How to charge your battery to 100% from the car

All cars have a voltage regulator.

I assume it is to regulate voltage.

Anyway, Robin is an Electrical Engineer and it makes sense to him. I have found it to work. Ian from RV knows his stuff.

I suggest you try the theory in practice before you discount it Mike. My multi meter tells me it works.

Cheers,

Jim.

I built my first electronic regulator for a car generator in 1968.

I obtained an Electrical Engineering with Honours in 1972.

I've been designing and building electronic systems since then.

If an Alternator were to increase its output voltage with increasing load drawn from it, it would have a negative internal resistance - I look forward to hearing an explanation for that.

most new car alternators use a sense , ign and light feeds to the rear of the alternator ign turns on the regulator and the sense picks battery voltage, light turns off your dash light. some newer models have these as well as a computer controlled field circuit to contoll the out put from the alternator in normal charging

Mike
Some alternators can sustain temperatures up to 120oC before regulation and some chargers are temp controlled to shut the unit down at 90oC alternator temperature.

If batteries become unstable and dangerous above 50oC it is hard to contemplate not using temp compensation of the batteries to cut back voltage.

Ian

Alternators need the same temperature-compensated voltage as 240 volt battery chargers do, otherwise they would hopelessly overcharge at high temperatures and hopelessly undercharge at low temperatures.

80 deg = 13.8
60 deg = 14.0
20 deg = 14.4
-20 deg= 14.8

Temperature compensation has nothing to do with alternator protection against overtemperature.

Good God Ill have to ring Sterling and tell them that the temperature connection sensor to the alternator that cpmpensates for the alternator temp and shuts down the Sterling once the alternator reaches 90oC is not required regardless of the ambient and that the Queen might take back his Award for Electronic excellence that he got for Marine and Automotive work.

The unit compensates both ends not just the batteries and I should have explained better.Sorry Mike.
Ian

Hi Mike

I don't disagree with your temperature effects explanation.

I don't think anyone means to suggest literally that the alternator increases its voltage in reaction to load (temperature effects not included) (mind you I am looking for a decent Tunnel diode right now!)

I think we are talking about second order effects caused by two factors , 1 when the engine revs are low and alternators output still varies and 2nd down near idle in some cars like mine there is an extra feedback loop in which the ECU sensing a drop in revs caused by loads reacts to return or even increase engine speed.

With low engine speeds like at traffic lights or 4wding the amount of time spent in the gray area is significant , or if charging from near idle as I do the overall effect is an increase in the effective charging voltage.

Chaps,

The technical waffle is immaterial.

IT WORKS.

Practical useage, not theoretical supposition, has proved it for me.

I don't make any money out of having a charged battery. I was just trying to share something worthwhile.

End of story.

Cheers,

Jim.

All your test showed was that your battery had good charge.

It did nothing to show that having headlights on gave a better charge.

Mike,

Get this through your over technical head.

I've had the same battery setup and fridge for four years.

I know it works. You hypothesize.

I'll put it really simply, IT WORKS FOR ME.

Pontificate all you like, but until you try it in practice, your words are just words.

Jim,
you have just proved well and truly beyond ALL & ANY possible doubt, an Alternator will FULLY charge an Auxiliary battery

Mainey . . .

Nice pick-up, Mainey....

;-)))

Ed,
Yes, after all the "well informed" and "eminently qualified" people who say an Alternator will only charge to ~80% and Jim goes and proves them all wrong, as 12.8 Volts, even after his (80 Ltr Waeco I believe) fridge has been running on the battery for an hour, is as close to fully charged as an AGM can get.
Also goes to show how terrific AGM batteries really are :)

Mainey . . .

Mainey,

I just call it as I see it. I don't have any technical qualifications that tell me something will or won't work. I'm a practical bloke with a reasonable ability to assess things.

I'm a stickler with my multi meter. I regularly check voltage to ensure battery life. The readings have never been so high at any time during the last four years. That's good enough for me.

So, yes I agree with you that the "experts" who tell us that an alternator won't charge a battery past 80% are wrong. I'm not sure if they are right with wet cells (I've never used a wet cell DC Batt), but an AGM can be charged to 100% from the alternator.

I frankly find it amazing that people tell you something can't work, when they haven't tried or tested it.

Cheers,

Jim.

Jim,
I'm only calling it as I see it

I'm one who agrees with your results :)
as i get the same results, with 14.2v shown at the AGM's via the Alternator charge, they never get below 12.8v anyway

Mainey . . .

Mainey,

I wasn't having a shot at you.

Just making the point that when you post something that you know works, based on experience and testing, someone comes along and tries to shoot holes in it based something they read in a book.

Cheers,

Jim.

. . . . "someone comes along and tries to shoot holes in it based something they read in a book."


You seem to have trouble interpreting what I wrote above -
"I built my first electronic regulator for a car generator in 1968.
I've been designing and building electronic systems since then. "


Find someone who has more practical experience in designing, building and testing charging systems !

And modest as well LOL

Mark, I have adopted the habit of always running with headlights on. Is this good/bad practice for the vehicles electrical system, or doesn't it matter. I am in the process of fitting a battery feed for the caravan fridge at the moment.
Very interesting thread going here.

Cheers from Fred.

Hi fred... before i even started my apprenticeship as an auto electrician (39 years ago this Tuesday) the method of controlling generator outputs was weird and wonderful. There was a thing called a 2 step regulator that controlled the voltage between a high point and a low point.

Was good in theory... but on long daylight runs in trucks and buses etc the battery would eventually overcharge as the regulator just wasn't that good.. it did not control the current from the generator, only the voltage.
Remember it was all electro mechanical.. nothing solid state. The answer was to turn on the headlights in order to put a load across the battery. Of course, there is no need to do this theses days.. however I always travel with my lights on when in the outback from a safety point of view!

The XM Falcon had a Lucas 3 bobbin regulator to control its 20 amp C40 generator. This regulator featured current control and voltage control. Of course, the Alternator finished all this stuff really quickly. The Current output of an alternator is controlled by the stator design/winding. The regulator controls the voltage.

Leave your lights on fred.. you'll live longer :-)

Cheers

Mark

"Was good in theory... "

Was that the regulator that Mike built in 1968?

I don't think so!

When we were at tech (1970) I built an electronic regulator for an EH (Bosch) generator to replace the 3 bobbin electro mechanical device that came with the car.

Was a good thing.

You know.. the reason cars have larger output alternators these days is to support the hi draw accessories that they all run. Think about the humble EH.. when it was running down the road in daylight, it only had the coil ignition system to power from its 20 amp generator.

Take a modern commodore... ign system, fuel injection, air conditioning fan (they draw a lot under load) and compressor clutch, hi output stereo (the EH came with no radio from the factory) and all the electronics to run the engine management computer and ABS brakes etc.

Oh yes.. and recharge the battery from the engine start!

A big diffference indeed!

Cheers

Mark T

How effective is advanced battery charging on a battery and can it damage the battery?
I am asked all the time; do I really need advanced charging on my batteries? What effect does a split charge diode have on charging? What percentage of improvement will our products make on a system? Will the extra fast charging boil my battery? Will it excessively gas the battery? What effect in real terms can I expect? Most of the questions stem from old wives? tales, rampant in this market. The idea behind this article, is to lay to rest all the old wives tales and offer the facts. Remember, the below results are extreme and meant to show just how hard you can charge an open lead acid battery with no adverse effects.

Part 1: The effect of voltage on battery charging
There is no magic with advanced charging systems. In effect all they do is increase the differential voltage between where the battery is and the charge voltage; in other words, the higher the voltage that is applied to a battery, the faster it will charge. However, the down side is, that if you do not control that higher voltage after the charge is completed, you will overcharge and damage your batteries. This simple experiment will show you the direct relationship between actual voltage applied to a battery and the current (amps) being absorbed by it. This will give you an insight into how your system can be improved and where the problem may lie.
This information is 100% accurate and can be reproduced on any test bench at any time, it is not a sales gimmick from Sterling; but a help sheet to show the general public in simple graphic terms what effect the higher voltage attained by advanced charging has on batteries.
The test is very simple and not open to misinterpretation. We will use a simple lead acid, so called 'leisure battery', of about 100 amp hrs; a low cost, nothing fancy battery. All we have done is to discharge the battery to about 50% of its capacity, then connect it to a 180 amp regulated power supply. We will simply pick key voltages and log the current the battery can absorb at different voltages as it charges.
For example, the red line shows that when the battery was 50% full at 13.2 volts the charge current was 35 amps and at 14.8 volts the charge current was 160 amps. An improvement off about 457%. However the black line on the graph which was taken when the battery was about 70 ? 75% full, shows that at 13.2 volts the current was about 1 amp (showing that at 13.2 volts the battery was full, in its opinion); whereas at 14.8 volts we were still putting in about 60 amps; a charge improvement of 6000%. (Rather an improvement to say the least).
Why the specific voltages?
The voltages chosen are real voltages which one would expect to see in real life.
13.2 Volts
This voltage appears in 2 main circumstances.
• If you use a split charge diode then one would expect this sort of voltage at the battery.
• Most alternators now have a built in temperature compensator on their regulator. When the engine room heats up (especially on a vehicle) then the assumption made by the alternator manufacturers is that the battery should be full. So as the warm air in the engine room is pulled past the regulator the voltage from the alternator is reduced; the end result is, that we have seen standard vehicle alternators start off at 14.8 volts and drop to 13.2 volts in vehicles (with the bonnet down) after about 20 minutes. This is o.k. for the starter battery but will ensure your secondary batteries never charges correctly (as per the graph).
14 Volts
This is where most alternators start from; and is a standard expected alternator voltage from a alternator.
14.4 Volts
This is the voltage used to charge sealed lead acid batteries to prevent gassing.
14.8 Volts
This is the voltage one can push up to in open lead acid batteries without any damage to ancillary equipment, which will be connected to the battery at the same time. Apart from the obvious increase in charge rate this prevents sulphation of the batteries.
Having established the dramatic charge improvement which a battery can achieve with the increase in voltage, the many sceptics amongst us will now say, well OK, the battery will charge faster, but you will gas the battery profusely. You will over heat it and boil it; and all that extra current going into it will not being stored; but simply gassed off. Meaning in essence, that the apparent fast charge is a waste of time and that all you have done is wreck the battery. All appear valid points and are prolific rumours. Now let?s see if they are true or simply old wives? tales.

Part 2: Will this fast charge rate cause problems?
With test 2, we take 4 x 100 amp identical lead acid batteries as per the above test. We connect all 4 together and discharge them to the same level. Then we charge one at a time (using a 200 amp regulated power supply) and over a 1.5 hour period and see how much charge in the form of amps are absorbed into the battery. Then using an amp hour counter we can measure the actual amp hours which have passed into the battery. After the battery has completed its charge cycle at the allocated voltage, we see if the amps are actually in the battery as storage amps. We do this by discharging the battery through an inverter with a 400 watt light bulb load; timing how long each battery can run the load after it has completed its charge cycle. If the amp hour counter shows more amps going into the battery and the load runs for a longer period of time; then the amps must have been stored in the battery. We also measure the battery temperature before and after the charge run to see if the battery is in danger (50C is when a battery starts to have problems) of overheating and boiling.
Answers to the questions based on actual facts
1. Will the fast charge rate also put more into my batteries? One can clearly see that on the 13.3 volt charge only 21 amp hours were put into the battery as opposed to 60 amp hours with the 14.8 charge. An improvement of about 300%.
2. Did this 300% improvement actually go into the battery or was it simply lost in heat and gas etc? The inverter discharge test clearly shows that the 13.2 volt battery ran the inverter for 48 minutes, whereas the 14.8 volt test ran the inverter for 114 minutes, a clear 230% improvement. So yes, the extra amps were being stored in the battery and were accessed by the inverter and used.
3. Will the high charge rate boil my batteries? One can see the rise in the battery temperature at 14.8 volts was from 18C to 32C, which is still well below the manufacturers recommended temperature limit of 50C. Also bear in mind that this test was charging a 100 amp hour battery at 150 amps, in real life with 4 x 100 amp hour batteries you would need a 500 amp alternator or battery charger to be able to reproduce this test run.
4. Is it possible to put a lot of power into a battery in 1 hr? The graph clearly shows that the bulk of the power absorbed by the charger was in the first hour. So obviously the battery was comfortable with this as the temperature rise was well within the battery's limits.
5. Does a 100 amp hour battery give 100 amps of useful power? Simply not true; even with the best charger, at least 40% or 40 amp hours tends to be no use in a battery.
6. Are there any other benefits from this fast charging? Yes, you also de sulphate the batteries, dramatically increasing the life of them. You will also reduce the running hours of your engine and fuel costs, associated with the charging of the batteries. In fact there are no down sides to this process.
Conclusion
It?s quite clear that all the fears are old wives? tales. Now all you have to do to harness this information is to add a computer program to store the charging curves, allowing the software to control the charge of your batteries and then, hey presto, welcome to the world of advanced digital charging from Sterling power products.


The graphs associated with the above can be viewed at
www.sterling-power.com

Hi Jim,
Interesting data you have posted. Just one question. If you apply these high current charging rates to wet cell deep cycle battery, will it damage it. I've learnt from experience using deep cycle batteries that to get the most life out of them is not to discharge more then 50% & not to charge at a high rate of amps but to trickle charge at low amps over a longer period of time. I await your comments. Cheers

I think the above post is self explaning as it addresses the myths and issues with smart charging .

Smart charging is a change of thinking with the technology of charging evolving in recent times whereas we used to soak a battery slowly and we now multi step charge a battery with bulk ,absorb and float which can dramatically cut down the charge time.

True smart charging is one where the charger can analyse the SOC of the batteries and set the bulk charge to suit that SOC.
Not many so called smart chargers do just that .

With temperature compensation and correct charge settings for the different battery types you cannot damage batteries.

The idea of DC DC Smart charging means you can smart charge your batteries to 100% while you car is going and working your battery in a higher percentage charge parameter you extend the life of your battery and increase the useable capacity.

Flooded wet cell deepcycle will charge as fast as if not faster than most AGM and Gel Batteries due to the acceptance voltage being higher.

The higher the voltage the quicker the charge.

high charge rate shouldnt harm the battery whilst being charged from the vehicle .in amost cases today most of these deep cycle batteries are using(good quality ones) calcium compounds in their make up and require a higher charge rate , hence all the 4 stage chargers on the market. the alternator's regulator should be able controll the charge rate thru the charging system

Auto
The hard part about that is that a calcium based battery used as a deep cycle will never fully charge off a vehicle alternator due to them needing 15.1V to fully charge.

With voltage drop taken into account even if you get 14V to the calcium that is alot of capacity short of 15.1V.

Some new mains powered chargers are just addressing this now and coming out with calcium charge included in thier selection.

Ian

"I think the above post is self explaning...". You've got to be freekin kidding!! (lolol).

I just start driving, and by some virtue of white-man's-magic my second battery get's charged.

George

Ian
I was very interested in your posts here. Didn't know of Sterling system. Sounds similar to Rotronics - only type I knew of previously that isolates alternator from cranker. Due to cost I didn't pursue that (went solar instead). So just wondering if you know what Sterling system which feeds camper battery and car aux. would cost fitted (just ball park)?
thanks

Doug
I have a plan of exactly that and it came from an Auto Electrician in North Qld and yes it works well.

Ian

Ian
Wouldn't happen to near Atherton Industrial would he

"there is no voltage regulation apart from a max output"
- the voltage output is fixed, regardless of how much current is drawn by the battery or vehicle loads.

"regulation is via temp rather than state of charge in the battery"
- that's right. Most vehicles have no way for the Alternator to be aware of the state of charge of the battery. They don't need to - once the Alternator has warmed up, it puts out the same voltage as the Float Voltage from a 3-stage charger. Fortunately LeadAcid batteries are self-regulating when the Float Voltage is applied.

Recent production cars are introducing more exotic ways of controlling the alternator - the above description applies to 95% of 4WDs on the road today.

Thanks Mike.

Mike a good example of that is the Disco 3 and the Range Rover Sport where they are having problems with split charge systems where the computer is sensing and assumimg a fault due to the isolation of the cranker and shutting down things like air bags.

Yes, Disco's are one example of Alternator Regulators with complex controls where no details are available from the manufacturer.

For example they could disable the Alternator when the engine is demanding maximum power. A modern Alternator puts out 1.5 kilowatts and that may put a 4 horsepower load on the engine. The Pajero turns off the Aircon compressor at high loads to reduce loading.

Or it may disable the Alternator at low revs, if the Power Steering and Aircon are demanding power, to avoid high loads on the engine at idle speeds.

But with all the older 4WDs on the road using conventional Alternator Regulators, I believe that 95% of 4WDs currently use conventional regulators - with quite a few still out there using Relay Regulators with NO Temperature Compensation !

Hi
Mike

Kym,

The Solar Panel was still in the back of the ute. It's the last thing to get unpacked.

Cheers,

Jim.