Simple Regenerative Braking System

[peifferu]

The plan is to use the alternator to generate extra energy while braking to charge the battery a little more so the alternator doesn't need to generate as much energy at other times, that way it won't need to use as much fuel. To do this I'm going to install a switch directly from the battery to the voltage regulator on the alternator. When I want to slow down, I'll close that switch which will cause the alternator to produce max power and slow down the car. When the battery hits it's limit (I have a voltage display) I'll open the switch and let the ecu take over control from there. After I test that, I'll probably install another switch to disconnect power to the alternator so it cannot produce any electricity. I will do this to bring down the battery voltage before brake-charging so I can produce more energy then, instead of having the car use gas to generate energy for a while before I have to slow down. If I decide I need a larger capacity for energy storage, I'll implement a supercapacitor, but that'll be a whole other ordeal. I'll follow-up once I get back to my car and try a couple tings. Any question? Concerns? Advice?

[evil_demon_01]

The plan is to use the alternator to generate extra energy while braking to charge the battery a little more so the alternator doesn't need to generate as much energy at other times, that way it won't need to use as much fuel. To do this I'm going to install a switch directly from the battery to the voltage regulator on the alternator. When I want to slow down, I'll close that switch which will cause the alternator to produce max power and slow down the car. When the battery hits it's limit (I have a voltage display) I'll open the switch and let the ecu take over control from there. After I test that, I'll probably install another switch to disconnect power to the alternator so it cannot produce any electricity. I will do this to bring down the battery voltage before brake-charging so I can produce more energy then, instead of having the car use gas to generate energy for a while before I have to slow down. If I decide I need a larger capacity for energy storage, I'll implement a supercapacitor, but that'll be a whole other ordeal. I'll follow-up once I get back to my car and try a couple tings. Any question? Concerns? Advice?

1) The alternator running at full capacity will not slow the car down.
2) It costs bugger all fuel to maintain battery charge.

[peifferu]

1. According to the law of conservation of energy, it will lol. I'm certainly not expecting a whole, lot, but that's why I'm trying: to find out. I don't really need it to slow down the car.
2. I'm sorry, mate, but I have you idea what you're trying to say.
Thanks for the response!

[evil_demon_01]

1. According to the law of conservation of energy, it will lol. I'm certainly not expecting a whole, lot, but that's why I'm trying: to find out. I don't really need it to slow down the car.
2. I'm sorry, mate, but I have you idea what you're trying to say.
Thanks for the response!

The alternator will provide resistance to the engine crankshaft yes.
Enough to slow a 2 tonne car down, No.

[deevergote]

You do not drive a hybrid. There is absolutely nothing to be gained from any sort of regenerative braking system. The alternator charges the battery while the engine is running. The battery only works when starting the car, or when powering components that require greater output than the alternator provides (which does not include any stock system... only aftermarket audio or computer systems.)

Buy a Prius.

[reklipz]

Just to elaborate on what everyone has said: In a stock vehicle, and likely even one with a typical aftermarket head unit, the battery is only sourced (tapped, used) when starting the car, as well as when the ignition is on and the engine is not. At any other time, the alternator provides all of the necessary power for the electronics in the car, and will also top-up (charge) the battery.

Turning on various accessories (e.g. heater blower, air conditioning, headlights) do place minor loads on the engine, but they are very minor. I don't know the specs for our vehicle, but I recently read that mid 2000s Chevy Silverados only require ~40 HP to maintain highway cruising speed and power all accessories...

[oyajicool]

I don't know how cost effective it would be to accomplish what you want accomplish on our cars. But don't stop what you want to do on your car.

You may come up with something new in the process.

[deevergote]

I don't know how cost effective it would be to accomplish what you want accomplish on our cars. But don't stop what you want to do on your car.

You may come up with something new in the process.

This is true. Sometimes a "pointless" project is a stepping stone to something really useful.

I take back my previous statement. Don't buy a Prius.

[C91BLX7]

The new Oddys got something kinda like this, the alternator pulley has some clutches in it so the speed can be regulated depending on different situations.

[peifferu]

Just to elaborate on what everyone has said: In a stock vehicle, and likely even one with a typical aftermarket head unit, the battery is only sourced (tapped, used) when starting the car, as well as when the ignition is on and the engine is not. At any other time, the alternator provides all of the necessary power for the electronics in the car, and will also top-up (charge) the battery.

Turning on various accessories (e.g. heater blower, air conditioning, headlights) do place minor loads on the engine, but they are very minor. I don't know the specs for our vehicle, but I recently read that mid 2000s Chevy Silverados only require ~40 HP to maintain highway cruising speed and power all accessories...

Ok, I guess I misunderstood how the whole system worked. But when someone's alternator goes out, the car still manages to go several miles just from the power of the battery, right? Couldn't I replicate the affect of a bad alternator by opening a switch to the alternator so the car pulls power only from the battery? and then just close the switch to alternator when I'm slowing down so it doesn't require any effort from the engine?

[deevergote]

What would you hope to gain from it? The alternator isn't that much of a parasitic drag on the engine. The potential benefits in terms of power or fuel economy will be minimal at best. Unless you used a deep cycle battery, you'd probably end up killing the battery with all the charge and discharge cycles.

[GeoffM]

I can see you rapidly overcharging and killing the battery.
Take it from me; battery acid hurts. Especially when it's in your eye.

I guess if you see success from your efforts, then perhaps
implement a blast shield for the battery, as well as a cooling system.

[Shadow1992]

What would you hope to gain from it? The alternator isn't that much of a parasitic drag on the engine. The potential benefits in terms of power or fuel economy will be minimal at best. Unless you used a deep cycle battery, you'd probably end up killing the battery with all the charge and discharge cycles.

Like Deev says, you would more then likely end up significantly shortening your battery life. Add to that the minimal savings in fuel and at best the cost of replacing th battery more often would balance out with your cost of slightly less fuel. But more then likely you would end up in the long run spending more money, as well as exposing your vehicle's systems to stress they were not designed for.

[reklipz]

I can see you rapidly overcharging and killing the battery.
Take it from me; battery acid hurts. Especially when it's in your eye.

I guess if you see success from your efforts, then perhaps
implement a blast shield for the battery, as well as a cooling system.

GeoffM is absolutely right; don't over charge the battery. That thing will explode! However, by my naive understanding of the charging system in our vehicle (which should already account for over-charging, otherwise batteries would be exploding left and right), and the mechanism you wish to use to disconnect (and reconnect) the battery, this shouldn't be a problem.

As well, to deevergote and Shadow1992's points: without knowledge of how the system works, changing the system could potentially shorten the lifespan of the battery, and potentially the electrical system in the car. Though again, given my naive understandings of the specific systems in the car, I would guess that this is not likely. You would have issues when driving for moderately long trips, as the battery would drain. Storing a battery at low charge is bad for it, and over charging a battery is bad. Otherwise, as long as the sulferic acid solution is maintained in the battery, the only real killer is the lead plates falling apart due to inherent construction quality (i.e. nothing you can do about that; just buy a good, quality battery, maintain it properly, and it will last a long time; 15+ years).

You would have to make sure the battery was capable of the deep-cycle charging/discharging you want to place on it; I don't think standard automotive batteries would cut it.

[evil_demon_01]

Deep cycle charging/discharging will not work in the system the OP is describing.
Deep cycle mean you can run a battery flat (20-50% capacity) and then recharge it with minimal damaging effects.





IF you run the car with the alternator turned off, and wait for 20-50% charge, by then the car will already have shut down due to lack of voltage to run the main components, or run a severe risk of damaging the ECU.

Ask anyone who knows anything, about what they think of disconnecting the battery while the car is running.
THEN apply that theory to a severely charged/discharged battery.






The idea is great, don't get me wrong.
But it would be the same as looking at it like:

I want to run the Alternator as a DC motor so that it can provide extra power to the engine to save fuel . . . .

Hmmmm