Any simple way to insure full charge on AGM?

[gregmchugh]

If you were trying to remove trapped hot air wouldn't it make sense to just mount a couple small computer fans right onto the back of the upper external vent to insure you would get air flow into the lower external vent and out the top vent? I have a couple small ones that only draw .06 amps that would fit right on the back of the vent.

[avanti]

I am not certain, but I bet that the ambient temperature around the coils is more important than air flow per se. If the area is cool, convection will do the job. My belief is that active exhaust from the cabinet is the most effective thing you can do if you don't already have excellent ventilation.

[booster]

I figured I would bring this back up as it came to mind today while doing something else (I have really odd thought patterns).

I think that for anyone who is doing a compressor frig upgrade, it is probably well worth their time to run it on the bench before installing it. Just put a watt meter on it, like the Watts up, and see what the power usage over a day is with free air all around the frig. This will be very near to an absolutely best case scenario for power use at the given temp. After you put it in the van, or have someone else do it, do the same test at the same temp. You should get the same amount of power use, within reason, and no more than about something like 10% difference I think.

We learned this the hard way, as we knew we had issues, but did not have a baseline to evaluate where we should really be. Once we knew, it made it a lot easier to know if improvements helped, and if we were actually as good as we could get. It gives you finish line, so you know when you are done!

[wincrasher]

I have the 4500 in both my Travato and on the Ranger Tug.

WGO told me that the model they put in the Travato, it comes with an additional fan from Nova Kool and consumes about 1 amp above the published spec for the fridge. I haven't been able to validate that, but I assume it's true. This fridge is mounted in the kitchen cabinet, but the rear is open to a slot that vents along the back side of the cabinet and the window above. No outside access. It seems to work adequately and I'm seeing the 2-3 amps per hour I was expecting.

On the boat, I don't have any information if there is an additional fan. It's also mounted in a cabinet that is open in the rear, but is against the hull. There is about a 10" gap between the rear of the fridge and the hull. It also seems to work very well despite high ambient temps and I'm seeing about the same consumption.

I've been thinking about installing a battery meter - this victron unit in particular. https://www.amazon.com/Victron-BMV-7...T73ZZ2C5YHPWAH

On the boat it's an easy install - just a matter of routing wires where they need to go. On the van, more problematic as I will have to drill a hole in the floor. My question is this - where to mount the shunt on a multi-battery bank. Is it only necessary to attach to one neg post on one battery? Or do I need to tap it into the main leads from the bank? Must it be as close to the battery as possible, or can it be up near the converter?

They also can add this for monitoring on the iphone: https://www.amazon.com/Victron-ASS03...uetooth+dongle

[booster]

Originally Posted by wincrasher

I have the 4500 in both my Travato and on the Ranger Tug.

WGO told me that the model they put in the Travato, it comes with an additional fan from Nova Kool and consumes about 1 amp above the published spec for the fridge. I haven't been able to validate that, but I assume it's true. This fridge is mounted in the kitchen cabinet, but the rear is open to a slot that vents along the back side of the cabinet and the window above. No outside access. It seems to work adequately and I'm seeing the 2-3 amps per hour I was expecting.

On the boat, I don't have any information if there is an additional fan. It's also mounted in a cabinet that is open in the rear, but is against the hull. There is about a 10" gap between the rear of the fridge and the hull. It also seems to work very well despite high ambient temps and I'm seeing about the same consumption.

I've been thinking about installing a battery meter - this victron unit in particular. https://www.amazon.com/Victron-BMV-7...T73ZZ2C5YHPWAH

On the boat it's an easy install - just a matter of routing wires where they need to go. On the van, more problematic as I will have to drill a hole in the floor. My question is this - where to mount the shunt on a multi-battery bank. Is it only necessary to attach to one neg post on one battery? Or do I need to tap it into the main leads from the bank? Must it be as close to the battery as possible, or can it be up near the converter?

They also can add this for monitoring on the iphone: https://www.amazon.com/Victron-ASS03...uetooth+dongle

A power monitor that measures only the watts or ah used by the frig is the only good way to tell where you are IMO. Use can vary over the day, and watching and guessing the run time is highly inaccurate, I have found.

It really doesn't matter which end of the wire the monitor is located, as long as that wire only feeds the frig. I would not bother with a shunt based monitor for this kind of test (but great for overall use). A Watts up goes in the power line only and can be moved wherever. They are also pretty inexpensive.

If you do the test, it will be interesting to see how the two applications compare to each other, and to the published specs.

[wincrasher]

Originally Posted by booster

A power monitor that measures only the watts or ah used by the frig is the only good way to tell where you are IMO. Use can vary over the day, and watching and guessing the run time is highly inaccurate, I have found.

It really doesn't matter which end of the wire the monitor is located, as long as that wire only feeds the frig. I would not bother with a shunt based monitor for this kind of test (but great for overall use). A Watts up goes in the power line only and can be moved wherever. They are also pretty inexpensive.

If you do the test, it will be interesting to see how the two applications compare to each other, and to the published specs.

Wouldn't pulling all your fuses except for the fridge circuit be close enough?

[wincrasher]

Originally Posted by gregmchugh

The shunt needs to placed such that all the battery negative terminals connect to one side and the ground connection on the other side so that all current in/out of the batteries flows through the shunt.

I found a manual online that doesn't show me a wiring diagram, but there is a discussion about lithium batteries. They warn you need to watch your parasitic draw from the monitor. So I'm assuming they are advocating an isolation switch for the bank. They mention the monitor is getting power from a cable that is run from the shunt's circuit board to pos terminal directly on the battery. Is this necessary, or just convenient? Could this power source be run from somewhere else on the other side of the disconnect switch?

[booster]

Originally Posted by wincrasher

I found a manual online that doesn't show me a wiring diagram, but there is a discussion about lithium batteries. They warn you need to watch your parasitic draw from the monitor. So I'm assuming they are advocating an isolation switch for the bank. They mention the monitor is getting power from a cable that is run from the shunt's circuit board to pos terminal directly on the battery. Is this necessary, or just convenient? Could this power source be run from somewhere else on the other side of the disconnect switch?

They normally want the power line right to the battery to assure accurate voltage readings at the meter. It wouldn't affect the meter running at all, or the AH reading. It could affect a watt hour reading if the meter had that option.

[tgregg]

Originally Posted by booster

A power monitor that measures only the watts or ah used by the frig is the only good way to tell where you are IMO. Use can vary over the day, and watching and guessing the run time is highly inaccurate, I have found.

Another way to measure the performance of the refrigerator and any modifications or enhancements is an hour meter.

Connect it to the F+ and F- pins on the compressor controller. Those are the pins used to power a fan which would run whenever the compressor is running. If your unit already has a fan connected to those pins use a couple of those 3 sided spade adapters that allow 2 spade connections to one spade lug.

We had an Isotherm unit with a fan on the condenser coils that ran a pretty consistent 3 hours a day. Our current Dometic unit without a fan runs around 3- 31/2 hours a day. I've added a computer fan to the compressor compartment and will get an idea of any improvement on our next trip.

If the daily usage jumps up above normal you know you have a problem.

[booster]

Originally Posted by tgregg

Another way to measure the performance of the refrigerator and any modifications or enhancements is an hour meter.

Connect it to the F+ and F- pins on the compressor controller. Those are the pins used to power a fan which would run whenever the compressor is running. If your unit already has a fan connected to those pins use a couple of those 3 sided spade adapters that allow 2 spade connections to one spade lug.

We had an Isotherm unit with a fan on the condenser coils that ran a pretty consistent 3 hours a day. Our current Dometic unit without a fan runs around 3- 31/2 hours a day. I've added a computer fan to the compressor compartment and will get an idea of any improvement on our next trip.

If the daily usage jumps up above normal you know you have a problem.

I did try the "clock" or time accumulator on our Isotherm, but found it to not match the watt or ah accumulator readings. It appeared to be from the varying amp draw of the compressor that changes some with exterior and interior temperatures, and also with how often it needs to run. It takes a while to stabilize the current at compressor on, so the more times it runs in a day, the more it will distort the reading. We particularly noticed it when the outside temp varied a lot day to night, as it would run many periods during the day, and hardly at all at night, giving very different readings than the same run time when the temps were more consistent. How much is in the frig also made a significant difference as it would "short cycle" with less food in the frig, making for more startups for the same amount of run time. IMO much easier and more accurate to use a watt meter.