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Old 11-01-2019, 06:44 PM   #1
darkstar66's Avatar
Join Date: Mar 2017
Posts: 52
shore power/ battery drain

Thanks to all who have taken the time to read this post. I bought my van a few years ago turn key and ready to go. Although somewhat limited the solar system worked. Knowing I would soon be van living full time I put it through many practice runs to determine what the system could provide vs what my demands would be. It was obvious the (2) unmatched panels(100 watt and 75 watt) were not enough for my needs. With the help of Light Harvest Solar in PDX I installed a new 305 watt panel with an ML 30A Solar MPPT Charge Controller, 12/24V and a Tripp Lite 3000W PowerVerter. We kept the original (2) panels and the Victron solar controller. I am unclear of the how but they work in sync together. These two systems charge the original (2) agm 6V 125AH batteries. I will be upgrading these at the end of the month. I have been in Astoria OR running a remodeling project to make some extra cash before driving to Guatemala for the winter/ spring. Astoria is very very grey. I have definately been pushing my system to the limit but have been cautious to not go below 50% capacity. For the most part... Well I am back in PDX for a few days and we are having some unusual but welcome clear blue skies. I figured my batteries would bounce back no problem. Usually read 14 - 14.5 when fully charged. Its been three days of cold but sunny weather and my batteries will not get above 13.4 v. Could this be because it is cold and they do not charge as high? Did running them and never topping them off for the last few weeks do some damage? I also have a 30 amp plug in that I have never needed to use. I plugged in this morning and the batteries are still maxing out at 13.5. And dropping to 12.5 fairly quickly. I am not schooled in the shore power option. Is there anything I should be doing when I plug in? Turn on the inverter? I keep it off unless I need AC which is rarely. I would think there would be some indicator on the displays showing that it is plugged into AC but I see nothing. Learning about these areas of my system will really help me round out what I have managed to learn since going full time a couple of years ago. So sorry for the long winded post and thanks so much if you made it through.

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Old 11-02-2019, 07:27 AM   #2
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Scalf77's Avatar
Join Date: May 2007
Location: Beaverton, OR
Posts: 1,764
A couple of observations.
The first one would be that two 6V 125 AH batteries with a 3000 watt inverter would be undersized. Not a huge issue depending on how much you use.

The two solar controllers rarely work in sync with each other unless there is and established master-slave designation. Again, that is not a huge problem, but you may not be getting much benefit out of having the two systems as you think.

You have been undercharging your batteries, 14 - 14.5 is usually the bulk/absorption range of your battery chargers the fact that you did not see them leave 14 - 14.5 would mean they never made it to float.

Now that you have more sun, you said your batteries never got above 13.5. 13.5 volts would be in a reasonable float voltage range, but you should have seen the still transition from to the absorption phase 14.2 - 14.5 then drop down to 13.2 -13.5.

Although the chargers may be temperature compensated ( each charge source would need a temperature probe on battery) the temperature compensation is higher voltage the colder it gets.

Typical charge routines start in the bulk phase, this will put out the max current that is available for your charger. The voltage will generally creep up in voltage as it becomes charged. At some point 80 to 90% charged it will hit the absorption voltage threshold, at this point it will move into the absorption phase. This phase will hold the voltage at absorption and start bringing the current down slowly. This is the longest phase of the charge cycle, and one that your solar controllers need enough current to maintain that charge. It is not unusual to see them drop back to mppt mode as the sun goes in and out.

So it sounds like you have been undercharging the batteries, this is more common than over charging them. Standard agm batteries do like to be brought to full charge as soon as possible, repetitive partial charges do take life out of the battery at a faster rate. It also does not bounce back when being fully charged.

The biggest solar problem we have in our area in the winter (besides lack of sun) is the angle. If your panels are flat on the roof their out put is diminished. I have set of auxiliary panels that I can deploy angled to the sun and can match the output of the two flat panels with have available power in the aux panel.

I live in the Portland area, if you wanted to stop by to discuss. just PM

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