12 volt accessory socket

[sas1]

The two 12 volt accessory sockets seem to share fuse 23 a 15a fuse behind the glovebox and not be independent 12v 120w each.

The rear 12v auxiliary battery seems to be charged at 4.5A max according to a note on the battery. So anything drawing more than 4,5 amps attached to the 12 volt battery would drain it flat.

I would like to put a 12 volt 20 amp accessory socket in the rear of the car to plug a 12 volt compressor fridge and other accessories in to.

Is there any where I can tap into to get an extra 20 amps at 12 volts dc without damaging the car.

With a normal car and battery, I would use a relay switched to the accessory switch on the ignition switch to provide the 12 volt fused line from the battery.

Can anyone help

 

[Regulo]

Can't help with your installation part, but you seem a bit confused over battery capacity as opposed to charging currents. The battery can store XX ampere/hours of electricity (say 100, can't be bothered to check!). So you could theoretically draw 1 Amp for 100 hours, or 10 Amps for 10 hours, or 100 amps for 1 hour. The 4.5 amps you refer to is the maximum charging current of the battery, to prevent damage to it internally. Any current drawn on the battery will drain it, but it's not limited to 4.5 Amps. Just make sure you fuse whatever you add, and use the correct rating of wiring. Good luck.

Edit: I think the PHEV battery isn't that great a capacity, so I'd be wary of taking too much out of it when stationary. But I think you know that, as you're experienced in fridge installations from before?

Edit, part 2, the sequel: Wish I'd read things before replying! I note the sockets have a 15 amp fuse - 15A x 12v = 180Watts (theoretical). Would that suffice?

 

[CJ1045]

No, the original poster is correct. If he has a device attached to the battery that draws 20A and the battery maximum charging current is 4.5A then at some point the battery will be flattened even if the car is charging the battery at full capacity. The length of time that happens will depend on the A/H the battery holds but it will happen. If the battery could be charged by the car with a charging current of 25A then the battery would never be flattened if the car was charging it.

CJ

 

[Regulo]

Would the car not take up the extra load by means of the traction battery, or ICE alternator? As in a normal ICE car? As you can see, I'm still relating the PHEV to my ICE car experience. Glad to be corrected. :|

PS: I've just read the auxilliary battery capacity is only 36Ah! That won't last long then, without some means of topping up. The manual is very sparse on info regarding this battery and where it's charged from while driving. Does the ICE have an alternator? Or is it topped up as necessary from the traction battery? Sorry to the OP for dragging this off topic. Perhaps I'll start a new thread.

 

[maby]

You really need to get expert advice before adding significant extra current drain to the 12V circuit. Unlike conventional cars that have beefy batteries and alternators to be able to source the cranking current for the starter motor, hybrids like the PHEV or Prius only have relatively low current 12V systems - all it is designed to do is to run the computers and lights. As has been noted, the 12V battery is quite low capacity and, while the generator is a beast of a thing compared with conventional alternators, it is producing a high voltage intended for driving the electric motors and charging the high voltage traction batteries. There is a down-converter that produces the 12V to charge the low voltage battery, but this will be sized for the design load - which is small. The car does not have a 12V alternator.

 

[user 258]

Hi,
Although the 12v battery is low capacity, and should only be charged at 4.5A maximum, it can float the charge from the traction battery and supply a much greater load without flattening the 12v battery. Heated seats normally draw 10A each, I would guess at about 10A for the heated window/mirrors, add to that the 15A from charge point plus MMCS plus all other 12v load and the car has been designed to power that lot without draining the 12v battery. That being said, there must be a maximum design power draw which might be a limiting factor. If the extra 20A is on a Gx3 then I'd say no worry as that is the same as the heated seats in the Gx4.
Kind regards,
Mark