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Author Topic: Solar question, what do I need? relay?  (Read 1538 times)

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Offline crabby1

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Solar question, what do I need? relay?
« on: Wed 28 Dec 14:33 2016 »
Setting up a Victron 75/15 MPPT to vehicle that on has cranking battery and fridge runs off it for the Ethotec Autofridge.
165Watt 44volt panel feeding it.

The fridge will run off the load terminals and cranking battery off the battery terminals.

My question is to cut the infeed if the PV will alternator is running would a relay work to cut the PV infeed to MPPT?
Would it be fitted in the positive wire?

Relay to my understanding works once the exciter wire bridges the relay, so I really require something that is connected with out power to the exciter wire and disconnects the PV once the exciter wire is active.

Was going to hook exciter wire to windscreen washer cable as live whenever ignition is on and alternator is charging and so stops the PV infeed.
Or have I ballsed it up all ready.

Other question is can Victron 75/15 run a fridge direct with no battery connected to battery terminals?

She is only going away Friday so not too much rush
After Xmas and overcast has made her rethink battery situation

Thanks

Offline beach bum

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Re: Solar question, what do I need? relay?
« Reply #1 on: Wed 28 Dec 17:08 2016 »
I'm no genius on the subject but would think that a battery is needed to continue to draw off once the Suns down n panel is no longer contributing. And that there would need to be some sort of logic on a pcb like a redarch or piranha ect that looks at voltage/current from solar vs engine n decides as to which will charge. As I don't think the regulator on the panel will be smart enough to stop the flow once the alternater kicks in n voltage goes up towards 14.4.   So I can see how your trying to get around it with a relay n think you might get away with it but would think the pcb logic would serve you better even tho more expensive. N could open the door to a gen set feed ect.
Looking forward to the next trip

Offline crabby1

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Re: Solar question, what do I need? relay?
« Reply #2 on: Wed 28 Dec 20:23 2016 »
No genset feed required on this setup.

The fridge is Ethotec Autofridge and side walls are filled with saline solution for fridge only really requires 5hrs in time per day to keep everything cold or it will freeze stuff. It is nothing like your Weaco or Engal in how you use it.

If can get it to work during daylight hours then no need to run at night at all. Be great if do not have to use the cranking battery as part of the circuit as vehicle and camper is limited space for 2nd battery.

Will email Victron and get answer but thought would ask here first.

Can do the plug/unplug for this coming weekend.

Will post the last 16days recorded use of panel /mppt especially over the couple days of rain at Xmas.
Well I find it interesting.

Offline beach bum

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Re: Solar question, what do I need? relay?
« Reply #3 on: Wed 28 Dec 20:48 2016 »

The fridge is Ethotec Autofridge and side walls are filled with saline solution for fridge only really requires 5hrs in time per day to keep everything cold or it will freeze stuff. It is nothing like your Weaco or Engal in how you use it.

I've always found them to struggle if anything is put in hot and heavy on 12 v power but if you can find a setup that works then it's happy days
Looking forward to the next trip


Offline crabby1

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Re: Solar question, what do I need? relay?
« Reply #4 on: Thu 29 Dec 09:42 2016 »
Yes BeachBum they struggle if add a boned out deer in them but that's not what thy where designed to run as.

Thinking a change over relay may work?

Wonder if either of there change over relays would work to handle 185W at 42Volts? with a 12volt wire to activate

http://www.ebay.com.au/itm/RC-1260R-BRITAX-12V-60-80A-CHANGEOVER-MINI-RELAY-SUIT-BCDC-CHARGER-HIGH-QUALITY-/121870283316?hash=item1c6008f234:g:D7MAAOSw5VFWHiqp

http://www.ebay.com.au/itm/L-K-BRITAX-MINI-RELAY-RC-2460R-24Volt-60-80Amp-CHANGE-OVER-/171958771265?hash=item28098a9e41:m:mvJ5haCPe7Tgta25Scf5BDg

Offline crabby1

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Re: Solar question, what do I need? relay?
« Reply #5 on: Fri 13 Jan 08:51 2017 »
Got reply to my email and don't required to introduce relay in PV feed.

Took out fit for drive before, as the battery is brought up to 14.2volts the MPPT reduces the PV infeed rate down until goes into FLOAT charge and draws  0 watts from the panel.

Save unplugging the  fridge and MPPT each time she wants to drive vehicle

Once download photos will do screen shots of the usage verse PV inputs.

Technology with solar and setups is easy to see why so many 4wd, vans, campers and offgrid homes solar if the first choice of charging batterys

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Offline crabby1

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Re: Solar question, what do I need? relay?
« Reply #6 on: Mon 4 Dec 16:25 2017 »
After running this setup for near 12months the single cranking battery still rates over its rating.

Nothing exceptional to report as setup works and requires no input with panel keeping up to tbe 5hrs fridge hrs per day.

Yes battery can be slow to crank engine if not driven for 3 or 4 days and raining or heavy overcast days in that time.