Off-Grid Power System Upgrades - LIFePO4 Battery Capacity Increase + More Solar (July 2024 Revision)

In this video, a look at the latest incarnation of our boat's primary house battery bank system. When we bought the 34" tri-cabin trawler named "Vestri" last summer, it came with two battery banks. The engine starter bank consists of two 12VDC AGM batteries wired in series and a house bank with four 6VDC golf cart-type batteries wired in series-parallel.
While the previous battery setup was sufficient for the previous owner, we were eager to boost the power capacity of our boat. This upgrade allows us to power a Starlink Internet Dish, 12VDC Freezer, our computers, and more, even during extended days at anchor. We've left the existing system intact and added a second house bank of lithium batteries, significantly increasing our power capacity. For more details, check out our off-grid system video from last summer. www.loveyourrv.com/our-boats-...
This year, I upgraded the second house bank batteries from three Aolithium 100Ah to two Xantrex 240Ah, which will mate well with the 2000W Xantrex Inverter/Charger we installed last year. www.loveyourrv.com/xantrex-fr... Total Ah capacity is increased to 480Ah.
To charge the larger-capacity Xantrex bank, I've added a couple of extra chargers to the system:
BougeRV 40 amp solar charger
SRNE 50 amp solar charger
SRNE 30 amp DC-DC charger
A separate 400-watt solar panel array feeds each solar charge controller. The 30 amp SRNE DC-DC charger is connected to the original lead-acid house bank so the boat's alternator can charge the lithium house bank when underway.
Like last year, I installed a Junctek battery monitor to quickly check the system by glancing at its display. So far, the system is working great!
Related Videos:
Xantrex Product Reviews - • Xantrex Product Instal...
SRNE Product Reviews - • SRNE Product Videos
BougeRV Product Reviews - • BougeRV Product Reviews
Boating Repairs, Mods & Upgrades - • Boat Repairs, Upgrades...
Renogy 400W Solar Panel Review - • Renogy 400W Folding So...
Junctek Battery Monitor - • *New Model* Junctek KH...
ABYC Wire Size Calculator - boathowto.com/wiresize/abyc/
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[@LoveYourRV]

*Related Links/Videos*
Xantrex Product Reviews - th-cam.com/play/PLp14lzXh07umTwWM6EoJGBa8PV7QZbD5o.html
SRNE Product Reviews - th-cam.com/play/PLp14lzXh07ukeM1-svWSPMrhwfKcs4pq2.html
BougeRV Product Reviews - th-cam.com/play/PLp14lzXh07ul-p4uf9c-It4b9Q1rPNq-7.html
Boating Repairs, Mods & Upgrades - th-cam.com/play/PLp14lzXh07ulNRcA1KdaHwQ-Qwknf8Mno.html
Renogy 400W Solar Panel Review - th-cam.com/video/D8FJnFpDUUw/w-d-xo.html
Junctek Battery Monitor - th-cam.com/video/KgjCxIGl7gQ/w-d-xo.html
ABYC Wire Size Calculator - boathowto.com/wiresize/abyc/

[@neilrankin9945]

Thanks for the overview Ray! I’m trying to imagine how you would use 400 plus amp hours of power. You didn’t mention any high amp output appliances.
You must have another 300-400 amp hours of power using power stations as well.

[@LoveYourRV]

Many boats have built-in generators that run on the same diesel tanks as the main engine, but ours doesn't. The best thing is to oversize the battery capacity so we don't have to run a noisy gas generator on deck in a quiet anchorage, which is also dangerous when stationary due to fumes.
We draw on average 10 amps per hour I find. In 24 hours that is 240 Amp hours. We have a Nova Kool DC fridge that draws 4.4A when running and in the summer warmth it runs quite a bit, also a Acopower DC fridge/freezer that draws about 3A. Starlink when on most of the day draws about 5A and then there are our laptops 17" HP 3A and Apple 13" 2A and Anne has a 27" computer monitor she sometimes uses for photo editing 6-8A. Then boat lights, water pump, electric toilet, various tool and camera chargers, etc. plus I use a 700W instant pot every few days. It all adds up, if we get socked in with fog, cloud and rain for a few days the batteries can get drained quicker than you think. :) Last night the Xantrex batteries were near full at 92% by morning we were down to 70% and these are the longest days. Good sun today and back to 100% by 3pm. But it only gets worse from here as the days get shorter. Solar harvest can vary when we are at anchor depending on how we swing around. The power stations are Bluetti AC240 and AC70 they have 130AH and 64Ah. The AC70 gets used to charge our phones and a few other small things and the AC240 gets charged by the original solar panels the boat had on it 200W. Then I use that power to heat up our water heater every few days for showers. Water heater uses about 60% of its battery. There is lots of room to conserve power but nice to not have to worry about it. The lead acid bank is my reserve and it has about 220Ah of usable power. Cheers, Ray

[@bradplueger7951]

Great overview as usual! What's your opinion on having multiple smaller MPPT controllers vs one larger one? I see you have multiple controllers; is that cause "you had them" or is that "the best way" to wire multiple/different wattage panels? Not holding you to it, just want your opinion. Thanks.

[@LoveYourRV]

Thanks! I used use multiple controllers in this situation because the two solar arrays I'm using have differing voltage/amp ratings and they are located on the boat where one will suffer shading while the other is in full sun. Also the chargers run cooler since they aren't having to work near their max amperage rating. I do the same in my RV where I have a roof that slopes toward the back and front from the middle. I use a different controller for the panels mounted on the back and front as they often see differing sun levels and I can use two smaller sized controllers vs one large one. And another plus is system redundancy. If a controller fails the system can still be made to keep working, which is great when traveling to remote locations like we do on the boat especially. :) Multiple chargers with lead acid can require a lot of setup to get then to charge in sync through various charge phases but with lithium the battery charge curve is very constant almost to full charge. The low internal resistant means that the lithium will easily sop up what ever amps are being produced by both chargers. Cheers, Ray

[@bradplueger7951]

@@LoveYourRV Excellent points! I didn't think about the redundancy concern that if one controller goes down, charging in some fashion continues on. Also like the point you made about overheating the controller when they are running at their intended max amperage rating. I'll ponder all of your comments in my modifications to my solar system. Thanks a bunch! Safe travels...

[@DavidJohnson-yy4iu]

Simple by comparison, but I have two 100w Renogy panels each of which comes with a charge controller. If I parallel the two downstream from the charge controllers, they fight each other, one controller seeing the output of the other and thinking the batteries have a greater charge than they do. I have to run both panels thru a single charge controller to achieve full potential. Your system has three inputs (the two PV charge controllers plus the DC to DC charger) all paralleled after these controllers. How do you keep them from conflicting?

[@LoveYourRV]

Lead acid batteries that charge in multiple phases (bulk, absorption, float) can be an issue unless the chargers are very closely set up for each phase and wiring size and length are closely matched or have a communication data line capability. However, lithium has a much different charging curve. Lithium batteries have very low internal resistance and stay in a bulk charge acceptance mode for over 90% of the charge curve. So basically, they will easily sop up all amps provided. It's not until the lithium battery gets to about 95% charged that the internal resistance will rise, amps drop and the voltage rises enough that the chargers may think they are near a float and conflict. By that time I'm not concerned as the battery bank is nearly full. Comparison between LA and LiFePo4 charge curves www.powerstream.com/z/lfp-la.jpg
I usually set my chargers to their lithium preset, usually 14.2 -14.4V and they work well together. It's best to have the charge controllers output wiring near the same lengths and met very close to the battery bank. Cheers, Ray

[@DavidJohnson-yy4iu]

That explains it. I'm charging lead acid batteries. Thank you.

[@michaelm9623]

I'm interested in your setup with two different charge controllers connected to the lithium batteries. Will they each provide full rated charge (on a sunny day) at the same time or will they affect each other? Seems like one controller would sense the output of the other controller and think the batteries are charged. I'm having difficulty understanding how this works.

[@LoveYourRV]

Lead acid batteries that charge in multiple phases (bulk, absorption, float) can be an issue unless the chargers are very closely set up for each phase and wiring size and length are closely matched or have a communication data line capability. However, lithium has a much different charging curve. Lithium batteries have very low internal resistance and stay in a bulk charge acceptance mode for over 90% of the charge curve. So basically, they will easily sop up all amps provided. It's not until the lithium battery gets to about 95% charged that the internal resistance will rise, amps drop and the voltage rises enough that the chargers may think they are near a float. I usually set my chargers to their lithium preset, and they work well together.

[@michaelm9623]

@@LoveYourRV Thank you, Ray.

[@dirtroadsailing6418]

I have to laugh at the names that some Chinese manufacturers give their products. I noticed your amp hour meter is a Junctek, did you buy that or did they send it to you?
It looks like you've put together a nice system. Has SRNE put their new products for sale yet that you reviewed quite some time ago?

[@LoveYourRV]

I bought an identical one called Koolertron, haha th-cam.com/video/jFU5Z_GPxmY/w-d-xo.html then the Junctek people sent me their updated model for review a while back th-cam.com/video/KgjCxIGl7gQ/w-d-xo.html So far SRNE hasn't got back to me with a North American purchase option though every time I ask they say it is going to happen. From the Facebook page it appears they have been to trade shows around the world lately including in the USA so likely setting up dealers.

[@LoveYourRV]

@dirtroadsailing6418 I noticed SRNE is looking for product testers. www.srnesolar.com/articledetail/375.html