Running appliances while still charging battery ??

Submitted: Thursday, Jul 03, 2014 at 15:51
ThreadID: 108587 Views:3709 Replies:5 FollowUps:7
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Wonder if it is safe in my van to run a compressor type fridge ( 12 v ) connected to 240v but going through a Mobitron box when charging the 12v battery via a charger ??
There is also a solar panel ( aprox 80 w ) via controller
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Reply By: Member - Frank P (NSW) - Thursday, Jul 03, 2014 at 16:54

Thursday, Jul 03, 2014 at 16:54
Brian,

What is a Mobitron box?

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FrankP

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Follow Up By: Member - Brian - Thursday, Jul 03, 2014 at 19:24

Thursday, Jul 03, 2014 at 19:24
Hello Frank ,
i think a simple way to describe it is a transformer , because the fridge runs only on 24v/12v it converts the 240 mains power back to 12 volt . Hope that describes it right ?
Thanks mate
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Follow Up By: Member - Frank P (NSW) - Thursday, Jul 03, 2014 at 19:48

Thursday, Jul 03, 2014 at 19:48
OK, Thanks Brian. That being the case, not only is it safe to run your fridge while charging with a mains charger, As I understand it you have possibly the most desirable setup.

As I envision it, your fridge is not a load on the battery while mains are connected. It is always better to charge a battery with no load on it, which is what you are doing.

Do other 12V loads (eg 12V TV) run through the Mobitron as well as the fridge? It would be good if they did.

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Follow Up By: Member - Brian - Friday, Jul 04, 2014 at 10:01

Friday, Jul 04, 2014 at 10:01
No Frank , the Mobitron is only used for the fridge , but when i am relying only on battery power i plug the fridge into a 12volt power point .
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Follow Up By: Nomadic Navara - Friday, Jul 04, 2014 at 15:38

Friday, Jul 04, 2014 at 15:38
Quote "i think a simple way to describe it is a transformer"

I hope it's not a transformer. A transformer transforms AC power at one voltage to AC power at another voltage. If you feed a fridge with AC power you will stuff it up. I would suspect it is a power supply, they deliver DC power.
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Follow Up By: Member - Brian - Friday, Jul 04, 2014 at 16:15

Friday, Jul 04, 2014 at 16:15
i thought it was a transformer Peter D but thanks for the correction
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Reply By: Patrol22 - Thursday, Jul 03, 2014 at 17:36

Thursday, Jul 03, 2014 at 17:36
Short answer is yes. There is also nothing to stop you continuing to run off 12 volts with the charger connected to the battery.
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Reply By: Honky - Thursday, Jul 03, 2014 at 22:39

Thursday, Jul 03, 2014 at 22:39
This is how I see it and if it incorrect, please advise.
The appliance gets the power first i.e. if the charger is 20 amps and the appliance uses 10 then only 10 amps goes to the battery.
If the appliance uses 30 amps and the battery charger is 20 amps than the appliance uses the 20 amps from the charger and also takes 10 amps from the battery.
My experience ( and very costly) is the voltage of the charger.
If the appliance range of voltage is say 11 to 13 volts and they charger puts out 14.8 than there is a chance that you may fry the appliance.
A simple view by a simple person.

Honky
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Follow Up By: Shaker - Thursday, Jul 03, 2014 at 22:48

Thursday, Jul 03, 2014 at 22:48
The alternator in your vehicle will output more than 13 volts!

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Follow Up By: Honky - Thursday, Jul 03, 2014 at 22:58

Thursday, Jul 03, 2014 at 22:58
The above volts where only an example.
My situation was that i had set up some 240 volt appliances that ran off an inverter that was not rate for input of over 13.8 volts.
Instead of disconnecting the 240 appliance from the inverter and plugged it into the 240 source, i just charged the batteries and this put in 14.8 volts into the inverter, the result was a lot of heat and smoke.

Honky
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Reply By: olcoolone - Friday, Jul 04, 2014 at 17:06

Friday, Jul 04, 2014 at 17:06
Are you talking about "Waeco Mobitronic Power Supply like a model MPS-50".

Brian most on this forum can not read minds and it makes it that bit harder when the name of something may be wrong!
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Reply By: The Bantam - Friday, Jul 04, 2014 at 22:45

Friday, Jul 04, 2014 at 22:45
If in this case we are talking about a Mobitronic MPS50A, power supply as used with many waeco fridges, this whole thing may be different to what some may envision.

This particular power supply actually outputs 24 volts ( nominal), if it is a waeco fridge it will run on a wide variety of voltages from its low voltage cut out threshold right up to well over 24 volts.

If you are realy concerned about the whole arrangement, the MPS50A power supply has the facility to switch from 240V mains supply to the battery supply automaticaly.

Read the manual on this device.

there is a set of terminals to connect the incomming 12 volt ( or whetever supply).
When the unit has 240V supply, the fridge is supplied from the 240v source and the alternate supply is disconnected.

When the 240V supply is lost, the unit switches to the alternate supply.

I have 2 of thses units, but I do not use the switch over feature...I either plug into the 12 volt supply or the 240 volt supply vis the MPS50A as required..as most do.

cheers
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