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]

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)

I looked at web sites like curry's and argos, going though some of there fridges and they listed nothing about power consumtion! But good google search you found there

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.

I would always go for the Platium brand myself as I know they have a good name in the motor factor biz

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But there again car batteries rang in life spam waranty from 1 year to 4 (or maybe 5 at best)
My mum and dad live in the out back with no mains electric and rely on a generator. When generator man showed up to fix it, I could not belive at fist what he was saying that the batteries they use last for 18 years

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.......

So the 2 plans I have is to either use a cooler room with room cooled to 10C that will run all the time, then into drinks chiller that will only run when the tap is open and beer is being served
Or just to run apox 8 domestic fridges all the time to do the work of bough (commonly know as a kegorator)

So if I went with the later one then I would have 8 domestic fridges. Based upon the numbers you supplied above.
0.5kWh X 8 fridges = 4kWh
I am unable to do the maths hear as I just dont understand the discharge (%) rates listed for batteries
But if I wanted to run 8 fridges off of a battery inverter and generator and I was prepered to run the generator twice a day to charge the batteries up. How many of those photonic batteries you listed before would I need?

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I know it states 200AH, But again I dont understand how this equates into discharge proportions.
Because I have experenced before that an inverter will automaticaly switch its self off when power from the battery is low

 

[ice man]

So if I went with the later one then I would have 8 domestic fridges. Based upon the numbers you supplied above.
0.5kWh X 8 fridges = 4kWh
I am unable to do the maths hear as I just dont understand the discharge (%) rates listed for batteries
But if I wanted to run 8 fridges off of a battery inverter and generator and I was prepered to run the generator twice a day to charge the batteries up. How many of those photonic batteries you listed before would I need?

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I know it states 200AH, But again I dont understand how this equates into discharge proportions.
Because I have experenced before that an inverter will automaticaly switch its self off when power from the battery is low

OK I have ad a brief go at the maths on how long that 200 amps/hr battery should last on 8 fridhes

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I am sure that this will be completely wrong! So please correct me

Fridges
0.5kWh a day x 8 fridges = 4kWh a day = 4000Wh /24hr = 166.6Wh

Battery
200Ah x 12V = 2400Wh

2400Wh/ 166.6Wh = 14.4hrs of battery life

 

[marconi]

I admire folk who persist and don’t give up. I will look at your sums tomorrow . But at the moment Maud, the recorded semis of the snooker and then line of duty have greater attraction ?

 

[marconi]

As I said I am no expert in batteries and brands of but I reckon there will be a difference between the battery life and guarantees/specifications of performance when it is used primarily for a few seconds to crank an engine and when used regularly for prolonged discharge to a deeper depth of discharge. Hence the rather odd phrase 'leisure battery'. I know nothing about the Platinum make.

To do the analysis of battery and generator charging I need to know how long the battery alone must provide power and remain above 50% discharge. In my clients case from shut up shop 7pm Saturday evening to opening up 7am Monday morning.

 

[pc1966]

I would agree with @marconi that you definitely want some over-provision of capacity to cover changes in load pattern, the battery capacity dropping over a couple of year's life, and losses in the conversion process from low voltage DC to 230V AC.

Also as already mentioned you don't want to be using 12V as then the current is huge, so your 5-10A for one or two fridge motors kicking in at 230V becomes 96A-192A at 12V. So if you and some PV specialist decide that, say 300Ah capacity is enough for your daily use-pattern it would still be far better to have that as 24V or 48V and consisting of a 2 * 150Ah or 4 * 75Ah 12V batteries in series coupled with appropriate protection and matching voltage of inverter/charger.

Also they will be a lot easier to wrangle as lead-acid batteries main disadvantage is high weight!

 

[Lucien Nunes]

Just to fill in this point:

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?

Yes it depends on the type of battery. Lead-acid batteries such as we are considering here do not like to be deeply discharged. Every deep discharge shortens their life; the deeper you go, the more they degrade. After using the battery, no matter how much or little charge has been taken out, the best thing for a lead-acid is to be fully recharged as soon as possible. For any ideal application there is a correct size battery that will give most bang for the buck, by not being over-large and expensive and not discharged very much per cycle, but also not being too small and having to go into deep discharge and losing lifespan as a result.

The idea of always discharging a battery fully related to NiCads in the 1980s and 90s, which would develop a 'memory' of how deeply they were discharged last time and deliver a reduced voltage on the next cycle if discharged more deeply. But since the ban on cadmium that chemistry is no longer used.

 

[ice man]

To do the analysis of battery and generator charging I need to know how long the battery alone must provide power and remain above 50% discharge. In my clients case from shut up shop 7pm Saturday evening to opening up 7am Monday morning.

I dont really understand this 50% discharge and how it relates to the 200AH quoted in the description

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[ice man]

Also as already mentioned you don't want to be using 12V as then the current is huge, so your 5-10A for one or two fridge motors kicking in at 230V becomes 96A-192A at 12V. So if you and some PV specialist decide that, say 300Ah capacity is enough for your daily use-pattern it would still be far better to have that as 24V or 48V and consisting of a 2 * 150Ah or 4 * 75Ah 12V batteries in series coupled with appropriate protection and matching voltage of inverter/charger.

But the overall power consumption (W) is still the same right!
If this was an advantage then all cars and bikes would be 48V

 

[ice man]

BTW I got this data sheet from the manufature of the drinks cooler

 

[ice man]

OK I have ad a brief go at the maths on how long that 200 amps/hr battery should last on 8 fridhes

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I am sure that this will be completely wrong! So please correct me

Fridges
0.5kWh a day x 8 fridges = 4kWh a day = 4000Wh /24hr = 166.6Wh

Battery
200Ah x 12V = 2400Wh

2400Wh/ 166.6Wh = 14.4hrs of battery life

I have just rang the above company about there batteries and asked him how the maths on 200AH work. And he states that that figure will be for 100% discharge which he strongly dose not recommend!
He said to aim between 30-50% of discharge to prolong the life of the battery. So meaning if I worked at 50% then 200AH would now only be 100AH

I also asked him when he though the inverter would trip and he said it depends on the inverter but its normerly about 11amps. He said it was hard to equate into amprage but reconed it would be about 70-80% of discharge. Again he stated going to such low level of low voltage is bed battery health

He also stated that the life spam of a battery is done on cycles and not over time (like a manufatures warranty) He said if it never got used and remained fully charged all the time then it would last forever, but he said they do discharge over a period of time even when not in use

 

[ice man]

OK I have ad a brief go at the maths on how long that 200 amps/hr battery should last on 8 fridhes

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I am sure that this will be completely wrong! So please correct me

Fridges
0.5kWh a day x 8 fridges = 4kWh a day = 4000Wh /24hr = 166.6Wh

Battery
200Ah x 12V = 2400Wh

2400Wh/ 166.6Wh = 14.4hrs of battery life

I have just rang the above company about there batteries and asked him how the maths on 200AH work. And he states that that figure will be for 100% discharge which he strongly dose not recommend!
He said to aim between 30-50% of discharge to prolong the life of the battery. So meaning if I worked at 50% then 200AH would now only be 100AH

So if I have gotten all of this right then. If I am aiming at charging my batteries twice a day at a 30-50% discharge then I am going to need 2 of the above battaries for this equation to work?

 

[pc1966]

But the overall power consumption (W) is still the same right!
If this was an advantage then all cars and bikes would be 48V

Electric cars often are 48V

Larger vehicles, boats, etc, often are 24V.

You need to look at the peak demands, what sort of inverts are available (i.e. are they 12V, 24V, etc) and then how they can be hooked up and protected. Cables rated to carry 200A for any length of time are pretty large and difficult to work with, and you (or the designer) need to consider aspects such as a breaker for fault/overload protection and to allow the supply to be isolated for maintenance work.

 

[ice man]

Electric cars often are 48V

Larger vehicles, boats, etc, often are 24V.

Well the last time I looked inside my engine bay it was a 12V battery.
The reason large vehicles are 24V and boats 36V. Is because they are longer then cars and the brake lights would flicker on a lorry at 50 feet at 12V

 

[ice man]

BTW I got this data sheet from the manufature of the drinks cooler

The data sheet for this beer chiller says it power consumption is 627W. The beer chiller will only work when beer is being drawn off of the beer tap.

So if we said I was to sell 100 pints a day at 30 seconds a pour would mean 50 minutes of use per day.
Which is (50mins/ 60 mins) 0.83 of an hour. X 627W = 522.5W total power consumption for this machine for one day.

So the battery in question is rated at 200AH x 12V = 2400Wh total battery life. But at a 50% discharge equates to 1200Wh battery power

1200W/ 522.5 = 2.30 days before the battery needs charging.

With out doing the maths or anything. Dose this sound about right for a load of this kind on a battery of this size?
Thanks

 

[ice man]

Now I am going to move on to the generator that I would need to charge my batteries up
Again based on my maths. But no one has commented yes as to if they are spot on or far out!

for the 200AH battery in question
200AH x 12V = 2400Wa @ 50% discharge = 1200Wh

if I want the generator to run for say half an hour to charge the battery then I am going to want a 2400W generator right? (1200Wh x 1/2hr)

So for charging 2 batteries in half an hour dose this mean a 4800W generator?
Thanks