Figure 1.The QDPC-200 Prius Hybrid Charger (November, 2015)
For Prius repair shops, similar high voltage battery applications such as high voltage diesel hybrids, but not the consumer market. For the Prius, there are two situations for which this device is designed: 1) A Prius Hybrid has been left idle for a period so long that the main battery has discharged to a level that will no longer start the engine, 2) A Prius Hybrid was driven on the battery after fuel is depleted, to the same result. At the present time, the consequence in most Prius shops is installing a new HV battery, because most shops don’t have an appropriate battery charger.
Improvements in the Model 200/210
Relative to the Model 100 [August 2012], the Model 200/210 features these improvements:
1) 90% less internal heat generated, so better electrical efficiency. The consequence is better safety if the cooling fan stops for any reason.
2) Bright blue digital voltmeter (DVM) with large characters and 1% accuracy reading the battery charge voltage.
3) 10.5A DC maximum output for 3 times faster charging.
4) The "HVDC" switch merely controls the logic circuits that switch on the high voltage, rather then the high voltage itself, so the switch contacts should last forever.
5) Greater safety, because the ammeter's internal terminals are at "ground" rather than high voltage.
6) Solid state relay switch which turns on at the power zero crossing to eliminate surges.
7) Will maintain charge on 12V and 24V batteries, too!
How it Works
The DVM shows the voltage at the clip terminals. If this increases rapidly when charging, the battery may have a fault which results in an internal resistance much larger than the usual 0.55 ohms, which usually would give at most a 1.5 volt change when charging begins. If internal resistance is much larger, there will be a larger change.
The analog ammeter shows charge current going to the battery. The Vset knob controls ultimate vcharge voltage. Fig. 2 shows the measured relationship. You need to use this graph to use the charger properly.
New feature: As you can see in Figure 2, this charger will now control at 12V and 24V, all the way up to 290V.
Figure 2. Stop charge voltage vs. DVM reading
Input and output are protected with 12-A fast acting fuses. Although deceptively small, the main power switch is a 50-amp circuit breaker. All components in the high voltage circuit are rated for 800 volts or higher; the main rectifier is rated at 1,000 volts, 35A. Charging cables are rated 10-A, 1,000V.
It is important to follow this sequence. Although damage will not always occur when it is not followed, proper operation may be compromised.
1) Make sure front panel switches are in the “off” position.
2) Plug the device in to 220VAC 50- 60Hz single phase power.
3) Turn the "Vset" knob counterclockwise to the stop. Attach the hybrid battery.
4) Turn on the HVDC switch. The sensing circuits will come to life, the green "power on" light will go on, the digital voltmeter will register the voltage on the battery, the green "charge complete" light will go on and the alarm will sound. Ignore the alarm. This is normal, and indicates the voltage on the battery exceeds what you have set with the knob.
5) If the alarm sounds and the red panel light comes on bright continuously, you have the battery connected backward. This is a highly dangerous thing to do!
6) Turn on the main power switch.
7) Turn the “Set Chg” knob clockwise until the alarm quits sounding and the “charge complete” green light goes out. Now you are charging the battery, and the DVM will show the battery voltage.
8) Slowly turn the "Set Chg" knob further until the desired final voltage is set. For example [Figure 2], for 200 volts, use a setting of 8.20.
9) The graph in Figure 3 indicates about how long it will take to charge a completely dead Prius 6 ampere-hour battery (blue curve) and what the approximate charge current will be at that time..
Figure 3. Charge voltage and current vs. time
10) The device can operate into a dead short indefinitely, but there is no point in doing this if the battery is not charging.
For Prius Hybrid batteries, the nominal voltage varies, a lot:
2000 Gen 2: 274 V
2004 Gen 3: 202 V
2010 Gen 4: 202 V
Do not overcharge. For a Prius, if the nominal charge voltage is 202V, the operating range is 100 to 235V during the normal charge/discharge cycle in operation in the car, so 200V is a great place to stop.
The charge rate is deliberately low so that there is little chance of overheating the battery. Compared to the maximum charge/discharge rate of a Prius cell in normal operation (Charge +40, Discharge -90 amps), 3A is insignificant, about 0.23 watts per normal cell at maximum charge rate. However, please note that if the battery is completely dead and will not take a charge, it could be overheated if you leave it charging at 3A for hours. Also, experience shows that some batteries which have not held a charge for a long time will have much lower capacity than normal, and reach 200 or 300V in seconds. You have to watch the charge process at least for the first five minutes and check on it every thirty minutes after that to be sure problems aren’t developing.
11) When the set charge is reached, the green “charge complete” light will come on again, the alarm will sound. Please note: because the circuit has disconnected high voltage from the battery, the red DVM will show the voltage available for charging, not the voltage on the battery. Charging may stop and start cyclically.
12) Turn off the HVDC and main power switches. In an emergency, the main power switch is your safety switch. You can turn off this switch at any time. Its contacts will tolerate the transient voltage.
13) Disconnect the charging cables and, after a minute or so, short them together for safety.
Efficiency: This device is 90% efficient. Operating into a dead short, it only generates 20W of waste heat.
Safety: Other chargers use transformers (heavy and hot) or high frequency IGBT’s [Insulated gate, bipolar transistors]. If the IGBT fails, nothing stands between the battery with its 30kW output and the power mains. Our charger provides an automatic limit on the charge voltage that can be attained, guarding against battery fires if the device is left unattended.
Four Levels of Safety in the Design:
1. Our Solid state relay will not conduct in the reverse direction, operated within ratings.
2. A tested snubber circuit prevents sudden spikes in the reverse direction.
3.The only way the attached battery could discharge is through 1kV of diode rating and an 800V capacitor.
4. Even if all these break down, 480V, 12A fuses and a 50A thermal breaker are in series with the battery lead.
Taken together, these features guarantee the device is utterly safe against a battery reverse discharge through the unit itself.
Safe Operating Procedures:
Never connect a battery in reverse polarity to the charger. The red cable is plus and the black one minus!
Never turn the device on without the charging leads being connected to something. It’s OK to have them shorted together, although there’s no point in leaving the power on when they are shorted.
Always wear suitable high-voltage protective gloves whenever you are handling the high-voltage leads and clips or working near the battery.
Never change fuses while the main power switch is on.
Keep the device away from water, humidity and steam.
Keep the device in a well-ventilated space. If the fan ever becomes plugged with lint, etc., use a gentle air stream to clear it. If the fan stops, do not use the device. Return it for repair within warranty.
There is an internal resistor which automatically discharges the capacitors in the unit after the power is turned off. The only way you will come in contact with high voltage generated by the unit after power is turned off is if the HVDC switch is left on, the charging cables are not shorted together, and that only for sixty seconds.
To place an order for the charger, contact us at 505-466-3877 or the email address below. We do use PayPal.
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