[KiwiEV]

Hi folks,

As you know, I'm not a technically minded person. I will be charging my car with a separate charger for each battery, including the "accessories" battery (I won't be using a DC-DC converter).

I've included a schematic of how I plan on doing this below. I invite you all to poke it and prod it and tell me any problems you can see.

It's very simple however I admit I'm getting tired tonight so I expect there to be a problem here & there!

Note:You can see there is a Turbo Timer set to keep the battery box fans running for 5 mins after the charger has been removed. One of the many rules for building an EV here and fairly smart one I suppose.

I'd love to know what people think of it and most importantly what errors people can see.

Cheers!
Gav

 

[rbgrn]

I see a problem. Both Pos and Neg from the charge fun ultimately end up at the pos term on the battery!! You'll have some problems with that.

My guess is that the neg of the charge fan should also go to the ground. In fact, the only thing you ever switch on and off is the positive connection and the grounds should always be connected. That's not quite the right schematic component for a relay. There will be 5 terminals.

(control neg) - to ground
(control pos) - to ignition
(normally open) - to charger +
(middle) - to battery +
(normally closed) - to speed controller +

that would make it so that when the ignition is off, it's charging (open) and when the ignition is on, the charger is disconnected and now the controller has power.

To make your diagram make sense you may want to add in a little speed controller box or a motor to make things look simple.

 

[KiwiEV]

Awesome stuff, cheers Rob!
I'll re-check the charging fan details on my "picto-schematic" diagram and make a rough version of the diagram in the garage this weekend and see what blows up.

 

[rbgrn]

No problem! Hope that helped. Let me know how it goes.

 

[KiwiEV]

Can a "Normally Open" relay be turned into a "Normally Closed" relay by simply reversing the poles? Or are "NC" relays actually made differently inside?

 

[rbgrn]

"Normally" refers to which poles are connected in an unpowered (no power to control side) state. So, NO is open when there is no power but is closed when there is power and NC is closed when there is no power but is open when there is power. What this means is that you can use both at once to flip-flop connections.

 

[KiwiEV]

I've revised the schematic for those who are curious:

If anyone was paying attention (obviously I wasn't) on the first schematic, they would have noticed that even when I unplugged the charger, the flashing light would keep going... Why? Because it would just feed off the battery from the other direction!
So, I've modified it in the new picture above. Not only that, I've bought a dual switching relay so that when the ignition is broken, the power is re-routed to the flashing LED in the dash.
Believe it or not, it all works. I spent last night and this afternoon fiddling with combinations and came up with this plan where everything works as it should.
So tomorrow, I'm going to install it into the car!

If anyone in the future plans on using one charger per battery including a standalone accessories battery, feel free to copy that idea!

 

[rbgrn]

Nice work! It looks to me, according to this diagram, that all the ignition controls is the flashing lamp and doesn't actually switch from charging to running but if you got it to work, then excellent!

 

[KiwiEV]

I see what you mean. The main contactors (which aren't installed just yet) will feed off the ignition after running through this switching relay. By breaking the ignition, there's no way the contactors will get power to click.
The relay is one of those cool "turn one part off, the other turns on" and vice versa relays. I'm sure there's a technical term for it! So when the ignition that runs through the relay is broken, the power is switched to the little LED.

I'm about to finish my cup of tea, hit the garage and put it all in there!

 

[KiwiEV]

It works!
Or should I say, "It worked!"

Everythng's fine in the charging department. I'm currently charging my accessories battery from where the gas cap used to be. The turbo timer is doing it's thing, the relay breaks the ignition (that's so cool) and the flashing LED flashed for a while, then the light stopped completely.
Crap.
Everything else still works fine but I think I needed a resistor in front of the LED. It said the LED was rated at 3V-15V but I think it gets a surge every 5 minutes when the turbo timer quickly clicks on and off while charging. Either that or the LED gets power fed through the other direction somehow. That would kill it for sure.
So after that ordeal I now want to use a normal small 12v light bulb with a simple flashing circuit.
I'll have a look around but if anyone can help with a basic schematic and parts list I'll attempt to make one myself. Preferably not an LED as they're just too light & fluffy and I might just fry the next one!

 

[Adrian]

A resistor in series with your LED would definitely help. If your LED drops X volts, and can take Y mA of current, the resistor value should be:

(End of charge voltage - X) / Y

Typical values are (15V - 3V)/15mA = 800 Ohms. A 1K resistor would probably do the trick!

 

[Adrian]

One more issue:

If your charger is connected but not powered (blown fuse, popped circuit breaker, AC power failure, etc) then your blinking LED won't flash.

What you're really looking for is the safety interlock shown on page 17 of the Curtis Controller manual. You want a switch that opens when the charger is connected (via fuel door switch, extra contacts in the charger plug, etc.). This switch is placed in series with the car's key switch, preventing activation of the vehicle if the charger is connected.

 

[KiwiEV]

You're right on the money there. I noticed that problem and re-wired the LED straight to the input from the charger. That way it flashed whether the ignition switch was on (but circuit was open) or off.
I'll definitely get a 1k resistor and give it a shot! Cheers mate!

 

[KiwiEV]

A resistor in series with your LED would definitely help. If your LED drops X volts, and can take Y mA of current, the resistor value should be:

(End of charge voltage - X) / Y

Typical values are (15V - 3V)/15mA = 800 Ohms. A 1K resistor would probably do the trick!

Do you think I'd be able to use the standard flashing LED + a super-bright LED together in series? That way they'd both flash but nice and brightly in the dash?
Perhaps that would overload the flashing part of the first flashing LED?

How about if I try a 500k resistor, a flashing LED and a bright LED in series?
Or am I just getting carried away now?

 

[Adrian]

Can't hurt to try them in series. I'm not sure if it will work or not, but it won't hurt anything. You will have to change the series resistor to maintain proper LED current.

If that doesn't work you may have to use one of the flasher circuits from your other thread.

 

[kittydog42]

You would want to install the LED's in parallel. A LED needs a resistor because it is a fixed current device. Some LED's may have an internal resistor. Leaving out the resistor is almost like a dead short. Here is a good link to sizing resistors for LED's.

http://www.metku.net/index.html?sect=view&n=1&path=mods/ledcalc/index_eng

Also, for your charger interlock, get a flanged relay such as this one:

http://www.rsnewzealand.com/cgi-bin/bv/rswww/searchBrowseAction.do?N=0&Ntk=I18NAll&Ntt=376-903

I found a New Zealand supplier for you to make it easier. You would wire your 240VAC power to the coil of the relay (terminals A & B, not polarity sensitive), then wire your control circuit normally closed (terminals 11 & 12) to this relay. This relay will open the contacts whenever there is 240VAC present. You could then also use terminals 11 & 14 on the second set of contacts to power your charging LED.

Hope this helps you.

 

[Adrian]

Putting the LEDs in parallel will guarantee that one of them doesn't flash...

In series, the second (non flashing) LED will probably flash - depends on the guts of the flashing LED. If they're both red:

14V - fully charged car battery
2V - approximate red LED forward voltage drop
20mA = maximum desired LED current

14V - 2V (flashing LED) - 2V (other LED) = 10V
10V/20mA = 10/0.02 = 500 Ohms

Try them in series with a 500 Ohm resistor. They should both flash when powered.

 

[Adrian]

This relay will open the contacts whenever there is 240VAC present. You could then also use terminals 11 & 14 on the second set of contacts to power your charging LED.

Be careful with this arrangement. If your car is plugged in but the power is off (tripped breaker, bad plug, blackout) it will be possible to drive off with the car plugged in!

The safest route is to add a secondary interlock switch - something that can only be activated when the car is unplugged. If your charging plug is where the gas cap was, a switch in the fuel door works well.

A friend of mine has taken this one step further and attached wheel chocks to his charging cord. Plug in the car and block the wheels. If he forgets to unplug the car he still can't drive off

 

[rbgrn]

Have a look at kittydog42's diagram

http://www.flickr.com/photo_zoom.gne?id=1353737312&context=set-72157601920644694&size=o

 

[kittydog42]

I changed it a little. I rewired the DC-DC converter so that it is powered all the time from the traction pack, instead of only on ignition. This is because my charger safety solenoids draw 1.2 amps and were killing my accessory battery. I am also in the process of adding a Curtis 900R Batter Fuel Gauge.