Off-Grid Upgrade Minimal Design – Victron Multiplus-II and 900AH Epoch LiFePO4

[jd1923]

Not that we need this much power, but a new Victron Energy MultiPlus-II 12/4k/160-50 120V just came out for $1,105 (no tax or shipping cost with this vendor). It's at a good price, having paid $997 for the 3K model July of 2024. Also, very good customer service with InvertersRUs. They serviced a warranty replacement for me on a small Victron MPPT SC. All I had to do was to email the pic of the Victron Connect app screen. They shipped a new one out immediately with return label.

It provides 4KVA (3.4 KW) inverted power and can charge up to 160A. It's 2" longer, the same width and 3/4" taller, plus 7 LBS heavier than the 3K model that several of us have installed, so it will just fit in the streetside basement.

With a whole lot of LiFePO4 Ahs, you could use this kind of power, if you're still running an ol' school single-speed compressor A/C and don't want to worry about what else you power up! No Soft/Easy Start needed with this bad-boy and you won't ever get stuck with a Multiplus failing for low voltage cutout. With required input as low as 9.5V your batteries may cutout before the MP2 ever will!

Wow, checking my thread above on page 1, it was two years ago to the day, when I finished my installation. We are rarely plugged in and never turn it off, so our MP2 has run 24x7 for a full 2 years now, always providing service without issue. 😎 

https://invertersrus.com/product/ve-multiplus-ii-12-4k/

[CRM]

1 hour ago, jd1923 said:

Not that we need this much power, but a new Victron Energy MultiPlus-II 12/4k/160-50 120V just came out for $1,105 (no tax or shipping cost with this vendor). It's at a good price, having paid $997 for the 3K model July of 2024. Also, very good customer service with InvertersRUs. They serviced a warranty replacement for me on a small Victron MPPT SC. All I had to do was to email the pic of the Victron Connect app screen. They shipped a new one out immediately with return label.

It provides 4KVA (3.4 KW) inverted power and can charge up to 160A. It's 2" longer, the same width and 3/4" taller, plus 7 LBS heavier than the 3K model that several of us have installed, so it will just fit in the streetside basement.

 

Nice, though I'll probably stick with the 3k model for size and weight. I know it's not too much, but I don't think I'll ever need that much power in my rig. 

BTW, it won't be long now before I'll be adding solar and lithium- so be ready to get your brain picked! 😂

[jd1923]

4 hours ago, CRM said:

Nice, though I'll probably stick with the 3k model for size and weight. I know it's not too much, but I don't think I'll ever need that much power in my rig. 

BTW, it won't be long now before I'll be adding solar and lithium- so be ready to get your brain picked! 😂

The 3K model is enough, especially with your efficient Turbro inverter A/C (or your new Chill). I hope you bought one of the open box/used MP2s at half price! With the 4K model out, look for deals on the 3K models coming soon! 

I just looked again at the picture of your beautiful hull #45! Remove that king antenna and mount solar panels sideways. I'll bet today you can get near 800W up there! Install two drive motors so you can pitch the panels up on both left or righthand sides! Would be so cool. Consider my brain picked (just for now)! 😎

[CRM]

20 hours ago, jd1923 said:

The 3K model is enough, especially with your efficient Turbro inverter A/C (or your new Chill). I hope you bought one of the open box/used MP2s at half price! With the 4K model out, look for deals on the 3K models coming soon! 

I just looked again at the picture of your beautiful hull #45! Remove that king antenna and mount solar panels sideways. I'll bet today you can get near 800W up there! Install two drive motors so you can pitch the panels up on both left or righthand sides! Would be so cool. Consider my brain picked (just for now)! 😎

Haven't bought anything yet, just still in the beginning of the planning stage. And that King antenna was removed within days of buying #45... Ended up bringing it to @mossemiwho also lives here in Tampa. 

Have to get my son off to college and complete the move to our new place in Floral City Fl, but once that's done, upgrades will be priority #1! 

[mossemi]

On 8/12/2026 at 5:31 PM, CRM said:

Haven't bought anything yet, just still in the beginning of the planning stage. And that King antenna was removed within days of buying #45... Ended up bringing it to @mossemiwho also lives here in Tampa. 

And I took the King antenna to the OTTO rally and couldn’t find any willing taker’s, dang it!  So I brought it back home and recycled it.

Mossey

[Dean and Mary]

jd1923, thanks for all the information you’ve shared about your Victron upgrade. I’ve read through this thread—and many others—while working on my own upgrade on a 2022 Oliver. When my upgrade is complete, I will share the information in a new thread.

You mentioned the new Victron Multiplus II 4000‑watt unit. One additional benefit in the 4K unit is the two cooling fans instead of the single fan in the 3K unit. The heat rejection has been substantial improved from 110 CFM to 260 CFM, which for me was actually the more important reason to step up to the 4K unit. The 1,200 watt increase in sustained output wattage would be a bonus, but one which I am not use I would ever use.

That brings me to my question about your installation. Your setup shows cooling fans pulling air from the basement and pushing it through the main equipment area under the bed. After installing and using those cooling fans, did you find that addition necessary? If so, how often do the fans run? Do you open the interior basement door to allow cabin air to be drawn through? And finally—would you recommend adding the additional cooling fans?

Thanks, Dean

[jd1923]

1 hour ago, Dean and Mary said:

jd1923, thanks for all the information you’ve shared about your Victron upgrade. I’ve read through this thread—and many others—while working on my own upgrade on a 2022 Oliver. When my upgrade is complete, I will share the information in a new thread.

You mentioned the new Victron Multiplus II 4000‑watt unit. One additional benefit in the 4K unit is the two cooling fans instead of the single fan in the 3K unit. The heat rejection has been substantial improved from 110 CFM to 260 CFM, which for me was actually the more important reason to step up to the 4K unit. The 1,200 watt increase in sustained output wattage would be a bonus, but one which I am not use I would ever use.

That brings me to my question about your installation. Your setup shows cooling fans pulling air from the basement and pushing it through the main equipment area under the bed. After installing and using those cooling fans, did you find that addition necessary? If so, how often do the fans run? Do you open the interior basement door to allow cabin air to be drawn through? And finally—would you recommend adding the additional cooling fans?

Thanks, Dean

Hello Dean, you're welcome and thank you!

Our upgrade was completed 2 years ago and I purchased the best Victron products available at the time. I didn't do our DC-DC upgrade 'til later which was a good thing as the Orion 50A had just come out which was far superior to the 30A model. This year Victron released a 70A Orion which like the larger inverter could be overkill.

I would also consider the 4KVA Victron if upgrading today (unless I could find a good closeout sale price on the 3K model). The 3K model is all we need and 1 or 2 fans doesn't matter as I'm certain each model has adequate cooling for its design. The higher CFM would be noisier. It's close to the same size and weight so why not have the newest most capable model?

Since we also upgraded our A/C to a variable-speed highly efficient A/C, I have not found the need where 3KVA has not handled our needs where we will run A/C and anything else at the same time without worry. When first installed, I had started our old Dometic P2, forgetting we already had the hot water heater running on inverter. That was the only time the 3K Victron struggled and BTW it outputted 3.5KW for a few minutes until I realized what happened. 

In answer to your specific question, re the additional Beech Lane fan I installed, I'd now say it's unnecessary. I've only used it a couple of times. The only time the MP2 gets somewhat hot is when battery SOC is low and we connect to shore power at a new campsite, heat of the afternoon, and the charger is set to full charge. Continuous charging is more of a heat issue than inverting and the MP2 will run fine up to 104F.

The 3K MP2 can charge at 120A max. I believe max on the 4K unit is 160A. What I do instead is recharge more slowly. You can adjust charge amperage using the programming interface. Though it's easier to use the Victron Connect app. Just tell the app your shore power is less. Set allowed input to 30A, given you have that at the pedestal, the MP2 will charge at the full rate. Set input amps to 15A or even 10A and the charge rate will be set lower accordingly only pulling max amps specified.

Love to see your installation. I installed a simple VE.Bus dongle to provide Bluetooth interface to the MP2 since I did not want a display. Your interface is via the Cerbo GX. The VE.Bus allows for adjusting input amps and can switch the MP2 (ON. OFF, Charger Only, Inverter Only). It also has a temp reading. I installed it on the wheel well above the MP2 to provide a reliable temp reading. If the MP2 is still charging when I'm going to sleep, I just reach for the phone and turn it off and back on when we wake. We're unplugged most of the time anyway. Charging is solar or DC2DC.