Alternator Capacity

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3rd April 2011, 03:09 PM
Wilbur

Quote:

Originally Posted by Blknight.aus

But more simply no-one has yet bought to bare the most important reason to not have one of those DC/DC charging units. They add unnecessary complexity to a simple situation.

At last, something I can agree with. I also dislike the added complication, but like many, I have very limited space, and with the DC-DC charger I can get away with less house batteries. Or I can have the same number of batteries and run a bigger beer fridge and do without something else......

However, having said that I will add that modern electronics are pretty reliable. Otherwise who would drive anything more modern than a 300tdi?

Oh and just a thought, if one was to accidentally leave the headlights on and flatten the car battery, the leads on the DC-DC convertor could be reversed to charge the car battery from even fairly well discharged house batteries. Could be useful.

Cheers,

Paul
3rd April 2011, 03:50 PM
drivesafe

I just re-read one of your earlier posts in this thread and again, Wilbur, you haven’t got a clew what your talking about.

Nothing is MATCHED to the BATTERY CHEMISTRY. Not alternators, AC battery charger or DC-DC converters.

You have just proven once again that you have read something but don’t have a clew what it means.

Please explain your claim?
3rd April 2011, 04:27 PM
drivesafe

Quote:

Originally Posted by Wilbur

Oh and just a thought, if one was to accidentally leave the headlights on and flatten the car battery, the leads on the DC-DC convertor could be reversed to charge the car battery from even fairly well discharged house batteries. Could be useful.

Actually, most will not work from another battery because most DC-DC devices are designed to shutdown automatically once the motor stops, and the voltage drop to a level just above or at the level of a fully charged battery.

If these devices didn’t do this they would flatten the cranking battery once the motor was turned off.

There are some exceptions like the Ctek that can be ordered with a special lower cutout voltage level but as this device does no longer knows when the motor is turned off, you have to add a conventional isolator or again, you risk having the cranking battery flattened.
3rd April 2011, 07:44 PM
wrinklearthur

er hello ?

Quote:

Originally Posted by Wilbur

At last, something I can agree with. I also dislike the added complication, but like many, I have very limited space, and with the DC-DC charger I can get away with less house batteries. Or I can have the same number of batteries and run a bigger beer fridge and do without something else......

However, having said that I will add that modern electronics are pretty reliable. Otherwise who would drive anything more modern than a 300tdi?

Oh and just a thought, if one was to accidentally leave the headlights on and flatten the car battery, the leads on the DC-DC convertor could be reversed to charge the car battery from even fairly well discharged house batteries. Could be useful.

Cheers,

Paul

Hi All

Guys ! its not April the 1st anymore, please calm down.

Ohms Law E = I x R, P = E x I

E = Voltage measured in Volts
I = Amperage measured in Amps
R = Resistance measured in Ohms
P = Power measured in Watts

Batteries, as they age, alter their internal resistance.
I say this as I now have cut the wiring to my dual battery smart? isolator, it was getting hot, both, the coil and the contacts that are rated at 200 ohms (new relay but I believe that it had tarnished contacts).

Both batteries were identical, except the one for the auxilliary was years older (maybe as much as five years), when coupled together I felt that the constant current drain was not good for the new Battery and would soon wreck it, hence the big snip !

I am quite capable of stuffing my own wiring up, so I don't get anyone else to do my own wiring, let alone pay them to do it.

Cheers Arthur
3rd April 2011, 08:09 PM
drivesafe

Hi Arthur, unless the old battery is actually stuffed and not holding a charge, then there should be no reason for a high current discharge from your new to your old other than that you have a low charged old battery, note not stuffed just low charged.

As to the Isolator being hot, it’s quite common for isolators and the adjoining cable ( the cable acts as a heat sink ) to be so hot you can’t hold them, so unless the isolator looked like it was about to melt, all should be fine.

If you want to play safe, leave the set up disconnected until you know you are going to be doing a longish drive, then connect everything up and let your alternator supply the current being pulled through the isolator so your cranking battery is not supplying any current.

At the end of the drive, turn your motor off and see if you still have a high current flow between the batteries.
4th April 2011, 12:20 PM
640Newton

I didn't realise that there were divided opinions on auto electronics, but if nothing else this "healthy debate" highlights to troubles that consumers exerience when trying to seek guidance on the best/correct way to do things.

Auto electronics is an area where I'll happily admit that I have very little understanding but this means that I'm at the mercy of whoever I seek advice from and it is now clear that my end solution will be determined by whatever school of thought that person comes from.

The benefit of forums such as these is that the person seeking advice can take the opinions shared and choose which camp they want to be in or go off and do more research themselves. Thanks for all your input.
4th April 2011, 05:48 PM
Bushwanderer

Hi Wilbur,
In post No. 12 in this thread, you say "Having spent all my life as an electronic engineer, ... ". I'd be interested in knowing what your formal qualifications are in this area are (and from where). Further, I'd be interested to know of what professional institutes you are a member.

Looking forward to your reply,
Peter
4th April 2011, 06:16 PM
Wilbur

Quote:

Originally Posted by Bushwanderer

Hi Wilbur,
In post No. 12 in this thread, you say "Having spent all my life as an electronic engineer, ... ". I'd be interested in knowing what your formal qualifications are in this area are (and from where). Further, I'd be interested to know of what professional institutes you are a member.

Looking forward to your reply,
Peter

Candidly it is none of your business. I offer knowledge, take it or leave it. Unlike other contributors, I have invited anyone reading my post to check with other experts.

I make this final post on the subject, in point form so it is easy to understand. It will also be very easy for anyone to verify, in the apparently unlikely event that you are more interested in science than in the fun of being offensive to someone trying to offer good advice.

1. Ctek, Projecta and a thousand other companies are not joined together in an almighty conspiracy to dump useless multi-stage chargers on the market.

2. Multi-stage chargers do give better results.

3. The DC - DC convertors refferred to simply work on 12 volts instead of 240 volts, just like you can buy a 12 volt television for your camper or a 240 volt television. They are multi-stage chargers just like the 240 volt versions.

4. Most car alternators deliver 13.8 volts. AGM and many other deep cycle batteries require around 14.4 volts to fully charge.

5, 13.8 volts will NEVER be able to fully charge an AGM battery.

6. If the alternator did put out 14.4 volts continously, it would cook the AGM because once an AGM is fully charged, it requires the voltage to be dropped to a float voltage of around 13.2 volts. Leave it at a higher level and the battery will over charge and reduce its life.

I simply do not understand what is going on here. I offer knowledge that unfortunately conflicts with the forum guru, and you are all too thick-headed to even try to find out who is telling the truth. It is very disappointing. I looked at this forum as one of the more reasonable and rational ones, but now I am very disappointed and disillusioned. Go burn your house batteries up after two or three years, it costs me nothing. Mine is still good after six years.
4th April 2011, 07:27 PM
drivesafe

Wilbur, you have not offered on bit of info, you have shown you have the ability to read something and not understand what you’re reading.

Again, no battery charge yet can compete with the versatility that an alternator offers.

You claim most car alternators deliver 13.8v. The average alternator output is 14.0 to 14.4v on older vehicles and on newer vehicles, like Toyotas and Land Rovers, the voltage is as low as 13.2v, and they have no problem charging all types of 12v lead acid batteries at this lower voltage, and this is fact, not what you THINK happens.
Wilbur, you have not offered one bit of useful info, all you have done is show you have the ability to read something and not understand what you’re reading.

Again, no battery charge yet can compete with the versatility that an alternator offers, and if you worked in this field, you would know that.

You claim most car alternators deliver 13.8v. The average alternator output is 14.0 to 14.4v on older vehicles and on newer vehicles, like Toyotas and Land Rovers, the voltage is as low as 13.2v, and they have no problem charging all types of 12v lead acid batteries at these lower voltages, and this is fact, not what you THINK happens.

Furthermore, D3s and D4s will charge at up to 15v and this does not effect the batteries, or are you saying you know better than the vehicle manufacturers?

Next, find one battery manufacturer that states you CAN NOT fully charge a lead acid battery with voltages as low as 13.2v.

What battery manufacturers and the makers of battery charges, including DC-DC devices, state is that the “MAXIMUM” charge voltage for standard AGMs and Gel cell batteries is 14.4v.

Now Wilbur, just to clarify this so that you finally understand what you have been reading, 14.4v is the MAXIMUM charge voltage not the required charge voltage, and the setting for the different types of batteries are there to make sure you don't over charge different battery types with the wrong "MAXIMUM" charge voltage.

Flooded wet cell batteries, and this includes most Calcium/Calcium batteries, and automotive grade AGMs can be charged with 14.7v.

Furthermore keeping these battery at the levels shown above will not cause any problems as you’re inferring and again an example to prove the point. When most people leaving home on the first day of a motoring holiday, They will do so with fully charged batteries ( at least they should be fully charged ) right from the beginning of their day’s drive. If according to you, this will cook their batteries, why doesn't it happened.

Wilbur, I have no idea of what section of electronics you come from ( if you actually do ) but it sure as hell had nothing to do with batteries.

BTW, I think Bushwanderer's question is a valid one, so why don't you want to answer it.
4th April 2011, 07:52 PM
isuzurover

I also think Bushwanderer's question is a valid one.

Btw - the (relevant) scientific literature I can find on DC-DC chargers:

Quote:

A system for charging of dual voltage level batteries in automotive applications

Author(s): Bouallaga, K.; Darcherif, A.M.
Source: 2007 IEEE International Electric Machines and Drives Conference Pages: 107-11 Published: 2007
Conference Information: 2007 IEEE International Electric Machines and Drives Conference
Antalya, Turkey, 3-5 May 2007
Abstract: The aim of the paper is to present a new system for charging of dual voltage level batteries in automotive applications. The proposed system is built as an arrangement of in induction machine and a bi-directional converter. In a near future, two batteries with different voltages will coexiste on the automotive electrical system board. A first one for power hungry devices, start-up, alternator, auxiliary motors and a second with 14 V for digital, calculation or radio circuits. The two batteries are recharged using a single alternator. An initial solution for this consists of using two converters. Firstly, the alternator recharges the highest voltage battery using a rectifier or a switching mode converter. Then the high level battery recharges the lower voltage battery, through a separate DC/DC step-down shopper. Compare to this traditional solution, a more economic one would be a DC/DC chopper by recharging the two batteries through a single switching mode converter. This article studies the resulting device and simulates its functioning in the case of an induction generator. Only simulations results are shown, practical results will be published in a next paper.

Quote:

Future system architectures based on the dual voltage electrical power system specification 42 V 14 V

Author(s): Schmidt F, Blumel R, Blauensteiner WD
Book Group Author(s): VEREIN DEUTSCH INGN; VEREIN DEUTSCH INGN
Source: ELECTRONIC SYSTEMS FOR VEHICLES Book Series: VDI BERICHTE Volume: 1415 Pages: 1117-1131 Published: 1998
Times Cited: 1 References: 0 Citation MapCitation Map
Conference Information: 8th International Meeting on Electronic Systems for Vehicles
BADEN BADEN, GERMANY, OCT 08-09, 1998
Verein Deutsch Ingn, Gesell Fahrzeug & Verkehrstech
Abstract: In order to be able to provide the amount of electrical energy needed in vehicles of the future, while, at the same time, reducing the fuel consumption, it will be necessary to redesign the on-board power supply. In working groups in Europe and the US, the specifications for a dual voltage power system have been defined, which will provide the basis for the development of the 42V PowerNet.

This article briefly describes the motivation for changes in the on-board power supply and describes the guidelines for a dual voltage power system. Based on the approaches for a 12V system, a multilevel converter will be presented as an example for new power electronics in the alternator. In order to implement the guidelines, new criteria far the power distribution to individual consumers will be defined and in the context of sizing converters the issue of "central or decentralized DC/DC converter" will be discussed, after having looked at the basic conditions pre-defined due to available battery technologies, an architecture with an extended concept for converters will be presented, which will meet the requirements of reducing the voltage range, while, at the same time, achieving optimum battery charging voltage.
Document Type: Proceedings Paper
Language: German

more to come... I note none are for 12V/12V systems

Quote:

Capacitive DC-DC Converter for Electric Vehicle Applications

Author(s): Pelczar, C.; Zirn, O.
Source: Proceedings of the International Exhibition and Conference for Power Electronics, Intelligent Motion, Power Quality. PCIM 2010 Pages: 686-91 Published: 2010
Conference Information: International Exhibition and Conference for Power Electronics, Intelligent Motion, Power Quality. PCIM 2010
Nuremberg, Germany, 4-6 May 2010
Abstract: This paper deals with the design and implementation of a capacitive DC-DC converter. We examined phenomena that influence the performance of DC-DC converters, e.g. capacitor charging losses, parasitic inductance, and switching frequency. The performance of the converter was tested over a range of loads and switching frequencies. The comparison of measurement results as well as design parameter studies elucidate the simulative design options as well as the achievable power and efficiency.
Accession Number: 11448029
Document Type: Conference Paper
Language: English

Quote:

Interleaved 3 Phase DC/DC Converter for Automotive Applications

Author(s): Cornea, O.; Muntean, N.; Gavris, M.
Source: 2010 12th International Conference on Optimization of Electrical and Electronic Equipment (OPTIM) Pages: 589-94 Published: 2010
Conference Information: 2010 12th International Conference on Optimization of Electrical and Electronic Equipment (OPTIM)
Basov, Romania, 20-22 May 2010
Abstract: The paper presents an interleaved 3-phase step-down converter that can be used to charge the 12 V battery and to feed the corresponding loads from the 42 V bus, in automotive dual voltage system. The converter has a maximum 3 kW output power and efficiency above 93% at full load. The simulation results show good responses under various input and output conditions.
Accession Number: 11431607
Document Type: Conference Paper

Quote:

New energy-storage unit for heavy-duty vehicles encompassing cold-weather starting

Author(s): Schupbach, R.M.; Balda, J.C.
Source: 2004 IEEE 35th Annual Power Electronics Specialists Conference (IEEE Cat. No.04CH37551) Pages: (Vol.4) 2786-91 Vol.4 Published: 2004
Conference Information: 2004 IEEE 35th Annual Power Electronics Specialists Conference
Aachen, Germany, 20-25 June 2004
IEEE Power Electon. Soc
Abstract: A standard light ignition (SLI) battery, the vehicle energy storage element, must deliver maximum energy and maximum power. These design requirements are self-excluding; consequently, compromises must be made in the battery design. Increasing energy demands of the vehicle electric accessories are moving this technology towards its limits. New SLI battery designs are not providing the required energy density and cold cranking capabilities (i.e., maximum power) at temperatures as cold as -40 degrees F. This paper explores a solution that uses an ultracapacitor pack in parallel with the starter motor and a unidirectional dc-dc converter allows optimal charging of the pack. The service battery could contribute a portion of the starter motor power using the converter. Lastly, load levelling of the vehicle electric accessories, and hence improved voltage regulation, can be provided to the vehicle power system at a cost by adding to the converter the bi-directional power flow feature
Accession Number: 8206019
Document Type: Conference Paper
Language: English

This one seems promising:

Quote:

A novel battery charger for automotive applications

Author(s): Vrankovic, Z.; Nasiri, A.
Source: 2006 IEEE Vehicle Power and Propulsion Conference (IEEE Cat No. 06EX1295) Pages: 6 pp. Published: 2006
Conference Information: 2006 IEEE Vehicle Power and Propulsion Conference
Windsor, UK, 6-8 September 2006
Abstract: In this paper, a new power electronics topology is introduced for battery pulse charging. The topology is based on a bidirectional isolated Cuk converter. The charging method provides positive and negative current and resting periods. This charging method results in less generated heat and longer battery life cycle. Different operating modes of the system and its small signal analysis are presented. The small signal system has been modeled using MATLAB. Simulation results are also provided to validate the mathematical analysis
Accession Number: 9486520
Document Type: Conference Paper
Language: English
Author Address: Vrankovic, Z.; Nasiri, A.; Power Electron. & Motor Drives Lab., Wisconsin Univ., Milwaukee, WI, USA

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