The Enerwatt WPLN120-24V is a 24 Volt 100 Ah LiFePO4 battery. These batteries are a cost-effective way to build a 24V lithium-ion battery bank. The dimensions are such that it fits a group N120 space (think “truck battery”). These batteries are just 1/3 of the weight of an equivalent lead-acid battery, and they last thousands of cycles. This makes them a great alternative for lead-acid batteries in cottages and such! Enerwatt is a Canadian brand, and warranty is with a Canadian company.
Also see our Finding Happiness with Lithium-Ion article, explaining the care and feeding of these batteries.
The Enerwatt WPLN120-24V lithium-ion battery is a true deep-cycle batteries, it 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.
Charge settings for Enerwatt LiFePO4 batteries:
- Bulk/absorb = 28.4 – 29.2 Volt, with 28.8 Volt ideal
- Absorb time = about two hours, or until the current drops to 3A or less.
- Float = not needed, set to 27.2 Volt or less
- No equalize, or set to 28.8 Volt if it can’t be disabled
- No temperature compensation, set to 0
- A charge rate of up to 100A is possible, 50A is advised for longevity
- Battery has to be warmer than 0 Centigrade (32F), or the BMS will not allow charging, discharge works fine down to -20C (-4F)
The maximum discharge rate is 100 Amp continuous, and 200 Amp for 10 seconds.
These Enerwatt batteries are meant for 24 Volt systems only! So no series connection, the BMS is not designed to handle over 24 Volt. They can be connected in parallel to increase the Ah rating. Parallel strings of batteries will increase the charge and discharge rates (i.e. 500A continuous current for two parallel strings etc.). Ask us if you have any questions about properly sizing a battery bank.
The recommendation is that for more than 3 batteries or strings in parallel series fusing is added to protect each string or battery. A 200 Amp series fuse for each string will do, so in case of a short-circuit in a string, and the other strings of batteries discharging into that short-circuit, it will blow the fuse. The MRBF fuse holders and fuses make a good choice for this.
Enerwatt WPLN120-24V batteries use LiFePO4 chemistry (Lithium-Iron-Phosphate). 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). 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.
- Zero maintenance!
- No memory effect
- Stores 2.5 kWh in energy!
- Compatible with standard charge controllers
- 24 Volt, 100 Amp-hour @ 10 hr discharge rate
- Only 1/3 weight of lead-acid & small footprint!
- Dimensions very close to group N120 battery size
- Very low self-discharge rate, holds charge up to 1 year
- Can be mounted in any orientation, zero off-gassing, no dangerous acid
- Maximum continuous discharge current of 100 Amp, peak of 200 Amp (10 sec)
- Active cell management through included battery management system (BMS)
- Long lifespan, true deep-cycle: 2500 cycles at 100% DOD, more if discharged less
- 3 years warranty