Also see our Finding Happiness with Lithium-Ion article, explaining the care and feeding of these batteries.
Quebec-based Volthium is working hard to bring lithium-ion batteries to the mainstream for battery banks. Not just for RVs and boats, but for for larger off-grid systems as well. They make various popular battery group sizes as a drop-in for lead-acid, and batteries for 19″ rackmount in a modular system that can be sized to fit any need. There is a Volthium battery for all your needs!
The Volthium 25.6-200-R and 25.6-200-R-H are part of their Rack Mount series of batteries, with 24 Volt 200 Ah (5.12 kWh of stored energy). These batteries are meant for mounting in a standard 19″ rack, they are 4U (height) units. Any sturdy 19″ rack will work, such as those from Tripp Lite or StarTech. The battery is available with or without a build-in heater. The heated battery allows safe use and charging all the way down to -30C (-22F)! The heater automatically kicks in when the BMS sees a charging Voltage and the internal temperature of the battery is below freezing. No user-interaction is needed. While heating the battery will draw a charge current of 5 Amp.
Up to 16 units can be stacked in parallel, for a total of 24 Volt @ 3200 Ah, storing nearly 82 kWh in energy (with 100% of it usable)! The BMS of each unit talks to the others, so rather than having individual batteries, the whole becomes one integrated battery bank that auto-balances.
The 2 AWG Amphenol SurLok connectors on the front of the unit are rated for 130 Amp. That means in case of multiple Volthium batteries they should wire to Volthium’s Busbar, to combine them, and from there to wire to the inverter(s) and other loads.
The batteries have VE.Can bus integrated into them, and can communicate directly with Victron GX equipment, such as their Cerbo, Color Control GX, or GX Touch. No additional battery monitor needed. RS-485 for connection to a PC is available as well.
Volthium lithium-ion batteries are true deep-cycle batteries, they can repeatedly be discharged a full 100% without damage. The battery has a build-in battery management system (BMS). The BMS allows them to be charged with regular solar PV charge controllers, with the same settings as for any other sealed battery (such as AGM batteries). The BMS also takes care of protecting the batteries from over- and under-charge, low Voltage disconnect, over-current, and automatic balancing of the cells.
The cells in this battery are certified to UL1973, the Amphenol SurLok case connectors are listed to UL1977, and the breaker is certified to UL1077 & CSA C22.2 No. 235-04 and UL489 & CSA 22.2 No. 5. Please note there is no CSA listing for the entire unit/assembly. For those that need to cut/crimp wires to SurLok connectors there is a video showing a step-by-step tutorial.
Charge settings for Volthium batteries:
- Bulk/absorb = 28.0 – 29.0 Volt, with 28.0 Volt ideal
- Absorb time = about two hours, not critical
- Float = not needed, set to 27.2 Volt or less
- No equalize, or set to 28.0 Volt if it can’t be disabled
- No temperature compensation, set to 0
- Charge rate of 100 Amp or less is preferred for longevity, though up to 150 Amp is possible
- Charging works from 0C (unheated battery) or -30C (-22F, for heated battery), discharge works fine up to -20C (-4F)
The maximum discharge rate is 150 Amp continuous, 200 Amp for 30 seconds, and 300 Amp for 3 seconds.
Volthium batteries use LiFePO4 chemistry (Lithium-Iron-Phosphate) in prismatic cells. This is very stable and is not sensitive to spontaneous combustion, in comparison to laptop and cell-phone lithium-ion batteries (which use Lithium-Cobalt-Phosphate chemistry). The cells have build-in protection for over-pressure, over-temperature, and contain a fire-retardant in the electrolyte and casing. These are very safe batteries!
Because lithium-ion batteries can be discharged to 100% DOD, and this can be done for more cycles, a smaller battery bank can suffice vs. lead-acid. Since there is no off-gassing these batteries can be mounted indoors, in any orientation.
- Zero maintenance!
- Integrated 125A breaker
- Soft-Start build into the battery
- Standard 19″ rackmount, 4U height
- Up to 16 units can be stacked in parallel
- Compatible with standard charge controllers
- No memory effect, can be left at any State-Of-Charge
- Can be discharged 100% repeatedly without damage!
- Very low self-discharge, can hold charge for up to 1 year
- Build-in automatic heater version available, can be charged from -30C (-22F)!
- VE.Can & RS-485 build-in, connects directly to Victron GX equipment
- 24 Volt, 200 Amp-hour @ 20-hour discharge rate (5.12 kWh of stored energy)
- Active cell management through included battery management system (BMS)
- Long lifespan, true deep-cycle: 2500 cycles at 100% DOD, 4250 cycles at 80% DOD
- 1 year full warranty, plus 9 years pro-rated, for 10 years total