Using a battery to increase voltage?

[SaylorMade]

Alright, I'm building a fridge box with two peltiers, only to be used when on shore power.
This thread is not about why peltiers contra compressor, so no need...

Anyway, I have two options:
1. Use a 12 Power supply running on shore power
2. Put a battery in between to power the fridge with a charger on it, and only running when on shore power.

The reason I think about putting a battery in between is that it will raise the voltage from 12v to about 14.4 volts (constant charge), which will give more cooling power.
Will the battery be damaged from this, assuming that the charger has more capacity than the peliters draw?

It doesn't seem to be possible to buy a 14 volt shorepower PSU, and chargers that I can find that can act as a perment power supply is quite expensive for some reason, when they need to be able to constantly output around 8 amps in this configuration.

[Calif.Ted]

I had a 3 way fridge in a camper which had a battery and a 12 volt converter, no battery charger except the truck engine while running. It was most efficient while on 110 when running from converter and was best method to get it down to temp. I got distracted once while on 12 volt and engine off and it sucked a group 27 down in short order. While running on 12 volts while driving (powered by camper battery charging from truck) it would keep things cool but took forever to chill warm beer. Can't say this is helpful other than to stress importance of figuring out how to power them most efficiently. Messed about with a couple on coolers but couldn't get past the excessive power requirements, maybe in a more temperate climate.

[SaylorMade]

Originally Posted by Calif.Ted

I had a 3 way fridge in a camper which had a battery and a 12 volt converter, no battery charger except the truck engine while running. It was most efficient while on 110 when running from converter and was best method to get it down to temp. I got distracted once while on 12 volt and engine off and it sucked a group 27 down in short order. While running on 12 volts while driving (powered by camper battery charging from truck) it would keep things cool but took forever to chill warm beer. Can't say this is helpful other than to stress importance of figuring out how to power them most efficiently. Messed about with a couple on coolers but couldn't get past the excessive power requirements, maybe in a more temperate climate.

Good input !
Yeah the battery would be dedicated to the fridge and not in any way connected to the house battery, and of course if I forget to turn it off while not on shore power it would take a toll on the battery, just wondering if it would do harm to the battery if it is constantly charged.
I sail where it unfortunately seldom get hot

[Mirage35]

Thoughts, without any specific knowledge of the subject:

If the fridge is designed to run on +/- 12v, I doubt if the higher voltage would provide significant additional "cooling power."

As you say, you live where it doesn't get hot, so the fridge probably has plenty of cooling ability in any case. So why are you worrying about it? Keep it simple.

[Ballsnall]

Originally Posted by SaylorMade

just wondering if it would do harm to the battery if it is constantly charged.

Any cheap lead acid battery will be fine with constant charge at 14v and will last many years.

[Ballsnall]

Originally Posted by AnglaisInHull

If the fridge is designed to run on +/- 12v, I doubt if the higher voltage would provide significant additional "cooling power."

With peltier modules the higher the voltage the more cooling so running a 14v supply is desirable.

[MBWhite]

Do you have an estimated total amperage draw for your peltier modules? That would be the place to start then design your system from there. Are you thinking 8 amps X 14 volts = 112 supplied watts? Also, I see your location is Denmark, is your shore power 110 or 220 volts or something else? (apologies for the ignorant question!)

[HeywoodJ]

How much voltage can you accept? 15V power supplies are easy to find, is that too much? Lots of old computer supplies that ran a 15V output at 7-15A.

Don't know if the link with search saved will work, DigiKey. Most of those would set you back about the same as a small battery.

There's also the option of a DC-DC converter, but in the power required that might increase cost over a battery solution.

[smac999]

just get a 14v power supply. Some will be adjustable


Look at the victron ip22 charger. It can be set to constant power supply at any voltage. In 15, 20, 30a models. With single or 3 bank output.

The 15a 1 output should be pretty cheap. Like 150usd Comes in 120v or 230v models

[PaulCrawhorn]

Are you saying you don't already have any House battery?

"12V" is just a label, hardly anything sits at that point exactly, means the range between 10.5V and ~15V.

Lead battery charging voltages are in the 13.8-14.8V range, so select a battery that specs at the higher end rather than lower, and use an adjustable charge source.

But in practice I bet your Peltier will perform just fine anywhere around that range