Strange Voltage based Fault on TS-MPPT-45 Morningstar

Wanderman · July 2012

Hey All,
I am going to do my best to explain this issue, but it's a bit complex on the surface.

As many of you know I have an RV with around 450 Watts of Panels (36v Nominal) going into a Morningstar TS-MPPT-45 MPPT controller that, in turn, feeds two Trojan 27TMX Deep Cycles at 14.8V (max as per settings).

In addition, the "House" batteries can be charged from the on board converter charger (Max 14.4V, Three stage.) or the Engine Alternator at ~14.4 V with a typical car engine Voltage regulator.

There is a separate "Engine" battery that is charged by the Alternator (obviously) and can be tied to the House system as well.

There is a 4 Position Perko Switch (OFF/1/ALL/2) that is wired into the system.

After much testing these are the conclusions:

Engine Off, Converter/Charger On, Solar On:

Switch at 1 House Batteries Charged by Converter/Charge AND Solar
2 Engine Battery Charged (House Still On Solar)
All Ties Both Together Everything Charges from All Sources.

Engine Off, Converter/Charger Off, Solar On:

Switch at 1 No Charge
2 No Charge (House Still Charged On Solar)
All Ties Both Together Everything Charges from Solar

Engine On, Converter/Charger ON OR Off, Solar On

Switch at 1 Engine Battery Charge, Solar Charging System FAULT 16.62V Over Voltage
2 Engine Battery Charge, Solar Charges House Batteries.
All Engine Battery Charges, House Battery Charges (No Solar Faults)

The Over Voltage Only happens when the Engine is Running..not a surge as it will go overvoltage whenever switched to "1"

This is VERY ODD!!

Ultimately, I would like to be able to "steal" some power from the House system (using an Ultra Trik-L-Start) so I don't cook the chassis starting battery AND get the proper 14.8V charge to the Trojan House batteries. Then when the Engine is started it will charge the House System WITH the MPPT Solar charger (if it's light out!) I shouldn't have to switch anything to do this.

What am I missing here???

Thanks,

Rich

boB · July 2012

Re: Strange Voltage based Fault on TS-MPPT-45 Morningstar

Sounds to me like your RV alternator charging system is charging at too high of a voltage.

With the MPPT45 set to charge at less than 15 volts, and your RV alternator bringing up the battery voltage to greater than this setting, the MPPT45 will not charge at all.
It's not doing anything at that point.

I would have your RV charging system checked. Over 16 volts sounds like it is not regulating properly.
The "field" is possibly being driven hard on and not regulating.

If this has been going on for a while, I would check the electrolyte level (water) in the batteries to make sure it has not boiled away and to add some distilled water to cover up the plates if they are exposed.

boB

SolaRevolution · July 2012

Re: Strange Voltage based Fault on TS-MPPT-45 Morningstar

Hmm.

A little food for thouhgt-

I recently worked on a system with 2 TS-45s (PWM) whith identical settings where one was showing an overvoltage fault. It turned out that the temp sensor in one unit was faulty and was reading around -30°F. The faulty unit was raising the charge voltage to compensate for it's faulty reading and the other was showing the high voltage fault.

Does your RV charger have a faulty temp sensor or some other fault in the voltage regulation controls?

-Alex

Wanderman · July 2012

Re: Strange Voltage based Fault on TS-MPPT-45 Morningstar

I checked the Chassis battery system with a voltmeter and a ammeter. No faults in that system at all. Charging at the normal 14.4V nominal. Only when it is added to the Solar charging does it produce a fault.

The temp sensor on the MPPT charger is reading true. at last check +89F midday. Rises and falls normally.

You can see why I am stumped!

Rich

CATraveler · July 2012

Re: Strange Voltage based Fault on TS-MPPT-45 Morningstar

Put a scope on it and see what kind of waveform you have. As a WAG did you add the Perko, wiring etc and possibly reducing the damping that the battery would normally provide?

Wanderman · July 2012

Re: Strange Voltage based Fault on TS-MPPT-45 Morningstar

CATraveler,
I don't have a scope handy, but the perko was there for a LONG time and everything works as advertised EXCEPT with engine running and Solar active.

Weird, huh?

Rich

Wanderman · August 2012

Re: Strange Voltage based Fault on TS-MPPT-45 Morningstar

OK NEW info.

After playing with the engine battery disconnect switch AND the Perko OFF/1/ALL/2 switch at great length, it seems that when switch is in position 1 and the battery is connected I get the high voltage condition. upon further inspection it looks like it is somehow connecting the engine battery in SERIES when the switch is in the 1 position. It does NOT do this in the ALL position (nor the 2 position). All charging on both sides, engine and solar...house and chassis, seem to work fine.

EXCEPT when the engine is running AND the engine battery is turned on at the battery terminal AND the perko switch is in the 2 Position.

My high level logic faculties are low on power...I MUST be missing some basic obvious fact. Something is miswired....but what?

Ideas???

Thanks for helping me puzzle this out.

I am leaving the chassis battery disconnected at the terminal AND the switch on ALL...I can then use all equipment on board AND start the engine if needed AND the house batteries will charge from the MPPT controller properly.

Thanks,

Rich

BB. · August 2012

Re: Strange Voltage based Fault on TS-MPPT-45 Morningstar

It sounds like a problem inside the transfer switch... If the Common wiper contact is burned/intermittent--I could see a problem with removing battery from charging circuits--which will usually cause voltage regulation problems.

I believe those types of switches are available in two types. Make before Break and Break before Make.

Normally I would use Make before Break to insure there is always a battery connected to the charging system when switching.

-Bill

CATraveler · August 2012

Re: Strange Voltage based Fault on TS-MPPT-45 Morningstar

An alternator produces AC and it then uses a full wave diode bridge to produce pulsating DC. This is what I suspect is triggering the CC over voltage. The pulses normally get damped by the wiring and battery. A scope would help to understand if this is the case, perhaps you can borrow one. The addition of the Perko and additional wiring may also be a factor. It's also possible that your alternator has larger pulses and/or other transients.

Many RVs use a solenoid to connect the two battery banks and I would think that if this was a common problem those with solar would have posted information. But I haven't done a good search. That's why I suspect that it's the alternator and/or your wiring.

What was the OEMs load isolator and how has it been changed? The Perko was there a long time meaning it has been added, right? Can you borrow some very large capacitors and see if you can filter out the problem?

CATraveler · August 2012

Re: Strange Voltage based Fault on TS-MPPT-45 Morningstar

BB. wrote: »

It sounds like a problem inside the transfer switch... If the Common wiper contact is burned/intermittent--I could see a problem with removing battery from charging circuits--which will usually cause voltage regulation problems.

If you move the wires on the back of the switch and connect them to one terminal (bypassing the switch) does the problem still occur?

If you restore the chassis wiring to the OEM configuration and then add a short jumper between the two battery banks does the problem still occur?

Strange Voltage based Fault on TS-MPPT-45 Morningstar

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