t71ford
Over 1,000 Posts
Re: Oh YEAH to Oh NO...Project Kool-Aid, up in smoke: Shorai disaster
I boned up a little on M/C regulator theory in the last day or so. The original R/R was a thyristor type, and most likely the original. The thyristor regulators, especially older ones, have the capacity to vary their charging rates widely, and then work overtime to keep up. The lead acid battery is better able to absorb the resulting swing of 12-15 volts much easier than the Lipo4 battery. As the regulator is constantly trying to maintain the balance between the charging system and the battery, the reduced margin for error of the Lipo4 creates additional stress upon the system (read heat). When the temperature of the internals of the regulator reach critical mass, they fail in one of two ways: off or on. Mine failed in on, and burned up the battery.
I am now switching to a MOSFET style regulator/ rectifier, as the MOSFET system is much less prone to charging system variables, although working in a much similar way to the thyristor systems. Therefore it is plug and play into the VTR charging system, and will allow for the use of the Lipo4 battery.
Having just spent a little time researching MOSFET and thyristors, as they apply to the regulator application, it becomes very clear as to why the former is the more efficient option.
Both perform a nearly identical function. However, once the thyristor (latching diode, while forward biased) has allowed conductance, it is much slower to release the "latch", especially if the anode current of the diode is exceeding the latching current. So, two things keep the thyristor conductance latched: trigger current, or annode current. If the annode current is above the holding current of the thyristor, it will remain latched. It can be manually switched off by changing the bias of the diode to negative. This method is not used in the Superhawk R/R, as the Superhawk relies on annode current to fall off, allowing the thyristor to open. However, the entire process is slow to react as it is entirely dependent upon the current differential between the trigger current and the anode current to release. This equals more heat. As you would imagine, the whole process is further slowed as the thyristor gets older.
The MOSFET transistor uses a positive gate, more likened to a light switch. When current is applied to the gate of the MOSFET, it closes the switch. When current is removed, the switch opens. This occurs much more quickly due to the switch action's direct relationship to the applied gate current, rather than on current differential between two points. It seems that as the switching action is much more reliant on gate current, this regulating system would be much less prone to the kind of burn down experienced on the SH than are the tyristor types.
Anyway, its kind of nice to know why the charging rates and variables are so much different between the two... The battery did contribute to the overall failure, although perhaps not outright causing it. The failure was due to a marginal regulator, forced to work overtime, and unable to do so. I would caution anyone considering one of these batteries to consider upgrading the regulator/ rectifier to a MOSFET unit (such as found on the Yamaha R6 or R1). The stator is not the issue, only the R/R. A complete measuring of the stock charging range would be in order as well, as the Lipo batteries prefer a range of 13.6-14.4 max for optimal operation.
I boned up a little on M/C regulator theory in the last day or so. The original R/R was a thyristor type, and most likely the original. The thyristor regulators, especially older ones, have the capacity to vary their charging rates widely, and then work overtime to keep up. The lead acid battery is better able to absorb the resulting swing of 12-15 volts much easier than the Lipo4 battery. As the regulator is constantly trying to maintain the balance between the charging system and the battery, the reduced margin for error of the Lipo4 creates additional stress upon the system (read heat). When the temperature of the internals of the regulator reach critical mass, they fail in one of two ways: off or on. Mine failed in on, and burned up the battery.
I am now switching to a MOSFET style regulator/ rectifier, as the MOSFET system is much less prone to charging system variables, although working in a much similar way to the thyristor systems. Therefore it is plug and play into the VTR charging system, and will allow for the use of the Lipo4 battery.
Having just spent a little time researching MOSFET and thyristors, as they apply to the regulator application, it becomes very clear as to why the former is the more efficient option.
Both perform a nearly identical function. However, once the thyristor (latching diode, while forward biased) has allowed conductance, it is much slower to release the "latch", especially if the anode current of the diode is exceeding the latching current. So, two things keep the thyristor conductance latched: trigger current, or annode current. If the annode current is above the holding current of the thyristor, it will remain latched. It can be manually switched off by changing the bias of the diode to negative. This method is not used in the Superhawk R/R, as the Superhawk relies on annode current to fall off, allowing the thyristor to open. However, the entire process is slow to react as it is entirely dependent upon the current differential between the trigger current and the anode current to release. This equals more heat. As you would imagine, the whole process is further slowed as the thyristor gets older.
The MOSFET transistor uses a positive gate, more likened to a light switch. When current is applied to the gate of the MOSFET, it closes the switch. When current is removed, the switch opens. This occurs much more quickly due to the switch action's direct relationship to the applied gate current, rather than on current differential between two points. It seems that as the switching action is much more reliant on gate current, this regulating system would be much less prone to the kind of burn down experienced on the SH than are the tyristor types.
Anyway, its kind of nice to know why the charging rates and variables are so much different between the two... The battery did contribute to the overall failure, although perhaps not outright causing it. The failure was due to a marginal regulator, forced to work overtime, and unable to do so. I would caution anyone considering one of these batteries to consider upgrading the regulator/ rectifier to a MOSFET unit (such as found on the Yamaha R6 or R1). The stator is not the issue, only the R/R. A complete measuring of the stock charging range would be in order as well, as the Lipo batteries prefer a range of 13.6-14.4 max for optimal operation.
