DC-DC charger- which one?

It seems that you have missed the point of variable voltage alternators and fuel savings drivesafe.

The car's software determines when the battery has reached full state of charge. Once that happens then it will use some of the energy in the battery to help minimise fuel consumption. It will use some of the battery's energy when the car needs moderate to full power..It does this by turning down the alternator output and therfore using less fuel. Some of the battery power is used to run the cars electrical system at that time. At those times the voltage will cycle down to 12.2v for a period of time.

The car wont let it stay at that voltage long enough to drain the main baterry significantly. When you then coast, brake or go down a hill the voltage jumps back up to 13.8 or upto 15v to recharge the partially discharged battery. It is this cycling that saves fuel.

Its is the complexity of this software managed algorithm that i dont want to interfere with and my reason for using a DC/DC charger. I dont know what assumptions that software makes about the capacity of directly connected batteries. The low voltage at times also impacts VSRs with them open and closing constantly as the voltage varies.

Peter

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Originally Posted by RoverLander

The car's software determines when the battery has reached full state of charge.

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There's the rub - the software has a bug (maybe on just some cars) and is not just saving energy when the battery is fully charged.

Maybe Tata did the coding on the algorithm:wasntme:?

Hi Peter and I am well aware of how variable voltage alternators work, not just the LR version but for many types of other vehicles.

You obviously do not understand how and why variable voltage alternators systems are designed to work the way they do.

With any DC circuit, as you lower the voltage, "MOST" devices connected to the circuit, will lower their "CURRENT" demand.

So by lowering the voltage in a vehicle you lower the total current requirements of everything connected to the circuit.

If you lower the voltage output of the alternator to 12.2v, but you have a fully charged battery, you can not lower the circuit voltage below 12.7v without having to discharge the battery, and discharge the battery with VERY high currents.

To continually discharge a lead acid battery in conditions like what you are implying, will mean the battery is not only NEVER going to get to s fully charged state, it will progressively loose charge capacity and will eventually go flat over night.

This is exactly what has been happening with a large number of D4s, because they have a software problem, not because they are designed to DELIBERATELY operate at 12.2v.

Now for some more info for you.

DC/DC devices are one of only a few DC devices that do the opposite when the voltage is lowered. With a DC/DC device, to be able to maintain a constant output current, as the input voltage lowers, the DC/DC devices input current draw INCREASES.

So, if your misguided theory was correct and the D4 is deliberately designed to operate at 12.2v, then your DC/DC device would just accelerates the demise of your cranking battery.

Ford had the lowest operating voltage of 12.4v and had so much trouble that they raised the variable operating voltage but also allow the dealers to delete the operation altogether if a customer requests it removal.

Once again, the operating voltage of the D4 is not intended to be 12.2v, and those that are operating at that voltage are having problems with trying to charge their cranking battery.

Furthermore, as soon as the owners of these D4s, with the software problem, go to the dealers and get the software updated, their cranking batteries start charge properly on the drive home from the dealers.

Ok Tim, so it therefore shouldnt be too long before i have a flat cranking battery right? Any prediction on how long? I dont charge the battery with any other charger. If my cranking battery dies in the next 6 months then i am happy to concede that you have been right all along.

So far i have been going 3 months and 5000kms driving with cyclic 12.2v.

How long do I have before a battery failure?

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Originally Posted by THE BOOGER

If your saying your alternators were providing unregulated amperage? then they had a problem with the regulator, a properly working alt will not provide unregulated voltage or amperage.

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My agm's should not be charged at more than 20-25amps. Batteries depending on S of C can pull more than they are designed to be charged at, therefore control is needed to prolong life...alternator will not prevent that from occurring (Disco may be different but not going to change from my method that works)

Brett....

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Originally Posted by bacicat

Hi Brett, what sort of lifespan were you getting from your batteries before fitting the redarc? And - as a general question to anyone - what sort of life would you expect out of your batteries? Obviously how the battery is used and what SOC it is drawn down to between charges also plays a big factor here. Personally, I get around 5 to 8 years from a cranking battery, and the top shelf deep cycle i've got is now 3 years old.

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2-3 years max for deep cycle batteries. I have never replaced a starter, as I have always given the starters a regular tickle with a battery charger.

Current 5 deep cycle batteries are minimum 5 years of age. Disco battery is 5 years old now, having been removed from previous car.

Camper batteries are almost 7 years and have been in 3 campers.

Brett...

Peter as already pointed out numerous times, the cranking batteries in the D4s with the software problems are going flat in a few weeks, max, not 6 months.

Hi Brett, all batteries have a maximum throughput of energy over their life span, and it makes no difference how you charge them, if you are a heavy user of battery power, the batteries will die sooner, of natural causes, than someone who only draws small amounts of energy when they use them.

So Brett, first off and the most obvious observation is that you are not using much energy from each of your batteries, probably because of the large number of batteries, which is good, but what is the likely hood that you would be getting the same or better life span from all those batteries if you just charged them off your alternator?

Furthermore, if we compare advantages between the way DC/DC devices work and how my systems work, then my systems will have your batteries lasting as long, if not longer, because my systems look after batteries far better than any DC/DC device would have a hope of doing.

My systems offer advantages like spreading the the current draw load over more batteries, which means a low current load per battery, compared to your set up, and this helps to extend the life span.

And each battery will not need to be discharged as low as yours will, for the same amount of energy used. This also helps to extend the life span.

Because none of the batteries in my system are as discharged as low as yours, they will have a larger number of cycles over their life span.

Because none of the batteries in my system are as discharged as low as yours, they will reach a fuller charged state at the end of a days drive, meaning more battery capacity for the next stopover, again, meaning the batteries in my setup are likely to have a longer life span.

If on the other hand, unlike your low usage, if someone is a heavy user of battery power while camped, then while it is highly unlikely that they will drive long enough to fully recharge their batteries, with any system, but with my system, because of the above advantages over DC/DC type setups, you will will have the ALL the batteries in a much higher state of charge at the end of a days drive.

So Brett, while your setup may work for you, it is nowhere near as effective at recharging batteries while driving, when compared to one of my systems and it has cost you a hell of a lot more to set and costs you more to charge your batteries while driving.

Last but not least, you have a 2 year limited warranty, while I back my gear with a 5 year unconditional warranty.

Just one point.

Not all Dcdc chargers are constant current a fair number of them attempt to replicate the output of an alternator and aim for a fixed volt?ge. With a varying amps rate once they are able to achieve that voltage.


For the purpose of this discussion the discrepancy is almost moot but for the fact that they won't overcharge a battery for the same reason an alternator won't and if your trying to diagnose them and are tracing the amps flow they behave slightly differently

As an apples and oranges comparison. In the D2, hasn't been started in 6 weeks. Yellow top AGM, only ever alternator charged. Traxide USI-160 installed but only one battery ATM, voltage at battery 13.4v. Pretty sure starting will be no issue, I know it sits on 14.7 running and idling with all lights (incl 150w fyrlyts) fridge, UHF, stereo (200W x 4) etc still sits on 14.7v.

is the charging software in the ecu or the alternator?

would be possible to change to a "normal" alternator?