GQ Altenator Q?

[oondy]

While away I thought I may have had some charging system issues, turns out my Exide ED5 is a hybrid content battery and needs 15.5V to charge it properly, the same with my main battery, Exide Stowaway ST620, but thats another story.

Since I thought I had issues I went hunting this morning.

Now I have a Diode Isolator (anode of two Diodes are connected to the Altenator output and the cathode of each diode is connected to each of my batteries.

Now I have my ED5 out of the car to charge it properly with the Gammatron GM205 battery charger. Now with both battery cables disconnected from my isolator, i still measure ~12.6V on each of the isolator battery posts, so I measure the altenator post, yup, ~12.65V.

Do the Nissan altenators have some sort of storage/filter capacitor in the regulator part of the altenator?

cheers

OONDY

[TonyH]

Cracks Knuckles.....

Oondy. If you are using a diode isolator, you will need to change batteries or the isolator. An isolator takes 0.5 volts from any power passed through it. So you're loosing half a volt to each battery below what your alternator is pumping out.

If you want your alternator to pump out and extra half a volt, simply add a diode into the circuit that runs from the charging output of the alternator (the one with the nut and thick white wire) to the voltage output sensing wire (the thick white wire that goes into the alternator via the plastic clip block connector thingy).

Welcome to a whole new world of pain. I destroyed three alternators over about two years in my old wagon, trying to make it put out enough volts to charge one of them stupid mongrel bastard deep cycle batteries. (They also need a higher voltage to charge effectively).

I don't love deep cycles (could you tell??) So now I use marine batteries. They have plate-lock technology for vibration and jumping resistance, and they have a semi-deepcycle capacity without the need for stupid charging rates to top them up. Given that they are still a cranking battery with low internal resistance, they charge up very quickly (as opposed to those other types of battery which have a high internal resistance and take ages to charge). The benfit of running marine batteries is that if you do run your batteries flat, you don't have to drive to Darwin and back to charge them up.

I run three marine batteries and once they can't run the fridge anymore, a one or two hour drive sees them charged enough to run the fridge for the next night (depending on ambient temperatures of course).

So I don't know if the Datto alternator has a flux capacitor, but I do know it will struggle to do what you want it to do.
I'm guessing you're running a deisel, hence, the alternator has the vacuum pump attached to it? If not, save yourself a heap of time money and heartache, and retrofit to a big kick ass 100 amp alternator, and see about getting an adjutable external regulator maybe???

Good Luck

Tony

[oondy]

Thanks for that TonyH.

Now...I work at Gammatron, designing Battery chargers......and work pretty close with the Chemist at Exide...greg the greek....he tells me that the exide marine and deep cycle batteries are a hybrid battery to and that they need the higher voltages of 15+ to charge them right.

After charging my ED5 with my fandangled charger - the SG of the electrolyte is back upto 1.3 from below 1.2. Next I'll check the SG of my Marine ST620, don't think it will be as low as my ED5 was but I suspect it will be around the 1.23-1.25 mark.

In my isolator that I built, I used some good Schottkey diodes which only have 0.3V drop across them.

any way...back to my initial Q....I think I'm seeing a high impedance voltage on the Alt output which is feeding back through the charge light circuit - I'm only guessing here though.

cheers

OONDY

[TonyH]

The marines have charged well and been very reliable since I started using them about 4 years ago, and I haven't blown an alternator since (touch wood). So it's got me stuffed what's was causing my drama's when using the deep cycle now. Perhaps they need a charge voltage in between that of the cranker and the deep cycle??? As I have noticed a definate difference in fridge running capacity, and if you knew how much I love maybe one or 20 beers, you'd understand my attention to these things hehe.

Seriously though, running the standard alternator, in my case, was never sufficient to charge the deep cycle battery, even when I only had a dual set-up, no matter how I tweaked the alternator. Some things worked, but always at the cost of alternator reliability. And they ain't cheap.

[Peter @ Aawen4x4]

Come and check out that alternator I'm holding for you Andy!! I think that you are talking about the same issues that saw me modding (well, getting it modded) the alternator to resolve them. And I think it did, too!

[sudso]

Now I have my ED5 out of the car to charge it properly with the Gammatron GM205 battery charger. Now with both battery cables disconnected from my isolator, i still measure ~12.6V on each of the isolator battery posts, so I measure the altenator post, yup, ~12.65V.

Do the Nissan altenators have some sort of storage/filter capacitor in the regulator part of the altenator?

cheers

OONDYDo you have any accessories wired up that might store voltage? I had the same thing on my dual battery solenoid/isolator (cables disconnected from the batteries but still read 12.2 volts across the aux battery cables. I unplugged the portable fluro in the back and presto! Voltage gone!

[oondy]

The only thing still connected to the 2nd battery terminal is the wireless and cb's. The wireless gets constant power from the aux battery but the 12v acc wire comes from the main battery. But with the ign turned off (no radio) I still get the voltage on the altenator output post.....hmmmm.....think its just a high impedance voltage source that I'm seeing though. I put a about a 2A load from it to the chassis and the voltage went to 0V, which suggests it's probably a voltage seen through the charge light on the dash me thinks.

cheers

OONDY

[TonyH]

If you mean you get that voltage on the alternator output when it's got nothing connected to it, then it must be a back feed through the excitation circuit. There is a filter, it's external though, and I think it's in a brown connector (can't remember, I took mine off ages ago).

It's a bit rough, but you could drop test the circuit by earthing it via a dead short. Two things may happen, you may blow the charge fuse - proving it's a feed from the charge light, or two, the charge light will illuminate in the dash - also proving that's where your volts are coming from.

Unless you have something drawing a major amperage, there;s no way that voltage could be induced in an automotive system.

Did you notice if the charge light lit up when you fitted the two amp load to earth? I reckon it may have. Although the volts could still be coming from the excitation circuit, without activating the charge light.....

[RanOx]

Gents,
We have developed a booster to fully charge batteries such as these deep cycle, which need more than the alternator output. It is mainly designed for caravan/camper applications, but it certainly would overcome your problems, without requiring ANY alternator mods. It acts as a dual battery isolator, which can BOOST (up to 15V @ 25A) alternator output. It is fully adjustable (0.1V and 1A steps), with optional temperature monitoring/compensation for the auxialliary battery. LCD and LEDs give full voltage and current details. In effect, better than a sophisticated mains charger, but runs from DC input (nominally 10 > 15 Volt @ 30 Amp.) See our web site "ranox.com.au" for more information. As far as we know, there is nothing else that compares to its abilities. The RanOx team.

[TonyH]

Hey yeah, a step up transformer. That's clever!