer or fridge insulation keeping contents cold enough when the van was closed for business. Alas, another licence holder, using the same scheme sold some burgers which had been defrosted while the gennie was shut down overnight in hot summer period and then refrozen when the genie was running again next day, and then cooked. the punter who ate them was very poorly afterwards.

You are only supposed to freeze raw meet once you see

6. My client buys domestic fridges and they are changed for new every couple of years. He buys LEC and the ones capable of being placed in a warm environment - fridges and freezers have environmental classes to suit where they are used in the world. This should be taken into account also for one placed in a warm garage or conservatory.

Domestic fridges are availbe and as cheep as chips second hand on ebay. And this is why I first considered using them as kegorators as they would do bough the work of the cellar cooler and the beer chiller. But I was concerned about over all power that they would use being to much.

So being an electrion man and since you have worked with domestic fridges. Can I ask you what the typical draw of an typical domestic under the counter fridge would use. And by that I dont mean warm start where it has to chill the contence of the fridge. I just mean its typical power consumtion keeping it all ready cool!

8. Yes, Fs and Fs need time and energy to cool their contents to the point that they are thermostatically regulated in temperature. Opening the door or lid of course will demand some energy during normal operation and placing products inside which need cooling. Every time the motor starts to run the compressor there is a brief surge in power/current drawn to quickly accelerate the mechanical components to running speed. When running the power/current is that necessary to run the refrigeration. Think about you having to quickly run up to speed a children’s roundabout and the compare that to with what is required from you to keep it at that speed. The same physics applies.

Yes I know what you mean! I pedal my bike up to speed then to keep it up to speed is nothing compared to getting it there. But if I let go I free fall all that energy I used to get it up to speed. So in the same way it takes a lot of energy and time to get the fridges to cool the contence. If you switch them off it will take a long time to heat back up again
Thanks

 

[ice man]

9. Batteries- a vast subject. You get what you pay for and their life and degradation of capacity t9 store energy over time depends much on how they are charged over time and depth of discharg and what temperature they operate in and what temperature the heating effect of the current which flows in them causes. Too much to cover right now. I specified top end victron brand batteries. Two years on the first few vans are still performing well on their original batteries.

Ow I hope you dont mind me bringing this question up; but briefly; what make those batteries you buy better then the typical Leisure batteries for caravan found at places like this

Leisure Batteries | Free Delivery | Leisure Battery

Leisure Batteries for Caravan, Motorhome, Motor Mover, Boat and Marine. Cheap Leisure Battery with Free next day delivery in the UK. Best Leisure Battery Range.

advancedbatterysupplies.co.uk

Is it the life span or power out put?
Thanks

PS is it some kind of fleet of tea wagons your client runs or something?

 

[marconi]

Fridge or freezer energy consumption: I would look up the specification of the appliance or a number of similar ones and then take the average. So for a typical fridge and freezer whose data sheets are attached the figures are 128kWh per annum and a freezer 209kWh per annum. Divide by 365 to obtain daily consumption. Then consider the difference between the domestic setting these figures refer to and your intended one eg: will the door or lid be opened more or less often.

Thus a larder fridge with auto defrost is 128/365 = 0.35kWh a day (I would assume a figure of 0.5kWh for clients use.)
For chest freezer 209/365 = 0.57kWh (I would assume a figure of 0.7kWh)

Batteries: I am not a battery expect so had to do some research on brands and specifications. I looked at Leisure and Boating forums and googled 'which is the best leisure battery?' or 'is victron a good make of lesiure battery?' There are other good makes no doubt but I settled on Victron which was also stocked by the equipment supplier we used who happens to be close to my client's offices. If I could not obtain a comprehensive specification on the brand and battery I did not consider them.

Victron Advanced Gel Matrix are good because they are safe (don't spill acid), well made, sealed, fully specified and certified, have high charge/discharge cycles, age slowly and provided charged up carefully and discharged to no more than 50% will only slowly fall in storage capacity. Victron is a Dutch company which appealed to my client and me. You will often find Victron equipment in smart motor yachts. We discounted Li ion as too expensive.

Yes teas, coffees, sandwiches, griddle cooked food, chilled soft drinks.

Sir.....spend some time writing down a requirement (what you want and don't want) and then contact a few local off grid supplier for a proposal and price. Or 'do it yourself' noting my earlier remarks well though and you may or may not be successful. My solution had to work and be safe and reliable because it was essential to the bottom line of my client. Your requirement is much different - 2 days a week for how many weeks? One off. You are the operator.......