peterdambier
Posts: 284
Joined: Thu Oct 04, 2012 3:26 am
Location: Bergstrasse, Germany

12V Battery and Charger

Mon Dec 03, 2012 3:04 am

Does the 12V battery get charged or not?

Now I can tell you for sure it gets charged when you plug in.

I modified a 12V 3/5 A charger (3A really, 5A eff) so I can plug it into the socket in the cockpit. No need to stay in the rain when experimenting.

When I switch to "ACC" the socket contacts and the battery draws same 2.5A. Switching to "READY" current drops to very little.

"ACC" again when I plug in current drops as well but the relays clicking inside the EVSE sound differently.

It still makes sense to have a 12V charger, just in case because I am told one of the few problems electric cars have is a dead 12V battery that even prevents you even from plugging in.
Peter and Karin Dambier, DL2FBA, www.piraten-fraktion-bergstrasse.de

MLucas
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Re: 12V Battery and Charger

Mon Dec 03, 2012 7:44 am

Yes, the 12v battery is charged during the charging process and while driving using the onbaord DC to DC convertor. Voltage is taken from the traction battery of 330v and converted to 12v to keep your battery topped up. It is true that if the 12v battery goes dead, you will not be able start or charge the vehicle at all. Jumper cables or a 12v charger will be necessary to get the 12v battery going again.

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Don
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Re: 12V Battery and Charger

Mon Dec 03, 2012 8:50 am

peterdambier wrote:Does the 12V battery get charged or not?

Yes, it does - The 'proof' is below

When I switch to "ACC" the socket contacts and the battery draws same 2.5A. Switching to "READY" current drops to very little.
When you switch to 'ACC' all of the accessories in the car are running off the 12 volt battery, or in this case, your battery charger. When you switch to 'READY' the cars onboard DC to DC converter switches on and THAT provides all the 12 volt power, both to run everything and to charge the 12 volt battery, so the current on your battery charger drops to nil. The 12 volt battery is also charged when the car is plugged into the EVSE

Don
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Lithim
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Re: 12V Battery and Charger

Mon Feb 11, 2013 6:12 pm

Owners manual suggests removing the 12v battery to charge/jump.
Does anyone know the reason for this?

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PV1
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Re: 12V Battery and Charger

Mon Feb 11, 2013 7:16 pm

The book says that because there is a risk that a surge can travel the lines and damage electronics on the 12 volt system. It's not necessary, but recommended.
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Vike
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Re: 12V Battery and Charger

Mon Feb 11, 2013 11:29 pm

PV1 wrote:The book says that because there is a risk that a surge can travel the lines and damage electronics on the 12 volt system. It's not necessary, but recommended.
Not to argue with the manual, but that does sound kind of paranoid. Wouldn't "jumping" any car run the same risk? They all have 12V systems, after all.
2012 Silver ES w/QuickCharge+DRL/foglights, Eaton Level 2 EVSE, since 9/9/2012

peterdambier
Posts: 284
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Location: Bergstrasse, Germany

Re: 12V Battery and Charger

Tue Feb 12, 2013 1:50 am

The 12V system: Cars, trucks, boats, airplanes, expeditions, spacestation, hamradio, ... has grown out of and independent from the old ICE car.

There has come so much out of that 12V system that we cannot live without it.

Growing bigger we got current problems. We pushed up voltage to reduce amperes. Cars and trucks and airplanes with 24V, even radio with 24V but they split the battery to allow 12V to coexist and created a big problem. 36V boats and 48V industry automation increased the pile but with dc-dc converters solved part of the problem. the 12V system is now isolated and the higher voltage battery is untapped.

The 12V system mutated into a universal problem solver, growing independent from whatever was feeding it and running from its own 12V battery.

Silently a 120V dc system evolved. You can use much of your 120V ac stuff with 120V dc. For some gear little adaptation to dc is needed but can easily be done. The heart of everything still is an internal 12V dc system evolved from the old ICE car and with a heart of lead more often than not.

With the i-MiEV for the electronics the 12V dc system is still the heart and it works even with the HV disconnected. It is actually what connects the HV in the first place.

When you disconnect the 12V dc the turtle looses all her memory. She no longer knows whether the battery is full or empty. She assumes it is somewhere in the middle and she needs to get to the point where the 2 lower bars are blinking to recalibrate.

There is no need for jump starting like in an ICE car. We do not need to turn a krank. As soon as we feed a little power through the lighter socket, key in ACC position, the battery and 12V system wake up. There are lots of 12V to 12V lighter socket cables available. You cannot jump start an ICE car from them but an i-MiEV you actually can.

I have seen so many silly people recently who were inviting disaster when connecting 2 cars by connecting the 2 batteries. There is an old rule (12V minus ground system) connect the 2 plus poles with one cable first. Now take a deep breath and think again. Do the cables stay fixed, unmoving? When you really feel like it connect the grounds with another cable.

Unplug the ground first and on both sides! Unplugging the plus cannot do harm now.

Simple rule. Is it really necessary - I am a hamradio operator after all and know what I am doing? Yes it is. You cannot imagine what can go wrong and how silly people including me, can be. A short can wreck both cars!

Those lighter socket to lighter socket cables have fuses on both ends and the are big enough for us even to "jump start". A modified 12V charger can do too. Just replace the alligators with a cigarette lighter plug. As soon as you switch the key from ACC to ready the builtin DC-DC will do the rest for you and now you can use your EVSE again.
Peter and Karin Dambier, DL2FBA, www.piraten-fraktion-bergstrasse.de

Llecentaur
Posts: 240
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Re: 12V Battery and Charger

Tue Feb 12, 2013 2:42 am

Peter thank you for the information, one can never be carefull enough...

Don't you guys think we should find out other Lipo or LiFepo4 to replace the original battery ? They would be lighter and more amps?

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