Thread: DC/DC chargers, How do they work and do you really need one.

SOC - thanks Ferret, trout and Dave - that's whats so great about this site - I've learnt so much over the years it scares me to think I ever had the nerve to pick up a spanner before joining (although I must admit I used to nearly always have spares nuts and bolts after working on an engine)

Originally Posted by incisor

State Of Charge as i under stand it

Good quotes in your signature Dave - looks like all the pollies follow Hitler and a very profound one from Anne Deveson - I never realised she was older than my parents but I guess we keep thinking of how people were back in their heyday.
cheers Gerald

Originally Posted by DeanoH

As you say Tim a learning experience for all concerned, similar problems can occur when mixing old and new batterys or lead acids with different chemistrys................

Deano

I've posted this before............. I have a Redarc VSR 80 (or similar) from memory that was installed about 15 years ago during a major reno of my POS.

Cranking battery was a Willow wet cell thing a couple of years old, and the aux was a new Exide wet cell with matching specs.

Over a couple of years the Exide deteriorated to nothing,even though it was only connected to earth and the Redarc.

(The Willow lasted for about 10 years from memory.)

A bit of ferreting showed that the Redarc manual for that time was saying that both batteries should really be identical.

The online version these days says something like 'should be of similar characteristics'.

My POS still has the same system with two old fashioned Willow batteries and has performed flawlessly for at least 5 years.

cheers, DL

@drivesafe (and others that pointed this out) the demo IS biased but it serves the purpose of demonstrating. My experience with mercedes (bosch) alternators on the venerable OM617 installed in boats down here got way to hot spinning in a warm engine room with no airflow. I do believe that -most- car alternators would cool sufficiently. All I'm saying I guess is: there are definitely cases where one can burn up an alternator.

Regarding lithium: I am not a fan but since weight is always an issue I might go for one eventually. In any other application where weight is not an issue (boats, houses, etc) I'll stick with newer lead carbon tech and the likes. Cheaper, can do almost the same as lithium, way better recyclability as I understand it and less demanding on the environment.

Cheers,
-P

Read most posts a couple of times.

I guess the OP has an answer on how DC-DC work and has confirmed he doesn’t need one.

My observations of systems when I’ve been touring or camping is what seems to be the big focus on AULRO is how close or how quickly one’s battery gets to 100% SoC doesn’t seem to be an big issue.

Nobody I camp with runs lithium, everybody does have an AUX in the tug and either one or a number in the trailer. Pretty much everybody has a DC-DC in their trailer, in the tug not sure exactly what each of them run, I suspect some would have VSR. All seem to camp/tour without stressing over battery capacity their systems seems to just work.

Up until recently I’ve moved from manual marine type isolator, than traxide, than redarc 1240D VSR. Same as my friends I never had issues with charge rates or capacity. To date I haven’t been tempted to switch to DC-DC.

Keep in mind these days Solar is very available these days and nothing wrong with starting the car up to top up the battery if thing are a little low at end of day.

I’m switching to Lithium as I type and have purchased a DC-DC. The DC-DC has 40amp output and with solar at the same time, ‘best’ case 60amp going into battery while driving.

It mentioned a lot on AULRO that DC-DC manufacturers pedal BS and don’t know what they are designing or talking about. I don’t see or hear many quality ‘name band’ systems not working or keeping up Lr being as bad as they are portrayed. There must be hundreds of thousands of systems out there just doing its job.

I’m happy with what I’ve chosen I reckon my system will just work.

Oh, I must say Lithium seems to be the next must have, like a kings awning, hi-lift jack, LED light bar. I reckon the VSR market will decline. Keep in mind I’m only changing because I’m ditching gas and am very limited on space.

Apologies to OP, I have nothing to add on ‘how’s does DC-DC’ work...apart from they are an option to charge batteries.

Looking forward to ditching gas.

This has been a great thread, lots of genuine information, just the way a forum ought to be.

It can probably be summarised as follows - subject to others opinions.

1. A VSR can charge 'house' batteries more quickly than a DC-DC converter.

2. If it is a Traxide VSR, there will be excellent installation instructions, and generous support.

3. A VSR will be lots cheaper than a DC-DCconverter.

4. A DC-DC converter can protect the vehicle alternator from overload.

5. A DC-DC converter can be tailored to suit different battery types.

6. A DC-DC converter can have a solar panel regulator built-in.

All in all, it is horses for courses. If you are camping up for a few days without a solar panel, then a VSR may be more suitable, so that you can boost the house batteries by sitting with your foot on the throttle for less time. If you plan to drive for several hours, or if you include solar panels when camped, then a DC-DC converter that includes solar input may be better.

Hi Deano and not real up on battery technology mate.
I’m on the road right now but will be back in the office late tomorrow and will reply in detail then.

But for now, if you have a back of batteries of different chemistry, they WILL NOT continually discharge from one battery type to another, regardless of type, age, or side.

if the batteries have been charged together, via an alternator, you can have batteries with a slightly higher SETTLED voltage when you first turn the motor off.

At this time, the the batteries with a higher voltage will slowly discharge back into the batteries with the lower voltage.

Then once all batteries are at the same voltage level, the discharging of ALL BATTERIES stops.

This is exactly how my isolators work. Allowing a higher charged auxiliary battery to slowly back-discharge into a lower charged cranking battery and thus, keeping the cranking battery in a higher state of charge than it would be in normal use.

When a lithium battery is connected to any form of lead acid battery, the lithium battery will continually discharge back into the lead acid battery until the lithium battery is discharged down to 12.7v, at which point, the lithium battery will be nearly flat.

Two totally unrelated situations.

Hi again Deano and I am a retail outlet for Sterling Products and the device you posted a link to is NOT SUITABLE for use in any vehicle with a SMART alternator operation, like Land Rovers.

I bet the unit in the video is not suitable either.

Furthermore, where the Sterling unit can be used, in thing like in large luxury boat and motor home, it has a failsafe system where if it does fail, the alternator automatically reverse back to its own regulator, the unit in the video require the regulator to be removed, so no false safe.