Running a 12 v fridge through a 240v battery charger

Submitted: Sunday, Feb 26, 2023 at 15:25

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Member - Outback Gazz

G'day All

In my space cab work ute I have a 50 litre fridge next to a battery box I made up which houses a 120ah agm battery a redarc bcdc charger, a Projecta 240v charger along with other things. A few years ago I wired in an external caravan plug and mounted it on the box and connected the 240v fridge cord to the plug so that when I pull up home I just grab the extension cord off a hook and plug it in to the caravan plug which then automatically switches the fridge from 12 to 240 v to save draining the battery. The 12v cord is connected direct to the battery with a fuse and anderson plug.

Well now I don't seem to be driving as far each day (which charges the battery) and with the hotter weather I'm worried about the drain on the battery as the fridge runs 24/7

The Projecta is a 10 amp 7 stage charger

Is there any reason I can't just plug the extension cord into the Projecta and leave it overnight or even two nights then just unplug it and the fridge is back on 12 volt ?

Would that run the fridge and keep the battery charged ?

Would the Projecta get too hot and cause an issue of some sort ?

Cheers and cold beers
Gazz

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Reply By: Member - Warren H - Sunday, Feb 26, 2023 at 15:46

Sunday, Feb 26, 2023 at 15:46

Don't know the details of your charger, but some designed to be used in an RV like my Victron, have a power supply mode. My Supercheap multistage charger for AGM or regular flooded cell batteries does not.

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Reply By: Member - Racey - Sunday, Feb 26, 2023 at 17:07

Sunday, Feb 26, 2023 at 17:07

Gazz, if it the "IC series" 7 stage charger it has a 13.8 volt power supply mode.

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Reply By: Member - Outback Gazz - Sunday, Feb 26, 2023 at 19:19

Sunday, Feb 26, 2023 at 19:19

Thanks Warren and Racey for your replies !!

Sorry but they didn't actually give me an answer to my 3 questions. It took quite a while but I managed to find the owners manual of the charger which is an IC1000 and from that I found out that .....

" automatic charging protects your battery from being overcharged so you can leave the charger connected to the battery indefinitely " so that answered one question.

Also I found out that the " battery chemistry selection " has different charge voltages for " GEL - AGM - WET " so as it's set for my AGM I'm assuming the charger will just do its thing.

So I have now plugged the charger in and hopefully I don't hear fire trucks at 0300 hrs putting out my ute lol lol

Thanks again guys for your replies

Cheers
Gazz

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Follow Up By: Allan B (Sunshine Coast) - Sunday, Feb 26, 2023 at 20:13

Sunday, Feb 26, 2023 at 20:13

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What you propose should work fine Gazz.
I think that "answers your three questions"?

Cheers
Allan

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Follow Up By: Member - Outback Gazz - Sunday, Feb 26, 2023 at 20:27

Sunday, Feb 26, 2023 at 20:27

Thanks Allan

Knew I would get the correct answer from you ;)

It's just that I've had very little to do with battery chargers - ever !

Everything worked fine for years with my set-up and lots of daily driving but since I don't do the hours in my work ute so much these days things have changed - so I've been having to run the Projecta a fair bit to keep the battery topped up.

Hope you are well and thanks for the reply

Cheers
Gazz

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Follow Up By: Allan B (Sunshine Coast) - Sunday, Feb 26, 2023 at 22:57

Sunday, Feb 26, 2023 at 22:57

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Thanks Gazz, I read that you intend to keep the battery in the circuit while using the charger and that's good because smart chargers will not produce an output unless they 'see' a battery at startup.
Some, and probably your Projecta, have an option for "Supply" which does not need to see a battery and they produce a ~13.8v output. In this mode they can operate a fridge etc. without a battery in circuit.
But do not use "Supply" mode when a battery is connected because it will overcharge the battery. The Projector in "Normal" mode will keep the battery at float level indefinitely.

Cheers
Allan

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Follow Up By: Member - Outback Gazz - Monday, Feb 27, 2023 at 15:42

Monday, Feb 27, 2023 at 15:42

Howdy Allan

"But do not use "Supply" mode when a battery is connected because it will overcharge the battery. The Projector in "Normal" mode will keep the battery at float level indefinitely."

According to the instructions that I found and have now read lol -

Power Supply Mode ... says

" This sets the charger in power supply mode giving a constant voltage of 13.8 volts. This mode is best used where appliances are drawing power from the battery, for example like a fridge. Although the charger is designed to work with a battery connected , it can also work without a battery "

The manual also states in the features section ......

" automatic charging protects your battery from being overcharged so you can leave the charger connected to the battery indefinitely "

I ran through the modes but there is no normal mode so from what I can work out and what the manual says I will just set it to Power Mode - it's been running for 24 hours now and I haven't needed to call the fire brigade so all is good !

Thanks

Cheers
Gazz

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Follow Up By: Zippo - Monday, Feb 27, 2023 at 16:31

Monday, Feb 27, 2023 at 16:31

Gazz, the Projecta will float your AGM at 13v3 if I recall correctly. Floating it across the POWER SUPPLY mode will deliver 13v8 which is higher than (Projecta's) recommended AGM float. That's the only caution.

I often use my Projecta IC1500 in SUPPLY mode on a collection of AGM/GEL batteries here (*), but only for a set time - out of respect for that lower target float voltage.

(*) and sometimes on the cranker too after it has been standing for a lengthy period. I don't ever leave the charger connected long-term. Personal choice.

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Follow Up By: Member - Outback Gazz - Monday, Feb 27, 2023 at 18:18

Monday, Feb 27, 2023 at 18:18

Hey Zippo

Nothing in the manual about float voltages just "maximum" voltage of 14.4 for AGM

I will just leave it on power supply mode and see how things go

Appreciate your reply

Cheers
Gazz

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Follow Up By: Zippo - Monday, Feb 27, 2023 at 18:47

Monday, Feb 27, 2023 at 18:47

Gazz, actually there is. In the table on P6 last item under CHARGE CONTROL (just above the POWER SUPPLY heading) is FLOAT.

Actually (recalling Murray Walker's famous lines) "unless I am very much mistaken" becomes "yes I am very much mistaken" as the Projecta float voltage is 13v7 so insignificant difference to using SUPPLY mode. I was recalling the 13v3 float from the Redarc BCDC series. Mea culpa.

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Follow Up By: Allan B (Sunshine Coast) - Monday, Feb 27, 2023 at 19:15

Monday, Feb 27, 2023 at 19:15

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Gazz, By "Normal mode" I meant one of the battery type modes: Lithium, AGM etc.

Nominal AGM float voltage is 14.4v but figures are a bit rubbery so 14.8 (supply) voltage should be OK. Just not my preference.

Cheers
Allan

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Follow Up By: Member - Outback Gazz - Monday, Feb 27, 2023 at 19:58

Monday, Feb 27, 2023 at 19:58

"Gazz, By "Normal mode" I meant one of the battery type modes: Lithium, AGM etc."

Allan - It's an interpretation thing - some people interpret things very different to others !

For example - the other day, my missus asked me if I could go to the shop and get a litre of milk and if they had eggs get six ?

When I got home I put the six litres of milk on the bench and then she asked me where are the eggs ?

I said what eggs ? you didn't ask me to get eggs you asked me to get a litre of milk and if they had eggs get six - I saw that they had eggs so got six milks

How we are still together after 35 years astounds me :)

Cheers
Gazz

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Follow Up By: Member - McLaren3030 - Tuesday, Feb 28, 2023 at 07:35

Tuesday, Feb 28, 2023 at 07:35

Yes Gazz, my older brother was not very “domesticated”. His wife told him to put the frozen pie in the oven at 180 degrees for an hour. When she got home, she found the pie in the oven alright, still in its now shrink wrapped plastic cover, and charred cardboard box. His excuse, “I did exactly what you told me to do”.

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Follow Up By: Allan B (Sunshine Coast) - Tuesday, Feb 28, 2023 at 08:48

Tuesday, Feb 28, 2023 at 08:48

.
.
FRIDAY FUNNIES ARE BACK!!!!!!!! ….. Even though it's only Monday.

Cheers
Allan

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Reply By: Bushranger1 - Sunday, Feb 26, 2023 at 20:52

Sunday, Feb 26, 2023 at 20:52

G'day Gazz,
You will be fine.
We have a permanent caravan setup on our bush block & I run an Engel off a 130ah battery.
It is connected for weeks at a time when we are there & every 3 days I start a small Gennie to charge the battery & phones etc. The charger is a 16amp 7 stage it comes on as soon as I start the Gennie & I leave the fridge connected to the battery. I notice if the battery is fully charged & the fridge comes on the charger goes off float mode to a slow charge mode then goes back to float mode when the fridge compressor switches off.
Been doing that for 10 yrs no problem at all.
In fact I asked the question here 10 yrs back & got all different answers so just thought "bugger it" I will give it a shot & all good

Cheers
Stu

AnswerID: 642947

Follow Up By: Member - Outback Gazz - Sunday, Feb 26, 2023 at 20:56

Sunday, Feb 26, 2023 at 20:56

Hey Stu

Awesome reply - thanks !

Cheers
Gazz

FollowupID: 922555

Reply By: nickb - Sunday, Feb 26, 2023 at 23:38

Sunday, Feb 26, 2023 at 23:38

As above, no problem doing what you propose. My Jayco Dove had everything run off the battery, the only 240V was the charger connected to the battery. 7 years with no issues. Have wired my latest van the same way and expect no issues.

AnswerID: 642948