DC-DC charger- which one?

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Originally Posted by discotwinturbo

After being involved with 4WD's with duel battery systems for more than 35 years, I had always used bulk chargers.

Up until about 8 years ago I got tired of short life cycles with deep cycle batteries.

A client, a battery developer, told me the reason for my battery failures was due to uncontrolled amperage going into my deep cycle batteries, in particular agm's. I did swap to orbitals for a couple of years, but for my type of camping and touring they simply did not hold on as long as a larger capacity agm (for the same size).

My batteries were dying prematurely due to them sucking more current into them, then they were designer to draw...not so for the orbitals which could have current smashed in heavily.

I have had no battery failures since using my 20amp redarc, and use another redarc in my camper (actually last 3 campers).

I will never be swayed to go back to bulk chargers.

Brett...

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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. It's the first time i've bothered getting something decent as most of the time I have used old sealed lead acids that I get from work. Used to get 18 months to 2 years out of a half shagged one of those, but I used to dump them as soon as they showed signs of slowing down. I run a 38 litre Engel and a few lights off my system, and I've never seen voltages drop below 12.2 (no load) on my system, usually a lot higher, and most days when camping my solar panel can get them back to almost 100% most days unless it's crap weather - which is the only time the batteries drop below 12.4

Interested to hear everyones experience on this point.

I would expect a minimum of 4 to 5yrs Gav, although with the type of vehicles the D3/D4/RRS are, maybe 4 to 5yrs is about as long as you will get, our D4 is a July 2011 build, so it's coming up to 4yrs in July.

We are on our second battery in the camper, we got almost 8yrs from the first one, the camper is 11yrs old, so I would assume the same from the second one, I have not been relying on the DC-DC charger in the camper to keep it charged fully, it is charged at home before we go away, then when we stop, we pull the solar panel out to keep it charged, basically the DC-DC charger is just to have charge to the battery when travelling, I could just remove it really, as it's purpose is null and void and really serves no purpose now, our Traxide unit could do it better anyway.

I am fixing a few electrical items in the camper at the moment, I think I found another job to do this weekend:o

Baz.

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My batteries were dying prematurely due to them sucking more current into them, then they were designer to draw.

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The batteries only take what's delivered. They don't "suck"

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Originally Posted by clubagreenie

The batteries only take what's delivered. They don't "suck"

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i agree but you can "hurt" a battery by delivering charge when its full.
a common example is AA battery chargers that work on a static timer.


i dont believe an alternator works like this though

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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. It's the first time i've bothered getting something decent as most of the time I have used old sealed lead acids that I get from work. Used to get 18 months to 2 years out of a half shagged one of those, but I used to dump them as soon as they showed signs of slowing down. I run a 38 litre Engel and a few lights off my system, and I've never seen voltages drop below 12.2 (no load) on my system, usually a lot higher, and most days when camping my solar panel can get them back to almost 100% most days unless it's crap weather - which is the only time the batteries drop below 12.4

Interested to hear everyones experience on this point.

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Same here. Our 80 watt solar normally gets our camper battery charged by lunchtime at the latest. We had a lead acid deep cycle which eventually died and I've replaced it with a 110amp AGM, which seems to be a good thing so far.
The solar doesn't go through the DC-DC charger, which only becomes involved when the trailer is plugged into the vehicle and the engine is running.

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Originally Posted by Eevo

i agree but you can "hurt" a battery by delivering charge when its full.
a common example is AA battery chargers that work on a static timer.


i dont believe an alternator works like this though

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Correct. A DC-DC unit can hurt the battery, whereas the alternator can't by it's very design.

I have been following this thread with interest. It's actually turned out to have a lot of good explanations along the way for the inexperienced like me.

But I don't understand this one:confused:

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Originally Posted by bacicat

A DC-DC unit can hurt the battery

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I understood the earlier points regarding DC-DC devices being inefficient and in many cases not required. But this suggests there is more at stake? I have a Traxide DBS but I'd still like to understand this issue.

Cheers,
Scott

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Originally Posted by LRD414

I have been following this thread with interest. It's actually turned out to have a lot of good explanations along the way for the inexperienced like me.

But I don't understand this one:confused:


I understood the earlier points regarding DC-DC devices being inefficient and in many cases not required. But this suggests there is more at stake? I have a Traxide DBS but I'd still like to understand this issue.

Cheers,
Scott

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DC-DC chargers are constant current units, not constant voltage like an alternator. If the unit faults, or is set incorrectly, it can continue to push current into the battery, damaging it or even destroying it or setting it on fire - all of those things have happened In the past.

An alternator can't 'push' any current into a battery, so as the battery charges, its current draw drops off, eventually to 0. No chance of damage to the battery.

Just for information...I wont be replying to rebutals..

On recent visit to the dealer i asked the following:

Is it normal for a D4 to cycle down to 12.2v while driving?
A) yes absolutely.. Its part of the energy management and fuel efficiency drive. Its normal.

Do you change any software or settings when a second battery system is installed?
A) No. We have no ability to do that.

Do you install second battery systems and how?
A) yes but we will only install DC/DC charger systems.. ( yes i know they only do that so they can steal more of your money...right?)

Ohhh Can you calibrate my dodgy fuel consumption readings... Out by 10%.
A) no we dont have access to that part of the software in the car. Only Landrover Aust or Factory may be able to do that....

Anyway thats the information I have....

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Originally Posted by RoverLander

On recent visit to the dealer i asked the following:

Is it normal for a D4 to cycle down to 12.2v while driving?
A) yes absolutely.. Its part of the energy management and fuel efficiency drive. Its normal.

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Now does the dealer mean that this is the SET minimum operating voltage of a D4 or is because so many D4s have a fault in their operating system that it is BECOMING the norm to find D4s operating at 12.2v.

There is no way you can allow the alternator to drop to 12.2v at any time without causing the discharging of the battery.

Furthermore, to operate continually at 12.2v means that even a battery with full usable capacity available, the battery will never reach more than a 60% charge capacity, at best.

Plus continually charging a battery with only 12.2v, the battery will VERY QUICKLY loose the use of what capacity it has and will just simply go flat over night.

This is exactly what has been happening with the D4s that have had software problems. The alternator has been operating at 12.2v and the battery is not being charged and simply fails to hold a charge.

Even when periodically charged with a battery charger, the battery still goes flat in a very short time, and I am talking of time frames of a week or less.

A fully charged battery has a settled voltage of 12.7v, and if you fully charge a battery with a battery charger and then have an alternator operate at 12.2v, you will actually be flattening ( discharging ) the battery while you drive.

And no matter what the dealers "THINK", not even Land Rover can rewrite the laws of physics, ( even though they think they can ).

The MINIMUM CHARGE VOLTAGE for a 12v lead acid battery is 13.0v and even at this voltage level, if the battery is in a low state at the beginning of the drive, with an alternator voltage of just 13.0v, you would need to drive for at least 20 hours, WITH OUT STOPPING!