What power supply for this large 12V Fridge/chiller?

[HappyHippyDad]

My customer wants to fit a large 12V chiller at her farm.

The supplier has said it is 12V and 80A.

A couple of questions..

1. What sort of power supply unit would you use for this? See link below of the ebay item.

2. Is this going to be 80A at 12V or 80A at 230V? At 12v it would only be 960watts which doesn't seem a great deal for such a large chiller. However I can't see it being 18.4kW??

Fridge/Chiller box/body 11f/3.3m long+Fridge equipment Carrier,Ideal Storage! | eBay

100% Dry and weather tight, Ideal for storage or fridge trailer or Cool room ! Fridge Insulated box body out of Sprinter mwb vans year 2016 ! The boxes are down on the floor now and ready to go !

www.ebay.co.uk

Cheers all

 

[James]

it is going to be 80A at 12V DC

I would be looking for about a 100A DC 12v power supply unit to power it as it will have a decent start up current that is over the 80A specified (I expect)

It may be best to use a 12V leisure battery combined with an automatic charger, possibly designed for a boat as they have that sort of power requirement, the battery will be able to provide the start up current surge and the charger will continue to float charge and supply the load.

speak to victron, they will help you specify the right solution

VICTRON CENTAUR 12/100 3 BATTERY CHARGER 12V 100A CCH012100000

VICTRON CENTAUR 12/100 3 BATTERY CHARGER 12V 100A CCH012100000 The Centaur range of battery chargers features auto-ranging input covering 90-265VAC…

batterygroup.co.uk

 

[DPG]

I'd say James' idea is a good one. That is going to really hammer a 12V power supply on start up.

 

[Lucien Nunes]

The battery and charger idea is good for accommodating the starting current. Any conventional lesiure battery of 100Ah or so will be ample for that, but using a battery with a small capacity compared to the load and charger output can lead to the battery experiencing abnormal charging conditions.

A conventional 3-step charger is likely to reset to bulk mode each time the compressor starts. Then when it stops, because the battery is relatively small, the current will immediately drop below the threshold and put the charger into absorption mode. If this has a proportional duration it could then overcharge the battery, which was never significantly discharged despite the charger seeing prolonged heavy load. Actually what you want it to do is drop out into float almost immediately, which it might do if there is no enforced minimum absorption time, or if the trip voltage can be set low enough.

The Victron charger is probably smart / adjustable enough to prevent overcharging but I have seen the effect with certain models of IUoU charger supplying heavy equipment loads. Because of the very low mean charge rate needed, there is some argument here for simply floating the battery across a constant-voltage regulated supply, although the temperature tracking of a proper charger is beneficial.

 

[pc1966]

Why chose a 12V fridge? Do they have plans for off-grid on large batteries for it?

Otherwise it seems to be an expensive option compared to a typical 230V AC model.

 

[James]

Why chose a 12V fridge? Do they have plans for off-grid on large batteries for it?

Otherwise it seems to be an expensive option compared to a typical 230V AC model.

I suspect, because it’s cheep and they haven’t anticipated a large bill for supplying it.

 

[HappyHippyDad]

Why chose a 12V fridge? Do they have plans for off-grid on large batteries for it?

Otherwise it seems to be an expensive option compared to a typical 230V AC model.

I suspect, because it’s cheep and they haven’t anticipated a large bill for supplying it.

After a little chat they are now looking for a 230V model .

There was no particular reason for 12V. It was just the size of this particular chiller was right for them and I suspect it was a lot cheaper than others they have seen.

 

[HappyHippyDad]

it is going to be 80A at 12V DC

I would be looking for about a 100A DC 12v power supply unit to power it as it will have a decent start up current that is over the 80A specified (I expect)

It may be best to use a 12V leisure battery combined with an automatic charger, possibly designed for a boat as they have that sort of power requirement, the battery will be able to provide the start up current surge and the charger will continue to float charge and supply the load.

speak to victron, they will help you specify the right solution

VICTRON CENTAUR 12/100 3 BATTERY CHARGER 12V 100A CCH012100000

VICTRON CENTAUR 12/100 3 BATTERY CHARGER 12V 100A CCH012100000 The Centaur range of battery chargers features auto-ranging input covering 90-265VAC…

batterygroup.co.uk

The battery and charger idea is good for accommodating the starting current. Any conventional lesiure battery of 100Ah or so will be ample for that, but using a battery with a small capacity compared to the load and charger output can lead to the battery experiencing abnormal charging conditions.

A conventional 3-step charger is likely to reset to bulk mode each time the compressor starts. Then when it stops, because the battery is relatively small, the current will immediately drop below the threshold and put the charger into absorption mode. If this has a proportional duration it could then overcharge the battery, which was never significantly discharged despite the charger seeing prolonged heavy load. Actually what you want it to do is drop out into float almost immediately, which it might do if there is no enforced minimum absorption time, or if the trip voltage can be set low enough.

The Victron charger is probably smart / adjustable enough to prevent overcharging but I have seen the effect with certain models of IUoU charger supplying heavy equipment loads. Because of the very low mean charge rate needed, there is some argument here for simply floating the battery across a constant-voltage regulated supply, although the temperature tracking of a proper charger is beneficial.

Just out of interest. Why would the option you have mentioned James be any better then a cheaper power supply which is say rated at 200A, or even more. If the 200A 12V power supply could take the in rush current then why would the battery option be better? Longevity perhaps?

 

[Lucien Nunes]

We don't know the starting current of the compressor. Many units have 3-5x running current although 12V units are inverter driven and might have modest starting requirements. The idea of a battery ensures that the startup demand is met, whatever it might be, as it was intended to run from a vehicle (with uprated alternator) and have the battery available by design.

I have always thought in terms of a price hike in pounds per watt of PSU when you go over 1kW but looking at current pricing that doesn't seem to be so noticeable now. A reasonable brand (Meanwell) 12V 200A PSU can be got for £500 which is less than I expected. On that basis I would consider checking with the manufacturers for the highest starting current and using a fully rated DC PSU without the battery. I also think it is a better idea that they are looking for an AC-powered coldroom.

BTW a good value option for high-current DC is refurbished server PSUs which offer high reliability and density, although tend to be noisy and 1kW max.

 

[James]

My point really was about the fact we don’t know what the start up current may be.
if for instance the compressor takes 4 x rated load for half a second you might need-to provide 320A for it to start. If during this time the voltage dips below the threshold of the controller it may power down and try again or go into fault.

a 100Ah battery will provide in the region of 1000A for a few seconds and would stop any power supply being overloaded.