Fridge Draw and dual batteries (1 Viewer)

[RFB]

Ok I got 2 oddessy extremes a 70AH starter and a 100AH house battery running only lights, invertor fridge thats it, and yet even with my 150amp sequoia alternator Im getting the low battery alarm by 10th hour of running only fridge at night and its only running at 30degrees nothing crazy, its a whynter 45l fridge too, nothing crazy. any ideas? seems like an awful lot of juice for one item running no?? I have 1 guauge made in USA flexible real deal welding wire running from battery back and the fridge is even sporting a insulation jacket.

 

[MANUCHAO]

Have you check actual draw on Fridge with ammeter ?
What about output to battery (aux)?
Faulty battery ?
I got the same set up as you do, with the exception of the Alternator.. its a 180amps
I can run the Aux battery Group 31 for about 5 days before the alarm on fridge goes off..
Fridge/freezer is 90L...

 

[Nas90tdi]

Something else is leaching power it sounds like. I have run Odysseys for years in all my trucks. Nothing come close to supplying power as long until you get into some even more expensive batteries. My Extreme 1500 in my LJ will run the fridge for 15+ hours and still crank the truck. The giant 2150 in my Land Rover will run it for longer then I have ever even bothered testing. And, my fridge is very old and not very efficient compared to the newer ones.

I would start by checking amp draw with all that off and see if the truck is diverting power somewhere, then check each item running at a time.

 

[spressomon]

100A battery x 50% is 50Ah. 5A x 10-hours...guessing your fridge + other draw appliances is drawing 5A/hour?

 

[RFB]

Have you check actual draw on Fridge with ammeter ?
What about output to battery (aux)?
Faulty battery ?
I got the same set up as you do, with the exception of the Alternator.. its a 180amps
I can run the Aux battery Group 31 for about 5 days before the alarm on fridge goes off..
Fridge/freezer is 90L...

now thats what I fiugred I went thru a lot of trouble making a group 31 fit in passenger side. and it dosent last even a half day. my wiring from battery to battery is 4 guage and then I have dedicated 1guage running back to invertor is that a prob??

 

[RFB]

100A battery x 50% is 50Ah. 5A x 10-hours...guessing your fridge + other draw appliances is drawing 5A/hour?

yea its drawing serious juice not a great name tough as hell works fine but draws............... looking into a snomaster now.

 

[spressomon]

yea its drawing serious juice not a great name tough as hell works fine but draws............... looking into a snomaster now.

Did you measure the amps leaving the battery?

What is connected to the inverter?

 

[RFB]

Did you measure the amps leaving the battery?

What is connected to the inverter?

I wired everything fused etc but Im stilling learning how to measure draw amps etc. my set up is solid im the weak link. so Im working on it as we speak/type.

 

[RFB]

the invertor is a 700 watt PSW go power the only thing coming off it is a power strip a regular 110v 6 plug strip I can plug fridge thru a fused anderson connector or simply plug it in, which is what I usally do. so the frdige sucking down a 100AH less than year old battery is wrong has to be.

 

[spressomon]

I don't know anything about your fridge but assume its a 12v compressor? If so, you should connect it directly to 12v rather than deal with the efficiency loss converting 12v to 110v via the inverter back to 12v at the compressor...

You might also check to see, if you leave your inverter on 24/7, how much current is being drawn by the inverter itself.

 

[RFB]

I don't know anything about your fridge but assume its a 12v compressor? If so, you should connect it directly to 12v rather than deal with the efficiency loss converting 12v to 110v via the inverter back to 12v at the compressor...

You might also check to see, if you leave your inverter on 24/7, how much current is being drawn by the inverter itself.

will do Im running the fridge alone off a humless 1500 to see how long it goes, but Im on the case Ill figure it out if I have to rewire it all agin
https://www.humless.com/wp-content/uploads/2016/11/1500Series-64kwh-lithium-battery-storage-1.pdf

 

[RFB]

Ok not sure if this will shine any light on my prob but I hooked up the genius charger and the 100AH with the charger on it alone only maxxed out at 12.7 on voltometer, when I put genius on main battery it ran thru dual battery (national luna solenoid) and that bumped both batteries after a while up to 13.8V total.

 

[ducktapeguy]

I have a whynter 45L and I can easily get a couple days out of a 44AH battery, if I plan for it. Are you pre-chilling the contents before running it on the battery?

Assuming your battery is good and there's nothing wrong with the fridge, the fridge max's out at 7A load, so it's entirely possible that you can drain a 70AH battery if it runs continuously. You might be overworking it by trying to cool the contents on battery power. These 12V fridges are great at keeping things cool, but suck a lot of energy getting them cool. By setting your temp settings to 30 degrees, you're trying to freeze everything, which takes a LOT of power to do. The fridge will try and run 100% of the time until everything becomes frozen.

I normally load up my fridge a few days in advance and freeze a bunch of water bottles on 110 power. Then I switch to 12V to maintain the temperature. I have an aux battery box powering the fridge with watt-meters to monitor the power going in and out. With pre-frozen contents I can get 4+ days of running from a 44AH (around a 20% duty cycle), but if I put in room temp contents and try and bring it down to temperature it'll kill the battery in half a day (at 100% duty cycle).

 

[Fj81]

When I went camping in March, we had the beer and water in my 80 series, in my 63qt edgestar fridge. I have no second battery, and I didnt have any issues with the battery draining all the way. Something must definately be draining your power.

 

[e9999]

RFB, if you don't have a good DC clamp ammeter (those are expensive but what a pleasure to use for this sort of stuff!), it's not very difficult to hook up an inline multimeter to measure the current. Or, you can get an inexpensive wattmeter for about $20 or $30 on ebay or amazon that you can leave inline and will measure V, A, Wh etc. (Ah is not as useful if the voltage varies a bit.) I got a couple of the little guys and was pleasantly surprised at their accuracy -considering the price- when testing them against top of the line equipment. I set mine up with Anderson Powerpoles and move them around easily as needed. You can also easily rig up a pigtail or 2 with PPs to use with a multimeter. Measuring power and current is really the best way to figure out issues like the ones discussed here. Removes most of the uncertainty.


here is the sort of meter I'm talking about (paid about $40 for mine a few years ago):
G.T.Power RC Power Analyzer Watt Meter for voltage (V) current (A) Power (V) P6S | eBay
(no affiliation, don't know the vendor, but meter looks exactly like one of mine - I don't believe the high amp spec though)

 

[george_tlc]

Long term, a AC/DC clamp meter is a good investment. e.g. parasitic current draw, fridge stuff, inverter stuff, new wiring and current flowing through it.

http://www.testequipmentdepot.com/e...ufF_LwWxYXMA2ZD71xbjt5wq9q5wsBXhoCFSMQAvD_BwE

is a decent brand and a decent price. It can also be used as a normal multimeter. Has low enough current resolution to see stuff in the 10 - 50mA range as well as going to 400A.

So much easier and safer than trying to do an inline current measurement with a conventional meter.

All you need to know is that for low DC current measurements (the mA stuff) that you need to a) zero the reading with the clamp meter in its measurement position and orientation b) don't re-orient the clamp without re-zeroing.

cheers,
george.

 

[e9999]

Long term, a AC/DC clamp meter is a good investment. e.g. parasitic current draw, fridge stuff, inverter stuff, new wiring and current flowing through it.

http://www.testequipmentdepot.com/e...ufF_LwWxYXMA2ZD71xbjt5wq9q5wsBXhoCFSMQAvD_BwE

is a decent brand and a decent price. It can also be used as a normal multimeter. Has low enough current resolution to see stuff in the 10 - 50mA range as well as going to 400A.

So much easier and safer than trying to do an inline current measurement with a conventional meter.

All you need to know is that for low DC current measurements (the mA stuff) that you need to a) zero the reading with the clamp meter in its measurement position and orientation b) don't re-orient the clamp without re-zeroing.

cheers,
george.

George, as I wrote above, a clampmeter is a great tool for this type of testing. However, as to the specific one you recommended, you might be able to see something showing on the display at 10 or 50 mA but I would question that you can measure a DC current in the mA range with any sort of meaningful accuracy with that tool as a clampmeter. Or any other tool in the same class for that matter. Obviously, resolution is not the same as accuracy. Having said that, if that is all one can afford, the Extech or similar would be useful and it will tell you whether the load is drawing 1/2A or 5, which is good to know, but assuming that you can do good measurements in the mA range would be a mistake IMHO.

You are right to point out that the zeroing is important. On a positive note, I was pleasantly surprised to see that on mine at least the position of the wire in the clamp does not matter as much as I feared.

 

[george_tlc]

I own one, it works just fine measuring down at that level. It does need zeroing and does need you to hold it at a fixed orientation to resolve at those levels - especially due to static magnetic fields, given it uses a hall sensor to measure DC current.

Wire position within the clamp will make next to no difference as you've discovered.

I are an injuneer (and electronical one at that) so know a little about how to measure and what to recommend

There's also extech units that will resolve to a mA, but do cost quite a bit more. There's a uni-t unit I have that resolves to 1mA and accurately will show a few mA and is in the $40 - $50 range.

These units are quite sensitive since they have lower current ranges versus the big brutes that have a minimum 40A 'low' range.

cheers,
george.

 

[e9999]

Well, if you know of actual data supporting the claim of accurate measurements from a few mA to 400A for a unit in the $70 range, I would be very interested in seeing those. And would buy one right away.
But that discussion might be best left for another thread than this one about fridges.

 

[george_tlc]

I own one. It measures just fine in the mA range. i.e. no worries showing the goods at 50mA and the high current end is much easier anyway.

I zero it and it displays 0.01 (amps). I clamp it to a lab power supply loop set at 50mA and I get 0.06. 5A and it reads 5.0A, 10A and it reads 10.0A that is the area of interest for me anyway. I have no doubt it is reasonably accurate at higher currents. After all, there is an actual datasheet/spec that you could look at

That's good enough for me for $70 give or take.

There you go.

cheers,
george.