Fridge spike suppression.

ProAsm

ProAsm

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I have a reasonable solar system which I've had since 2015, consisting of 4 x 105 A/H batteries, 1000 watt inverter, 2 x 300 watt solar panels etc running on a separate circuit through out the house and works very well.
The problem I have is the spike that the fridge sends out at switch on.
I have modified the inverter so as not to reset when this happens, but still the spike is big enough to dip the lights and restart the DSTV decoder.
I have tried several suppressor plugs without much success.
Other than getting a bigger inverter is there any device I can use to successfully suppress this spike ?
 
Does this happen during loadsdhedding when you cutover from mains to battery/inverter?
 
That is pretty common, most fridges will spike up to 1000 watts of power when switched on.
Either a bigger inverter or go pure sine wave.
or a new fridge that runs a DC motor.

Either way you going to have to spend some money unless someone knows a quick easy fixaround for this
 
Do you know if its the inverter that is struggling at that second or the batteries supplying the inverter?

If the latter I'd suggest getting a capacitor from your local car audio shop to help with that short burst of required current.

I don't know if you'll get the same thing for 220v after the inverter.
 
Measure the fridge draw when it's turned on, and it's draw when the compressor kicks in and the draw when it defrosts. Fridge's draw more when certain activities are happening (cooling/regulating temp/powering on etc)

This will arm you with the figures to either rule out the inverter or not.

That being said, you didn't mention the inverter type - is it Pure Sine or modified Sine?
What other appliances/device are on the same circuit? Have you tried to simulate it with the fridge load on its own without anything else running?
So many variables here though
 
1000W Inverter is most likely the limit.

Fridges, especially older models' start-up current is rather high. Thus more than likely, the spike you speak off is actually a dip, due to a lack of power supplied from the inverter....
 
D4N_CPT said:
1000W Inverter is most likely the limit.
Click to expand...

Agreed somewhat. Would be unlikely though a fridge when powered on peaks at 1000w.
With additional load from other appliances, the inverter being the issue would make absolute sense though.

That's why I mentioned a good starting point would be to simulate with just the fridge load and see if it behaves the same. And measuring appliance draw too.
 
Cheaper to replace the fridge with a new inverter DC motor compressor.

More energy efficient, less total power draw therefore less of a problem to accommodate on your power setup.
 
Last edited:
How long does it take 2 panels to recharge the batteries?
 
Thanks for the reply's.
Well let me answer some of the questions here.

MEIOT:
Yes during load shedding and the other 101 times we loose mains here in Hilton.
My system is programmed to go off every day if it's sunny.

Chuckmyster:
Yes I'm looking for an easy way out :)

AstroTurf:
Trying to avert that.

gamer16 and MEIOT:
Ok, the fridge runs 120 watts in normal state (eco friendly) and spikes to 1800 watts on switch on.
The inverter is a somewhat modified Luminous ION Digital Pure Sine Wave.
No I have not tried the fridge on it's own.
The Inverter supplies 5 outside security lights on a day/night switch, and about 7 lights inside (all 5 watt LED).
It also supplies 2 x 32" TV sets and one 55" TV set + DSTV decoder (Explora), 2 x desktop computers and one laptop and 1 x LTE modem, 2 cell phone charges, 2 digital clocks, 1 x shaver, 2 x electric blankets on No 1 in winter and a variety of small items in the house.

D4N_CPT:
It's quite a modern Sharp Eco fridge not sure the capacity but quite large.
We also have a small chest freezer that draws 180 watt which I also want to put on but with a timer so in no way can they both switch on at the same time.

The_MAC:
Yes, if I get a bigger inverter it will be the Axpert 3Kw from Sustainable.

shearder:
From 50% battery, about 4 hours with good sun shine.
Currently the panels face North but I want to change that so they face West-North-West.
 
ProAsm said:
Ok, the fridge runs 120 watts in normal state (eco friendly) and spikes to 1800 watts on switch on.
.
Click to expand...

Yeah - thats the problem. Inverter not sufficiently specced for that load
 
Geoff.D said:
Cheaper to replace the fridge with a new inverter DC motor compressor.

More energy efficient, less total power draw therefore less of a problem to accommodate on your power setup.
Click to expand...

Where can I go to get more info on this DC Motor fridge as I must say, I've never heard of this before although don't camping fridges use this system ?
 
MEIOT said:
Yeah - thats the problem. Inverter not sufficiently specced for that load
Click to expand...
Yes, you are right and that's why I figure there must be a way to electronically suppress that spike.
Hell it's only for a millisecond or so and with all the technology today we have no solution.
I have a problem with that.
Basically the inverter used to switch off when the fridge came on and I had to go and manually get it going again.
This was a real pain in the butt, so I stripped down the inverter and modified it slightly with a feed back system on the reset transistor (FET).
Problem with this is if there is a genuine serious overload etc it could burn out the inverter.
Well the fridge only trips it once so that works ok, but still the DSTV decoder restarts and you can emagine the flack in the house :)
 
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