How To Upgrade To a Victron Solar Controller

[profcbutler]

I have a 2025 R25. It came with the Abso (Kisae) DC to DC charger. Abso was also used for the charger and inverter. Nothing against Kisae but the Bluetooth reporting in the Victron world is a whole lot better. One of the challenges I have is seeing (clearly) what is going on with the solar panel at any point in time as well as historical. Based on prior suggestions from this wonderful group on Tugnuts I have placed two additional Victron monitoring devices on the Thruster and Starter battery (easy install). It was also suggested that upgrading to a Victron solar controller is a worth while endeavor. I just took the boat out of the water for the winter and have some extra time on my hands! So my question to the group is this....

Has anyone done a Victron Solar controller (or monitoring device) on my year and model (with the above configuration)? Again, my main goal is to get better information from the solar panel. I have heard this is a fairly easy upgrade but based on my current configuration it looks like the Abso DC to DC battery charger needs to be swapped out (I am assuming). I believe the input ports are different between the Victron and Abso. It does not look like a one to one swap out. I have not been able to find any Youtube install videos on this. Has anyone done this and if so what does the install look like?

 

[Brian John]

The model of the boat should make no difference. On an R-31, I upgraded to a Victron 3000-watt inverter, solar charger, GX 50 display, and Lynx Distribution. Separately, I installed two AC Digital displays for voltage and current.

 

[Submariner]

I have a 2025 R25. It came with the Abso (Kisae) DC to DC charger. Abso was also used for the charger and inverter. Nothing against Kisae but the Bluetooth reporting in the Victron world is a whole lot better. One of the challenges I have is seeing (clearly) what is going on with the solar panel at any point in time as well as historical. Based on prior suggestions from this wonderful group on Tugnuts I have placed two additional Victron monitoring devices on the Thruster and Starter battery (easy install). It was also suggested that upgrading to a Victron solar controller is a worth while endeavor. I just took the boat out of the water for the winter and have some extra time on my hands! So my question to the group is this....

Has anyone done a Victron Solar controller (or monitoring device) on my year and model (with the above configuration)? Again, my main goal is to get better information from the solar panel. I have heard this is a fairly easy upgrade but based on my current configuration it looks like the Abso DC to DC battery charger needs to be swapped out (I am assuming). I believe the input ports are different between the Victron and Abso. It does not look like a one to one swap out. I have not been able to find any Youtube install videos on this. Has anyone done this and if so what does the install look like?

I did a solar upgrade on an R25-OB for a fellow boater. I installed a Victron 100/30 Smartsolar MPPT controller, took off the existing solar panel and replaced it with a pair of 210 watt solar panels.
It's fairly straightforward on the R25. I mounted the solar controller in the cave on the back bulkhead. With your DMT1250, you simply have to disconnect the solar + and - wires and back haul them to wherever you want to install the solar controller. Then run some wire back to the house battery with a fuse for the 12volt house battery side of the solar controller.

Note: You do not swap out the DMT1250. It's a dual-purpose device. It does engine to house DC to DC charging for engine charging of the LFP house bank, and it does solar charging (but not at the same time). Installing a dedicated solar charger provides for solar and engine charging at the same time.

I'm currently working on an electrical overview of the LE's with LFP to publish on our YouTube channel. Similar to the one I did for the NW edition, but specific to the LE's with LFP.

 

[Submariner]

The model of the boat should make no difference. On an R-31, I upgraded to a Victron 3000-watt inverter, solar charger, GX 50 display, and Lynx Distribution. Separately, I installed two AC Digital displays for voltage and current.

The electrical systems are different. Having a DMT1250 DC to DC charger/Solar controller means the boat is LFP. The NW editions are AGM batteries and started out with a PWM solar controller. The end result is the same, and the work is nearly identical, though, whether it's a NW edition or LE with LFP. The R25-OB is actually pretty easy to run wire for 12volt DC, and has plenty of room to install the solar controller.

 

[profcbutler]

I did a solar upgrade on an R25-OB for a fellow boater. I installed a Victron 100/30 Smartsolar MPPT controller, took off the existing solar panel and replaced it with a pair of 210 watt solar panels.
It's fairly straightforward on the R25. I mounted the solar controller in the cave on the back bulkhead. With your DMT1250, you simply have to disconnect the solar + and - wires and back haul them to wherever you want to install the solar controller. Then run some wire back to the house battery with a fuse for the 12volt house battery side of the solar controller.

Note: You do not swap out the DMT1250. It's a dual-purpose device. It does engine to house DC to DC charging for engine charging of the LFP house bank, and it does solar charging (but not at the same time). Installing a dedicated solar charger provides for solar and engine charging at the same time.

I'm currently working on an electrical overview of the LE's with LFP to publish on our YouTube channel. Similar to the one I did for the NW edition, but specific to the LE's with LFP.

Martin, I was hoping you would respond to this. Thank you! Just a few questions...
If I connect it up in the way you are suggesting it would only support the house batteries. Am I wrong in thinking that the current configuration keeps a charge from the solar on the starter and thruster batteries?

In the marina I am at I have no access to power over the winter. Keeping a trickle charge on those two batteries is not an option...hate to have to pull them and bring them home. Of course I will remove all the loads but I hate not being able to charge them time to time. Any thoughts on this? As for the house batteries I am working with the boat wrap folks to put a clear panel at the top to allow sunlight to charge the house batteries from the panel.

What gauge wire would you suggest to put back to the batteries from the Victron MPPT ( I would mount it on the bulkhead in the cave as you suggested. Close to the house batteries on the port side)?

What Victron model would you suggest? You have done a good job prior explaining parallel versus serial with multiple panels. For now I am going to stay with the OEM panel (I think its around 180w).
Very much appreciate the guidance!

 

[Submariner]

Martin, I was hoping you would respond to this. Thank you! Just a few questions...
If I connect it up in the way you are suggesting it would only support the house batteries. Am I wrong in thinking that the current configuration keeps a charge from the solar on the starter and thruster batteries?

In the marina I am at I have no access to power over the winter. Keeping a trickle charge on those two batteries is not an option...hate to have to pull them and bring them home. Of course I will remove all the loads but I hate not being able to charge them time to time. Any thoughts on this? As for the house batteries I am working with the boat wrap folks to put a clear panel at the top to allow sunlight to charge the house batteries from the panel.

What gauge wire would you suggest to put back to the batteries from the Victron MPPT ( I would mount it on the bulkhead in the cave as you suggested. Close to the house batteries on the port side)?

What Victron model would you suggest? You have done a good job prior explaining parallel versus serial with multiple panels. For now I am going to stay with the OEM panel (I think its around 180w).

Your boat is a LE with LFP batteries. You have a DMT1250, which is an MPPT solar controller. A disadvantage to this device is you get either engine charging or solar charging, but not both at the same time. Your boat currently only gets solar power to the house bank.

The engine and thruster batteries are fairly well isolated from electrical loads. AGM batteries lose up to 3% charge a month. If you shut off the DC switch for the house and engine and thruster, that'll isolate those banks from the loads. All that would remain is the 24x7 loads off the house bank. The factory solar panel, with LFP should be able to keep up with that throughout the winter.

Being a 2025 model, you probably have the two G31 Dakota 320AH batteries. LFP batteries can't be charged in sub-freezing temperatures. However, those G320 aH batteries from Dakota have a thermal blanket. The BMS will turn it on when the temp falls below 40 degrees to keep the LFP cells warm so they can be charged in sub-freezing temps (down to around -10dgrees F). Your Victron battery monitor won't accurately show this since the load is within the battery and bypasses the shunt. I don't know what part of the country you are in. If it's Anchorage or Fairbanks, I'd give different guidance than if it were Seattle as the length of time spent frozen with the amount of sunshine provided matters. It also matters how many months you plan to put the boat away for.

If you do add a dedicated solar charger, I'd go with a Victron MPPT Smartsolar 100/30 or the 150/35. That'd future proof your setup should you ever decide to add a second panel in the future. The max wire size those solar controllers support is 6AWG, and install a 40 amp fuse. The simplest way to do this is to replace one of the MRBF fuse holders on your bus bar next to you T-class fuse with Dual MRBF Fuse Block.

This is what I'd recommend.

https://www.bluesea.com/products/2151/Dual_MRBF_Terminal_Fuse_Block_-_30_to_300A

This makes it easy to connect the solar controller to the house bank, properly fused. With your existing solar panel, you could get away with 10AWG wire on a 30 amp ATC fuse. But here again, it all depends what you plan to do with the boat in the future.

AGM batteries, and LFP, can be left unattended for a period of time without harm, without any loads on them. When we left for our SE Alaska trip, we were gone for 55 days. I had three vehicles in my driveway without solar, without a trickle charger, and without being ran, and started up just fine.

 

[profcbutler]

Your boat is a LE with LFP batteries. You have a DMT1250, which is an MPPT solar controller. A disadvantage to this device is you get either engine charging or solar charging, but not both at the same time. Your boat currently only gets solar power to the house bank.

The engine and thruster batteries are fairly well isolated from electrical loads. AGM batteries lose up to 3% charge a month. If you shut off the DC switch for the house and engine and thruster, that'll isolate those banks from the loads. All that would remain is the 24x7 loads off the house bank. The factory solar panel, with LFP should be able to keep up with that throughout the winter.

Being a 2025 model, you probably have the two G31 Dakota 320AH batteries. LFP batteries can't be charged in sub-freezing temperatures. However, those G320 aH batteries from Dakota have a thermal blanket. The BMS will turn it on when the temp falls below 40 degrees to keep the LFP cells warm so they can be charged in sub-freezing temps (down to around -10dgrees F). Your Victron battery monitor won't accurately show this since the load is within the battery and bypasses the shunt. I don't know what part of the country you are in. If it's Anchorage or Fairbanks, I'd give different guidance than if it were Seattle as the length of time spent frozen with the amount of sunshine provided matters. It also matters how many months you plan to put the boat away for.

If you do add a dedicated solar charger, I'd go with a Victron MPPT Smartsolar 100/30 or the 150/35. That'd future proof your setup should you ever decide to add a second panel in the future. The max wire size those solar controllers support is 6AWG, and install a 40 amp fuse. The simplest way to do this is to replace one of the MRBF fuse holders on your bus bar next to you T-class fuse with Dual MRBF Fuse Block.

This is what I'd recommend.

https://www.bluesea.com/products/2151/Dual_MRBF_Terminal_Fuse_Block_-_30_to_300A

This makes it easy to connect the solar controller to the house bank, properly fused. With your existing solar panel, you could get away with 10AWG wire on a 30 amp ATC fuse. But here again, it all depends what you plan to do with the boat in the future.

AGM batteries, and LFP, can be left unattended for a period of time without harm, without any loads on them. When we left for our SE Alaska trip, we were gone for 55 days. I had three vehicles in my driveway without solar, without a trickle charger, and without being ran, and started up just fine.

Martin, very much appreciate all the recommendations. I do have the Dakota 320ah batteries and store the boat on the upper chesapeak in MD. Real cold is not an issue, but it is stored for around 6 months. I also appreciate the Blue Sea block recommendations (did not think about that). Look forward to all the videos you post. You are greatly appreciated by all of us Ranger Tug owners!