Any simple way to insure full charge on AGM?

[gregmchugh]

It will be interesting to see how it works out.

I did run into a gotcha with the Battery Check Bluetooth shunt based battery monitor.

I bought it online from Car ID since it was a little cheaper and faster than Amazon. Both advertise it as a Zamp product but it is made by Setec in Australia and Zamp sold them in the US. It kept loosing Bluetooth sync with my iPhone so I called Zamp and they disavowed anything having to do with the product. They said they stopped distributing them in the US over a year ago because of the returns from iPhone users who had the problem and there was no fix from Setec. Does seem to work fine with an Android device. I asked why they were still being sold and they claimed that none of these merchants were authorized Zamp sellers. Dead end with Zamp...

I sent an email to Setec in Australia and they at first wanted to me to send it in for a replacement and pay shipping for the return but after I made a case for them to just send a new one along that is an updated version that works with Apple devices they are doing that with shipment here in just 3 days and told me to keep the one I have. I am testing it with an Android device to see if it has sync problems. The sync problem on the iPhone happened every couple of days and required a power down to reset it and then it reached the point where wouldn't sync at all even with a reset.

The whole deal with Zamp seems pretty fishy, they are still being sold with the Zamp name on the box so somehow these merchants including Amazon are getting units to sell from somewhere. Setec is standing behind the product so that is good.

[markopolo]

A bit late for this topic but I'll add the Samlex units to the discussion here:

The 15A model transitions from bulk to float when the current decreases to 1.5A. There's no temperature compensation as far as I can tell though.

More info: http://www.classbforum.com/forums/f8...html#post38826

[gregmchugh]

Originally Posted by markopolo

A bit late for this topic but I'll add the Samlex units to the discussion here:

The 15A model transitions from bulk to float when the current decreases to 1.5A. There's no temperature compensation as far as I can tell though.

More info: http://www.classbforum.com/forums/f8...html#post38826

Yes, I noticed you had been using a Samlex and I am looking at one of those as an alternative to the PD unit. Would like something larger than the 15 amp model but want to fit it into the space where the Tripp-Lite is located under the driver's seat so the larger Samlex models may be too big. I does look like a good option though...

[markopolo]

I like the periodic boost to 14.4V feature of the PD units.

I had to put a motion triggered camera in my van to confirm the timing of the boost event. The camera was aimed at the Trimetric and it emailed photos to me when the numbers on the Trimetric changed. The boost occurs approximately every 28 hours in my van. The manual spec'd approx. every 21 hours but I'm happy with the longer interval.

I would think that keeping the Tripp Lite in place and functioning in addition to a second lower amperage endings amps based charger would be a option also. I think the Tripp-Lites are OK units and the biggest complaint being that they could transition to float too early because they're timer based. You could turn off the Tripp-Lite using the AC panel breaker to force the lower amp endings amps based charger to finish the job (if necessary).

The PD units are timer based but I think we've determined that the optional pendant lets you force it back to bulk if needed.

[booster]

All good information, and there do seem to be more options that they used to be.

On thing to remember is that the Samlex (IIRC from the previous discussion) does the float transition based on amps, but those amps are set at 10% of the charger capacity. If you go to a bigger charger, the transition amps will go up, and not give you the 1.5 amps Marko mentioned for the 15 amps charger. This type of profile seems to be getting more common, and again IIRC, Xantrex if doing a similar thing.

As Marko said, PD seems to be the go to for anyone looking to be able to do manual control to get accurate transitions, because they can be forced. Other than that, they are straight timer setups.

[gregmchugh]

In the end, I keep coming back to the PD option also...

Yes, I remember now that when I read the Samlex manual that it used a percentage of charger amps to switch so only the 15 amp would be close for my 220 amp hour batteries.

[gregmchugh]

I have a plan to log the charge voltage and current for several different chargers including the Tripp-Lite, engine charging, and the Ctec 20 amp charger using a Mooshimeter Bluetooth logging multimeter. The Moshimeter has two channels and one can be used for low voltage signals such as the voltage drop through a shunt while the other can record charge voltage. I am going to measure the voltage drop across the Battery Check (which has an internal shunt) and calibrate it to the current reading from the Battery Check. Hopefully the calibration will show a linear relationship between the two readings indicating that the internal path through the Battery Check can be regarded as a shunt for current measurement purposes. The Mooshimeter has a microSD card recording capability, creating a CSV file with time stamps and the two channels of data. Should be an interesting experiment...

https://moosh.im

[gregmchugh]

So, i did a test of data logging with the Mooshimeter yesterday. At the start, the van had been plugged in for a day or two with the only major load being the Nova-Kool R4500 compressor fridge with very little contents at the moment. It is in the 90's here and the Nova-Kool is running continuously during the day, not sure if it is cycling at night or not.

I disconnected the shore power and let the van run on battery power for about 4 1/2 hours and plugged it back into shore power. Looks like the Nova-Kool was pulling about 3.5 amps or so continuously. The initial peak charging current from the Tripp-Lite was a little over 30 amps and it was back into float within 1/2 hour. I calculated that there was about a 15.5 amp hour discharge of the batteries and the Tripp-Lite was still 7 amp hours short of replacing those amp hours when it was in float again.

[booster]

Originally Posted by gregmchugh

So, i did a test of data logging with the Mooshimeter yesterday. At the start, the van had been plugged in for a day or two with the only major load being the Nova-Kool R4500 compressor fridge with very little contents at the moment. It is in the 90's here and the Nova-Kool is running continuously during the day, not sure if it is cycling at night or not.

I disconnected the shore power and let the van run on battery power for about 4 1/2 hours and plugged it back into shore power. Looks like the Nova-Kool was pulling about 3.5 amps or so continuously. The initial peak charging current from the Tripp-Lite was a little over 30 amps and it was back into float within 1/2 hour. I calculated that there was about a 15.5 amp hour discharge of the batteries and the Tripp-Lite was still 7 amp hours short of replacing those amp hours when it was in float again.

Good information to have, Greg. I am not surprised about the Tripplite, as when we had one, it regularly undercharged. My guess is that with yours, you did not even get a full absorption charge, and it probably just ran the "minimum" absorption time. From what I could tell when we had ours, the Tripplite looks at the battery voltage when shore power is initiated. If it is above a set "threshold", it will just do the minimum time, as it considers the batteries to be full. If it is below the threshold, it will run the full aborption time of, I think, about 4 hours. Many chargers do the same, including our Magnum (which is totally silly IMO), so it is very common. This is the exact reason a PD with a Pendant is such a good choice. You can just manually put the charger back into absorption if it doesn't get you full. You might want to run the batteries down further and see if you get a full absorption run. I think you will.

The 3.5 amps for the frig is typical, I think, but I am very surprised it is running continuous at only 90* ambient. Our Isotherm was running only about 50%, on the lowest compressor speed setting, when we were in Zion last year, and it was at over 95/98 degree days with frig side of the van facing unshaded southern sun. What internal temp did you have set? This sounds similar to what we saw when we had ventilation air looping on ours, but I haven't ever heard of it on a NovaKool. You would use quite a few AH per day at the duty cycle.

[booster]

Looking at your graph, it appears that it went to absorption at about 10.8 amps or so, which is about 10X what you want. To get to the lower amps would probably take upwards of 4+ hours, although it can be highly variable on very small discharges like you had.

Also remember that you will need to replace substantially more AH than you used. I have found our Lifelines to be at 110-115% of used on the various discharge runs I have done (most to 50%). One a very shallow discharge, it may even go higher than that.

[gregmchugh]

Originally Posted by booster

Good information to have, Greg. I am not surprised about the Tripplite, as when we had one, it regularly undercharged. My guess is that with yours, you did not even get a full absorption charge, and it probably just ran the "minimum" absorption time. From what I could tell when we had ours, the Tripplite looks at the battery voltage when shore power is initiated. If it is above a set "threshold", it will just do the minimum time, as it considers the batteries to be full. If it is below the threshold, it will run the full aborption time of, I think, about 4 hours. Many chargers do the same, including our Magnum (which is totally silly IMO), so it is very common. This is the exact reason a PD with a Pendant is such a good choice. You can just manually put the charger back into absorption if it doesn't get you full. You might want to run the batteries down further and see if you get a full absorption run. I think you will.

The 3.5 amps for the frig is typical, I think, but I am very surprised it is running continuous at only 90* ambient. Our Isotherm was running only about 50%, on the lowest compressor speed setting, when we were in Zion last year, and it was at over 95/98 degree days with frig side of the van facing unshaded southern sun. What internal temp did you have set? This sounds similar to what we saw when we had ventilation air looping on ours, but I haven't ever heard of it on a NovaKool. You would use quite a few AH per day at the duty cycle.

Definetly need to see what is going on with the fridge. It is pretty much empty which doesn't help and the thermostat is probably set too low forcing it to run continuously during the day. Running continuously during the heat of the day and shaded only part of the day the temps are running 36-38 in the fridge and 16-18 in the freezer using a max-min thermometer over a 24 hour period. It may be cycling at night.

[gregmchugh]

Booster, what was the ventilation air looping issue you had?

The Nova-Kool was installed by a marine refrigeration shop and he felt that the standard upper and lower vents that Roadtrek uses for the Dometic 3 Way on the Sprinter would work fine for the Nova-Kool. His only concern was water coming in the lower vent from road splash since the compressor and electricals are exposed at the bottom of the fridge. There is the option to wire an exhaust fan on the Nova-Kool. I could easily mount a muffin fan on the inside of the upper vent if needed.

[booster]

Originally Posted by gregmchugh

Booster, what was the ventilation air looping issue you had?

The Nova-Kool was installed by a marine refrigeration shop and he felt that the standard upper and lower vents that Roadtrek uses for the Dometic 3 Way on the Sprinter would work fine for the Nova-Kool. His only concern was water coming in the lower vent from road splash since the compressor and electricals are exposed at the bottom of the fridge. There is the option to wire an exhaust fan on the Nova-Kool. I could easily mount a muffin fan on the inside of the upper vent if needed.

I don't know if you have seen how Isotherm does their compressor and fan, but it is located in a notch in the cabinet at the upper rear. Very small and self contained fan, compressor, and condenser. The ventilation is designed for a boat, that would take in air under the frig door and have it go up the rear of the frig to the fan which is on the very rear of the compressor assembly. The fan blows toward the front of the frig, so the air goes over the compressor, though the condenser, and out the front of the frig above the door. Works great in boats, it appears, but with the air not being able to get out into the van, it would just loop around and go back in the fan inlet and get hotter and hotter. Only a bit of it would go out the upper vent and be replaced from the lower vent. I finally made an air feed duct from the lower vent and sealed it to the van inlet. Then I put a divider between the upper and lower vents, completely isolating them from each other, so the fan had to take air from the lower vent, and air had to exit the upper vent. The unit has run very efficiently since, as shown be how well it kept up in the heat and sun at Zion. We were very surprised at that.

I think the NovaKool has regular rear coils with the compressor at the bottom? I would think that would work better than our original Isotherm setup, but perhaps there is too much gap to the van wall and it just backfeeding there. I know Roadtrek had a baffle from the van wall to near the coils for the absorption frig, probably for that reason, in our stock frig.

[avanti]

Oor GWV Legend has no external vents. I installed a small muffin fan to force air from behind our NovaKool into an adjacent closet. It is controlled thermostatically. Works great.

[booster]

Originally Posted by avanti

Oor GWV Legend has no external vents. I installed a small muffin fan to force air from behind our NovaKool into an adjacent closet. It is controlled thermostatically. Works great.

There was a lot of talk quite a few years ago about add on fans to move the air away on all kinds of frigs, so when I had ours out for another reason, I added a decent size fan an speed control at the upper vent. We tested it quite a few times under various conditions, and there was very little if any improvement to how the frig ran or how much power it used. If we added the fan power consumption the daily total, we went backwards, using more power than without, even if it was just using it during the hottest parts of the day. The air we have exiting the upper vent is not very warm, I would guess not much more than 15 degrees above ambient (should measure that some day, I think).

Having a thermostatically controlled fan would be a good idea if you do have periodic times when the condenser cooling is an issue, as during those times the fan power will probably be less than the extra run time without it.

[gregmchugh]

Thanks for all the info, I will see how it goes when the fridge is working when it is loaded up on our trip...

[avanti]

Originally Posted by booster

There was a lot of talk quite a few years ago about add on fans to move the air away on all kinds of frigs, so when I had ours out for another reason, I added a decent size fan an speed control at the upper vent. We tested it quite a few times under various conditions, and there was very little if any improvement to how the frig ran or how much power it used.

It depends on where you are starting from. In my case (without external venting), the fridge box was unambiguously getting too hot. A little fan made a huge difference.

[booster]

Originally Posted by avanti

It depends on where you are starting from. In my case (without external venting), the fridge box was unambiguously getting too hot. A little fan made a huge difference.

Absolutely true, and it may be something that is happening a lot more that we know about. It is easy to see the amp draw on a monitor, but much harder to see the watts or amp hours per day. I finally would up getting a Watts Up and temporarily installing it so I could actually tell what was going on. It was a bit of PITA to use because it was on the back of the frig, so I had to remove the lower vent cover to read it, but that was once a day usually, and I only had on for short amount of time to get test information.

Most folks won't have a clue of how much power they really are using with the frig without some sort of accumulating meter for it by itself, as the duty cycle changes so much over a 24 hour day.

[gregmchugh]

The Nova-Kool installation instructions show typical internal ventilation paths and recommended vent areas but don't address vents to the outside, probably because they aren't addressing retrofits into RVs with existing external vents. I think the auxiliary fan connection on the Nova-Kool probably powers the fan whenever the compressor is running.

[booster]

Originally Posted by gregmchugh

The Nova-Kool installation instructions show typical internal ventilation paths and recommended vent areas but don't address vents to the outside, probably because they aren't addressing retrofits into RVs with existing external vents. I think the auxiliary fan connection on the Nova-Kool probably powers the fan whenever the compressor is running.

It would be interesting to see where they put the fan. When we were looking maybe 5 years ago, the add on fans for the compressor on the bottom, convention condenser on the back, units put the fan blowing right on the compressor, taking low in the compartment air without a duct, from right at the lower corner. I have no idea how that would affect the airflow in and out of the external vents as they would be quite a ways away.