ARB fridge questions (1 Viewer)

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Wheelingnoob said:
I have a deep cycle group 27 in mine with 110aH, i wanted to 31 but none of the ones i found fit other than the $300 sears platinum. Had it for 2 years now but have damaged the outer case and its leaking acid, need to replace it. Even in its compromised state it keeps the fridge going for 2 days till it hits my power shut of that is set at med.
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Jeremy could you explain me how to calculate group 31 aH?
I bought two odyssey (group 31) I tough they were the heaviest available but all I can find on is:
http://www.odysseybatteries.com/battery/pc2150.htm
Reserve capacity: 205 minutes on 25amps
205mins/60mins *25amps give me 85aH?
how come your 27 is 110aH?
thanks
btw they are fxxxing huge.... about 78pounds
PC 2150S Design:

Absorbent glass mat (AGM) technology
12V battery pure VRLA
SAE group 31 footprint
Rugged construction
Brass SAE terminal with 3/8 in. (9.5mm) corrosion-free stud terminal underneath
Can be mounted in any orientation
Suitcase lifting handle
US DOT and IATA certified non-spillable
Shipped fully charged - just install and go
Container and cover made from oil resistant plastic
Performance Features:

PHCA: 2,150A at 80°F (27°C); for 5 seconds
CCA: 1,150A at 0°F (-18°C)
CA/MCA: 1,370A at 32° (0°C)
HCA: 1,545 at 80°F (27°C)
Reserve capacity: 205 minutes on 25amps
Short circuit current: 5,000A
Deep cycling capability: 400 at 80% DOD
Design life: 12 years
Typical service life: 6 to 8 years
 
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Odyssey batteries have gotten way too expensive. My advice is to go visit Polar Batteries and let them explain and sell you what you need for your applications. http://www.polarbattery.com

I say this from experience with owning both Odyssey and (pos) Optima batteries.
 
The standard amp-hr rating is usually pulling a load like 5 amps for 20 hours, which equals 100 amp-hr.
Your rating is quite a severe rating drawing 25 amps for 3.4 hrs - that is a big battey reserve!
The thing to note is the draw amperage and draw time are not linear - the higher the sustained amp draw the shorter the time you get. This means if you discharged that same 100 AH battery by a 100 amp load, it will not give you one hour of runtime.
 
The guy I bought it from told me 110aH, I have no idea if that's correct or not. It lasted 3 days with the ARB set at 2c on Med.

No idea where its at now with aH the battery is dyeing a slow painful death in my garage with the rest of the truck.
 
Wheelingnoob said:
The guy I bought it from told me 110aH, I have no idea if that's correct or not. It lasted 3 days with the ARB set at 2c on Med.

No idea where its at now with aH the battery is dyeing a slow painful death in my garage with the rest of the truck.
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I read in my researchs not to store a deep cycle if its not full charge...

@Glenn

understood its not linear... got 25 amps at 3.4hrs, but 20 hours at 5 amps, and probably something like 120 hours at 1 amps? all the curves stop at 5 amps... the formula is a logarithmic one, I saw it this morning it was euler or something similar. with my dual in parallel that would give me 50 amps for 3.4hrs or... 10 days at the average 1 amps per hour... 20-25 minutes on winching with the engine off

YabedudeOdyssey batteries have gotten way too expensive.


Not that bad, around 300$each, for 80 pounds quality battery (and about 500$ in Canada :()
 
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Badaboum said:
I read in my researchs not to store a deep cycle if its not full charge...

@Glenn

understood its not linear... got 25 amps at 3.4hrs, but 20 hours at 5 amps, and probably something like 120 hours at 1 amps? all the curves stop at 5 amps... the formula is a logarithmic one, I saw it this morning it was euler or something similar. with my dual in parallel that would give me 50 amps for 3.4hrs or... 10 days at the average 1 amps per hour... 20-25 minutes on winching with the engine off

YabedudeOdyssey batteries have gotten way too expensive.


Not that bad, around 300$each, for 80 pounds quality battery (and about 500$ in Canada :()
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Rule of thumb is 2 to 3 days depending on ambient temperatures and a fridge setting of 2-3C before your truck may not start. Yours a bit longer. See Post #40.
 
Glenn-BJ74 said:
Rule of thumb is 2 to 3 days depending on ambient temperatures and a fridge setting of 2-3C before your truck may not start. Yours a bit longer. See Post #40.
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Hi Glen, I found out this formula witch I believe is the difference with the thumb rule, and witch indeed make the significant difference between an odyssey and another one.
Capacity = In x t (cant cut n paste correctly but the n is exposing)
n​
​
​
​
​
is 1.112 for the Group 31​

battery

I've look at the whole formula to try to calculate t under ARB 50QT 1.35 Amps/Hour
but since the capacity table vs amps stop at 5 amps, I believe I am missing something (look at page 10 and 11) here: http://www.odysseybattery.com/documents/US-ODY-TM-001_0411_000.pdf

I wrote to odyssey to ask the capacity at 1 amps...
 
so here are the replies from ARB (see attached) and from odyssey...

For the 31-PC2150 battery, you cannot take more than 100 Ahr total energy out and at a 1.35 amp draw, the cutoff voltage needs to be 11.25V or 100Ahr total discharge from a full charge whichever comes first at 1.35 amps.



Discharge rates below 5 amps can pull more than 100Ahr out if there is no voltage cutoff.



If the group 27 you talk about is a wet-flooded format, you could be correct on the Ahr capacity that could be discharged, but going below 11.25V would also damage the oxide bond to the grids.



Deeply discharging lead-acid batteries can shorten their cycle life, especially when discharges are 100% capacity or greater without low voltage cutoffs.




Bruce R. Essig

National Sales Manager

Tech Article 4-8-10


ARB Freezer fridge wiring faults



With the introduction of the new ARB Freezer Fridge that utilizes a highly sophisticated power supply with low voltage cut-off and fault code diagnostic system we’ve found these units are very sensitive to poor performing power sockets and the associated circuits of the vehicles they are used in. Typically the problem plugs are at the rear of a vehicle and the problem is low voltage at the socket. The result is a fridge that reads an incorrect dead battery and shuts off flashing a low voltage code.


Symptoms:

Fridge runs normally on 110AC and on 12V in a running vehicle, but with the engine off the fridge shuts down and flashes a code (1 flash every 5 seconds) on the display indicating a problem. In this case the code is “low voltage battery protection.”

Once the vehicle is restarted the fridge turns back on and operates normally.


Cause:

Voltage under load (fridge running) has dropped below the specified setting on the fridge power supply (low 10.1V, med 11.4V, high 11.8V) resulting in fridge shut down.


Testing:

Important: All tests to be performed with the engine not running.

First confirm with a digital volt meter (DVM) that the battery has sufficient charge (voltage) and is simply not old and weak causing the problem. Under no load the battery should be about 12.5 volts during this test confirming a good charge.

After confirming the battery is good check the output of the power socket being used for the fridge with the DVM and compare the voltage with no load on the circuit. The voltage should be very close to battery voltage with no more than .2 volts drop at the socket.

Now the circuit needs to be tested loaded. This can be done a couple of different ways, either piercing the insulation on the fridge cord itself with the fridge on and running or by using a 55 watt bulb mocked up (an old fog lamp works well for this) to create the needed load. With the load on the circuit (fridge running or bulb lit) recheck the voltage. If the drop exceeds .7 volts the circuit is insufficient to keep the fridge running during extended periods of engine off time. In some vehicles we have found the loss to be as great as 3 volts at rear mounted sockets.








The Fix:

ARB now offers a kit with 18 foot of appropriately sized wire, needed terminals, fuse, and female socket to wire a full time permanently hot fridge plug into the vehicle. This is a cost effective solution to add the needed power capacity for the fridge and gain an additional outlet in the rear cargo area of the truck ensuring the fridge functions as it was designed. The kit part number is 10900011.


Alternatively, a do it yourself solution should use a minimum of 10 gauge wire directly from the battery for a run of 18 feet or less. Marine grade wire and connectors are recommended to avoid corrosion problems in harsh off-road conditions. For distances greater than 18 feet wire diameter should be upsized as required.


Conclusion:

The most common problem by far for an ARB fridge to have is a poor power source. Even without all the above tests if the fridge shows a low voltage code and your battery simply isn’t low then it can be assumed that the circuit supplying power is suspect at best and should probably be upgraded to avoid the inevitable possibility of spoiled food or warm drinks in the future.
 
"we’ve found these units are very sensitive to poor performing power sockets and the associated circuits of the vehicles they are used in. Typically the problem plugs are at the rear of a vehicle and the problem is low voltage at the socket. The result is a fridge that reads an incorrect dead battery and shuts off flashing a low voltage code. "

That might be part of your problem boys !!

If you are using the stock 'mickey mouse' gauge wire you are experiencing excessive voltage drops across the wire conductor, which the fridge senses as low battery voltage, which it is using as a proxy for state of battery charge.

For 20' wire run to the fridge from the battery (including back to the negative) for up 5 amps (60 watts) for a max 3% voltage drop use at least 14 gauge. Rereading the post they say no more than 0.2 volt drop over the conductor on 12 volt = 1.6% so go with no less than 12 gauge. Fuse it at the battery with 10 or 15 amp fuse.

If the stock wire is 18 gauge or smaller you may get a 10% or more voltage drop - causing the premature fridge shut-offs.
 
As Sailor suggests - marine grade wire is superior to automotive wire in several ways -its tinned copper and heavier for equivalent gauge (SWG vs AWG), which is what I generally use.
 
canucksafari said:
Got any links for locally available DC battery chargers (24-12V)?
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Sure- but the stuff I use is pretty pricey...

12- 32 volts dc and I have inverter chargers up to 3.5 KW and 150 amp chargers..
 
sailor said:
Sure- but the stuff I use is pretty pricey.
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Ya, I forgot the other adjective: "affordable". At least for someone who can't afford a yacht. :D

I had another look at the Aussie DC chargers. I think it makes more sense to just go with a combination of charging via the DC converter, small 70-100W solar system and a hard wired 110V DC charger.
 
My ARB 37L has been plugged into an outlet in my basement and set at -18C for over six hours. It reads -9C and has barely formed any ice in the handful of ice packs that I have in there. There's plenty of room on all four sides of the thing. This seems rather uncool to me.
 
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The temperature gauge isn't super accurate, and the temps vary slightly in different areas of the fridges.
It's less efficient when it's trying to cool a big void. I'd think 6 hours would be long enough though for ice.
 
ikeedikeed said:
My ARB 37L has been plugged into an outlet in my basement and set at -18C for over six hours. It reads -9C and has barely formed any ice in the handful of ice packs that I have in there. There's plenty of room on all four sides of the thing. This seems rather uncool to me.
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So six hours ago it was at room temperature, you set it to -18, put a bunch of defrosted freezer packs into it, also at room temps, and after 6 hours it's at internal ambient of -9?
That's pretty normal.
Or you started with -18 and put the packs in?
Then depending on how many and how warm they were that would affect it. If you put in something that was at 22*C, and a lot of it, then it would raise the temps internally, but 6 hours is a bit long.
 
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