Well, finally had a few free minutes today, so once I was done bolting in "Corey's Big Boy Seat Mod" to raise the front of the seats for better thigh support I had a chance to try out another mod I've been curious about. I will give a detailed version below, or just skip to the end for the summary.
The issue:
Most literature states that light braking kicks in the regenerative braking system with the hydraulic brakes kicking in when more braking is required. In reality, the Insight uses a fairly standard hydraulic braking system such that even under light pedal pressure, the hydraulic system is slightly actuated. The percentage of regenerative braking versus mechanical braking is dependent on how deftly the operator can touch the brake pedal. But even in the best circumstances, there appears to be a slight drag from the mechanical brakes.
In the quest for maximum efficiency, one would need to have pure regenerative braking (and supply the battery pack with the maximum amount of recharging). The regenerative system needs to be triggered independently of the hydraulic system. This brings the question, "what triggers the regenerative mode in the first place?" I had suspicions that the regen may be triggered by nothing more than the actuation of the brake lights as many cars already use a signal from the brake lights to disengage the lock-up torque converter in an automatic transmission.
To test this theory I performed the following procedure:
Materials required - two lengths of 14-16AWG Wire, 1 SPST Momentary switch Normally Open, basic soldering equipment
To get started I stripped ~1/2 inch of insulation off of each end of the two lengths of wire. Solder one length of wire to each terminal of the switch and "tin" the loose end of each wire with solder. Follow the cars brake pedal up to a switch. This is the switch that actuates the brake lights. It should have a connector with a black/white wire and a pure white wire facing the aft end of the car. Insert one end of the tinned wire alongside each factory wire. This is commonly called "backprobing" If you are a contortionist, you do not even need to pull the plug. The wires can also be removed with no permanent damage to the car. Once the wires are inserted and secure, turn the key to the "on" position and press the switch...the brake lights should illuminate. If not, double check the connections. Locate the switch in a convenient location.
In operation, when driving down the road and regenerative braking is desired, simply depress the switch. Your brake lights will illuminate to caution other drivers of your slowdown and the regenerative braking system only will be actuated. This insures that every watt of power is delivered to the battery instead of being burned away as heat at the brake rotors. If at any time you desire more braking the hydraulic brake pedal can be depressed as normal.
Testing - I took a ~5 mile drive through mixed traffic and a short trip on the highway. The modification did not set any codes or appear to affect any systems in a negative manner. So the good news is that it appears to work, and should be fairly failsafe. If the switch were ever to fail to close, you simply will not get regenerative braking until you step on the pedal (system will revert to normal operation as it will if you simply don't press the installed button) If the switch were to stick in the closed position, regenerative braking would be applied, however, you could simply disconnect the installed wires to revert to normal operation as well.
In summary, hooking a momentary switch in parallel to the brake light switch would give the user command of "100% regenerative braking mode" However, I can not vouch for the amount of savings this would generate...in theory it would probably be pretty small. But so is the investment in parts and labor.
I welcome any thoughts or discussion.
The issue:
Most literature states that light braking kicks in the regenerative braking system with the hydraulic brakes kicking in when more braking is required. In reality, the Insight uses a fairly standard hydraulic braking system such that even under light pedal pressure, the hydraulic system is slightly actuated. The percentage of regenerative braking versus mechanical braking is dependent on how deftly the operator can touch the brake pedal. But even in the best circumstances, there appears to be a slight drag from the mechanical brakes.
In the quest for maximum efficiency, one would need to have pure regenerative braking (and supply the battery pack with the maximum amount of recharging). The regenerative system needs to be triggered independently of the hydraulic system. This brings the question, "what triggers the regenerative mode in the first place?" I had suspicions that the regen may be triggered by nothing more than the actuation of the brake lights as many cars already use a signal from the brake lights to disengage the lock-up torque converter in an automatic transmission.
To test this theory I performed the following procedure:
Materials required - two lengths of 14-16AWG Wire, 1 SPST Momentary switch Normally Open, basic soldering equipment
To get started I stripped ~1/2 inch of insulation off of each end of the two lengths of wire. Solder one length of wire to each terminal of the switch and "tin" the loose end of each wire with solder. Follow the cars brake pedal up to a switch. This is the switch that actuates the brake lights. It should have a connector with a black/white wire and a pure white wire facing the aft end of the car. Insert one end of the tinned wire alongside each factory wire. This is commonly called "backprobing" If you are a contortionist, you do not even need to pull the plug. The wires can also be removed with no permanent damage to the car. Once the wires are inserted and secure, turn the key to the "on" position and press the switch...the brake lights should illuminate. If not, double check the connections. Locate the switch in a convenient location.
In operation, when driving down the road and regenerative braking is desired, simply depress the switch. Your brake lights will illuminate to caution other drivers of your slowdown and the regenerative braking system only will be actuated. This insures that every watt of power is delivered to the battery instead of being burned away as heat at the brake rotors. If at any time you desire more braking the hydraulic brake pedal can be depressed as normal.
Testing - I took a ~5 mile drive through mixed traffic and a short trip on the highway. The modification did not set any codes or appear to affect any systems in a negative manner. So the good news is that it appears to work, and should be fairly failsafe. If the switch were ever to fail to close, you simply will not get regenerative braking until you step on the pedal (system will revert to normal operation as it will if you simply don't press the installed button) If the switch were to stick in the closed position, regenerative braking would be applied, however, you could simply disconnect the installed wires to revert to normal operation as well.
In summary, hooking a momentary switch in parallel to the brake light switch would give the user command of "100% regenerative braking mode" However, I can not vouch for the amount of savings this would generate...in theory it would probably be pretty small. But so is the investment in parts and labor.
I welcome any thoughts or discussion.
