Electric car conversion: Project ForkenSwift

[Lazarus]

How do you know when your batter pack has had enough? Beside it won't move. Do you monitor the pack voltage?

[MetroMPG]

Well the very first time I drove the car any distance (on the junk forklift company donated batts), the car shuddered to a halt a block from the house. Waited a while for them to recover, then whipped them mercilessly down the last block. I didn't know any better at the time, but that's how you kill batteries. I did in fact ruin one that episode.

What you watch is pack voltage under load. (Resting pack voltage can be misleading, as I've discovered). Voltage drops when under load, and it's important not to let it drop too low to avoid damaging the batteries. In the case of 6v golf cart batt's, they need to be kept above 5.25v under load - normal resting full charge is around 6.35v.

The further I drive on a charge, the more the pack voltage "sags" under load, and I have to start backing off the go pedal to keep voltage from going dangerously low.

And a simple way is to just keep an eye on the trip odo. In winter driving, I know that going past about 10-12 km is getting into "feather the go pedal to protect the batteries" territory. In the summer it's more like 15-20 km.

[bestmapman]

Can you regen on hills?

[MetroMPG]

Nope. It's not common on DC conversions with series motors.

So I just pop it into neutral and freewheel where I can.

Regen would be nice for those times you misjudge the length of a coast, need "engine braking", or have to slow down unexpectedly.

[DifferentPointofView]

It'd be nice if you hooked up a generator to the rear wheels that recharges the batteries while your coasting and keeps them running at highway speeds. (it's fwd so I figured it'd be a problem).

[MetroMPG]

DPoV: running a generator off the drivetrain while coasting would be regenerative braking, technically. I'd rather just coast - it's more efficient in the end. (Although every once in a while I misjudge a coast, or come down a hill where it would be nice to have regen - but not often.)

And you know that if you run a generator/alternator while driving an EV, you'll actually end up going a shorter distance, not farther. There are too many conversion & charging losses for that scenario to work.

----

Well I finally did it!

Yesterday I drove away... with the car still plugged in!

No damage, fortunately. Just a big, self-administered dope slap when I instantly realized what I'd done.

I suppose that's why some EV owners build safety interlocks into their charging systems, so the main contactor won't close if the charger is plugged in.

Let that be a warning to all you future PH/B/EV drivers ... or block heater users for that matter.

[Who]

Well I finally did it!

Yesterday I drove away... with the car still plugged in!

How was the acceleration???

[Peakster]

I've done that before with an interior heater for my car. The heater was just thrown into the passenger floor area with the cord coming out of the door on that side. When I left, the cord disconnected, drug on the ground until I took a turn and the cord caught under the rear tire. BOOM! The heater got sucked into the door opening and the cord was ripped right off .

Glad you didn't have any damage.

[MetroMPG]

Originally Posted by Who

How was the acceleration???

It was fantastic! I'm tempted to go out and buy a much longer extension cord...

Know what, Peakster? Your story reminded me I've actually done something similar before - but with the block heater cord. So this was only the first time I've done this with the electric car.

Didn't you notice your 120v heater was running when you got in though? Or were you that distracted?

[Peakster]

I must've been distracted somehow or in some sort of rush where I didn't notice. Typical.