Off-Grid Upgrade Minimal Design – Victron Multiplus-II and 600AH Epoch LiFePO4

[John Dorrer]

JD, This is great thread for those with older trailers. I'm always amazed by the depth of knowledge by a number of members.

 

Hoping our 2022 carries us for years to come, without having to do anything major. Anything electric is over my head🙃

 

Thanks for sharing all your mods.

 

JD

[jd1923]

Who's ready for ne LiFePO4? Got an email on this today, 15% OFF Epoch!
https://www.epochbatteries.com/collections/rv-van-camper-lithium-batteries

[Teaney Hull 292]

On 2/4/2025 at 11:21 PM, johnwen said:

Thanks for this awesome post with pictures, JD!  Although my installation is a little different it was very helpful, to me, to see that these batteries indeed fit into the battery tray.  And thanks much to Scuba RX ,here at the "Q", with helping me  remove the wiring rat nest in the battery cave....+ and - bus bars were so easy to install!  I now have only 2 wires inside my battery cave!  Pictures later after my DC to DC charger installation.......happy camper again!

John

Look forward to the pics

[jd1923]

Epoch batteries were on sale again for Black Friday and I'd been thinking about adding another one. Our 600 Ah system has been great, all we needed for the last year+ (MP2 Inverter always ON with many AC appliances running). Since we're adding an efficient A/C this will allow us to run air long enough on those hot afternoons! We're tired of having to be in a campground on hot days!

I was back and forth on spending the money, so I asked Chris and, in a heartbeat, she said "Do it!" I've finally let go of the RV owner's syndrome known as SOC-Worry! I'm now just fine when it gets under 50%, but it worries Chris some. Hopefully, NOT anymore!

Two Epoch 300 Essentials fit nicely in the OEM battery tray. I knew adding #3 meant a custom installation. First to-do was to remove the battery tray. Would you believe that alone weighs 30 LBS! Then cleaned up the bay and filled the mounting holes. I had scrap rubber from the TSC stall mats I used to line my truck bed (the wheel-well cutouts) and after trimming them a couple inches shorter they fit perfectly!

I kept looking at that big bolt in the center of the bay, and wondering why OTT would have done that!? Our friend @mountainoliver gave me a heads up on that and I got under the streetside bed and found the support beam the other end of the bolt (pic2). I started thinking I could somehow secure 3 batteries using that bolt. After sleeping on it, I thought of replacing the bolt with a 1/2" eyelet bolt and use it to strap and lock the batteries down!

[jd1923]

I found this great supplier of Made-in-USA cam-buckle straps and tie-downs:
https://www.amazon.com/stores/PowerTyeMFG/page/66AA148A-1600-4E0D-A1AA-AEA3A1050247?lp_asin=B017BYSJ7I/

I purchased this cable lock to secure the batteries: https://www.amazon.com/dp/B00006407M/?th=1

I turned the eyelet bolt on an angle so that the cable lock and strap would fit nicely. I placed foam around and between every side of the batteries. I put 2" of foam between the 2 inside batteries to give the eyelet space, keep it from rubbing.

I have an 8-ft cam-buckle strapped tightly around all 3 batteries and these cam-lock straps cinch nicely! A 4-ft strap and the cable lock go through the eyelet to pull the outer battery inwards.

I also had to make two more 4/0 battery cables. I planned the layout so the main ground is convenient right-front. And now without the battery tray, I can reach all the way in, over the batteries. I tightened all 6 battery terminal bolts after all 3 batteries were tied down, so these can be easily checked and tightened when needed.

Edited December 20, 2025 by jd1923

[jd1923]

Once I got to this point, I started thinking a thief could possibly undo the battery cables, loosen the straps and even with cable lock in place, slide out the outer battery, then steal them all. Oh No!

So, I had a 12x12x1/4" sheet of aluminum left over from another job and it became the perfect solution. Now besides a taking a crowbar to the battery door, a thief would have to cut the 3/8" hardened steel cable. Now these expensive batteries ain't goin' nowhere!

I'll cinch down the straps and cable lock again, after putting on some miles...

Ya gotta love the new look of our Epoch app! 900 Ah - Priceless! 😎

[tallmandan]

Wow JD!  You've gone an one-up'd those of us that have installed the 2 300 Ah Epochs.  Very impressed and good to know that this can be done.  I've been very happy with my upgrade to 600 Ah with the these two Epoch batteries but if I ever decided to upgrade to the 3000w inverter and try to run off-grid a/c then this would be the way to go! 

Thanks for sharing and thanks again for all the help and advice you share on this forum.

[CRM]

10 hours ago, jd1923 said:

I have an 8-ft cam-buckle strapped tightly around all 3 batteries and these cam-lock straps cinch nicely! A 4-ft strap and the cable lock go through the eyelet to pull the outer battery inwards.

Clean install. In the planning stages of adding solar/lithium and it's nice to know that 900ah can fit in the battery box. 

[jd1923]

9 minutes ago, CRM said:

Clean install. In the planning stages of adding solar/lithium and it's nice to know that 900ah can fit in the battery box. 

Thank you @tallmandan and @CRM and other forum members for the 👍!

@rideadeuce was my inspiration. Mike installed 920 Ah Epoch back in April 2024.

He purchased two of the Epoch 460 Ah Elite Series that come with Victron Comms, upgraded internal components and special cases. I didn't need the extras and preferred the lower price point of the Epoch Essentials Series. They call them Essentials, but they include the app, built-in heaters, internal protection, temp sensors and alarms. Even their Essentials Series batteries are industry leading!

Two Epoch 460 Ah Elite Series batteries just barely fit in the bay (see Mike's post linked below). Two Epoch 460 Ah Essential Series will NOT fit! The two side-by-side would be an inch too wide (the Elite Series batteries are much taller). Too bad, or I would have gone that way to begin with.

I didn't see that Mike secured his batteries into the bay. Likely they are so big/heavy, sitting on rubber, and since they fit wall-to-wall they would not budge! I felt the 3 smaller batteries should be strapped into place and I was also able to add a locking mechanism which minimizes theft worries. At 900+ Ah these are surely forever installs! 😎

 

[jd1923]

Final touches on the battery door to seal the vent openings and insulate the door...

I put a bead of clear silicone around each hole. Then pushed in the 1" rubber disc into place (pic1). The silicone oozed through the perforated openings as I wiped off the excess with many small pieces of paper towels. Final step was to clean the silicone from the outside with paper towels soak in rubbing alcohol.

Then I used some bubble insulation that came in a recent shipment. The lines you see are carpet tape to hold it in place (pic2). The insulation is only 1/4" thick and now the door is nicely tight when locked.   

[rideandfly]

On 12/20/2025 at 12:39 AM, jd1923 said:

Ya gotta love the new look of our Epoch app! 900 Ah - Priceless! 😎

 

Really like your installation! We just purchased new Epoch batteries to replace the BB batteries, really like Epoch's App, too!

[John Dorrer]

14 hours ago, jd1923 said:

Final touches on the battery door to seal the vent openings and insulate the door...

I put a bead of clear silicone around each hole. Then pushed in the 1" rubber disc into place (pic1). The silicone oozed through the perforated openings as I wiped off the excess with many small pieces of paper towels. Final step was to clean the silicone from the outside with paper towels soak in rubbing alcohol.

Then I used some bubble insulation that came in a recent shipment. The lines you see are carpet tape to hold it in place (pic2). The insulation is only 1/4" thick and now the door is nicely tight when locked.   

Nice idea

[jd1923]

3 hours ago, rideandfly said:

Really like your installation! We just purchased new Epoch batteries to replace the BB batteries, really like Epoch's App, too!

Thank you Bill, and I'm happy for you! I remember reading re your BB situation, and I'm glad it all worked out for you. 😄 Yep, Epoch batteries and their app are great!

[jd1923]

I'm running into something funky, wondering if anybody has seen this before. I believe I did the correct configuration settings for the Victron Inverter/Charger and apps for Victron and Epoch, showing the upgrade from 600 to 900 Ah.

It seems like the new battery is being picked on. Could that be by design, since it has less charge cycles recorded? When we run something via the inverter it often takes charge from the new battery and none from the others! It got down to 30% SOC when the other two were high 60s. Then I connected to shore power and got all three to 100%. Now a week later unplugged, it's down to 20% SOC (see pic).

We just started the fridge on DC since we're leaving soon to Quartzsite. It's drawing -17A and right now it's pulling an even amount from each battery, but often does not. You can tell the new battery which has 4 charge cycles in history and the other near 1 1/2 year old batteries have 52 and 58 cycles. When I had the two original Epoch 300s they always stayed with 2-6 % points from each other.

I'll charge them back to 100% before we leave, but I'm leaving it unplugged just to see how low the new battery will go before the BMS prefers the two with greater charge/voltage. I may have to call Epoch and/or Victron next week to check on my settings. Any ideas?

[rideandfly]

John,

I'm just learning about Epoch batteries, are all the cells on Epoch 3 close to the same voltage on the Cell page? 

Edit: The more I look at it they are probably close to the same since the voltages are 12.8 on all batteries.

Geoff in support at Epoch has answered all of my questions, so far. 

 

 

Edited January 18 by rideandfly

[topgun2]

14 hours ago, jd1923 said:

I may have to call Epoch and/or Victron next week to check on my settings. Any ideas?

jd - 

I really don't remember exactly how you wired your three batteries - but - it is possible that if the batteries are wires in such a way that what happens to be the newest battery is the "last in line" (i.e. the positive cable which feeds into the Ollie comes off that newest battery) more juice will be drawn from that battery.  The preferred way to prevent this is to run all the negatives to a buss bar and all the positives to another buss bar and then connect the related positive and negative in such a position as to be as equi-distant  from each of the battery connections as possible.

Having said this - it still sems to me that the differences you are noting are larger than what I would have thought.

Bill

[jd1923]

13 hours ago, rideandfly said:

John,

I'm just learning about Epoch batteries, are all the cells on Epoch 3 close to the same voltage on the Cell page? 

Edit: The more I look at it they are probably close to the same since the voltages are 12.8 on all batteries.

Geoff in support at Epoch has answered all of my questions, so far. 

Thanks, Bill. I went and checked the individual cell batteries last night after reading your post. All 12 cells (4 cells x 3 batteries) were 3.2V (12.8 / 4). As far as the three being 12.8, as long as they are connected the voltage is across the set. You have to separate batteries to read individual voltages. Not sure why the BMS would report even voltage across all cells while showing one battery at 20% SOC and the others at 60%+.

The new battery got down to 15% by 10PM last night, with our fridge still getting down to temp. I plugged into shore power and we have all three batteries back to 100% SOC this morning.

Our Oliver friend Ken contacted me and asked if I had the wiring straight. I sure believe so but I'll check. He also suggested wiring the new battery in the middle (see pic, not directly connected to B+ or B- cables). Sounds like a good idea.

Heading to Q tomorrow, so when we get there I'll pull the batteries out with all the Oliver experts and observers in tow at Dome Rock! 🤣 The new battery should be low again and I'll read with a multimeter when the cables are disconnected.

[jd1923]

4 minutes ago, topgun2 said:

jd - 

I really don't remember exactly how you wired your three batteries - but - it is possible that if the batteries are wires in such a way that what happens to be the newest battery is the "last in line" (i.e. the positive cable which feeds into the Ollie comes off that newest battery) more juice will be drawn from that battery.  The preferred way to prevent this is to run all the negatives to a buss bar and all the positives to another buss bar and then connect the related positive and negative in such a position as to be as equi-distant  from each of the battery connections as possible.

Having said this - it still sems to me that the differences you are noting are larger than what I would have thought.

Bill

Bill, we were writing at the same time! Your "last in line" comment may be correct, TBD soon. I'm not wanting to add buses but will check the wiring (to be as pictured above) and wire the new baby in the middle, so not to be first or last in line. Thanks

Edited January 18 by jd1923

[jd1923]

Reviewing this picture taken during installation, I'm pretty sure the new one is the outer one. Hard to see all the wiring though. But it really shouldn't matter! Two shorty 4/0 cables have negligible resistance. I'll soon see if I wired it incorrectly.

Edited January 18 by jd1923

[rideandfly]

11 minutes ago, jd1923 said:

Reviewing this picture taken during installation, I'm pretty sure the new one is the outer one. Hard to see all the wiring though. But it really shouldn't matter! Two shorty 4/0 cables have negligible resistance. I'll soon see if I wired it incorrectly.

If the wiring is correct, also thought there may a loose or bad connection in a cable, but the current draw looked even across all the batteries. The minimum torque on my Epoch lugs is 70 inch pounds. Geoff gave me the torque in NM that I cannot find, but I had converted the minimum torque to inch pounds.

When you go to Q, there will be plenty of knowledge there to draw upon.

[jd1923]

9 hours ago, rideandfly said:

If the wiring is correct, also thought there may a loose or bad connection in a cable, but the current draw looked even across all the batteries.

Upon inspection, the wiring was correct. I decided to work on this today. I didn't want to travel and camp in this odd state. It took me 30 min (given it's locked down, all the straps, etc.) with only a 13mm ratcheting swivel wrench. OMG, it could have taken a good extra hour at the Q with all the helpers and advisors! 🤣 (remember the car club days, parking lot discussion to the wee hours...)

@mountainoliver had texted me an idea yesterday, to swap the batteries, making the new battery the middle one in the wiring scheme, not directly connected to the main B+ or B- cables. As previously wired, I had the new battery positioned last, attached to the main ground.

Ken was right, the capable engineer that he is! 😂 At least it's been working as it should today. Lesson Learned is when adding a new 3rd battery, wire it in the middle position. Who knew? We never read this in all the online advice we get.

I disconnected shore power this morning, before doing the work. It's been off all day with on average -17 Ah use (our fridge on DC is -12A compressor on, plus other stuff). After 7 hours, we should be down to 87%, but at 5PM tonight ALL 3 batteries are at 94%, meaning the rooftop solar added 9 Ah on average today (which is all rooftop solar does on average, and it was another sunny day in AZ to boot)! The numbers add up.

LOVE it! 😎 My upgrade may now be working as designed. I'll report after a day or two at the Q!

Edited January 19 by jd1923

[johnwen]

JD, I talked to Geoff last year about adding a new, third battery  to my two existing 300's and he  said that they indeed don't play well together.  I couldn't tell you why as it's over my head.  But he did tell me if I added a third battery I should only use it and not the other two until I cycle the new one through 20 - 30 charge cycles and then all should behave.  But my disclaimer is to talk to Geoff.  I'm not totally sure of the number of charge cycles.  See you tomorrow :)

John

[johnwen]

JD...I did save Geoff's number at Epoch.  (888) 859-7544

[jd1923]

11 hours ago, johnwen said:

But he did tell me if I added a third battery I should only use it and not the other two until I cycle the new one through 20 - 30 charge cycles and then all should behave.

That would be a pain, to go from 600 Ah to 300 (only using one) for 6 months (took me 18 months to get to 50 cycle). We'll have to let Geoff at Epoch know the middle battery trick! 

This morning all three batteries are 81-81-83, now very level after 23 hours, averaging 82% SOC. The fridge was on DC the whole time, some lights, the inverter, etc. The app shows 734 Ah available, net -166A were consumed. When the fridge was cooling down it was pulling 17A but on a day and night basis average hourly use was -7.0 Ah. When this app screenshot was taken total amps to the batteries shows +1.5A. Positive amps from the rooftop solar, sunny morning but tight solar angle 9AM in the winter, and minus a small load (fridge cold and presently cycled off).

Most would plug in before boondocking a few nights, but while our solar will net-zero our fridge on DC while towing, the Orion XS 50A DC-DC Charger should supply +40 Ah and have us up to 95% SOC after the 3-hour drive, Prescott to Quartzsite! 😎

Edited January 19 by jd1923
Added screenprint

[jd1923]

We turned the fridge on DC one full week ago, the old absorption fridge running on DC 24x7 since. Courtesy Lights on 24x7 too. Coffee water heated daily with 1100W electric kettle. TV and soundbar on morning and night. Cooked on the induction plate, fired the Emeril Air Fryer and ran the new Chill Cube A/C three times just to play with it!

It’s been winter hazy, smoke at the Q with fires in the distance and all the dirt RV’rs stir up, not much solar, say +6A on average.

We just got back home. If we were camping longer, I could have setup the Renogy 400W suitcase. Still running the fridge since by Monday we’re “on the Road Again!” Might be time to plug in! Though we still have 128 Ah available! 🤣

Looking at the app, it’s so cool LiFePO4 batteries can be down to 14% SOC and still have 12.9V potential! I can tell the fridge isn’t cooling at this moment, since we are charging net +7.3A. My new 3rd battery is again lower than the others, but not the major delta as before. It’s nice not being in a hurry to switch to LP or plug in! 😎

Edited Friday at 06:41 PM by jd1923