Ideas for my first EV.

[oil pan 4]

Originally Posted by Ryland

There are people who put alternator's on their motor...
When you see an EV conversion like that, it's always because the person didn't any reach and didn't understand it would hurt their range.

I always figured this was done as a cheap reliable proven unimaginative way to power up the 12v electronics, such as lights, radio, cab blower, A/C.
(not try to extend the vehicle range)

Don't try to put an alternator on an electric vehicle to charge the drive battery.

It wont work because they are so inefficient. By the time an alternator puts out 1 mile worth of driving charge its taken 2 or 3 miles worth of drive power to turn the alternator. So its pointless.

Trust us, it will not work.

[cRiPpLe_rOoStEr]

Some electric engines also work as generators, so adding an alternator is pointless at all. If you really WANT to get an alternator, use a BAS (belted alternator-starter) from some Chevy or Buick fitted with eAssist.

[rmay635703]

Originally Posted by RedDevil

More like to make a cheap build work.
If you don't have a decent DC-DC converter but you do have an alternator, and it is still hooked up to the remaining parts of the original engine, and your range does not matter, why not?

It would just power the 12V bits, albeit at max 75% efficiency versus the 90% from the DC-DC converter.
It would thus eat into the range more than the DC-DC converter would.

You could also charge a separate battery for the 12V system and not use alternators or converters altogether. But then you'd have to watch both battery charge levels.

Alternator can be used for low level regenerative braking, there were setups that engaged it via the control wires during braking only used in conjunction with a 12v deepcycle.

You still have belt losses but an alternator can add cheap braking regen to a series wound setup.

Perpetual no, charging 12v battery yes.

[RedDevil]

Originally Posted by rmay635703

Alternator can be used for low level regenerative braking, there were setups that engaged it via the control wires during braking only used in conjunction with a 12v deepcycle.

You still have belt losses but an alternator can add cheap braking regen to a series wound setup.

Perpetual no, charging 12v battery yes.

Even in a hybrid like mine, regenerative braking makes up for just a small portion of electic use.
The 12V system drains some 150 to 200 Watt constantly so it would eat the power generated by one long braking session (say 15 seconds at 10 kW) within a quarter of an hour. If I hadn't used it up by accelerating away again.

A regular car alternator can generate way less than that.
At 500 Watt 15 seconds would yield just 7500 Joule, just enough to power a 150 Watt system for 50 seconds.
I bet the belt drag alone would annihilate that gain in most situations.

[oldtamiyaphile]

Originally Posted by RedDevil

Even in a hybrid like mine, regenerative braking makes up for just a small portion of electic use.
The 12V system drains some 150 to 200 Watt constantly so it would eat the power generated by one long braking session (say 15 seconds at 10 kW) within a quarter of an hour. If I hadn't used it up by accelerating away again.

A regular car alternator can generate way less than that.
At 500 Watt 15 seconds would yield just 7500 Joule, just enough to power a 150 Watt system for 50 seconds.
I bet the belt drag alone would annihilate that gain in most situations.

I have a pair of cars with regenerative alternators.

My 0.9l two cylinder engine's alt has been ramped up- all the way to 120A! That's 1680 watts The limiting factor is the batteries charge acceptance.

[RedDevil]

Originally Posted by oldtamiyaphile

I have a pair of cars with regenerative alternators.

My 0.9l two cylinder engine's alt has been ramped up- all the way to 120A! That's 1680 watts The limiting factor is the batteries charge acceptance.

I think it is a good idea to use an alternator for regenerative braking - if you have to have one in the first place and can use the regeneration without adding much cost or weight.

There has to be some way to store the power.
A regular lead acid battery in operation will usually be charged close to max.
Your Fiat must have some extra capacity to fill or it would all go to waste?

[oldtamiyaphile]

Originally Posted by RedDevil

A regular lead acid battery in operation will usually be charged close to max.
Your Fiat must have some extra capacity to fill or it would all go to waste?

The alternator normally runs at 12.5v, this also eliminates the loss of efficiency as the battery reaches full (keeping a Pb battery at 14v is quite wasteful).

[RedDevil]

Originally Posted by oldtamiyaphile

The alternator normally runs at 12.5v, this also eliminates the loss of efficiency as the battery reaches full (keeping a Pb battery at 14v is quite wasteful).

Mine battery voltage alternates between 12.6 and 13.8 Volt. Of course, it is fed by the DC-DC converter so that controls the behaviour.

Our 2nd gen Insight 12V batteries have a tendency to fail prematurely, typically one cell gets out of balance and gets worse and worse until the battery dies.
Keeping it at 14 Volt would prevent that - even if it wastes 20 Watt continuously...
So keep an eye on your battery voltage...!