Lithium on the cheap.

[alanmalk]

With a couple of years of lithium battery experience with my 1 man pontoon boat, I decided to see what could be done with my 2015 E'21. My AGM lead/acid batteries were approaching 7 years old and my back is approaching 99, more or less. I really shouldn't (can't?) be lifting 150 pounds of batteries out of the trailer any more. So, it was time to take the plunge into light metals.

As many of you know, I do love doing things as cheap as possible, whenever I think I can get away with it. So, off to Ebay and snagged a pair of Renogy 100 AH LiFePO3 (lithium phosphate) batteries in late 2021. These are not the latest versions that have Bluetooth and internal heaters, but they do have battery-to-battery communication via Ethernet (the only battery I have seen with this, but not terribly useful, just an interesting feature). Total cost with shipping and tax - $950 USD.

Next, a couple of Powerpole 100 Amp switches plus some bits and pieces of wire, and - not much else. The switches now disconnect the solar panel from the GoPower and totally disconnect the batteries from the trailer. (Note! The emergency brake will not function with no battery power. Turn "on" before driving.) Some heavy gauge, professionally crimped short wire to connect the batteries in parallel. Total expenditure, about $1050 USD.

What I didn't get was an upgrade to the original GoPower PWM solar controller. Nor did I get shunt based monitoring (Victron) system, nor a lithium ready 110VAC battery charger (aka "converter"), and finally, no DC-DC charger.

One by one: No DC-DC changer because I didn't feel the need to charge my batteries while driving and wasn't worried about reverse charging the tow battery while the engine was running. No converter upgrade because while at a site with full hookups I didn't worry about keeping the lithium batteries at a 100% (and most manufactures don't recommend keeping lithium batteries at 100% for long periods). No monitoring device because my DC needs are modest (the heaviest load in my trailer is a 400 Watt sine wave inverter, used mostly to warm my mattress pad). And finally, no lithium ready solar controller, and this is worth a few extra words to follow.

The original GoPower PWM solar controller can only charge to a maximum of 13.8 Volts - as recommended by most lead/acid battery makers. But lithium needs the occasional 14.4 Volts to both top off and to balance internally. My trick was to raise the GoPower controller above ground by 1/2 Volt by using a diode. How did I get away with this? It turns out that the GoPower doesn't need to be attached to a high current ground. The heavy wires that go to the solar panel(s) and the heavy wire that go to the batteries are not necessary even though the trailer comes wired with them attached to the controller. But in the interest of a sane wiring system I brought all grounds to a single point ("bus"). Specifically: battery ground, trailer power ground, frame ground, solar ground, and perhaps one or more that I have forgotten. To the GoPower I connected a thin ground wire connected to a diode in turn connected to the common ground. Bingo, the GoPower is fooled into providing 1/2 Volt more than it thinks it is providing. Note the 2 fuzzy photos of the GoPower voltage reading and a meter directly connected to the battery terminals. One with solar supplied and one without solar. The half Volt is obvious. Not photographed, one of the "-" connections on the GoPower is now empty.

Those with a sharp eye will note that I am leaving some solar power on the table since the PWM is not as efficient as MPPT - but recall my modest needs. And the really sharp eyes will observe that 13.8 + 0.5 = 14.3. True, not quite reaching the magic 14.4 V. I might switch from a Schottky diode to a silicon diode some day, or even an adjustable artificial ground if I feel adventurous - as long as its cheap.

But the experiment continues. I left the batteries in the unheated trailer over the 2022-2023 winter in Denver. Our official low was -17F, darn close to the minimum of -20F recommended. So I conducted a load test recently to see how things were holding up. Look at the photo of the battery and assorted parts. The load is the wirewound "hotdog cooker" thing - a 500 Watt, 1 Ohm resistor (with a hollow center for cooling, or cooking hotdogs, like previous owner may have been doing - it smells awful when hot.) 1 Ohm at 13 Volts (a constant voltage under load - one of the really nice characteristics of lithium batteries) is a constant 13 Amps. Also connected is a really bright 12 Volt led strip light to alert me if the BMS shut off the battery, which it did not after 5 hours. That's 65 Amp-hours or 2/3rds of the total battery capacity. With almost no voltage drop I am now convinced that I didn't freeze the battery. (Tested battery #2 also.)

Bottom line - so far, so good. What could go wrong? (Sticks head in sand).

[iamunique127]

I admire your adventurous mods.

[SageRpod]

Thanks for sharing your journey with the lithium batteries. Bottom line is if it is meeting your needs, then you have the best setup for you, which I believe is the most important aspect of RVing. What is optimal on paper, may be too expensive and complicated for an individual's use case. Adapt and adjust according to your needs and you will be the happy camper.

[Perry Butler]

I always like someone who doesn't follow the herd.

Congratulations Alan!

With good batteries (AGM, SiO2 or LiFePO4) you don't NEED:

Solar Panels
Different Charger
Battery Management
Different Solar Controller
DC-DC

But you can choose what YOU want. Our choices:

Solar - we had 463 watts on the roof of our 5.0s, and haven't needed a charger for nearly three years now (well over 300 nights without services). We have 400 watts on the roof of our Bigfoot and may re-install our 160 watt panel that came with the trailer.

Charger - I just ripped out our Progressive Dynamics 45a charger with Charge Wizard that can fuly charge lithium, because we don't need one. Our foolishly purchased, but simple, Victron charger is stand alone, not connected, and is only for emergencies.

Battery Management - luckily, when our AGMs were fried the WFCO decided to randomly charge at 20.3 volts. I saw the 20.3 volts on the Victron 712's history, researched WFCO chargers and found a couple of others who's batteries were fried by the WFCO charger. I pulled the fuses for the WFCO charger and found out it wasn't needed.

Solar Controller - since we don't use a charger (we foolishly purchased a stand alone Victron BlueSmart 30a charger, but not wired in), a good controller is preferred, but not needed.

We chose SOK batteries ($520 with bluetooth that was only $20 extra last January, not the $70 extra today) that are $499 today without needless (I found out) bluetooth, and feel BattleBorn, Victron, and other batteries are grossly overpriced, YMMV. With our Victron BMV-712 the SOK's bluetooth is just redundant. However, after all was said and done I should have bought another set of SiO2's. This is a case of, "Choose wisely my friend."

IMO, DC-DC is the least needed item and only if you don't have decent solar, at best. DC-DC is a pain to install, and for most another item to remember to hookup. If you have roof solar and a smart alternator it's not needed and as has been shown here in the past to be fussy to install. If you have solar, but not a smart alternator, just disconnect the charge line from your 7 pin connector. Let your solar panels do the work. Eazy Peazy.

I feel your better off starting with the basic needs like Alan and then add later as you feel the need.

Like Alan, I march to a different drummer.

Enjoy,

Perry

[alanmalk]

Originally Posted by Perry Butler

With good batteries (AGM, SiO2 or LiFePO4) you don't NEED:

Solar Panels
Different Charger
Battery Management
Different Solar Controller
DC-DC

...

I say with a chuckle - you forgot the most important item to leave at home. A gasoline generator!

[Perry Butler]

Originally Posted by alanmalk

I say with a chuckle - you forgot the most important item to leave at home. A gasoline generator!

Had a Yamaha genny a couple of decades ago. Got grief for using it and never took it camping again. I eventually gave it to our school.

KISS,

Perry

[oldwave]

I admire the ingenuity. Still a decent mppt controller is not very expensive in the scheme of things, Renology makes a cheaper one than Victron.

I’m a fan of high quality equipment and am willing to spend the money. But we are lucky enough to be able to afford it.

[Perry Butler]

Originally Posted by oldwave

I admire the ingenuity. Still a decent mppt controller is not very expensive in the scheme of things, Renology makes a cheaper one than Victron.

I’m a fan of high quality equipment and am willing to spend the money. But we are lucky enough to be able to afford it.

Who is Renology?

We have a 100 watt panel from Renogy, not Renology. Having taught grammar makes me OCD at times.

Enjoy,

Perry

[oldwave]

Originally Posted by Perry Butler

Who is Renology?

We have a 100 watt panel from Renogy, not Renology. Having taught grammar makes me OCD at times.

Enjoy,

Perry

Lol
I stand corrected for my spellink

[CE Vogel]

Originally Posted by alanmalk

What I didn't get was an upgrade to the original GoPower PWM solar controller. Nor did I get shunt based monitoring (Victron) system, nor a lithium ready 110VAC battery charger (aka "converter"), and finally, no DC-DC charger.

I installed three of the same Renogy batteries in my trailer three years ago and am very pleased with them. Renogy offers a low-cost monitor for these batteries that replaces the Victron setup, as well as allowing you to turn off the batteries internally for long term and winter storage: https://www.renogy.com/monitoring-sc...attery-series/
Redarc offers a one-piece solution for MPPT solar charge controller and vehicle DC to DC conversion: https://www.redarcelectronics.com/us...attery-charger. I have this, and aside from requiring heavy wiring from the tow vehicle, it has worked well.

[Ron in BC]

Originally Posted by CE Vogel

I installed three of the same Renogy batteries in my trailer three years ago and am very pleased with them. Renogy offers a low-cost monitor for these batteries that replaces the Victron setup, as well as allowing you to turn off the batteries internally for long term and winter storage: https://www.renogy.com/monitoring-sc...attery-series/
Redarc offers a one-piece solution for MPPT solar charge controller and vehicle DC to DC conversion: https://www.redarcelectronics.com/us...attery-charger. I have this, and aside from requiring heavy wiring from the tow vehicle, it has worked well.

I haven't had the same good experiences with Renogy. As far as the ability to put it into storage mode goes I had one drop to 10.5 volts. Several different problems related to that.

Renogy is a master at deflecting a warranty claim. They will smother you with continuing requests by several people for more data until you give up.

I have several of their items and was going to buy more but I'm looking at other brands now.

Ron

[SageRpod]

Originally Posted by Ron in BC

Renogy is a master at deflecting a warranty claim. They will smother you with continuing requests by several people for more data until you give up.

I have several of their items and was going to buy more but I'm looking at other brands now.

Ron

Had the same experience when I installed their battery monitor in our old camper. Worked great for a while then flipped out. When I contacted Renogy, they wanted pics of the entire length of the installation and all other kinds of unrelated information. They finally sent me another along with a new shunt, but I vowed I would never own another Renogy product.