Wiring question for the SmartSolar MPPT Controller

DIY
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I have solar charge controller question.

Last year I bought a 2017 2800BH that comes with a 180W solar panel and a PVCM25 Solar Charge Controller made in 2016. I upgraded the lead acid batteries to a single 230 amp Lithium Iron battery. The PCVM25 is definitely not designed for Lithium however it is charging the battery just not to it’s full capacity. I want to upgrade to a Victron SmartSolar MPPT charge controller in order to fully use the capacity of the lithium battery and have run into a potential wiring issue.

The PCVM25 has three wires coming out of it. The manual showed the the yellow wire connected the solar panel’s positive terminal, red wire to the battery’s positive terminal, and black wire to the battery’s negative terminal. Therefore the solar panel’s negative terminal is directly connected to the battery’s negative terminal. All the wires go into the space under the main bed so unless I want to make some wood panel repairs, I can’t trace to confirm these connections or make any changes. See the link for the PCVM25 wiring arrangement.

The Victron charge controller is familiar to me since I had installed it another camper. The solar panel’s positive and negative terminals are both wired directly to the Victron controller.

So the question here is, can the Victron controller work with the wiring arrangement of the PCVM25? IE will the Victron work if the solar panel’s negative terminal is connected directly to the battery’s negative terminal, bypassing the Victron?
Thanks in advance!

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Generally yes. The PV-ve and Battery -ve are internally connected inside the MPPT range.
however, the PVCM25 Solar Charge Controller is a PWM charge controller.
Do check to see that the Max power voltage of your solar panel is high enough to use an MPPT charger. This needs to be 5V higher than the battery voltage to start charging. Typically with a 20V solar module and a 12V battery, this can be a marginal situation - the panel will need full sun to start charging with the battery near full charge. Once started the PWM can work down to 1V above battery voltage.

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Thanks! I’ll definitely check the panel’s voltage output. It’s a renogy 180W panel and no longer on Renogy’s data sheet site so I may have to take it off the brackets to see the label underneath.

So PWM can work down to a low voltage output? So if I’m not disperse camping a lot, would it make sense just to leave the PWM (PCVM25) in place?

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That depends on if you can set the voltage points in the PWM charger to match the battery. Victron’s PWM chargers can be programmed, but you need a special interface, which makes them expensive for a one off job.

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