Generator Vs Combi Fridge/freezer

[Marvo]

The only info I have on the jaixipera compressors is a cross reference chart that shows the max start current as 10.6A (230v @ 50Hz) which is pretty close to what Defy told you so I'd probably work on an 11A maximum requirement from your generator at 240v. I think the 2.2KVA unit may be a little shy of the mark, as Lucien says it will depend very much on the electronics in the generator's AVR. If you can try before you buy then I'd start with the 2200VA or 2500VA Honda, if not and you want to guarantee it will work I'd go with a 3000VA Honda which will give you 12.5A Max, that way there's a small allowance for power factor there as well.

*Edit* I personally wouldn't recommend you run a 50Hz compressor on 60Hz, it will affect the head pressure the compressor is under, the system may also under condense especially in high ambient temperatures in Zambia and could result in refrigeration problems and maybe even premature compressor failure. Domestic refrigeration on R600 can be a bit skittish and sensitive at the best of times. I'd suggest you stick with a 230-240v 50hz genny which should be the local standard.

 

[pemaldini]

Dear Paolo,

http://cdn.powerequipment.honda.com/pe/pdf/manuals/31ZB0010.pdf

I have looked at the HONDA GX2200x specification and it only provides 120 Volts 60 Hz output and your fridge requires 220-240 Volts at 50Hertz (Hz). Disappointingly then it is not suitable to power your F-F. MARVO reckons(earlier post) 2kVA supplied by a HONDA or other good make would be sufficient. I think to reduce the risk, unless you can try a 2kVA set out first, you should aim to procure one of at least 2.7 kVA - I know they work.

PS: The wiring diagram for the GX2200x shows an Automatic Voltage Regulator. When you buy a set enquire what kind of voltage regulator is used as Lucien Nunes has discussed.

Hi Marconi

I have checked on the genset in question, and I guess it is a model that was made for our part of the world, as it outputs 220V and it clearly states on the machine 50Hz.

 

[pemaldini]

I have now had the genset serviced, and connected it up to the fridge. It runs fine whilst the fridge is in "running" mode, and every 15mins or so, I guess the compressor "starts up" and you can hear the genset take some strain but seemingly manages to power on through. Not long after it settles down again as it goes back to "running" mode.......Rinse and repeat.

My temperature logger inside the fridge som far appears to show that temperatures are being maintained, although I need to run it longer to confirm this.

 

[Marvo]

I'm glad your generator is handling things. Just out of interest how often are you experiencing power outages and what duration are they?

Also have you considered rather using an absorption refrigerator which can run on LPG or even a 12v battery? They're often sold as camping fridges. You could set up a solar panel and battery charger and use LPG as a back-up power source if there's insufficient solar. I'm sure this would work out cheaper in the long run and would remove the headaches of constantly servicing and fueling the genny not to mention removing the noise pollution as well.

 

[marconi]

I have now had the genset serviced, and connected it up to the fridge. It runs fine whilst the fridge is in "running" mode, and every 15mins or so, I guess the compressor "starts up" and you can hear the genset take some strain but seemingly manages to power on through. Not long after it settles down again as it goes back to "running" mode.......Rinse and repeat.

My temperature logger inside the fridge som far appears to show that temperatures are being maintained, although I need to run it longer to confirm this.

By Marconi A satisfactory outcome. Forgive the tooing and frooing on detail but I am sure you appreciate the detail matters if one wants to avoid doing something unsafe or which might cause damage or a fire.

I (and I am sure 'we') do not recommend you power sensitive electronic or electrical equipment - such as computers and TVs - at the same time as you power the F-F . Lighting would be fine.

 

[Lucien Nunes]

Absorption fridges are really heavy loads on 12V - the mains/LPG/12V one I used to have on the boat used 9A continuously without thermostatic control and it was a tiny 2 cu.ft. They are only supposed to run on 12V when your vehicle engine is running. I replaced it with a 6 cu. ft. 12V compressor fridge and that reduced to an average 0.5-1A depending on weather. 2A while running, 25% duty cycle up to about 50% in peak summer. That is definitely practical to run on battery / solar, although if the OP needs a similar amount of freezer space the consumption mounts up.

 

[Marvo]

Yes, the R717 (ammonia) absorption systems generally need a heater of around 100-120watts. On 12 volt this would equate to 8-10Amps which isn't a great prospect on its own because it will be a considerable drain on batteries...but you can use a 12v heater so efficiency-wise there would be no conversion losses. The massive advantage is that with an absorption fridge you can use grid power when it's available with solar/battery for back-up plus it could run on one of those little baby generators they sell for emergency/camping lighting if there was a long outage. The load it presents is linear and there's no nasty start currents to worry about. I've even seen one set up to use direct sunlight with a Fresnel lens and a curved mirror. Also the absorption fridges tend to be better insulated because whilst they'll easily achieve minus 18C, they're not as powerful and fast as a recip compressor so they usually go to town on the insulation to compensate somewhat.

 

[pemaldini]

I'm glad your generator is handling things. Just out of interest how often are you experiencing power outages and what duration are they?

Since September 1st we have been given increased load shedding shedules of 9 - 10 hours daily! We have also been told expect to put up with load shedding to some degree for the next 3 years at least!

Zambia is almost 100% reliant on Hydro electric power. The impressive Kariba dam on the mighty Zambezi river producing a large percentage of the Nation's power, as well a number of various other hydro electric plants. The problem we have been facing since around March this year is blamed on numerous factors:

The powers that be largely blame the usually reliable rainfall which over the past 2 years has been very poor resulting in much lower than normal water levels in dams across the country. This is true to a degree.

What isn't acknowledged so much is the mismangement, lack of planning for the future and looking at alternative power sources other than hydro electric.

Upgraded original British pumps at Kariba funded by the Chinese now require considerable extra water throughput to generate the same amount of power as their older British counterparts.

Development in Zambia has been quite positive over the past 2 decades and consequently demand for power has increased substantially (largely from heavy industry such as our expansive mining sector and growing agricultural development). Sadly investment in electricity provision has not kept up.

Power in Zambia is cheap, very cheap and this also adds to the government electricity supplier ZESCO battling for capital to invest in new projects.

The list goes on and on, and I won't bore you all with more details, but suffice to say the outlook regarding electricity in the region is quite bleak. Not only are the outages long and frequent, but power spikes and low voltages are a constant issue.

Also have you considered rather using an absorption refrigerator which can run on LPG or even a 12v battery? They're often sold as camping fridges. You could set up a solar panel and battery charger and use LPG as a back-up power source if there's insufficient solar. I'm sure this would work out cheaper in the long run and would remove the headaches of constantly servicing and fueling the genny not to mention removing the noise pollution as well.

The genset that we have been discussing has been test run for about 1hr 30mins and appeared to handle the starting amps - one could hear it taking a bit of strain on the odd occasion. The F/F compressor starts up about once every 25mins. Running amps is quite low and the genset seems to cope with that happily. What I don't want is to be reliant for any great period of time on such a small genset, its really there as a backup to our old Lister 7.5kVa 3 phase genset, which touch wood is running said fridge and a number of other components - but she is old.

For now I'm stuck with my DEFY 230V 380ltr fridge/freezer. What I may consider doing in the not too distant future is looking to invest in some kind of invertor battery based system as a backup for the vaccine F/F for when the power is off. I may also like to compliment this with solar owing to our abundance of sunshine in this part of the world. I would also like to add in the ability to power my chicken lights and borehole pump.

 

[Marvo]

I read an engineering report on the Kariba hydro a while back and it didn't paint a pretty picture. It's interesting to hear the electrical supply woes of another country, I'm in Cape Town and SA has been suffering bouts of load shedding on a national level on and off for the last few years and they've been very regular for the last 6 or 8 months. It sounds like we're nowhere near as deep in the kak as you guys but it's a forgone conclusion it's going to get worse before it gets better. At present the evening peak is the big issue and at the worst stage we were getting load shed for 2 hours each day and 4 hours on the odd days. One of the big problems is that they're running open cycle gas turbines for prolonged periods on diesel to make up the load side deficit which is costing them billions of Rands/Dollars in fuel so there's no budget to do anything constructive to address the root problems.

Anyway, back to your fridge. The problem with using a generator to supply a fridge is that the efficiency and cost will be appalling, the generator will be running for long periods when the fridge is at its set temperature and the compressor isn't running. A grid tied inverter with deep cycle batteries would be better, it would take advantage of grid power when it's available and obviously have batteries for backup. Look at the Victron Multiplus if you have a reasonable budget, they can handle multiple inputs including wid turbine, PV panels, batteries and grid power. If it's a bit much then check out the Axpert inverters which can handle PV, batteries and grid and prioritize accordingly.

If you want to use back-up power for a borehole pump then install a ramped soft-start to flatten the inrush current. If the pump isn't compatible with a soft start I'd seriously consider replacing it with one that is otherwise the spec of the inverter will need to cover the start current which will cost a fortune compared to one that just needs to cover the running current.