is there a solar charge controller that can do this?

PaulDavis

Member
That was mostly correct, except for one sort of important detail. The charge controller is using remote voltage sensing. Consequently, the voltage readings in the Tristar remote meter and the Trimetric are always in step (to the nearest 0.1V), and there is no discrepancy between them.

I agree with you that it is probably sensible for me to talk to Morningstar.
 

sprint2freedom

2008 NCV3 170ext
There's a nice comparison and discussion of several different charge controllers and their algorithms for switching from absorb to float in this blog post:
https://roadslesstraveled.us/solar-charge-controller-marine-rv-battery-charging/

The Morningstar controller is discussed about 2/3 of the way down the page:
https://roadslesstraveled.us/solar-...battery-charging/#morningstar-tristar-mppt-60

The Morningstar TriStar TS-MPPT-60 Solar Charge Controller multi-stage charging algorithm is the following:

BULK: Deliver the maximum amount of current possible until the batteries reach the Bulk voltage.

ABSORB: deliver as much current as necessary to keep the batteries at the Absorb voltage until the following thing happens:

2 to 2.5 hours has gone by (depending on battery type)

If the batteries fell below 12.5 volts during the previous night, then extend the Absorb stage by 30 minutes.

FLOAT: Deliver as much current as necessary to keep the batteries at the Float voltage. If the batteries are drawn down below the Float voltage for an hour or more due to big loads in the RV or boat (vacuum, power tools, microwave) or due to sudden cloud cover, the charge controller will switch back to Bulk mode and start the cycle over again. If the batteries fell below 12.3 volts during the previous night, then the solar charger will not enter the Float stage the following day.
This is yet another creative approach to the various problems caused by the unreliability of sunshine. The idea of setting up the charging parameters today based on the lowest voltage the batteries reached overnight is cool, since that is truly the biggest determining factor for how much charging the batteries need right now.

However, note that there is no criteria for switching from Absorb to Float based on the current falling below a minimum value as with the other charge controllers. There is also no provision for lengthening the Absorb stage if the Absorb voltage can’t be maintained, although there is if the Float voltage can’t be maintained.
I haven't verified any of the statements made above against the controller manual, but if the OP is not in float, perhaps it's because the battery voltage fell below 12.3 the previous night. That, along with "no provision for lengthening the absorb stage" statement.. makes me think there might be an algorithmic trap of some kind-

In the bulk stage the controller is a constant-current source (limited by available sun). In the absorb stage it is a constant-voltage source. If the state diagram has no way of exiting absorb and/or does not react to a condition where the absorb voltage cannot be maintained, then it could remain in a constant-voltage mode even when the toaster is on. That's not necessarily a problem as it should still be trying to output its maximum current in order to raise the battery voltage to the absorb voltage, but if the bank was/is at a high SoC during this test then it's worth pointing out that the charge acceptance of AGMs is going to be limited even after dropping the SoC a couple percent with a toaster.
 
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autostaretx

Erratic Member
From another thread, here is a charger than (A) accepts three charging sources (solar, shore, alternator) to feed (b) your choice of battery.
This charger *includes* shunt monitoring, so it DOES intelligently increase charging current if it sees a load being applied.
If it sees a load arrive, and solar can't supply the charger's 30 amp maximum, it will "add current" from one of the other sources.

The RedArc Manager30 BMS1230S2-NA.
Manual: https://www.redarc.com.au/Content/Images/uploaded/Manuals/BMS1230S2 Instruction Manual.pdf

The Australian company's website https://www.redarc.com.au/ has a pop-up to their US site .. but the link is broken.

--dick
 

elemental

Dis member
The RedArc Manager30 BMS1230S2-NA.
Manual: https://www.redarc.com.au/Content/Images/uploaded/Manuals/BMS1230S2 Instruction Manual.pdf

The Australian company's website https://www.redarc.com.au/ has a pop-up to their US site .. but the link is broken.

--dick
I have one (RedArc Manager30). The link to the US site is https://redarcelectronics.com/. The manual for the North American version of the product is here. I haven't finished integrating it into my system yet because it just became available in the US in January. They have been around in Australia a bit.
 

elemental

Dis member
That was mostly correct, except for one sort of important detail. The charge controller is using remote voltage sensing. Consequently, the voltage readings in the Tristar remote meter and the Trimetric are always in step (to the nearest 0.1V), and there is no discrepancy between them.

I agree with you that it is probably sensible for me to talk to Morningstar.
Any news? I'm curious...
 

PaulDavis

Member
I didn't contact them (yet). I do plan to.

One interesting thing I did note (or maybe it's not interest, I dunno ....) ... most of the time the remote meter for the Tristar says that it is in "MPPT" mode. A couple of days ago, it was (unusually) in "Absorb" mode. In this mode, the charger seemed very responsive to actual loads on the system. I plugged in my laptop, turned on the inverter, and the charged immediately jumped up the watts it was delivering. However, very importantly, we're talking about much lower power situations - without the laptop, the charger was pulling about 15W from the panels, with the laptop it jumped up to 65W.

So it occurs to me that one reason for the behavior I am seeing is that I really am seeing the full power output of my panels (for whatever reason: dirt, solar incidence angle, time of year, wiring fault), and that the charger can't respond to loads either because (a) it is in MPPT mode (b) there is no more power (c) both.

I will get in touch with Morningstar and report back.
 

jbm-sd

New member
I'm starting to look for a solar controller and read this entire thread. I'm interested as to whether or not you ever solved your issues with the Morningstar controller?

Thanks,
Jason
 

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