Thread: 12 volt power efficiency.....

The quite expensive one they bought at work is a POS that wont even start a Vanguard V twin petrol engine let alone a car.

It cost about $400 and is yellow and black and quite big and heavy but if the engine doesnt start the first couple of times round then it's useless.

I have got rid of the tiny transformer that came with it to charge it as it had no over charge protection and now plug it into the normal battery charger and it has made a small amount of difference but not much.

I returned it once because they said it must have been not working properly and they told me that we had over charged it and ruined the battery but it said in the instructions that it should stay plugged into the mains unless needed so thats what we were doing.

They replaced the battery but said it wouldnt be covered by warrenty again.

It is good for running a spot light for about 15 to 20mins though but I wouldnt recomend them to anyone.

There is no way that this one would have a chance to start a Disco, V8 or Diesel It wont start any of my 3 cyl NA kubota diesels, will hardly crank them over.

Buy the way, it was purchased through my mobile tool supplier whom no longer deals with them after the trouble he had getting warrenty through them.

Completely useless.

For all the cost why not just fit a dual battery and solar panel. No drawing from the main and tops it up all the time, even when your sitting at camp?

Like others have said I can't see any gain, just loss over using the alternator.

We bought a small battery pack from whitworths marine. 17amp pack and charger which we use for running lights etc around camp (fridge stays in car) works a treat for us as we don't tend to be camped long in the one place. About $60 on sale when we got it and a lot more compact than the jump start style. Even came with a carry pack

Originally Posted by Feral

OK, this is all good but I am not convinced either way yet

Originally Posted by Captain_Rightfoot

Well, I'm not sure I understand what the issues are here. However I just installed a second battery and one of drivesafes systems. We just had a 5 week trip, with our fridge and camping gear running off the aux. The beauty of this system is I didn't think about it for 5 weeks... it just worked. How good is that.

Ok, Ok, I hear you...I am now convinced

I have installed the dual battery using one of drivesafes systems.

Here are some specifications if others would like to install into a D2.

The controller is attached at the end of the fuse box. This position was really the only place to put it that was high in the engine bay and allow the cables to flow through to either end of the D2. The cable used is 18.8mm sq. from main battery to auxiliary battery via a SC 40 controller.

The position of the auxiliary battery is in the drivers side storage bin. Originally I was going to have it in the passenger side but my main objective was to have the battery to be fully charged as quickly as possible. The length and voltage drop would be less as the cables only runs along the drivers side.

The wiring after the auxiliary battery is all 10mm sq. At this stage it powers an Engel 40L fridge, the standard accessory plug in the cargo area and the jayco van. This is run via an Anderson plug and it will only be for the fridge when driving.

The Fullriver AGM HGL 120 a/h sits nicely in the storage bin and allows us to have the liner in its original position. When everything is in and the lid closed, you do not see evidence of a dual battery.


Here are some pics.....

http://www.aulro.com/app/showfull.php?photo=6543

http://www.aulro.com/app/showfull.php?photo=6542

Installing the positive and negative cable underneath was just as intense as some of our deliberations on this subject

This has been lifted from the D3 Zone about Dual Battery problems......




Quote:
Originally Posted by drivesafe
Hi jik22 and discomaniac, I’m pretty sure you won’t have any problems with my gear but I am just following up on info that has come to me from a number of different sources.

What’s happening and because of the situation where it happens, my units, because of the way they work, should not be effected but this is what’s occurring and it occurring at the worst possible time.

The vehicle is started in the morning and as it is starting cold, the charge voltage quickly rises to around the 14 volt mark. This is well and truly high enough to turn on any battery isolator. Alls well so far.

Your off on your holidays and drive for a few hours then stop for fuel or a break.

After the break, ( during which time, most battery isolators have cut out because the motor wasn't running ) you start the motor and off you go.

Here’s where the problem is occurring, because the motor is still hot, once the motor is running, the voltage in the newer D3s is not rising much over 13.2 volts which means the other battery isolators are not cutting in again and the auxiliary battery is actually being discharged by the fridge and what ever else may be drawing power from it instead of getting power from the alternator.

The end result is that when you get to your days destination, your auxiliary battery is anything but charge up.

The reason for posting this thread is to try to get as much info as I can on this situation.

BTW a similar problem is also effecting auxiliary battery charging it new Toyota cruises.

Cheers.



Feral's response....

Although I own a D2, this is exactly how things are happening with my auxiliary battery setup.

I have gone overkill on wiring - 18mmsq. using a Traxide SC40 coupled to a Fullriver 120amp/h.

I have a newish battery - 1.5 years - new 120amp alternator and the whole system does not work efficiently.

I have had my discussion with "12 volt power efficiency" and I am over it.

Why?

Just a couple of questions....

What voltage does a battery need to charge? = 13.8 or more.

What voltage should your alternator put out to charge that battery? = 13.8 or more.


Has anyone heard of this....lifted from a caravan site...

"To get heaps of current into a battery you need to supply it with 14.5 V or higher. Most vehicle alternators will not produce this sort of output when the motor is warmed up (due to alternator temperature compensation.) So the battery will not absorb the full current output available from a vehicle alternator."


The guy's user name is DiscoPeter....whats the chance he owns a Discovery?

Why is my Commorore VT 2000 model has a voltage of 14.2 at the battery yet my D2 has 12.8 - 13.6 at the battery which is all dependent on the temperature. The only time I have seen 14 plus volts was when it was about 1 degree and that was at the cig lighter!

I have just been through to Alice Springs and the whole auxiliary battery set up was a disaster. Even after driving for 6 hours the aux. battery would be reading 12.4 at best. How long do you think the battery would last just running the Engel fridge. It lasted less than 4 hours before the cutout tripped out at 11.6 which means the aux battery is technically flat i.e after this point you are damaging the battery.

As you could possibly tell I am totally frustrated with this whole project. I have collected my research and the finding with my experience firmly confirm you cannot fully charge a battery (100%) by using your altenator. There are too many computers controlling the current for it to charge.

Over to you.


Drivesafe Reply.......

Hi Feral, you need to get voltage regulator/alternator checked because ( excluding the D3 ) all vehicles MUST produce no less than 13.8 volts or the battery(s) will never fully charge.

The average voltage of most vehicles is 14 to 14.2, for yours to be running at as low as 12.8, there is something seriously wrong with your alternator.

Being a new one, the voltage reg is probably built in and if it is new then it should still be under warranty.

By the way, although wet cell batteries can be safely charged with up to 14.7 volts, most AGM batteries will not tolerate that high a charging voltage so if you alternator can be adjusted, keep the maximum voltage to about 14.4 volts. This will resolve your charging problems.

One more point, it is nothing more than a myth regarding not being able to fully charge an automotive battery using an alternator IF the alternator is working properly and yours is not.

Cheers
Drivesafe.



Now this is my position.

This problem is well known and has been a discussion for some time. There is nothing wrong with the Traxide system so don't get me wrong on that. Drivesafe has been very helpful and I do not hold him accountable for anything.

It's the theory.

I now am the proud owner of two alternators that give a charge of anywhere between 12.8 - 13.6 - 14.1 volts. At $700 a pop how many alternators would you like me to try before I get a satisfactory charge to the auxiliary battery. I am losing only .2 volts through the Traxide system so there is no reason to look at that.

What I would like to know is the exact working description of a D2 alternator. Is it as what has been said previously that it is temperature compensated?
The alternator most like will output at 14+ volts but only for a brief period and this just replenishes what has been taken out from starting, etc. After this it just idles along i.e 12.8 - 13.6 volts.


Like I said, I am totally lost on this issue..over it.

With this information I do not believe that a D2 alternator will show constant 14+ volts forever for it to charge an auxiliary battery. And this is what you need to charge a battery efficiently.


Leave it with you.

I got one of the cheapy kmart ones... AS a jump pack its a WOFTAM... (although when the wifes astra struggled to start (couple of turns then the dreaded tickticktcik of the solenoid) it did have enough in it to turn that over

as a portable light, 12v source for the air pumps I use for inflating air mattresses and a weight for the corner of the tent its GOLD, I didnt pay full price for it tho I got it from the broken goods trolly. Its even got a little aircompressor built in thats not much chop on the internal battery but if hooked up to the main battery via the jumper cables actually makes the advertised 120PSI...

Well ive got a projecta jump start pack this one here http://www.projecta.com.au/catalogue...6/asset_id/60/

Its great tho the battery in it has had a hard life and could do with replacement it will start most cars and 4x4's no probs if its fully charged and i mainly use it to run a couple of 2 foot fluros at camp and the pump for the airbeds and it will go for 3 nights running 2 fluros its great ive had it about 4years or more now cost me 100 buck and has saved my ass and many others plenty of times anyone who bags em must be using the cheap cr@py ones as ive had a great run from this one and no complaints

Originally Posted by Feral

I am losing only .2 volts through the Traxide system so there is no reason to look at that.

Hi Feral, first off there should be no voltage drop through my unit.

One thing that could cause this is that your alternator is just not putting out enough current and because the auxiliary battery is low, there is a voltage drop being created across the system, from the alternator to the auxiliary battery.

Try removing the NEGATIVE terminal from your auxiliary battery, leave the positive terminal in place.

Then, with the motor warmed up and running, try measuring the voltage at your cranking battery.

You haven’t posted what type of cranking battery you are using. I will presume it is a wet cell ( correct me if otherwise ) Even if your cranking battery is low, the very maximum a wet cell type battery draws is 25 amps so your alternator should easily handle this load and you should have at least 14 volts coming from your alternator.

If you don’t then the alternator is definitely the problem.

Start there at let me know what you find.

Cheers.

One more question Feral, how often do you drive the vehicle and when you do drive it, how long do you drive it.

Cheers