Fridge on solar

Jan 27, 2018
764
627
Northampton
Funster No
52,151
MH
Rapido & Bongone
Recently I've read some old threads even back to 2014 about running a fridge on solar power. Now i have an aes fridge votronics solar controller with aes control. Slight problem i cant find the S+ connector and it has been said that it wont work with a cbe box that supplies the 12v power from the hab battery (this needs D+). Snowbird Techno used a diode on a D+ line at the CBE box, what diode and which way around? Also any thing controlled by the D+ will also be on, i have a votronics 1230 b2b what effect will the aes have on it. Is it just a question of connecting the aes on the solar controller to the D+ at the cbe300.
Have i enough solar, 550w, should be.
 
Apr 27, 2016
3,117
3,056
Manchester
Funster No
42,762
MH
A class Hymer
Exp
Since the 80s
I'm not an expert on this, but I can see the general idea. If the solar controller AES output is simply fed to the fridge D+ control, the fridge will work OK but as you say the D+ will feed back so that everything else on the D+ will be activated. You can solve that by cutting the connection between the fridge D+ and the other D+ circuits. However that in turn will mean the fridge will not turn on from the standard D+ when the engine starts.

A diode (electrical one-way valve) between the fridge D+ and the other D+ circuits will allow the engine D+ to pass through, but will block the solar controller D+ from feeding back to the other D+ circuits.

The D+ is a low-current circuit, so a low-power diode will be good enough.
 
OP
the1andonly
Jan 27, 2018
764
627
Northampton
Funster No
52,151
MH
Rapido & Bongone
Thanks autorouter i think i now understand what i need to do in terms of sussing what the D+ ive tapped into is, ie the feed from the alternator or feed to fridge.
Fuse 10 is simulated D+ exit.
Item 16 white wire is D+ signal i used for b2b..so votronics feed to fridge side and diode to connector/ b2b.

Diode i have the odd 1N4148 in my box of tricks, a bit too low power?

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Apr 27, 2016
3,117
3,056
Manchester
Funster No
42,762
MH
A class Hymer
Exp
Since the 80s
Diode i have the odd 1N4148 in my box of tricks, a bit too low power?
It's only a 300mA diode - but the D+ is a low-current signal. I think I'd measure the D+ current at that point with a multimeter just to be sure. It can take up to 100V, which should be fine. You can get surprisingly high spikes from the alternator, but any diode over 60V should be OK.
 

Lenny HB

LIFE MEMBER
Oct 18, 2007
30,090
52,537
On the coast in West Sussex
Funster No
658
MH
Hymer B678 Dynamic Line
Exp
Since 2008 & many years tugging
A pair of 1n5401 in parallel?
No, that won't work with diodes but a single 1N5401 but a single one should be OK.

I have my fridge wired to my Votronic you may not get the same problem as I do as you are using the D+ connection. On my fridge the primary energy selection has 12v solar at the top of the list. So when on EHU the Votronic sees the batteries as fully charged so turns on the AES signal the fridge sees the signal and switches to 12v. I fitted a mains relay in line with the AES wire to stop it happening.

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funflair

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Dec 11, 2013
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I'm not an expert on this, but I can see the general idea. If the solar controller AES output is simply fed to the fridge D+ control, the fridge will work OK but as you say the D+ will feed back so that everything else on the D+ will be activated. You can solve that by cutting the connection between the fridge D+ and the other D+ circuits. However that in turn will mean the fridge will not turn on from the standard D+ when the engine starts.

A diode (electrical one-way valve) between the fridge D+ and the other D+ circuits will allow the engine D+ to pass through, but will block the solar controller D+ from feeding back to the other D+ circuits.

The D+ is a low-current circuit, so a low-power diode will be good enough.
I wired our old 8 series fridge to run on the D+ signal from the Votronic, yes I had to put a diode in but to stop the signal going down to the -ve through the alternator rather than to stop it turning other things on or off, I guess it depends if you rely on a old style D+ from the ignition wire or a simulated one from a relay.
 
OP
the1andonly
Jan 27, 2018
764
627
Northampton
Funster No
52,151
MH
Rapido & Bongone
I wired our old 8 series fridge to run on the D+ signal from the Votronic, yes I had to put a diode in but to stop the signal going down to the -ve through the alternator rather than to stop it turning other things on or off, I guess it depends if you rely on a old style D+ from the ignition wire or a simulated one from a relay.
Mine is a 9 series, i am using the D+ because the cbe controls the high current supply not the S+. The D+ is feed to the CBE via connector 16 white wire. in the photo it is the red crimped male. The blue crimped fatter white wire is the D+ feed to the b2b
20210430_124918.jpg


Lenny HB now waiting for delivery of rectifier diode P600 6A.
I will assess need for relay when it all works (or otherwise).
Am i right in thinking i would need to isolate the votronics aes feed from the b2b triger (blue crimped wire).
Thanks for all input to date.

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OP
the1andonly
Jan 27, 2018
764
627
Northampton
Funster No
52,151
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Rapido & Bongone
Well diodes tried and it doesnt work. The relay wherever it is doesn't trigger. A circuit diagram would be handy, but hey ho.
I have an alternative idea. Use the aux input unused on pin 1(fuse 7) as feed to relay switched by votronics aes signal.
Would need to splice into pin 2 . Mocking up with flying leads works. Now question is best way to connect 2 30A cables to 1 pin. Strip insulation 2" from crimp and solder/ heatshrink.
 

Lenny HB

LIFE MEMBER
Oct 18, 2007
30,090
52,537
On the coast in West Sussex
Funster No
658
MH
Hymer B678 Dynamic Line
Exp
Since 2008 & many years tugging
Mine is a 9 series, i am using the D+ because the cbe controls the high current supply not the S+. The D+ is feed to the CBE via connector 16 white wire. in the photo it is the red crimped male. The blue crimped fatter white wire is the D+ feed to the b2b
View attachment 491140

Lenny HB now waiting for delivery of rectifier diode P600 6A.
I will assess need for relay when it all works (or otherwise).
Am i right in thinking i would need to isolate the votronics aes feed from the b2b triger (blue crimped wire).
Thanks for all input to date.
I don't see what the B2B has to do with it. I don't understand why you don't just connect the aes output of the Votroic to the S+ on the fridge.
 
OP
the1andonly
Jan 27, 2018
764
627
Northampton
Funster No
52,151
MH
Rapido & Bongone
Slight problem i cant find the S+ connector and it has been said that it wont work with a cbe box that supplies the 12v power from the hab battery (this needs D+). Snowbird Techno used a diode on a D+ line at the CBE box,
Also any thing controlled by the D+ will also be on, i have a votronics 1230 b2b what effect will the aes have on it. Is it just a question of connecting the aes on the solar controller to the D+ at the cbe300.
Sorry Lenny HB cant find the S+ (was another thread on it as well) most connectors are in a less than accessible location

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Dec 17, 2016
440
335
Malvern
Funster No
46,488
MH
Hymer B525 2006 A cl
Exp
2012
S+ is next to all the other connections on the back of the fridge.
I thought my S+connector was on the back (indeed I think I said so on a different thread, perhaps yours the1andonly , for which I apologise) but when looking the other day when sorting out my new Votronic solar controller I realised that it is on top of the fridge behind the control panel. Mine is a 6 series fridge I think from 2006.
 
Dec 17, 2016
440
335
Malvern
Funster No
46,488
MH
Hymer B525 2006 A cl
Exp
2012
Don't think fridges before the 8000 Series had an S+ connection.
Just checked and mine is a 7655 not a 6 series:rolleyes:. It does have a S+ but I haven't checked if it works yet as I have a complicated cable run but will let you know when I do...
 
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