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Author Topic: Morningstar TS45 high voltage disconnect  (Read 4310 times)
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Posts: 8

« on: June 04, 2010, 12:26:20 PM »

Hello all
I have recently fixed (well....maybe fixed is a bit optimistic) a few broken Morningstar TS45 controllers. All had blown the TVS diodes.

I have been testing one in its 'Solar Battery Charging' mode on a small solar setup- 80W panel with about 400aH of battery at 12V. The system seems to operate normally, but twice now the Morningstar has started flashing the Green and Red LED's alternately, indicating a 'High voltage disconnect'. At these points the voltage of the bank has risen to about 15V.

My question is, why does the Morningstar allow the voltage to rise this high? I have not used the additional battery voltage sense inputs, but the cable to the batteries is short and adequately rated.
Thanks for your help
Hero Member
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Posts: 764

« Reply #1 on: June 04, 2010, 04:46:27 PM »

"fixed"   "maybe"  "optimistic"  "broken"  "blown"

Take your pick of the words you've used.

Then ask yourself :-
Why did the diodes blow?   
Are the replacement components used as replacement identical to the defective ones ?
Is there some other fault? 
etc etc

Hero Member
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Posts: 928

« Reply #2 on: June 04, 2010, 05:01:11 PM »

The obvious question, is the input voltage from the PV within limits?
2.8kW PV, SMA Sunny Island 5048, 5 PzS 700 battery bank, stinky diesel.
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« Reply #3 on: June 05, 2010, 09:09:13 PM »

Do you have the schematic.

Hero Member
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« Reply #4 on: June 08, 2010, 10:59:23 AM »

The TS45 is programmable and someone may have programmed it badly.

The High Voltage Disconnect set point is related the the battery voltage going above the HVD set point (not the PV input voltage).  So if someone programmed it for a 16V equalisation (maybe it was used with L16 batteries before that have very high EQ voltage requirements) and then someone else set the HVD at 15V because 16V would blow their inverter input (or at least cause the inverter to trip its own over volt alarm) then the thing could charge up to 15V and then trip the HVD.

The HVD can also alarm if there is some other source of charge to the battery that the TS is connected to (e.g. another charge controller or genny).  The HVD in this case is often used to protect sensitive DC loads from EQ charging when the TS is used for load control rather than charging.

There's a warning on the Morningstar custom config software that it is possible to cause damage by setting silly values to the custom parameters.

This may have come about by someone using that TS45 as a charge controller and then a load controller.  The two roles have different settings.  It also depends on whether it was set up for series charge control or dump load control.

If one of the MOSFET switches has fused short circuit then the charge control will have been lost (as the PV cannot be disconnected from the battery) and this will cause the battery volts to rise above the HVD set point and trip the HVD alarm also. 

If some of the MOSFETs are damaged they can be replaced see

The TS is rated to 125V PV input so a single 80W module won't be the problem.

If the transient voltage protection diodes have blown, was there the possibility that there was some lightning or an inverter without galvanic AC/DC separation was used and 230V AC leaked into the DC side.  The battery would probably be ok but the HVD would alarm and the transient diodes would blow.  Another thing that can damage the transient diodes is connecting a motor or other inductive load to the load terminals (in load control mode).  The manual recommends connecting a protection diode externally to the terminals to short out the inductive transients.  A good example of such a load would be a DC fridge or any pump.  The diode needs to be rated at >80V and >45A.

The TriStar should never be used to load control an inverter (the inrush current is too high).  Use a slave relay.
3.58kWp & 800Ah LiFeYPO4 off-grid(ish). See 'Cobbled together PV in W.Sussex' (in "Show Us Yours")
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