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Ian Jordan avatar image
Ian Jordan asked

MPPT, Orion TR Smart and BatteryProtect query

So I've been troubleshooting my new system and things are starting to come together.

I still have an issue with the integration of my external BMS into the system, but I think that's only a couple of cables away!

Anyway. I'm having issues with the BP65 I've got set up to protect my LiFePo4 battery from the Orion and MPPT. It seems to work fine with my Orion, but when I commissioned my Solar Panels this weekend I've been getting very mixed results.


Originally I think I shorted out my High Pin signal from the BMS, got that short fixed and fuse replaced.


Then I started having issues with the BP going to E1 when turning back on. This kept happening. Eventually I figured out that if I reset the MPPT by turning the breaker off and on it would work OK.

I think there's an issue with inrush current, vs cable length. My charging source to BP IN are less than 50cm, but I hooked up the ground wire to the main neg busbar. So the total neg cable length is probably over a meter, which may well be causing the issue? Also if my MPPT and Orion are off, does that mean the BP is unpowered and therefore off too?

How would I connect the neg differently? My Orion and MPPT negs go down to the neg busbar to connect, so I don't think I can connect to one of them for the BP, as the other charging source negative would effectively be 2 meters away from the BP.


Here's a schematic of my system (the charging system is protected by DC breakers in a DIN rail box, solar panels in (+ & -), Orion and MPPT positive out):

luna-wiring.jpg

MPPT SmartSolarBattery Protect
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1 Answer
Ulrich avatar image
Ulrich answered ·

Hello, I will try to answer your questions and comment on your installation.

The first thing I notice is that different solar modules are connected in series in the drawing. If the voltages of the modules are different, then one of the two groups will not work and the current of the other will be passed on via the bypass diode. The voltages of the modules must be exactly the same so that the power can be processed by the MPPT solar charge controller.

A Victron Energy Smart solar charge controller can receive data from the Victron Energy SmartShunt via Bluetooth so that it can adapt its charging curve precisely to the battery. So it does not necessarily have to be switched off by BatteryProtect.

The OrionTR adjusts its charging curve due to the more inaccurate voltage measurement method. I switched the OrionTR behind a Smart BatteryProtect so that my BMS can switch off the charge.

With the BatteryProtect you have to pay attention to the direction so that they switch correctly and are always supplied with voltage. But if the MPPT solar charge controller and the OrionTR do not supply any voltage, then the BatteryProtect is off.

If different cable lengths are used, the different voltage drops must be compensated for by different cable cross-sections. If the earth resistance is lower, there should be no problem, otherwise the currents may seek another path. The difference between 1 / 2m and 2m is very significant.

Was there anything I could help you with? I would be happy if I can answer any further questions you may have.

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Ian Jordan avatar image Ian Jordan commented ·

Thanks for your response. These panels work fine in series, as the currents are within 0.03A of each other and the voltages add when wired in series. These are already working.

My BMS will trigger from cell voltage, pack voltage, cell temp, pack temp, internal comms error, etc. So I need to use the BMS signal. The BMV and shunt are not as robust as they do not have any connection to the internals of my battery pack. Although I have still set up the MPPT to shut down if overall temp and voltage acceptable ranges, as its good to have the redundancy.

I shall have to look at the ground cable length and see how best to achieve the short length to the voltage source.

Thanks for the reminder about the BatteryProtect orientation. I have made sure the charge sources go to In and battery is connected to Out.


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