New charging system shakeout trip

[booster]

We have been out bit short of two weeks now, with and without shore power, with good and bad sun, so we have seen many of the situations that we will in the real world.

The Blue Sea charger has performed well. Whenever we have shore power it has taken the batteries to completely full (hydrometer confirmed). I did take the minimum absorption time to the minimum of .3 hours and let it use the ending amps to signal going to float. Depending on what is running in the van (which it sees as charging amps), a quick shutoff of the van power for 30 seconds will let it go to float, but even that is rare as I have the ending amps a bit high on the single gp 27 which we have been using to run on when not on shore power. Once in float it stays there, running the van stuff, until it is unplugged and replugged. It then does the minimum absorption, ending amps cycle again. There is very little gassing, as the charge time is very short, so water use should not be a problem. All and all it has worked as expected.

Even though we didn't get the big alternator in time for this trip, we have been using the alternator to run the microwave through the inverter when we don't have shore power. It has worked very well, and uses about 20 amps of battery power. The new alternator should make it so their is no battery power used. This was a very good modification for us.

The solar power output has been pretty much as was expected. Near 80AH on a good day, as low as about 25AH on rainy days. Also as expected, we sometimes have a daily deficit, sometimes surplus, with a net probably close to break even or better. One thing that became apparent quickly was that the AH meter on the solar panel is a very deceptive piece of data sometimes. It is nowhere near telling you what the solar COULD put out in the conditions you are in, it is only telling you what it DID put out. If the batteries are full, and the van is using very little power, you could easily see a total AH on the meter of only 10-15 amps on a day that is capable of doing near 80AH. It is easy to think the solar isn't working well, when it is, under those circumstances.

The solar is a problem from a control standpoint, it appears, especially when the Blue Sea has filled the batteries totally full, or when the solar is on while the Blue Sea is charging, or if we have more solar available than the batteries need. If the solar is on, the Blue Sea will kick out on ending amps early, because the solar is supplying a lot of the charge to the batteries. The solution is not difficult for this, you just shut off the solar when on shore power. The other problem comes with driving after coming off shore power, and thus full batteries. It would be nice to have the solar supply power to the van stuff like the frig while driving, but if you have it on, it will be in absorption for the entire time on its timer, putting high voltage on the full batteries for a long time. The solar also uses the same time for every cycle, so if you have the absorption time set for all day to assure recharging on cloudy days, you may be done before noon on a sunny day and put the high voltage on the batteries again for a long time. I have been watching the amps going to the batteries on the Trimetric and shutting the solar off when it gets there, but then the batteries are discharging for the rest of the day. It sure would be nice if the solar charger would go to float on ending amps like the Blue Sea. If not that solution, at least a button to push to force it into float so it could run the van once the batteries are full. I will be contacting Morningstar and running it all past them to see if they have any possible solutions or suggestions. For the first week, I let the solar run all the time, just to see if it was really an issue, or just theoretical, and the water in the coach batteries dropped by 1/2 in that week. Without the solar, we could go many weeks without adding water, so the issue appears to be real. Selectively turning the solar on and off minimizes the issue but is a PITA to watch the Trimetric and turn off and on the solar all the time. Progressive Dynamics has a button to force float, I think, so I don't think it would be a big deal, and the Blue Sea uses ending amps to go to float, so someone should be able to have a solar controller that would do both or either. If we can find solar controller that goes to float on ending amps, life would be very good. The solar could be on all the time, except when on shore power, and the batteries would never see extended periods of higher than desired voltage, and the van would always have power being put to it when not plugged in (assuming daylight). We also had the battery temp sensor for the solar controller fail, so the voltages were messed up for a while, but with it disconnected and running off the internal sensor, all is good.

That is how our system is reacting and cooperating, or not. When I think of how it would work with some of the other chargers out there, the solar might help cover a weakness a bit (Tripp-lite that quits early) or make it worse (Progressive Dynamics that always gives a 4 hour absorption regardless of battery state of charge (I think). Interesting stuff.

[markopolo]

You could say everything (separately) is working too well. A "force float voltage" button for the solar controller might be solution. Maybe set at a high float voltage like 13.8v. Maybe a controller with a manual mode in addition to full automatic if anyone even makes such a thing.

It will be interesting to hear if Morningstar has any suggestions.

[booster]

Originally Posted by markopolo

You could say everything (separately) is working too well. A "force float voltage" button for the solar controller might be solution. Maybe set at a high float voltage like 13.8v. Maybe a controller with a manual mode in addition to full automatic if anyone even makes such a thing.

It will be interesting to hear if Morningstar has any suggestions.

The working too well was one of my first thoughts, also! I think it all is making things clearer in regards to why folks have such varying results as they put systems together of the various parts. If you had a Tripplite that was leaving you less than full, the solar running after a shore charge might be just what you need to get the batteries full, same if you don't have a disconnect on the van alternator. If you have a PD (4hours of absorption at each plug in IIRC) the same solar may contribute to existing overcharge possibilities.

I certainly do think that certain models of things, which may be good in many ways may cause trouble in other ways. The Blue Sea charger is one of them, because it takes the batteries 100% full, leaving no room for other charge methods to be used after it, without overcharging. IIRC the Mornigstar MPPT controller came with only 4 or 5 hours of absorption time programmed, which surprised me because I would think you would need all day sometimes. It wasn't clear if that time included the bulk charge time or not, though. I need to get that info from Morningstar or test it. I have it longer now, which makes more sense, but makes overcharging more likely. If the time does not include the bulk charge, I may be best off to just program in 15.0 volts absorption, with a very short time. It would stay in bulk to 15.0 volts (Trojan likes a 15 volt bump at the end, anyway) and then quickly time out to float. If the batteries were already full, that would happen very quickly. It would be almost instantaneous, if I set the solar absorption the same as the shore charger and a minimal time, but the batteries wouldn't get as full. I still like the float button best so far.

[booster]

I think there is a one switch way to take care of the solar overcharging issue. I haven't heard from Morningstar yet, but I did dig into the MS View software and the wiring for the system a bit more. It wouldn't be a force to float switch, but an entire program flop.

The controller has 4 battery charging profiles available. The way they are selected is a little unusual, as is the programmability. They have a dip switch and a terminal jumper wire to do the selecting. The jumper out or in toggles between the two programmable profiles when the dip switch is in one position, and between the two non programmable profiles when the dip switch is in the other position. By adding an on/off switch across the terminals for the jumper, I should be able to go back and forth between the two programmable profiles.

All I need to do is have one profile setup to do the good solar charging, like we do now, and the other program with the absorption voltage at 13.5 and the float at 13.2 volts, with the timers at 3 minutes. If the batteries are full, and we want to have the solar running the van stuff and maintain the batteries, we can flip the switch and it will run at 13.5/13.2 volts max so no overcharge. If it all works as it looks like it will, this will be a very simple and useable solution. No turning off and on all the time.

[booster]

Since we were off to dump tanks, get groceries, and some mini golf, I decided to see if the solar second program would really work in practice, and not overcharge full batteries. I put a wire jumper on the controller where the switch would be to switch it to the second programmable profile that is set at 13.5/13.2v. Unplugged from shore power and off we went for the day. Reset the Trimetric to 100%/0AH.

Short story, short-solar ran all the van stuff (detectors, computer/phone/tablet chargers, detectors, Fantastic fan when parked, etc) for about 6 hours of sun then rain. Voltage never topped 13.6 (temp comp) and was mostly at 13.2. Trimetric showed 100% full when we got back,with a tiny minus 1 AH. When we went back on shore power, the charger went to float immediately after the .3 hour min absorption time (due to ending amps), so we know the batteries were totally topped off, just as they were when we started.

Based on this, I think the solar overcharging issue is essentially solved, as we will be able to get the best of results in all situations.

[Davydd]

That probably makes you feel pretty good.

[markopolo]

So this gives you two primary modes of operation:

#1 - touring mode / everyday mode
#2 - extended dry camping mode

You probably would leave it in #1 position most of the time.

I wonder if the available available amps output from solar increase with the lower voltage? That would be good for mode #1.

Looks like you've come up with a good solution

[booster]

Originally Posted by markopolo

So this gives you two primary modes of operation:

#1 - touring mode / everyday mode
#2 - extended dry camping mode

You probably would leave it in #1 position most of the time.

I wonder if the available available amps output from solar increase with the lower voltage? That would be good for mode #1.

Looks like you've come up with a good solution

I think that is pretty close to the way it will work, with two modes of operation.

In everyday mode, assuming shore power every night, we wouldn't even need to run the solar at all. We would use 15-20AH of battery during the day off the batteries, and replace it at night. Same as before we had solar. We would use the float program if we came off shore power and were going to dry camp that night, so we were full when we got there.

Dry camping mode would most often use both modes, I think. Full charge mode every day to recover the batteries, and then if they got full early a shift to the float program, for the rest of the day. During this trip we were full before noon several times.

The big claim to fame for the MPPT controllers is that they always put out maximum watts, so I assume the lower voltage would allow higher amps, but that would be a tough one to test accurately.

[booster]

Still going along with the solar set on the float voltage program as we have shore power. Off during the day and return to the shore power, which continues to just run its minimum absorption time and go to float on ending amps. Batteries should be totally full based on that, but we will confirm when we get home after an all day drive.

The float voltage solar program also gave us an unanticipated benefit. The solar, if on and putting out at absorption voltage would mess up the shore charger ending amps by adding the solar output to the system and putting the charger to float early. At the lower voltage, the solar doesn't contribute anything when the shore charger is in absorption, so it doesn't go to float early. This makes it so the solar can be on all the time, in the float voltage program, and we can come on and off shore power charger without its charging being affected. This will be a big convenience for us during the times we have shore power.

We will be very interested to see if used a lot less water the last two weeks, using the solar disconnect and alternate program, compared to the first week when we just let the solar run normally. Again, we will find out when we get home.

[booster]

We got home last night after a long drive of 720 miles. Came off shore power, solar still on at the float voltage program, separator overridden open so no engine charging. Were were bringing home a bunch of frozen buffalo meat for folks, so we had turned the compressor frig to as cold as it would go (got to 28*) to use it as a freezer, with compressor speed increased, so we were using quite a bit more power to run it. We never ran the generator or had the separator closed to charge off the van alternator. The separator was only closed on the occasions that we were running the engine to power the microwave off the inverter, to save the batteries. We also ran the microwave just off the batteries and both ways worked well.

I just went out and checked the coach batteries, which had been shut off since we got home, no charger, no loads. The water on both the GC2s and the 12v were barely down at all, after two weeks of going on and off the shore charger regularly, and with the solar running, but at the lower voltage. The GC2s checked at 1280 specific gravity, which is totally full for them. The SCS200 12 volt checked at 1285+, which is totally full for it.

It looks like we have gotten to the point of being able to get the batteries completely full, and hold them there reliably without overcharging them. Will be adding the switch to the solar to change programs, and two more switches and remote temp sensors so we can chose which bank to monitor, but all seems to be very good at this point.

I think it makes it clearer why the charger folks tend to leave the batteries less than fully charged. The risk of battery failure is less, and slower to appear, than if the batteries are overcharged, and the chargers are not sophisticated enough to not overcharge. It probably also helps explain the proliferation of much larger battery banks, as most are not getting all the capacity they think they have, especially after the batteries start to deteriorate due to chronic undercharging. From what I have seen on this trip, the one 115AH 12v battery would probably take care of our needs 95% of the time, now that it is getting totally full all the time.