Site Search
Print Page Setup Profile Login
You have 4 items in your shopping cart
Section Image

Battery pack

Submitted: Tuesday, Nov 12, 2002 at 00:00

Blackie

When I plug a power pack (which came with my Waeco fridge) into my cig. lighter my ignition light immediatly comes on. Does my vehicle think its now on ? I presume that the power is now flowing into my vehicle. Is this likely to cause a problem? I guess if I left it like this it would eventually flatten the power pack. How can I prevent this?
Advertisement
ThreadID: 2352 Replies: 6
Views: 425 FollowUps: 7
This Thread has been Archived
Thread Summary
Thread Watch Back To Forum Alert Moderator FAQ
AnswerID: 8425   Submitted: Tuesday, Nov 12, 2002 at 00:00

OziExplorer replied:

The only way to prevent this happening, would be to put a small Bosch type mini-relay into the ingnition circuit, so when the ignition was switched off, it would disconnect/unlatch the relay and allow the contacts to go open circuit.

You could put a suitable size diode into the lighter circuit, however, this is not the preferable route, as a diode will drop the voltage .6 volt to your appliances and also to your battery that needs to be charged. .6 volt does not sound like much, but it is approximately 20% of the charge of your battery.
Reply 1 of 6
FollowupID: 4082   Submitted: Tuesday, Nov 12, 2002 at 00:00

Member - Nigel posted:

You'd have to think carefully about how a relay was wired up, as the voltage from the battery pack may keep the relay switched on after the ignition switch is turned off.
FollowUp 1 of 4
FollowupID: 4097   Submitted: Wednesday, Nov 13, 2002 at 00:00

Savvas posted:

Sorry to be a pedant...but 0.6v is only 5% of the nominal 12v charge. The effect should be minimal on the appliances and battery.
FollowUp 2 of 4
FollowupID: 4110   Submitted: Wednesday, Nov 13, 2002 at 00:00

Member - Nigel posted:

Savvas, do you run your battery down to 0 volts?

A battery is considered totally flat at 11.89 volts (with no load and rested for a while) and fully charged at 12.65 volts. That leaves a usable range of 0.76 volts - do you really want to lose 0.6 volts of that?

BTW those are the voltages quoted by the manufacturers.
FollowUp 3 of 4
FollowupID: 4111   Submitted: Wednesday, Nov 13, 2002 at 00:00

Oziexplorer posted:

Savvas a bit of research on the internet about the effects of .6 volt on a 12vDC automotive style lead acid battery will surprise you. My statement is perfectly correct about the percentage. What is more, that is on the conservative side, as the modern batteries it can be has high as 31%.
FollowUp 4 of 4
AnswerID: 8444   Submitted: Tuesday, Nov 12, 2002 at 00:00

Steve replied:

Blackie: what make of vehicle are you using/talking about ?
Reply 2 of 6
FollowupID: 4090   Submitted: Tuesday, Nov 12, 2002 at 00:00

Blackie posted:

Its an '88 RR EFI.
FollowUp 1 of 1
AnswerID: 8449   Submitted: Tuesday, Nov 12, 2002 at 00:00

Steve replied:

Sorry, no comments other than that I don't want to start a flame war !! other than that I reckon you will never solve the problems with that unit....
Reply 3 of 6
AnswerID: 8458   Submitted: Tuesday, Nov 12, 2002 at 00:00

Eric replied:

Blackie.
I am not familiar with RR ccts but every other vehicle has the lighter conected to the acc terminal of the ignition switch and there is no connection between acc and ign when the switch is off. I suggest you wire your lighter the same way or you will have a very flat power pack and possible damage to you electric fuel pump.
Eric.
Reply 4 of 6
Activities Index
Summer Refresh Treatment Summer Refresh Treatment
Blue Mountains - NSW
Imagine indulging in a full body exfoliation with our frangipani body polish, followed by a frangipa
Melbourne to Adelaide - 3 Day tour Melbourne to Adelaide - 3 Day tour
Adelaide - SA
Tour Great Ocean Road with a maximum of 12 passengers.
Team Building Dance Workshop (2 hrs) 10 people Team Building Dance Workshop (2 hrs) 10 peop
Sydney - NSW
Design your own 2 hour team building dance workshop for a fun way to fire up your friends or work co
ANZ Stadium Tours ANZ Stadium Tours
Sydney - NSW
Visit the place where legends are made - ANZ Stadium.
Book Now - Things To Do
AnswerID: 8461   Submitted: Wednesday, Nov 13, 2002 at 00:00

Savvas replied:

Blackie ... Excuse the dumb question here. Why are you plugging the waeco power pack into the cigarette lighter with the ignition turned off anyway?
Reply 5 of 6
AnswerID: 8462   Submitted: Wednesday, Nov 13, 2002 at 00:00

Savvas replied:

Oops...pressed submit too quickly.

I'd rig up a little adaptor between the power pack and the cigarette lighter that has an appropriate diode inline. This should prevent current flowing from the power pack back into the vehicle electrics, and you won't have to modify the vehicle wiring.

All you need is a cigarette lighter socket, cigarette lighter plug, some appropriately rated figure 8 wire, and an appropriate diode placed inline on the +ve wire. You could pick up all this stuff from Jaycar, Dick Smith, etc.
Reply 6 of 6
FollowupID: 4113   Submitted: Wednesday, Nov 13, 2002 at 00:00

Oziexplorer posted:

Savvas under *NO* (shouting from top of hill) would you want to use a diode between the battery and the cigarette lighter. You cannot afford to loose .6 volt. You would need a Schottky diode, and for one of the required capacity would cost to many dollars. Schottky diodes are not normally used over forward currents of 1 amp. However, even a Schottky diode would not satisfy me. Any charge loss is to much.

The battery will not get properly charged to peak voltage.
It is no big deal to put a Bosch type mini-relay directly from the ignition circuit.

Personally, I would much prefer to see a better quality polarised plug and socket to connect that battery to the vehicle to charge. Cigarette lighters are generally shockers.
FollowUp 1 of 2
FollowupID: 4126   Submitted: Thursday, Nov 14, 2002 at 00:00

Savvas posted:

Oziexplorer...I agree with you that cigarette lighters are shockers.

However, I must still be missing something here. I'm guessing that the power pack is plugged into the cigarette lighter to charge the power pack. Hence I would only do that when the vehicle is running and the alternator is charging. Therefore, I wouldn't expect either battery to go flat.

FollowUp 2 of 2