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My first Q is "what do those commenting refer to as a deep cycle battery"? Many older auxiliary setups under the hood use a wet cell deep cycle battery where alternator output is usually fine. Not so for an AGM as I've stated many times.

The days of an alternator output being a nominal 13.8 volts are fast disappearing. My current diesel runs at 14.9 to 15.0 volts most of the time. As is said, "oils aint oils".

I have never said an alternator will not charge a deep cycle AGM battery. What I have said is that at 13.8 volts it will not charge it properly and in most instances reduce the life span of the AGM. At 15.0 volts, that is also too high and can damage a battery if not be dangerous.

Voltage is only one part of the equation, as the current (amperage) output of an alternator is in most cases unknown to most users (unless a meter is installed) you have no idea if the charge rate is too high or indeed too low. Alternator charging is single stage, especially in older systems.

The optimum voltage for an AGM is gradually increasing in Boost to 14.4 to 14.5 VDC until absorption mode is reached, then down to the charger float voltage of approx 13.8 volts in the latter part of the cycle.

If I used my alternator at 15 volts, it would very quickly boil off the electrolyte, never getting to float as long as the engine was on. = another battery replacement. :)
 
I beleive the basic redarc dc-dc ($185) is a cheap and easy way to keep an auxiliary battery topped up, in a particular range of vehicles and needs.
And works well together along side of solar to supplement the charging.
They are basically a "solenoid ", with a diode that dosent let current return back past it.
To " piggy back" only means you will always be drawing/ charging power from both batteries, unless you fit at least a two position switch in between. And then draw power from the auxiliary battery when not driving.
And both batteries should be identical. Mixing them is a bad idea!
And the cables used used to link them should be at least 1000amp rated. As you are cranking from this battery as well.
Speaking of such, the basic redarc DC-DC Solenoid also comes with a override switch wire, that allows you to fit a " momentary " switch, that allows you to crank from both batteries.
This is only meant to be used/ fitted when you have battery grade cables fitted to the auxiliary battery. With no fuse link in-between them.
Or you are just going to melt your standard cables used.
A fuse unit should always be fitted before and after the solenoid, and then on every independent run out from the auxiliary battery .
If you have both, and a simple volt and amp meter fitted, you might find after driving to your destination you may not have to get the generator out and run it, or even find the ideal sunny spot on short trips.
If you have the so called "smart" charging system, and you want to be able to hook all types of battery styles, solar etc.
In the redarc.. ( starting around $600) ... but this unit also enables solar power to charge the battery to its peak performance etc
The DC-DC has an led thats illuminated when charging. I think you will be surprised how often you see it on.
At the end of the day, it depends on your needs and what your willing to pay for.
The nick name " Smart Alternator " is a bit misleading. And has nothing to do with the Alternator itself.
Not even the regulator! But further down the the wiring loom harness.
There is 14.4v leading up to this point. Disconnecting this part will always give you up to 14.4v
Of course do your own research etc.
And yes it would void warranty on any coverage.
 
mudgee hunter said:
The nick name " Smart Alternator " is a bit misleading. And has nothing to do with the Alternator itself.
Not even the regulator! But further down the the wiring loom harness.
There is 14.4v leading up to this point. Disconnecting this part will always give you up to 14.4v
The ECU controls the "smart" alternator voltage output (~9v to 16v) based on what various sensors are telling it is happening in an effort to reduce mechanical load & fuel consumption as a result.
I assume you're talking about removing the battery sensor on the negative lead to "trick" the ECU & hence "smart" alternator?
Some are adding a boost diode too.
Probably as much good (pros) written about doing these things as there is bad (cons)?
Playing with or removing ECU sensors on a new vehicle isn't something I'd be doing myself.
Have read some who claim that Ford will disable it if you ask but unless I seen it myself....... :|

At least with a DC DC charger the majority of cons you read are to do with the cost. $80k 4wds but won't spend an extra ~$500? :playful:
 
Yep! Most I have hacks i have seen are the negative terminal hack.
Still looking to see any negative results of doing such yet but......
Except perhaps voiding warranty etc.
Can anyone please explain in layman's terms " less drag/ strain , fuel consumption on the motor?
As the alternator has exactly the same drag on the belt, reguardless.
HEI, High energy ignition. Loves plenty of volts from the coil.
I can't phantom any bonus, except a couple of volts running through the pitty full sized cable in wiring looms in these day vehicles!
 
An example here regarding wire size.
When we bought the van in 2008 an 8 pin plug was used to connect vehicle/van, one of the 8 wires connected to van batteries.
We chilled our van down with mains power leading up to departure.
Have a wireless thermometer with the sensor in the van fridge freezer.
Leaving home set to 12V the freezer was about -12C.
The freezer temperature rose slowly, by the time we pulled up to free camp for the night and swapped fridge/freezer to gas, the temp was around -3C.
Before next trip, I purchased some light welding cable and upgraded..
Vehicle alternator - deep cycle - cable- battery- fuse - Anderson plug.
Caravan -Anderson plug - cable - fuse - twin deep cycle.
From that day on, when we pull up for the night the van freezer is holding -12C. (No more voltage drop)
My vehicle is a (computer/ECU etc etc free) 2002 Nissan Patrol Coilcab (originally 4.2 turbo 6 cyl diesel) now Brunswick 6.5 turbo diesel.
The fridge is cold and the fuel consumption went from 18/20L/100km down to 12/14L/100km.
:inlove:

In a nutshell the set up is.
Starting battery separated from auxiliary with a solenoid, auxiliary only activates when ignition is in start/run position.
Auxiliary has separate connection to solenoid with on/off switch in the event the main battery goes flat.
Auxiliary battery is separated from deep cycle with another solenoid and another on/off switch.
This system has worked faultlessly since the cable resize.
No DC DC charger required.
:perfect:
 
OK so my alternator may not charge up the battery but no one has mentioned the fact that I have 200w of solar panel on the roof going through a controller do we just ignore that fact? Or is that going to finish of the charging ? I'm interested to hear the advise on this.
 
Nightjar said:
An example here regarding wire size.
When we bought the van in 2008 an 8 pin plug was used to connect vehicle/van, one of the 8 wires connected to van batteries.
We chilled our van down with mains power leading up to departure.
Have a wireless thermometer with the sensor in the van fridge freezer.
Leaving home set to 12V the freezer was about -12C.
The freezer temperature rose slowly, by the time we pulled up to free camp for the night and swapped fridge/freezer to gas, the temp was around -3C.
Before next trip, I purchased some light welding cable and upgraded..
Vehicle alternator - deep cycle - cable- battery- fuse - Anderson plug.
Caravan -Anderson plug - cable - fuse - twin deep cycle.
From that day on, when we pull up for the night the van freezer is holding -12C. (No more voltage drop)
My vehicle is a (computer/ECU etc etc free) 2002 Nissan Patrol Coilcab (originally 4.2 turbo 6 cyl diesel) now Brunswick 6.5 turbo diesel.
The fridge is cold and the fuel consumption went from 18/20L/100km down to 12/14L/100km.
:inlove:

In a nutshell the set up is.
Starting battery separated from auxiliary with a solenoid, auxiliary only activates when ignition is in start/run position.
Auxiliary has separate connection to solenoid with on/off switch in the event the main battery goes flat.
Auxiliary battery is separated from deep cycle with another solenoid and another on/off switch.
This system has worked faultlessly since the cable resize.
No DC DC charger required. :perfect:
My 4wd is a 2014 & has a fixed voltage alternator (old school) so I could use either way without too many issues depending on set up.
And that's the big question - set up - what suits mine/yours may not suit everyone's set up!
Rather than just a toy for the boys IMO DC DC chargers can be a necessity to some depending on their own wants/needs, vehicle, aux battery type etc. etc. but not required at all by others. :Y:
 
Harbourmaster said:
OK so my alternator may not charge up the battery but no one has mentioned the fact that I have 200w of solar panel on the roof going through a controller do we just ignore that fact? Or is that going to finish of the charging ? I'm interested to hear the advise on this.
Probably not enough emphasis on how important those with solar set ups on their dual batteries are (especially if using a MPPT controller) but not everyone uses solar in their set up either.
IMO where a DC DC charger isn't used (where it could/should be benificial) the solar + MPPT controller may not only be keeping or getting the battery fully charged but may also be helping to prolong the battery life if you use the solar fairly regularly or it's fixed. I don't have any technical back up or facts on that. It's just a thought/opinion.
Hopefully someone with more tech background might comment.
 
Nightjar said:
Are we being conned, is a DC DC charger necessary?

If we test the voltage output from our vehicle's alternator we may discover it is a waste of 100's of $$$'s. If your check reveals your alternator is putting out 13.6-13.7 Volts, purchasing and fitting a DC/DC charger would actually limit the charge rate too your auxiliary battery/batteries.
Have had 12+ years relying on the alternator while travelling and solar while camped up. The caravan is on its second set of deep cycles the first purchased in 2008.
My feeling it is an expensive, unnecessary "toy for boys?"

Can someone agree or disagree with this?

In my old Jackaroo I charged the deep cycle agm aux. from the alternator with a redarc isolator, now with the 2018 Isuzu mux with it's "smart" alternator I have the same setup, but turn my parking or head lights on which makes the alternator a "dumb" alternator. Charges the battery fine. No need for a dc-dc crap
 
The redarc basic solenoid DC-DC ($180) unit has a built diode that dose not allow power to return to the primary/cranking battery!
There is no need to fit another diode.
Fitting another (3rd auxiliary) battery is an excellent choice.
2 position switches are generally, on, off. Or forward/reverse
3 position, A, off, B .
4 position, A, off, B , ( A +B) draw
DC dose have a preference to shorter the better.
And undersized cable isn't worth doing re- current loss over labour $$$
So up for debate...
If a decent auxiliary" thermo fan drags 90amp phr....
20 times more than a fridge...
How much chop is this crap "smart alternator " theory???
Other than cost cutting in production.
Pcm/ ecu's ( vehicle computers) run about 5v, FA AMPS! Not 12V
There is ZERO difference in HP drag on a the crank/ belt to drive a standard alternator compared to a "smart alternator" . There is no clutch to disengage the alternator...
So show/ tel me how this improves economy or less strain on the motor?
To me, the whole "smart alternator " is a wank festival that consumers have gone along with.

But! ...
My Torana did run points of course originally, they usually run at about 7.5V .
After fitting a 19" thermo , and when it kicked in i would lose 150rpm easily at idol.
35 amp was a stock size alternator.
Built it up to 85 amp alternator, VC 12V electronic ignition distributor, + coil to suit, different plugs with wider gap,
No rpm lost at idol with fan....
But gained heaps of HP!
 
The redarc solenoid $180 job is a DC-DC charger...
The DC-DC part just means 12V DC is being redirected on and staying 12V DC further without modification of current.
No rectifier etc.
And yes, some vehicles charge better with the lights on, especially 9n high beam.
A discharged auxiliary battery in some cases can demand extra power to be charged, similar to turning on the high beam , thermo fans etc.
With the regulator opening up open due to demand of power. No excess surplus being made and shutting off.
Perhaps try on your vehicle when testing alternator volt output at idol, then 1500rpm.,, etc,
Connect a drawing device, like a flat battery ( mimicking an auxiliary battery) asking for currently.
And see if on your vehicle iincreases volts upon demand.
Or get someone to turn the AC whilst watching the multimeter. The AC fan should kick in and demand power.
A demanding flat auxiliary battery is the same as a thermo f a n kicking in and asking for power.
 
But! ...
My Torana did run points of course originally, they usually run at about 7.5V .
After fitting a 19" thermo , and when it kicked in i would lose 150rpm easily at idol.
35 amp was a stock size alternator.
Built it up to 85 amp alternator, VC 12V electronic ignition distributor, + coil to suit, different plugs with wider gap,
No rpm lost at idol with fan....
But gained heaps of HP!

Youd be toast if ya pulled up at the lights next to my fx,fire breathing grey it is......
 
Yes, I have read such before.
But not this entirely as yet.
Fudging figures, and swaying ones reason of energy lost is their ploy from what I understand so far.
Its a bit like throwing away your mechanical water pump on your vehicle to save 7hp, and then fit an electric water pump instead..
They can spin your head with on paper stats that look factual.
Step back and look again.

#Alternator = driven by belt via crankshaft. No variables of friction loss of hp output reguauding regulator.
#voltage at electronic fuel injection (EFI) MAX 6V low amperage draw via pcm/ecu.
#HEI ( High Energy Ignition) please don't cut my energy with BS low voltage!

If a combustible engine vehicle has no chance of making enough power to run an auxiliary battery....
What's your thoughts now of hybrid?
Think for a moment...

I want to see independent printed dyno facts of fuel loss and extra labour demand on a motor firstly.
Not what GM etc are ramming down our throats to beleive.
 
mudgee hunter said:
Yes, I have read such before.
But not this entirely as yet.
Fudging figures, and swaying ones reason of energy lost is their ploy from what I understand so far.
Its a bit like throwing away your mechanical water pump on your vehicle to save 7hp, and then fit an electric water pump instead..
They can spin your head with on paper stats that look factual.
Step back and look again.

#Alternator = driven by belt via crankshaft. No variables of friction loss of hp output reguauding regulator.
#voltage at electronic fuel injection (EFI) MAX 6V low amperage draw via pcm/ecu.
#HEI ( High Energy Ignition) please don't cut my energy with BS low voltage!

If a combustible engine vehicle has no chance of making enough power to run an auxiliary battery....
What's your thoughts now of hybrid?
Think for a moment...

I want to see independent printed dyno facts of fuel loss and extra labour demand on a motor firstly.
Not what GM etc are ramming down our throats to beleive.

True, I'd like to see what energy loss they are talking about, because if you take an alternator off of a vehicle and spin the pulley by hand it will keep going for quite a while with nothing driving it, So I doubt any HP is lost at all, But sure a water pump or Fuel Pump would consume a couple of HP because the water and the fuel is pressurized which causes resistance, Where as an Alternator offers no resistance because it is free running, :Y:

The Radiator Fan would chew a little bit of power too.
 
To condors reply, yes, specific batteries different to primary battery may require diodes to correctly enable the current needed.
This is where the $600 redarc unit becomes needed .
Basically pay, plug and play.
Or screw around with diodes to get an exact match for the battery fitted at the moment!
MAJOR over looked part is getting your battery to 100% charge.
Many will get you to 90% and that is it .
That 10% is crucially over looked in a lot of cases.
Get what you pay for.
And pay only for what you grasp!
Sometimes the people with cash, who don't understand it at all......
Say just " DO IT"!
And never need to even look back at it.
Too busy looking forward....
 
Ridge Runner said:
True, I'd like to see what energy loss they are talking about, because if you take an alternator off of a vehicle and spin the pulley by hand it will keep going for quite a while with nothing driving it, So I doubt any HP is lost at all, But sure a water pump or Fuel Pump would consume a couple of HP because the water and the fuel is pressurized which causes resistance, Where as an Alternator offers no resistance because it is free running, :Y:

The Radiator Fan would chew a little bit of power too.

RR, beg to differ about the free running alternator.
We were experimenting some years ago. Clamped a 240V variable speed drill to an alternator shaft, the alternator was set up to charge a bank of batteries.
We wound up the drill revs and when the alternator cut in the drill struggled and finally a "poof" of smoke and the drill burnt out.
That told us, alternators do need added power to charge.
 
Nightjar said:
Failed to mention in last post. The experiment we were carrying out was the early stages of a wind generator for our bush camp.
The answer was, a wind generator should be built using a "generator" not an power hogging "alternator."
"Power hogging alternator "
How do you conclude to such?
From using a gutless AC drill? To make DC? Most AC drills you can stall by grabbing the chuck !
I have Matabo 1750W 5" grinders, spinning around 4000 rpm. With a welding glove on , i could gab the disc and stall it almost instantly.
Don't try this at home kids.
A lot of petrol/alternator welders need a 6-1 ratio to even catch up rpm
Firstly AC is utter :poop: for horse power over DC .
And a back yard experiment years ago seems a bit lame to still be swearing by NJ.
Regardless of HP loss , i believe an alternator working or dead still has the same drag on the crank.
Unless seized due to bearing failure etc.
Therefore I can't imagine any fuel economy change.
 

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