Statpowers True Charge Battery Charger

Tested by Richard Perez

©1995 Richard Perez

Battery chargers haven't changed much in thirty years. These 120 vac-powered battery chargers mostly use large transformers and have minimal regulation. Statpower's new series of TrueCharge™ battery chargers is radically different. Gone is the large transformer—replaced with a modern high-frequency switching power supply. Gone is the simplistic control of just voltage regulation—replaced with three-stage, computer-controlled battery recharging.

Statpower TrueCharge™20 Specifications and Features

This 20 Ampere (continuous) battery charger is powered by conventional house current or generator power. It will accept 60 Hz input from 90 to 135 vac rms (240 vac, 50 Hz models are available). It is designed for all types of lead-acid batteries—from flooded "wet" cells to sealed "gel" cells. Output voltage range is 13.8

©1995 Richard Perez

to 14.8 VDC with float voltage ranging from 13.2 to 14.0 VDC. There is a user-initiated equalization function which defeats the voltage limits and allows a controlled overcharge of the battery. Efficiency of the charger is rated at 85%. The TrueCharge™ battery charger will recharge either one or two different batteries.

The TrueCharge™20's modern 75 kHz switching power supply technology offers users several distinct advantages. One is small size—the TrueCharge™ measures 11.5 inches (29 cm) by 6 inches (15.25 cm) by 2.75 inches (7 cm) and weighs only 5.5 pounds (2.5 kg). Another is totally silent operation—the TrueCharge™ is totally quiet both to the ear and to radios. Using switching power technology allows this charger to be easily and efficiently controlled for "smarter" recharging.

Statpower uses a three-stage, recharge scheme for their computer-controlled TrueCharge™ models. The first stage is known as "bulk charge" and replaces about 75% of the energy withdrawn from the battery. During bulk charge, the TrueCharge™ delivers its maximum rated current. After the battery has undergone the bulk charge, it is ready for the second stage called "absorption charge." During absorption charge, the battery is held at near-gassing voltage and the charging current is steadily decreased. This minimizes water loss. When the absorption charge is finished, the battery enters the third stage of recharge—"float charge." During float charge, the battery is held at a full state of charge and at a reduced voltage level. The battery can be left under charge in float mode continuously without damage. A fourth stage of recharging is also available for equalization charges. Here, all voltage limits are defeated and the battery is overcharged and allowed to gas extensively.

Shipping Carton & Documentation

The Statpower TrueCharge™20 arrived here on Agate Flat, Oregon in fine shape via UPS. The shipping carton was more than adequate—it is stout enough for air dropping into the Alaskan bush. The documentation provided by Statpower is outstanding. The 34 page manual is clear, complete and concise. I can only wish that all RE equipment came with docs this good!

Test System

I tested the Statpower TrueCharge™20 at our home and office on Agate Flat. This charger is the 20 Ampere model, but 5, 10 and 40 Amp models are also available. I powered the charger from either of our two sine wave inverters (Exeltech 1 kW and Dynamote 2.3 kW). I charged a variety of lead-acid batteries with the Statpower TrueCharge™20. I recharged five 65 Ampere-hour, 12 VDC sealed recombinant lead-acid batteries and two 100 Ampere-hour, 12 VDC flooded lead-acid batteries in our electric tractor. We use the sealed batteries because they are portable and easily transported to energy fairs.

Our PV/wind system here on Agate Flat is large. I often find myself treating our system like we were plugged into the grid. We generate and use between six and thirteen kiloWatt-hours per day (mostly consumed by Home Power's computers). Our system is oversized to provide the necessary reliability during the winter. During the spring, summer and fall months, we often have a substantial surplus of power. We use this surplus power to pump water, to refill smaller, more portable, batteries and to recharge the electric tractor. The Statpower TrueCharge™20 is the only charger efficient enough to even consider powering from our main PV/wind system. I installed the Statpower TrueCharge™20 on 24 March 1995 and it has been in intermittent service since then.

Charger Installation

Installation was fairly straight-forward thanks to the great manual. I do, however, wish that Statpower supplied a cord and plug for the charger's 117 vac input. Instead there is a small junction box on top of the charger, and the user must supply the wiring and connect it to 117 vac either via junction box or with a plug. This is a result of the charger's Canadian CSA (ULspec. 1236) listing.

Since the charger only puts out 20 Amps max, I wired it to the batteries with 10 gauge copper wire. The wiring connectors on the charger's low voltage output are adequate, but could be more robust.

Charger Performance

Operation is user transparent. Just set the switches for the appropriate battery type (flooded or gel) and battery temperature (cold, warm, or hot). The rest is totally automatic.

The TrueCharge™ takes a moment to begin charging—the computer is sensing the battery's voltage and takes about five seconds to initiate charging. As the battery fills, the charge rate gradually decreases until the battery reaches float mode. I left the sealed recombinant batteries under continuous charge for ten days without damaging the cells. These cells are cased in plastic and tend to bulge about the middle if recharged too rapidly. I then proceeded to recharge the electric tractor's batteries (flooded cells). The TrueCharge™ refilled both with ease and more quickly than I expected based on recharging with a 60 Hz transformer-based charger.

As a coup de grace, I charged two different batteries at the same time. The charger merely divided its power between the batteries, giving each what was required at that point in their state of charge. I have never before had a battery charger that was a "set it and forget it" unit. The TrueCharge™ is truly automated and capable of minding the recharging process all by itself.

Conclusions

The TrueCharge™ is an outstanding battery charger. It is highly intelligent, automated and efficient. Retail price for the 20 Amp model I tested is $389.95. While this may seem expensive, I consider it in line with performance, efficiency, and quality of this Statpower charger. The TrueCharge™ is the only charger efficient enough to consider operating from our main RE system. Thumbs Up, Statpower!

Access

Author: Richard Perez, c/o Home Power, PO Box 520, Ashland, OR 97520 • 916-475-3179 • Internet e-mail: [email protected]

TrueCharge™ Battery Charger maker: Statpower, 7725 Lougheed Highway, Burnaby, British Columbia, V5A 4V8 Canada • 604-420-1585 • FAX 604-420-1591 «w

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