When it comes to boondocking and exploring off-grid in your camper, few things are more important than your 12 volt batteries. This power is needed to run everything from your refrigerator, furnace, and water pump to your fans, electronic charging stations, and lights. Indeed, a fully discharged battery bank, without the aid of a generator, can totally ruin an outing. In the past, the gold standard had always been the AGM deep cycle battery. This is what we used in the Truck Camper Adventure Rig before and it worked great, but like the standard lead acid battery, the usable capacity of an AGM battery is only 50 percent. Horrible yes, but there wasn’t anything you could do about it. This old paradigm, however, changed with recent technological developments of the lithium-ion battery, which now offers an astounding 90 percent usable capacity. This is a Review of the Expion360 VPR PowerMod Lithium RV Battery, one of the best lithium batteries for recreational vehicles in today’s market.
Lithium (LiFePO4) Pros and Cons
What makes the lithium battery so great for off-grid adventures? We already touched upon the biggest pro—the 90 percent usable capacity—but the lithium battery offers so much more. Not only does it weigh less than the lead acid battery, about 50 percent less, but it also provides a higher current and voltage output. It also charges faster because it can be bulked charged to 100 percent and isn’t constrained by the limitations of Peukert’s Law. It also lasts longer than a standard lead acid battery or AGM battery (between 2,000 and 5,000 cycles), and doesn’t suffer from voltage sag like a lead acid battery. Better yet, the Lithium Iron Phosphate (LiFePO4) chemistry, now used in most lithium batteries, offers greater dependability and safety compared to the basic lithium-ion battery chemistry, which can sometimes catch fire when overcharged or when other problems occur.
Are there any negatives associated with the lithium battery? Only two though they’re pretty significant. First, the cost for a lithium battery is much higher than a standard lead acid battery with a Group-24 ranging anywhere between $800 and $1,300, that’s seven to 10 times more than a wet cell lead acid battery. Not only that, this higher cost doesn’t take into account the charging devices needed to properly charge a lithium battery, which add even more cost at start up (14.6 volts is needed to properly charge a lithium battery). Second, you can’t charge a lithium battery below freezing. Doing so can irreparably damage a lithium battery (using them below 32 degrees F is fine, you just can’t charge them below freezing). This is why many lithium battery owners like to keep their lithium batteries stored inside the camper and not in an compartment outside where they can be exposed to colder temperatures.
Released in 2018 by Expion360, the VPR (Viper) PowerMod is a 120 amp hour Lithium Iron Phosphate (LiFePO4) Deep Cycle Battery made specifically for recreational vehicles. The battery has the most capacity (120 amp hours) in the smallest footprint (Group 24 Size) of any lithium-ion RV battery. Like all Group 24 batteries, the face of the VPR PowerMod measures 10.25 inches, is 6.75 inches wide, and 8.875 inches tall. The battery weighs only 32 pounds, making it ideal for truck campers due to its light weight. According to the Oregon-based company, you can parallel connect up to eight VPR PowerMods, and because it is sealed, it can be installed practically anywhere inside or outside of the coach. Since the VPR lithium battery doesn’t contain any electrolyte that can leak out, it can be mounted in an upright, sideways, or upside-down position.
Unlike other lithium batteries, the Expion360 VPR PowerMod comes with its own removable and serviceable Battery Management System (BMS). The Expion360 BMS, which has its own CPU, performs several vital functions including cell balancing, short circuit protection, current limiting (250 amps), over discharge (8.5 volts) and over charge protection (15.6 volts), thermal protection (149 degrees F), and a low voltage disconnect (8.5 volts). It’s also designed to be the protective link between the individual cells of the battery. If damaged, the BMS can be replaced more easily, and with less expense, than the lithium cells. This translates into a greater savings if a problem were to arise with the battery at some point in the future.
The VPR PowerMod’s BMS comes with its own LED status light on top, making it an excellent troubleshooting tool when problems arise. When the light is solid green, the battery is operating normally. When the light is blinking red, the BMS has recognized a fault, but has not yet disconnected the battery bank. If the problem is not resolved quickly, the BMS will disconnect the battery bank to protect the individual cells from damage. When the BMS is in a full protection state there will be no LED warning light on. According to Expion360, one of the main reasons the LED status light will blink red or shut off is that the battery is empty or almost empty and is at its lowest voltage reading. To reset the BMS, all you need to do is connect the battery to shore power or to your truck’s 12 volt starting batteries using a pair of jumper cables.
As chronicled in an earlier article, we installed our two Expion360 VPR PowerMod batteries underneath the rear dinette seat in our truck camper. Installing them was just as easy as installing a pair of regular lead acid batteries. Expion360’s low profile, insulated bus bars were used to connect the two deep cycle batteries in parallel, giving our camper a rock-solid, 240 amp hour battery bank. Together, the two lithium VPR batteries weigh only 64 pounds, a 68-pound reduction compared to the two Lifeline 6 volt AGM batteries we had in the camper previously. With the 90 percent usable capacity of the Expion360 batteries, the upgrade gives our camper 216 amp hours of usable capacity compared to the 110 amp hours we had before. As you can see, we’ve nearly doubled the capacity of our battery bank at less than half the weight. The 216 amp hours is like having four 6 volt AGMs in our camper now, a HUGE improvement over what we had in the camper before.
The charging of our Expion360 VPR PowerMod batteries is accomplished three ways:
- Solar Power – Using our 330 watt roof top solar power system, which is controlled by a Zamp ZS-30A PWM Charge Controller (upgraded with the LiFePO4 setting).
- Shore Power – Using an upgraded Progressive Dynamics 4655MBA/L 55 Amp Charger with the Wildkat Remote Pendant in our WFCO Converter-Charger Unit.
- While Driving – Using our truck’s alternator using a Victron Cyrix Lithium Battery Switch, which controls charging and prevents the lithium batteries from “back feeding” or charging the lead-acid starting batteries in our truck.
Several other mods were made in conjunction with the Expion360 PowerMod Lithium upgrade. For winter operation, we recently upgraded the installation to include a battery heating system for lithium batteries, which we detailed in a recent article. To monitor the performance of our lithium batteries we’re using Expion360’s excellent Universal Battery Monitor, which displays everything including the battery’s State of Charge (SOC), without having to toggle though all of the display settings (look for a review on this battery meter soon). We also installed a Go Power SW1500TS 1,500 watt inverter with a built-in transfer relay, which we mounted on a plywood platform above the batteries. We use this primarily to power our 1,500-watt induction cooktop and the wife’s hair dryer.
VPR PowerMod Performance and Recommendations
We’ve now owned our Expion360 VPR PowerMod batteries for one year, using them in the heat of the summer and in the cold of the winter. Having the extra battery capacity has been tremendous boon to our outings. We’ve never wanted for power at any time. The lowest SOC we ever experienced was 38 percent and that was during an extended period of overcast skies. Of course, one of the biggest benefits of having a lithium battery is the higher voltage output. Even though the battery is rated for 12.8 volts, this is a nominal rating only (13.2 volts is what the battery will put out when fully charged). As the VPR PowerMod batteries are discharged you’ll see a decrease in voltage, but nowhere near the rate you’ll experience with lead acid batteries including AGMs. For example, at a 46 percent SOC our battery meter displayed 13.0 volts; at a 42 percent SOC the meter showed 12.7 volts; and at a 38 percent SOC 12.5 volts. Impressive! As you know, a lead acid battery would be lucky to generate 11.9 volts at a 50 percent SOC, a voltage that is basically useless in an truck camper.
Here are a few recommendations based upon experience. During excessively cold spells never let the camper fall below 45 degrees inside. This is more than high enough to keep the batteries safe and warm inside while at the same time providing a safety buffer for the batteries. Having a way to heat the batteries during an excessive cold spell, however, is a must, so make sure your lithium battery system has this capability. A heating system can be built for your lithium batteries for less that $100. Details on how you can do this battery mod can be found by clicking here. We also recommend that a battery meter be installed so that the battery’s SOC can always be observed. It also a great tool at determining the biggest power draws in your camper. Finally, if you’re one who likes to boondock in below freezing temperatures consistently, including temperatures below 0 degrees, I wouldn’t recommend getting a lithium battery. The risk for damage is too great. However, if your winter boondocking involves an occasional dip below 32 degrees, then I would go ahead and make the purchase. This is how we camp and we’ve been fine. Just keep an eye on your battery’s SOC and the inside and outside temperatures to avoid any trouble.
Going lithium has been one of the best modifications and improvements we’ve ever made to our camper. We can’t state enough how much we’ve enjoyed having them and how much they’ve improved the operation of our camper. For anyone who likes to boondock and run extra electronics and electrical devices, the Expion360 VPR PowerMod Battery is an absolute must-have item to have in your rig. Sure, the up front cost to go lithium is pretty high, but as you probably already know, the battery compartments in most truck campers are small with most being large enough to hold only one or two Group 27 batteries. With lithium, you can double the usefulness of that valuable space at half the weight. It’s true that other makes of lithium batteries can be purchased for less money, but they’re larger and heavier and possess less amp hour capacity. Not only that, but with the Expion360 VPR PowerMod you get a lithium battery with a serviceable BMS. The others don’t. What would we rate Expion360’s VPR PowerMod Lithium Battery? On a scale of 1 to 5 with 1 being the lowest and 5 being the highest, we enthusiastically give it a rating of 5+ stars. It’s an amazing product you won’t regret buying.
Great article! What changes did you make on the vehicle side for truck charging? How many charging amps?
For me the price needs to come down. My camper has room for 2 group 31 but I use the GC-2. I have a built in generator plus the solar. Performance is there price and capacity after aging is another matter.
Excellent article and certainly lays out a great case to go Lith. So, with a bit of research, I finally found the cost of the kit: Expion360 240Ah Lithium Battery Bank with Monitor. This is a complete Expion360 battery system using two batteries with a Victron BMV-712 Bluetooth battery monitor. $2,950.00 https://amsolar.com/rv-lithium-battery-banks/40-liexbmv240
That is a high entry bar but I think if boondocking is a significant part of your travel plans. I think it would be wise for RV parks to consider more non-electric spaces and just provide water/sewer. Great if you are traveling and only need an overnight stay having this could reduce your costs and give you a lot more freedom. I think if you are willing to spend this much coin it could be a wise investment.