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Old 10-25-2017, 01:22 PM   #1
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Solar Controller vs. AC-DC converter/charger

How do these 2 not conflict with each other in some way? They both seem to have their own charging profiles as to how long on bulk, absorption, then float....but since they're both connected to the same +12v bus, won't they see each other's voltage on the line, and get kind of confused?
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Old 10-25-2017, 04:42 PM   #2
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Hi

The simple answer is that a single integrated unit would be better. The full answer is that the solar charger handles a modest amount of current. It's not going to have much of an impact on the charge methodology of the shore power system. They do understand enough about what's going on that they do not directly interfere with each other.

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Old 10-25-2017, 05:10 PM   #3
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Seems like there ought to be some sort of a transfer switch arrangement so that the solar is "off" when shore power becomes available. I suppose the need for an ac transfer switch (when more than one source is possible) is more of a safety issue due to the larger currents involved.
Anyway, as long as its ok to have both inputs on the same bus, that answers my question.
Now I have DC wiring questions...probably deserves its own thread.
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Old 10-25-2017, 09:20 PM   #4
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My trailer had a major upgrade done by "Lewster", an experienced tech who is active on these forums. He added an inverter/charger and a solar system. Both systems have a display that shows system voltage and charging current. Both systems are configurable as to what the voltage should be for bulk, absorb/acceptance, and float charging.

The way it is set up, the target voltages on the solar system are 0.1 volts higher than on the on the inverter/charger (the specs for my batteries allow a range of 0.2 volts so both systems have valid settings). This means when we have sun, the solar usually provides enough voltage that the other system says "full charge, nothing to do". But if we are drawing a lot of power, the i/c kicks in.

At night when the sun fades away, the i/c kicks in.

This mostly works well. But on our last trip out, we did notice one time when the batteries needed some charge, and the solar was doing its best in a shady camping site. However, the solar was basically just keeping up with the trailer's loads but not completing the charge of the batteries. The inverter/charger saw high enough voltage that it did not pick up the slack. Even after dark, the i/c charger stayed in float mode. (I think we went to bed at -9 amp-hours from full. The next morning, we were at full charge.)
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Old 10-26-2017, 10:11 AM   #5
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Hi

No matter how you set it up, the chargers will get "confused" by load current on the trailer. That will put them into this or that mode from time to time. Any issues created by the low current solar charger are minor compared to this.

Bob
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Old 04-18-2021, 03:45 PM   #6
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Reviving an old thread... I am in the final stages of a solar install on my 2005 trailer and had a similar question as the OP. In looking at my Iota Converter/Charger and Renogy Rover MPPT solar Charge Controller, the Iota charges at 13.6V and the Rover charges at 13.8V. So, as stated above, the Rover would do most of the work when there is sun, and the Iota would kick in when cloudy or dark (if connected to shore power). Okay, that's fine. Would it make sense to turn the Iota (converter/charger) breaker off when in a sunny or even partly cloudy area while camping (when connected to shore power)?

Another question: Is there not (or should there be) a combination Solar Charge Controller/120V Converter/Charger that could manage all this?
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Old 04-19-2021, 09:02 AM   #7
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Quote:
Originally Posted by 10Smiles View Post
Reviving an old thread... I am in the final stages of a solar install on my 2005 trailer and had a similar question as the OP. In looking at my Iota Converter/Charger and Renogy Rover MPPT solar Charge Controller, the Iota charges at 13.6V and the Rover charges at 13.8V. So, as stated above, the Rover would do most of the work when there is sun, and the Iota would kick in when cloudy or dark (if connected to shore power). Okay, that's fine. Would it make sense to turn the Iota (converter/charger) breaker off when in a sunny or even partly cloudy area while camping (when connected to shore power)?

Another question: Is there not (or should there be) a combination Solar Charge Controller/120V Converter/Charger that could manage all this?
Hi

In answer to the combo question - yes, Victron makes stuff that will network (with a network hub) to manage this sort of thing. Not cheap and the hub does use power ....

What's really going to happen with your two chargers:

It's dark out and the shore power setup runs up to full voltage and then *should* cut back when it sees the current drop. If you have no loads running, that's what will happen. ( the current drops to zip...). The converter then sits in "float" mode.
Yes, loads mess this stuff up.

Sun comes up and the solar starts it's thing. Shore power is still in float. Shore power does no charging, solar does everything.

A cloud goes over the sun and the solar cuts back. The shore power fires up, goes to full voltage and sources all the current. Cloud goes away, solar sees near zero current and it goes into float mode. Now shore power is doing everything.

Just how this switch back and forth goes is dependent on the loads in the trailer and the current trigger points on the controllers. It also *assumes* both controllers have a "float" mode (they should ...).

So, pretty much, only one or the other will be doing anything. No need to turn this or that off. Let them fight it out.

Bob
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Old 04-19-2021, 02:44 PM   #8
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Hey there Uncle! Thank you for the reply. That all sounds great, am really looking forward to our new found independence. We have dry camped in the past at some national parks and such, but we did have to have a generator, this will be really fun.
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Old 04-19-2021, 07:51 PM   #9
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I also have an iota charger and victron solar controller. I considered swapping out the iota as it is a bit low with voltage for lifeline AGMs. In the end, as described above, they play pretty well together. The only thing I dont like is the iota has a weekly automatic "equilize" cycle. Well, sort of. Its 14.7v, so it's more like a timed absorption cycle, so it's ok.
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