How does the 12v battery charges?

[GStam]

In my diesel car I have an alternator that charges the 12v battery. But how does it work in ours PHEV?

Is there also a 12v alternator besides the 300v on the engine?
Is there a 240v to 12v charger besides the 300v charger?
Is it charged via the main battery, 300v->12v?

I.e. is it possible to run out of power in the 12v battery if I run 100%in EV mode?

 

[GStam]

E-mailed a Product Manager at Mitsubishi motors.
He answered me, freely translated to English from Swedish.

“The 12v battery is charged by the driving battery during driving and during charging.”

For those of you who understand Swedish, here is his answer. The rest of you can use Google translate at you're own risk ....

-“ Det finns ingen separat generator som laddar 12V batteriet.
Det finns inte heller någon direkt matning från 230V till laddning av 12V batteriet.
12V batteriet underhållsladdas av drivbatteriet, dels under körning och dels vid laddning.

Du kan inte köra ”torsk” på drivbatteriet. Det finns en inbyggd säkerhetsmarginal som stänger av bilen när den når cirka 13% nivå. Återstående laddning är dels för att skydda livslängden på batteriet och dels för att kunna starta bilen igen när bilen åter igen fyllts på med bensin.

Bensinmotorn kommer mycket riktigt alltid starta när batterinivån blir låg (startar vid 26%). Bensinmotorn driver då generatorn och eventuellt bilen. Generatorn laddar högspänningsbatteriet med överskottsström och drivbatteriet ser till att det finns spänning 12V batteriet.

Om du skulle använder många 12V komponenter när bilen inte är i ”Ready”-läge så kan du tömma batteriet. Vid det tillfället krävs att du laddar batteriet eller kablar igång den med ex en annan bil.”

 

[Garrett]

Hi,

Pretty much correct. When the system is in "Ready" - mode, there is a transformer that charges the battery from the 300VDC drive battery.

However the dealer is incorrect on one thing. The 12V battery is not charged when the drive battery charge cable is connected.

So, if you leave a door open or lights on the car - you may drain your 12V battery even when your charging cable is connected. This will lead to a stupid situation. Your drive battery is full, but you cannot connect the power on, because you are out of 12V...

 

[ActionableMango]

Why is there a heavy lead acid battery in the first place? Why not just a 300V to 12V converter and run everything off the drive battery?

 

[jaapv]

Because the car must keep running / be able to start up with the auxiliary systems active, even if the main battery is exhausted and you are driving on the ICE only.

 

[Goldie]

E-mailed a Product Manager at Mitsubishi motors.
He answered me, freely translated to English from Swedish.

“The 12v battery is charged by the driving battery during driving and during charging.”

For those of you who understand Swedish, here is his answer. The rest of you can use Google translate at you're own risk ....

This was a very interesting thread about how the smaller/auxiliary battery is charged, so when I picked out my new Outlander PHEV yesterday (Friday), I asked the head tech guy about it.
The auxiliary battery is important as it is required to fire up the PHEV. If this battery is dead, PHEV will not start.
As well as the strong advice on not using the PHEV to jump start any other vehicle as you would fry your electrics, he did say you could jump start the PHEV though and showed me the contact points.
As to the auxiliary battery: there is an On Board Charger (OBC)/DC-DC converter. This DC-DC converter decreases the high voltage of the drive battery to approximately 14 V to charges the auxiliary battery as required.
Goldie
Outlander PHEV owner
Victoria Australia

 

[nlkruigerm]

Please also see the other discussion on the subject that I posted on the 12V drain problem.
That the 12V battery is not charged when plugged in to the charger is new to me. I did not even know that the 12V battery needed re-charging frequently. So how about stopping with a drained 300V battery? it wil not be able to charge the 12V anymore?
In trust my wife's 10 year old Kia Rio better regarding reliability........I just used it's very old and corroded battery again the jump start the PHEV......

 

[maby]

Because the car must keep running / be able to start up with the auxiliary systems active, even if the main battery is exhausted and you are driving on the ICE only.

I'm not sure that makes any sense, you know. The PHEV does not have a 12V starter motor and, even if it did, the 12V battery is not man enough to start the car. The control circuits do not allow the traction battery to go totally flat - the lower limit is believed to be about 20% charge. The ICE is not going to start with a genuinely flat traction battery and the car will not be going anywhere.

I think the justification for having the 12V system is to protect the traction battery when the car is powered down. If it drew its standby current from the traction battery, there would be a risk of depleting that and, once it is flat, there is no question of a quick jump-start. With the actual design, the 12V battery can go flat with no disastrous impact - it can be jump started from any car or from a small portable battery. In the worst case, if the 12V battery is physically damaged by excess discharge, a replacement will cost a few tens of pounds rather than the thousands of pounds estimated for the traction battery.

 

[nlkruigerm]

Well, just got the car back again after some problem with the software, I kept on have the motor management light on. Meanwhile the problem of a drained 12V battery persists and garage also changed a relais of the towbar. Just measured this morning and guess what: still I'm loosing 0,5V over 12hrs, meaning still draining quickly. (Started at 12,6V now at 11,9V)
As far as I can measure the program to maintain the 12V battery by means of the drive battery does not work, all I can measure is a steady drop in voltage, no refreshment at all. I have the car not connected to the charge unit.
How should this program work and how can I check if this program is active in this car (program version maybe?)

 

[maby]

Well, just got the car back again after some problem with the software, I kept on have the motor management light on. Meanwhile the problem of a drained 12V battery persists and garage also changed a relais of the towbar. Just measured this morning and guess what: still I'm loosing 0,5V over 12hrs, meaning still draining quickly. (Started at 12,6V now at 11,9V)
As far as I can measure the program to maintain the 12V battery by means of the drive battery does not work, all I can measure is a steady drop in voltage, no refreshment at all. I have the car not connected to the charge unit.
How should this program work and how can I check if this program is active in this car (program version maybe?)

Is the voltage drop continuous? If you leave the car unused for 24 hours, has it dropped a whole volt? Lead acid batteries do drop their output voltage quite a lot in the first hour or so after the charging current is removed, but should then stabilise and hold their charge for many weeks.

 

[Lyra252]

Looks like this would be handy

http://www.ebay.co.uk/itm/Digital-12V-24V-LED-Car-Cigarette-Socket-Voltmeter-Voltage-Battery-Tester-/310908050329?pt=UK_CarsParts_Vehicles_CarParts_SM&hash=item4863905b99#ht_1385wt_1199

£3.49

Chris

 

[jaapv]

The car is supposed to recharge the 12V battery during use and when not, once a day. Have that checked out, it would not be the first time.
Note that alarm systems can cause battery drain, as can WiFi.

 

[t3lmo]

When the car is stopped, the main battery will charge the 12v auxiliary one, every day at 2 pm, but only if the car is plugged in.
There will be some beep noises inside that will turn off when the door is open.

 

[HHL]

Well, just got the car back again after some problem with the software, I kept on have the motor management light on. Meanwhile the problem of a drained 12V battery persists and garage also changed a relais of the towbar. Just measured this morning and guess what: still I'm loosing 0,5V over 12hrs, meaning still draining quickly. (Started at 12,6V now at 11,9V)
As far as I can measure the program to maintain the 12V battery by means of the drive battery does not work, all I can measure is a steady drop in voltage, no refreshment at all. I have the car not connected to the charge unit.
How should this program work and how can I check if this program is active in this car (program version maybe?)

Is the voltage drop continuous? If you leave the car unused for 24 hours, has it dropped a whole volt? Lead acid batteries do drop their output voltage quite a lot in the first hour or so after the charging current is removed, but should then stabilise and hold their charge for many weeks.

It should really not drop below 12.5 just sitting there overnight. There was one other comment about the charging. It definitely charges the aux battery while it is plugged in. I have fitted a voltage controlled relay to power a radio. This turns on when the voltage is above 12.8 and it always comes on when the charge cable is plugged in and power is available.

You can easily check the current draw by just using a clamp meter on the negative lead, which is readily accessible from the cover in the boot. It will draw about 4A while it is in accessory mode, and briefly increase to over 10A when the ready mode is selected, before charging commences.

When the car is powered off, there is negligible draw on the aux battery.

 

[anko]

.., but only if the car is plugged in...

Can I ask, how do you know?

 

[Sunder]

Can I ask if anyone knows how big the 12v charger is? I'm thinking of hooking up an inverter directly (fused) to the 12v battery for short bursts of high power. My dad has an off grid farm. We usually just bring a couple deep cycle batteries charged from home, but if the PHEV charger is small, I could charge the deep cycles there. If he charger was large, I could probably do away wih the deep cycles all togeher and just run it straight from the auxillary battery.

I think I heard someone say it was 100a, which would br fantastic (1200w inverter would be possible.) But I can't confirm that and it seems a tad large to me.

 

[jaapv]

I'm a bit lost here. Outside Japan you cannot run power off the car main battery. If you try and draw any serious amount of electricity off the 12 V battery, you will drain it double-quick, as it is considerably smaller than a normal car battery, as it does not have to turn a starter motor.
I suppose that the internal 12 V charging circuits are not built for high power drain either, as there is no need.

 

[HHL]

I'm a bit lost here. Outside Japan you cannot run power off the car main battery. If you try and draw any serious amount of electricity off the 12 V battery, you will drain it double-quick, as it is considerably smaller than a normal car battery, as it does not have to turn a starter motor.
I suppose that the internal 12 V charging circuits are not built for high power drain either, as there is no need.

I wouldn't expect it to be able to charge at much more than 10A. The battery is only 35Ah. It is sealed, possibly a deep cycle battery.
Seeing that it is not used for high current starting and it is not in a hot area, one would expect it to last a long time.
The periodic charging that happens when the car is not used is only enabled in the models with the wi-fi remote.

 

[Sunder]

I'm a bit lost here. Outside Japan you cannot run power off the car main battery. If you try and draw any serious amount of electricity off the 12 V battery, you will drain it double-quick, as it is considerably smaller than a normal car battery, as it does not have to turn a starter motor.
I suppose that the internal 12 V charging circuits are not built for high power drain either, as there is no need.

I wasn't expecting to convert off the traction battery, or run solely off the 12v. I think it's only 36ah, compared to most cars which have a 80-120ah battery. (Though I was thinking of beefing it up to around 90Ah using LiFePo4 cells).

Before I bought the car, I did a bit research. And while I came to the same conclusion as you did, there was one post on a forum (don't think it was this one), that said because the two power sockets were 10A each or 15A total, plus the heated seats (10A each), window demisters (10A), Plus all the other 12v electrics (headlights, fuel pump, igniters, computer, wifi, etc) added up to so much, Mitsubishi had to account for every one of them to be on at once without draining the auxiliary battery, and so installed a 100amp 300->12v down converter.

I don't know if 100A is realistic, but there's no way it's only 10A: If that was the case we couldn't run the headlights and anything else at the same time without killing the battery. Of course, I could be wrong - It's possible all this stuff runs directly off the traction battery - but that wouldn't make sense to me from a manufacturing point of view - they could have the pick of OEM and third party 12v devices manufactured in bulk and common between all Outlanders, if not multiple model of cars. Or they could build their own to run off 300v. I know which one makes more commercial sense.

 

[Sunder]

Unless someone comes up with a solid answer in the next week or so, I think what I'll do is measure the battery voltage, and apply a 10A load to it for an hour, then measure the voltage again. If it doesn't drop, then we know the charger is at least 10amp.

I'll then apply a 20A load and repeat, until at some point I can see the voltage drop. At that point, we know that the charging circuit is less than that size.

I'll post the results up here if I can. Unfortunately, all my inverters are up at the farm, and I'm not going up for another two weeks.