Power Designers Chargers
Pamala
Now featuring single cable outputs for opportunity and fast, high-ampere applications, the new Revolution battery chargers by Power Designers simplify charging and provide a compact, lower weight and more cost-effective solution over standard dual cables.
The single cable option makes the unit quicker and easier to connect and disconnect, as well as limits the number of cables and adapters to maintain. Comprised of multiple 1.3-kilowatt power modules that can be combined to provide outputs from 4 to 31 kilowatts, if one module stops working, the others will continue charging.
Battery capacity if measured in WH=Voltage*ChargeCurrent*Time. With host software, you can time how long the charger has been charging with constant charge then multiple the ADC reading for VBAT*ChargeCurrent*Timecharging to approximate battery capacity.
Seems very odd that the BQ25790 cannot measure the battery charge level using some internal algorithm. This seems very difficult chip to use, if the user must write their own battery charge monitoring algorithms...
1. Historically, semiconductor processes could be optimized for high power output (for providing charge current) or digital switching speed (for a gauge with ADC), not both. Processes have evolved in recent years to include both types of components (primarily the FETs) but there is still the problem of heat from high power components affecting the accuracy of the gauge ADC.
2. Battery chargers are essentially application specific power supplies. The chip design expertise for analog power supplies is not the same as for digital processing needed for a gauge. So analog power designers developed the charger and digital designers developed gauges.
3. Battery chargers need to be safe and somewhat unhack-able. If the battery charger was controlled with gauge processor software/firmware, instead of the charger's asynchronous state machine, user's could alter the charge profile via firmware/software and create unsafe charging. That said, most host controlled chargers now have so much flexibility through I2C registers that control the state machine, the risk of unsafe charging has grown in recent years.
The REVOLUTION Series is an innovative line of high frequency battery chargers incorporating cutting edge modular power design to deliver peak efficiency greater than 93% and efficiencies greater than 90% throughout the entire charge cycle. As the charge cycle progresses and the output current tapers down, the charger will turn off unneeded modules, allowing the remaining modules to operate at peak efficiency.
Conventional charging entails that the battery is charged over an 8-10 hour period, rests for another eight hours, and is used over an eight-hour shift. As such, conventional charging is ideal for one-shift applications where no battery changing is required.
Opportunity charging is a good choice for extended shift operations where battery changing can be eliminated. Opportunity charging extends the run time of aging batteries and recoups the lost capacity that comes with age.
Opportunity charging frees up warehouse space and personnel as it often eliminates the need for dedicated battery rooms, spare battery storage, battery-handling and battery-changing equipment. It also cuts down on time spent traveling from worksites to battery rooms, significantly increasing productivity and decreasing the risk of injuries suffered while hoisting heavy batteries in and out of trucks.
Fast charging charges the battery at rates three to four times that of conventional chargers, and at every opportunity possible. This includes breaks within and in-between shifts, and can eliminate the need for additional batteries.
The parallel module design provides built-in redundancy that ensures that in the event of a module failure the charger will continue to operate until the problematic module is replaced. The charger display will indicate the module failure, and with the removal of a few screws the faulted module can simply be unplugged and a new module plugged in. Diagnosis and repair of a REVOLUTION is the simplest and fastest of any charger in service today.
The reason why your Apple/Samsung devices do not draw more current is simple.It is because there is additional data communication going on between the Apple/Samsung device and their dedicated power supplies. This makes both devices recognise eachother and agree on a higher current to be used. The charger sets certain voltages on the USB data lines and this is recognised by the phone or tablet.
Your 20 Amps supply does not supply these voltages on the date lines so it does not "talk" to your Apple/Samsung device therefore these assume it is a normal "dumb" charger and do not draw more current than what is allowed by USB standard which usually is only 100 or 500 mA
Also, depending on how full the battery is the charge current is also limited. It will only be maximum when the battery is 30 - 70 % charged (these numbers are just my guess). Charging with a high current is bad for the battery when it is very low or almost full.
We believe the key reason Apple release 2.4A charger is for better user experience when charging and playing at same time. When play high quality video games, like Infinity II and charging at same time, my iPad3's battery percentage increase is very very slow, e.g, 30mins later, only increase 2percent which drive me crazy.
The USB standard does not allow more than 500mA to be drawn from a standard USB 1 port. Until the device establishes communication with the USB host device it has no way to know how much current is available.
The USB standard actually requires devices to drawn no more than 100mA before communicating with the host and requesting more power. This is important because a standard unpowered USB hub will consume 500mA - 100mA for itself, and 100mA for each of its ports. This means that an unpowered hub cannot, and should not, attempt to supply 500mA to a USB device.
The reality is that few USB ports are unable to supply 500mA without being asked. Many don't even bother to monitor current consumption and shut off non-compliant USB devices. It's almost always safe to draw 500mA from a USB port without asking the host port for the maximum power.
USB chargers are typically not intelligent, and don't implement a full USB host port. They use some short cuts - generally using resistors on the D+ and D- lines to signal the USB device that the charger is capable of more power without an official request.
Further, some devices, such as the Apple iOS line, will also monitor the voltage provided, and scale back the current consumption based on voltage drop. For instance, if a charger reports that it can supply 2A, but the voltage doesn't stay at 5V, the iOS device will consume less than the maximum current. It will not charge below 4.5V, nor above 5.5V. So not only does the charger have to present the correct signals to indicate full current is available, it has to maintain good regulation at the maximum current draw.
Keep in mind that this is a safety feature. Not only does the charging device need to be able to supply the current, but the USB cable used needs to be able to carry it. It might not seem like a lot of current, but there are many very cheap thin USB cables on the market that will noticeably warm up with 2A flowing through their undersized conductors. Put that under a flammable pillow and let the heat build up, and you might find more than melted insulation.
Apple not only verifies the charger, but also the cable (using their proprietary chips inside the cable connector) so they can avoid liability for possible losses associated with dangerous chargers and wiring.
The Apple standard has been loosely adopted by others, or is accepted by others, and consists of placing specific voltage levels on the D- and D+ lines at a low current. Placing approximately 2.0V on the D- line, and 2.75V on the D+ line will signal 2A (10W) is available for charging. This can be done with simple resistors:
For example, if you have the supply set up for a 5 volt output and you put a 5 ohm resistor across its output, it'll supply 1 ampere to the resistor because that's all the resistor wants with 5 volts across it.
A USB device will only draw the amount of current that it knows it can definitely draw without causing damage to the charger. The Apple and Samsung devices have no idea how much is safe to draw from your charger, therefore they fall back on the USB Standard. USB Standard says "0.5 Ampere is safe". (If the charger identifies itself as a USB charger but cannot handle 0.5 Ampere, that's not the phone's fault but the charger's problem).
The only way to convince the device to draw more current is to implement the communication in the charger that would happen between an Apple device and an Apple charger, or a Samsung device and a Samsung charger. It's not very difficult, and you can buy decent quality chargers at reasonable prices that do this. Your charger doesn't do it, so 0.5 A is the limit.
If you connect the Data+ and Data- signals together through a small resistor (for protection.. something around 100 ohms), you'll be in compliance with the USB Battery Charging specification, which allows a device to draw a minimum of 1.5A.
"Komatsu has evaluated the Thunder Maxx product thoroughly and committed to purchase," said Romeo Power CEO Mike Patterson. "This pack powers any make or model 48V forklift with a 24-85-17 or 24-85-21 tray. And we have the engineering capability to custom design a lithium battery and charger package for any customer or application."
Less equipment also frees up valuable warehouse space by eliminating the need for a dedicated battery room. Also, unlike lead-acid batteries, Thunder Maxx produces zero emissions and requires zero maintenance: no hazardous watering or time-consuming equalize charging and the end of toxic dust, fumes, and spills.
Thunder Maxx lithium packs are charged exclusively with Power Designers Sibex's REVOLUTION high frequency, modular battery chargers that deliver peak efficiency greater than 93%, and efficiencies greater than 90% throughout the entire charge cycle. As output current tapers, the charger turns off unneeded modules. Fleet owners can combine multi-voltage 1.3kW modules to produce over 30kW output depending on their needs.
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