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Old 01-21-2019, 10:29 PM   #1
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Default Alternator vs. Solar Charger Conflict

Is there a conflict between the alternator charging the House battery and the Solar charger ALSO charging the same battery.

Should the Isolator block excess power from the Alternator if the Solar Controller believes the battery is full?
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Old 01-21-2019, 10:46 PM   #2
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Is there a conflict between the alternator charging the House battery and the Solar charger ALSO charging the same battery.

Should the Isolator block excess power from the Alternator if the Solar Controller believes the battery is full?
\


The two charging sources probably won't car much about each other and both may or may not be prone to overcharging a full battery based on what the solar controller is, and if the alternator is just off the stock system or has it's own external regulator controlling it. The isolator will not automatically shut off charging to a full battery in the coach from the engine. If it really is an isolator and not a two way separator, it will block all charging from the solar to engine battery all the time.


In general, if you are just charging off the stock van charging system through an isolator or separator and drive a long day on a full battery, you almost certainly will be overcharging the battery. Solar controllers will usually time out at about 4 hours on most moderately priced units so can overcharge, but not as much.
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Old 01-21-2019, 10:57 PM   #3
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Default Makes Sense

So it sounds like overcharging to a degree would be pretty much normal. On my Solar system I haven't noticed a problem. My friend, in cold weather got a 16 V overcharge in quite cold weather with a TriMetric Solar Controller. He sent the charger back to Bogart who upgraded it to correct the overcharging. His subsequent discussion with their engineer surfaced the potential overcharging issue from the Alternator.

From what I hear you say, it's likely the "routine" overcharge is not a problem. Hopefully the TriMetric upgrade will solve my friend's problem.
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Old 01-21-2019, 11:06 PM   #4
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So it sounds like overcharging to a degree would be pretty much normal. On my Solar system I haven't noticed a problem. My friend, in cold weather got a 16 V overcharge in quite cold weather with a TriMetric Solar Controller. He sent the charger back to Bogart who upgraded it to correct the overcharging. His subsequent discussion with their engineer surfaced the potential overcharging issue from the Alternator.

From what I hear you say, it's likely the "routine" overcharge is not a problem. Hopefully the TriMetric upgrade will solve my friend's problem.

I certainly am not saying the overcharging is not a problem. I am saying it is very common, though, and most certainly is shortening battery life for folks. The Bogart would likely have temperature compensation so he voltage will go up a lot in very cold weather. 16v gets to be a bit much, as much for the van components as the batteries, and there should be a setting for max voltage allowed in the Bogart.


If properly setup and running on the shunt, with the right settings, a Trimetric solar controller will not overcharge the batteries. It is one of the few moderately priced units that won't, so a very good choice. The solar and battery monitor are built in together so the battery monitor can be watched while driving to see if the batteries are full, or not. At that point you can shut off the isolator or separator if you have one that you can manually control.


In general, watching volts won't tell you much. You would watch state of charge or even better charging amps to know if the batteries are full.
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Old 01-21-2019, 11:11 PM   #5
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Thanks for the additional explanation.
We were discussing making a cut-off which would be based on the SOC.
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Old 02-14-2019, 03:33 PM   #6
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Thanks for the additional explanation.
We were discussing making a cut-off which would be based on the SOC.
Max
I am curious about the details of what you have in mind.

An AGM battery needs (energy to charge at room temperature) + (energy to drive the reaction when not at room temperature)

The typical multi stage charge profiles that you see published are for room temperature conditions, and the battery needs to be fully charged, ideally every time, but at least fairly often in order to work properly.

When the battery is cold, additional energy (in the form of voltage) is needed to make up for the lack of thermal energy. This is the whole point of temperature compensation - raise or lower the voltage as needed, depending on temperature.

In cold weather, these voltages can rise substantially - 16 volts is not uncommon.

Are you thinking of an algorithm that uses changes to the finishing stages to make up for the lower bulk charge voltage?

Thanks

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Old 02-15-2019, 09:24 PM   #7
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We have the TriMetric meter and controller. In very cold conditions, I’ve seen mid-15's volts. The voltage from the alternator is reasonable for bulk and absorption, but way to high for float, so I have a switch on the dash for the Surepower1315 separator. When the meter says 100%, I flip the switch.
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