24v to 12v

[Diemjoe]

Hi, I recently added an mpp solar All in 1 24v converter/inverter. I reconnected my 4x12v Lead Acid batteries to 2x 24v batteries. That's working well. I did have to buy a 60w 24v to 12v 5A reducer for the preexisting cabin wiring
Some lights, USB charging ports for my phone and a Costway DC powered fridge. Listed at 50watts (no amp draw listed).
I have a woltage meter on the USB port that shows 12.2v when no draw. But when the fridge draws it drops to as low as 11.3.
I was wondering if this big drop is an indicator that the reducer needs to be replaced with a higher amperage version.

thank

 

[Ampster]

I was wondering if this big drop is an indicator that the reducer needs to be replaced with a higher amperage version.

Possibly if it is running hot? The 50 Watt frig is 4 Amps so that is not much room. My experience with some ratings on devices is that it is better to run them at 50 percent because some manufacturers are optimistic.

 

[Rednecktek]

60w really isn't very much, I'm surprised your fridge will even fire up on that. As a reference I got the 70a buck transformer for my camp because the amperage draws of the 12v heaters is pushing 40a when they first get rolling.

Watts are like grams, it takes a lot to get a little done.

 

[12VoltInstalls]

have a woltage meter on the USB port that shows 12.2v when no draw. But when the fridge draws it drops to as low as 11.3.

After I got past the 5V spec in my head I’m going to ask what was actual voltage on your VO meter at the DC out of the ken’n’barbie-sized 12V converter/transformer?
12.2 is wicked low imho

There’s a reason I advocate keeping a 12V battery and little SCC with a 100W panel for legacy systems. On top of that the low volts could be attributed to poor/small oem DC wiring circuits.

 

[Diemjoe]

I actually was just no thinking about the 2 12v lithium Big batteries that I have not been able to use because they don't seem to work in 24v serial setup. Might see about using them for DC and the MPP solar for the 120v

This is a very temporary setup until I get my cabin built but that is a couple of years off given the state of building supplies.

 

[rmaddy]

I did have to buy a 60w 24v to 12v 5A reducer

Much too small. Get a 480W 24V-12V 40A DC-DC buck converter. Then you'll have no trouble running some of your 12VDC loads. Be sure you use proper sized wire and fuses.

12.2 is wicked low imho

Assuming that's the output of the DC-DC converter then that is a very typical voltage.

 

[Diemjoe]

Possibly if it is running hot? The 50 Watt frig is 4 Amps so that is not much room. My experience with some ratings on devices is that it is better to run them at 50 percent because some manufacturers are optimistic.

Thanks. I was just thinking that same thing. It is pouring rain out now so the electrical box is not a place I want ro be feeling around right now. Will check after it Dries up a bit.
As I responded to another response, I have a couple lithioums here that aren't being used. I may use them for my 12v needs but would require more solar panels and 2 Guage wire to be run.

Don

 

[Diemjoe]

Much too small. Get a 480W 24V-12V 40A DC-DC buck converter. Then you'll have no trouble running some of your 12VDC loads. Be sure you use proper sized wire and fuses.


Assuming that's the output of the DC-DC converter then that is a very typical voltage.

Thanks. I will head over to Amazon next.

 

[Diemjoe]

Just ordered from Hsrfington. I think I have been lucky so far with the cool weather so far. That fridge will be working hard I. A couple of weeks. (I hope).

 

[12VoltInstalls]

Assuming that's the output of the DC-DC converter then that is a very typical voltage.

I will file that away.

I’ve actually never used a DC to DC converter like that so I know nothing. I use a tiny 12V-3VDC transformer cube to ignite my water heater instead of buy D-cell disposables. 3.2V+ output

 

[rmaddy]

I’ve actually never used a DC to DC converter like that so I know nothing.

Most DC-DC buck converters will take a variable range of input voltage and then output a single specific voltage. For example, mine accepts 18V-35VDC input and outputs 12.0V though I think in reality it outputs 12.2V. It's perfect for converting my 24V LiFePO₄ variable battery voltage (24.0V up to 28.6V) to give me a constant 12.2V for my 12V loads.

 

[Kapow_Network]

Exploring a similar issue for 36v. While this regards 36v the principles might be the same.

 

[mikefitz]

Most 12v compressor fridges will automatically operate on a 24 volt supply.

Mike

 

[12VoltInstalls]

Most 12v compressor fridges will automatically operate on a 24 volt supply. Mike

Safely? As in voltage control?

Or do they just have volt tolerance in that range and cool a bit faster at 24V LOL

 

[mikefitz]

The control electronics in the fridge test the input voltage and decide to work at 12volts or 24 volts. The manual for the fridge or an Id plate on the unit will confirm, or a search on the Internet. Typical running current is 4 amps at 12 volts and 2 amps at 24 volts.
With all the DC low voltage fridges the control electronics takes inthe DC power and converts to a multi phase supply to drive the compressor motor.
As with all compressor systems the starting current is 3 to 5 times the running current, cable and fuses must be adequate for this.

Mike

 

[12VoltInstalls]

Thank you

 

[Zwy]

Most 12v compressor fridges will automatically operate on a 24 volt supply.

Mike

Yes, my Dometic CFX freezer/fridge has 12/24V DC input and 120V AC. Automatically senses whether on AC or DC and at what voltage.