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Elecric 12v fridge


colmac

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Hi, bit of a continuation of a previous post Have now fitted a 12v fridge. In the manual it says " when using a rapid charging device the fridge should be disconnected to avoid damage to the unit" It is a Dometic ( ex electrolux ) crx50. Anyone with any advice or experience of this ? I am assuming that, by "rapid charging device" they mean 240v shore mains.

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1 minute ago, colmac said:

Hi, bit of a continuation of a previous post Have now fitted a 12v fridge. In the manual it says " when using a rapid charging device the fridge should be disconnected to avoid damage to the unit" It is a Dometic ( ex electrolux ) crx50. Anyone with any advice or experience of this ? I am assuming that, by "rapid charging device" they mean 240v shore mains.

I have never had problems in the past with any 12 volt fridge during any charging regime. Most have a 12/24 volt unit fitted anyway?

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3 minutes ago, colmac said:

Hi, bit of a continuation of a previous post Have now fitted a 12v fridge. In the manual it says " when using a rapid charging device the fridge should be disconnected to avoid damage to the unit" It is a Dometic ( ex electrolux ) crx50. Anyone with any advice or experience of this ? I am assuming that, by "rapid charging device" they mean 240v shore mains.

What they are referring to is when your battery charger is in 'equalisation' mode and kicking out 15+ volts.

Apparently they 'don't like it up em' and give-up.

Just switch the fridge off at the switch panel for a while when doing equalisation charging.

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Prob because of high voltage, if you do an equalisation charge you should disconnect all electronics anyhow.

The manual also says “Always keep and use the device out of the reach of children under 8 years of age.”,  for a under counter fridge - how do you do that?

Edited by Robbo
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7 minutes ago, mrsmelly said:

The fridge and freezer I have sold to forum members said 12/24 volts on them.

It will be either be 12v or 24v, it’s not 12v to 24v, the cut in/out voltages will be different for what ever voltage it detects (or set) for.  

Looking at the manual it will cut off at 10.4v or 20.8v.  And cuts in at 11.7v or 24.2v.

Edited by Robbo
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10 minutes ago, Robbo said:

It will be either be 12v or 24v, it’s not 12v to 24v, the cut in/out voltages will be different for what ever voltage it detects (or set) for.  

Looking at the manual it will cut off at 10.4v or 20.8v.  And cuts in at 11.7v or 24.2v.

So... if it sees 16V+, what will it think I wonder?

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6 minutes ago, WotEver said:

So... if it sees 16V+, what will it think I wonder?

Doesn’t say In the manual but guessing it’s a Danfoss compressor so from that manual.

 

BD35/50/80F/250GH/100CN: 12V DC systems: 10.4V (9.6V min.) - 17V max. ; 24V DC systems: 22.8V (21.3V min) - 31.5V max.
BD35F/BD35K: Solar systems: 10V - 45V, no battery protection.
The low voltage limits stated in brackets () can be established if a connection is made between the ter- minals C and P, please see also the passage Optional battery protection settings page 9.
The electronic unit will calibrate to the applied voltage. This means that if the battery voltage is less than 17V, the electronic unit assumes that it is working in a 12V system. If the voltage is higher than 17V, the electronic unit assumes that it is working in a 24V system. Consequently, the compressor does not run at power supply voltages between about 17V and the desired battery protection cut-out voltage for 24V systems. A continuous voltage range from 9.6V to 31.5V can be established if a 220kΩ resistor (wir- ing diagram item 9) is connected between the terminals C and P. This wide voltage range makes the BD compressors very suitable for photovoltaic powering.

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1 hour ago, Robbo said:

Doesn’t say In the manual but guessing it’s a Danfoss compressor so from that manual.

 

BD35/50/80F/250GH/100CN: 12V DC systems: 10.4V (9.6V min.) - 17V max. ; 24V DC systems: 22.8V (21.3V min) - 31.5V max.
BD35F/BD35K: Solar systems: 10V - 45V, no battery protection.
The low voltage limits stated in brackets () can be established if a connection is made between the ter- minals C and P, please see also the passage Optional battery protection settings page 9.
The electronic unit will calibrate to the applied voltage. This means that if the battery voltage is less than 17V, the electronic unit assumes that it is working in a 12V system. If the voltage is higher than 17V, the electronic unit assumes that it is working in a 24V system. Consequently, the compressor does not run at power supply voltages between about 17V and the desired battery protection cut-out voltage for 24V systems. A continuous voltage range from 9.6V to 31.5V can be established if a 220kΩ resistor (wir- ing diagram item 9) is connected between the terminals C and P. This wide voltage range makes the BD compressors very suitable for photovoltaic powering.

Based on those figures then it’s a non-issue for 99.9% of boaters, including the OP :)

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32 minutes ago, OldGoat said:

I have a Danfoss BD35 setup in my boat and regularly run it up to 29v (24V NiCd battery bank) and have been using them since 2000 with no problems.

But that's only equivalent to 14.5V on a 12V boat - that voltage isn't unexpected when charging, so you really shouldn't have problems.

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1 minute ago, Sea Dog said:

But that's only equivalent to 14.5V on a 12V boat - that voltage isn't unexpected when charging, so you really shouldn't have problems.

That's my point - the Danfoss can cope with it. I've been up to 30v on occasion.

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26 minutes ago, OldGoat said:

That's my point - the Danfoss can cope with it. I've been up to 30v on occasion.

That was also my point - even 30v on a 24v system is the equivalent of 15V in a 12V boat, so I'd hope so or they'd be failing all over the place! :D

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26 minutes ago, Richard10002 said:

So, if it can run without damage from about 10V to about 32V, why does it need the warning in the OP?

Read Robbo’s post again. It can’t (as standard) run from 10V to 30V. It can run from 10V to 17V or from 22V to 31V (approx). So any voltage between 17 and 22 is invalid. 

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1 hour ago, WotEver said:

Read Robbo’s post again. It can’t (as standard) run from 10V to 30V. It can run from 10V to 17V or from 22V to 31V (approx). So any voltage between 17 and 22 is invalid. 

So, if it can run without damage from about 10V to over 16V, why does it need the warning in the OP. :)

Unless I’ve missed something, there aren’t any standard chargers that can equalise at over 16V. In other threads where this has been questioned, bench power units have been mentioned, but this requires some extraordinary effort, and special knowledge.

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14 minutes ago, Richard10002 said:

So, if it can run without damage from about 10V to over 16V, why does it need the warning in the OP. :)

Unless I’ve missed something, there aren’t any standard chargers that can equalise at over 16V. In other threads where this has been questioned, bench power units have been mentioned, but this requires some extraordinary effort, and special knowledge.

Yes indeed. As per posts 10 & 13

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11 hours ago, Richard10002 said:

So, if it can run without damage from about 10V to over 16V, why does it need the warning in the OP. :)

Unless I’ve missed something, there aren’t any standard chargers that can equalise at over 16V. In other threads where this has been questioned, bench power units have been mentioned, but this requires some extraordinary effort, and special knowledge.

Although you may well be correct in respect of typical on board chargers I am not so sure about commercial portable rapid chargers like most garages had in the past and may still do.. I suspect at least some may charge at a much higher voltage, at least for a while.

That warning is very similar to solar controller instructions saying you must connect the batteries first. They do not explain this is so the controller can measure and set itself to the battery voltage. We have had a statement on here in respect of solar that makes me suspect this was ignored and the boater got his controller set to 24 volts with a 12V battery set up. I am sure the instructions for the fridge are for the same reason because the manufacturer has no way of knowing where it will be used so it could be in a vehicle of some sport

 

 

Edited by Tony Brooks
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13 minutes ago, Tony Brooks said:

I am sure the instructions for the fridge are for the same reason because the manufacturer has no way of knowing where it will be used so it could be in a vehicle of some sport

Indeed, their main market is caravans and motorhomes. 

14 minutes ago, Tony Brooks said:

We have had a statement on here in respect of solar that makes me suspect this was ignored and the boater got is controller set to 24 volts with a 12V battery set up

Yup, he never admitted that but it’s the only logical scenario for what he described. 

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Many thanks to all for the replies to my post. Proves the value of this forum. Hate to show my ignorance but can someone explain what an " equalisation charge " is please.The only problem with this forum is it really exposes huge gaps in my knowledge of things electrical. Thank you.

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