Alternator Capacity

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Originally Posted by Blknight.aus

now that sounds a little defeatist of you...

or do you mean that you cant actually answer the simple question of how a dedicated alternator wont correctly charge a set of batteries?

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Okay. A modern deep cycle battery requires three stages of charging - bulk, which is a constant current until the volatge across the battery reaches a specified level, then absorption which is a constant voltage until the current drawn by the battery drops to a specified level, then float whereby the voltage acros the battery is reduced to prevent overcharging.

A typical automotive alternator gives out a constant voltage regardless of anything unless it is so heavily loaded that the voltage drops. This is quite adequate for the vehicle battery which is required to give only very short bursts of very high (cranking) current. While the vehicle is running, all the accessories are supplied by the alternator, not the battery.

The opposite is required of the house battery. It is required to give relatively low output current but for long periods. While a cranking battery may supply hundreds of amps it does so only for a few seconds. The house battery might cruise at 5~10 amps, but it does so for many many hours each day.

As to your 'tip' that your 15 amp alternator will charge a battery more quickly than a good 25 amp DC - DC convertor... if you live anywhere near Bega I am prepared to buy a DC-DC convertor (I need one anyway) and bring it to your place with two identical batteries and put it to the test. I would be delighted to have a little wager on the result if you are game......

As always, no offence meant.

Regards

Paul

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Originally Posted by drivesafe

It is crap and the author of the crap is one of the biggest liars I have ever come across.

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Now don't hold back why not tell us what you really think of the man and his work. :lol2:

cheers,
Terry

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Originally Posted by drivesafe

Hi Wilbur, and thanks for that letting me know where you got that CRAP from.

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No Drivesafe, as I specified this is NOT where I get my information. I simply did a google on the subject and this seemed the one that would give the best laymans terms type of dissertation on battery management.

I can't remember where my info came from, it is just such basic knowledge. I am sure that blknight can't remember where he learned that it was bad for engines to put valve grinding paste in the sump, but I'll bet he knows it just the same!

Try asking a battery maker - Welcome to Fullriver! for example - what they think of the idea of connecting one of their deep cycle batteries direct to an automotive alternator.

If you want to go deeper, ask them for the correct charging regime for their batteries. You will find it very interesting.

The whole point is that battery technology has changed over the last few years and (unusually) it has changed for the better. However, these benefits do require a change in the way we manage our batteries.

Regards,

Paul

Wilbur, I think you need to learn a bit more about the different types of batteries and their intended uses because your misunderstanding what you're reading.

Fullriver make a large range of batteries, MOST were never intended for automotive use and as such, should never be connected “DIRECTLY” to the alternator. This means like a cranking battery, but Fullriver now make a few cranking battery type AGMs, and these can be connected directly to the alternator.

As for the rest of the Fullriver range of batteries, as long as there is a decent cable run between the alternator, usually from the cranking battery, and the AGM battery then there is no problem.

Standard AGMs like fullriver, do not tolerate high temperatures so by mounting them away from the engine compartment and the cable run, which will act as a quasi voltage/current regulator means you can safely connect them to any vehicle’s electrical system.

Now, your correct that battery technology is advancing but you need to understand what these advances are and how they fit into RV/automotive situations.

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Originally Posted by Wilbur

Okay. A modern deep cycle battery requires three stages of charging - bulk, which is a constant current until the volatge across the battery reaches a specified level, then absorption which is a constant voltage until the current drawn by the battery drops to a specified level, then float whereby the voltage acros the battery is reduced to prevent overcharging.

A typical automotive alternator gives out a constant voltage regardless of anything unless it is so heavily loaded that the voltage drops. This is quite adequate for the vehicle battery which is required to give only very short bursts of very high (cranking) current. While the vehicle is running, all the accessories are supplied by the alternator, not the battery.

The opposite is required of the house battery. It is required to give relatively low output current but for long periods. While a cranking battery may supply hundreds of amps it does so only for a few seconds. The house battery might cruise at 5~10 amps, but it does so for many many hours each day.

As to your 'tip' that your 15 amp alternator will charge a battery more quickly than a good 25 amp DC - DC convertor... if you live anywhere near Bega I am prepared to buy a DC-DC convertor (I need one anyway) and bring it to your place with two identical batteries and put it to the test. I would be delighted to have a little wager on the result if you are game......

As always, no offence meant.

Regards

Paul

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sadly with bega being about 1400KM away, thats a bit far..

but if you're happy to go and get yourself an excide N70ZZ (which is a fairly typical cranking battery) and a century 89t (which is a fairly typical deep cycle flooded cell battery) find a 15 amp bosch alternator as fitted to a dumb as a post kubota lighting plant diesel 3 pot to charge them from you can do the experiment yourself.

drop the deep cycle battery down to 0v across the terminals (nominal bat temp 25degC nominal measured load 0A )
drop the starting battery down to 9.8v(same nominal battery temp and load)
start the engine
charge both batteries to their nominal max charge using the 15A alternator (10mm2 wiring from the alternator to the starter 16mm2 to the starting battery 16mm earth cable with a direct 20mm flat braid from the earth lug to the alternator mounting bolt) with say 10m of double insulated figure 8 16mm2 or better hooked terminal to terminal from one battery to the next including a 100A solenoid/relay in the wiring.

got a time?

cool.

Reset the batteries and remove the solenoid from that setup then install your dc/dc inverter in its place, IF you feel that you need to wind the size of the wiring back to 8mm2 so you can use the normal screw block terminals, the normal crimp splice or the normal recommended wire size for most of those DC/DC inverters feel free.

now repeat the test.

Last time I did it, the DC/DC inverter wouldn't even recognize the AUX battery until Id manually charged it to 9.8v

I love these threads... :cool:

And lets go 5000km services, dance naked to Pagan Gods and see if we can sail to the edge of the world :wasntme:

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Originally Posted by drivesafe

Wilbur, I think you need to learn a bit more about the different types of batteries and their intended uses because your misunderstanding what you're reading.

...............................

Now, your correct that battery technology is advancing but you need to understand what these advances are and how they fit into RV/automotive situations.

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Drivesafe, I have learned a LOT about the different types of batteries, and I fully understand what these advances are and how they fit into RV/automotive situations. I understand the chemistry (to an extent) and I understand why they need the charging regime that the manufacturers specify. I know how to design and build the harware to charge these batteries to the manufactureres specifications.

In the year 2011, I assumed that no one would use old technology batteries for the house batteries in a camper or motorhome. I still assume that, though there will of course be some who don't want to learn how to deal with new technology and will stick with the old tried and true system.

The old systems worked but if applied to modern batteries, the life of the modern battery will be greatly reduced. If properly handled the new batteries are very much better than the old ones. Haven't you wondered why there are so many multi-stage 240 volt driven chargers on the market? All the DC - DC convertors do is to offer this technolgy (multi-stage charging) for those who charge their batteries from their alternator instead of or as well as from 240 volts.

In 640newtons case, with a vehicle like that and the set-up he seems to have, I would be VERY surprised if he hasn't bothered to get modern batteries for the two in his camper. All he needs now is a proper charger. By modern batteries I don't mean cutting edge 2011 technology, just a plain ordinary AGM or similar, such as has been around for quite a while now.

Blknight, the less said about your "test method" the better.

In all honesty I think this thread has gone far enough - it really had been a hijack of 640newtons thread. I strongly urge anyone contemplating adding batteries to contact the battery manufacturer for instructions on which type of battery to use, and how to look after it.

Thanks for the sparring match, it has been fun - even if it is two against one!

Cheers,

Paul

Wilbur, enough is enough.

It is not two against one, you have absolutely no idea what your talking about and are doing nothing more than using some fancy phrases without out actually saying anything and you haven’t posted a single bit of info to back your claims.

For your info, the most advanced batteries on the RV and automotive market today are not AGMs, these will very shortly be nothing more than a specialised battery group.

The most advanced batteries of the market today a Calcium/Calcium batteries, these are, as you put it, OLD TECHNOLOGY batteries, better known as flooded wet cell batteries.

As I have posted, you read a bit of info but because of your lack of knowledge of the way everything works together, you have no idea of how things will be effected by other related situations in the systems these batteries will be used in.

Furthermore the very fact that you think a battery charger, whether it be a 240vac charge or a DC-DC converter can do a better job than an alternator can just shows you are doing nothing more than parroting what you have read on the side of some corn flakes packet.

There is NOTHING on the market that can beat an alternator when it comes to charging batteries while on the move, further more, the larger the capacity that needs to be charged, the greater the problems these DC-DC converters will cause, to the point where their use will actually result in the rapid shortening of the batteries life span.

If you what to believe the garbage that these snake oil pedlars are spinning, so be it, but don’t come here and make out you are an expert in a field you quite obviously don’t work in and also as obvious, you don’t understand.

Newton has asked some legitimate questions and he is after legitimate answers, not misleading advertising hype.

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Originally Posted by drivesafe

Wilbur, enough is enough.

It is not two against one, you have absolutely no idea what your talking about and are doing nothing more than using some fancy phrases without out actually saying anything and you haven’t posted a single bit of info to back your claims.

For you info, the most advanced batteries on the RV and automotive market today are not AGMs, these will very shortly be nothing more than a specialised battery group.

The most advanced batteries of the market today a Calcium/Calcium batteries, these are, as you put it, OLD TECHNOLOGY batteries, better known as flooded wet cell batteries.

As I have posted, you read a bit of info but because of your lack of knowledge of the way everything works together, you have no idea of how things will be effected by other related situations in the systems these batteries will be used in.

Furthermore the very fact that you think a battery charger, whether it be a 240vac charge or a DC-DC converter can do a better job than an alternator can just shows you are doing nothing more than parroting what you have read on the side of some corn flakes packet.

There is NOTHING on the market that can beat an alternator when it comes to charging batteries while on the move, further more, the larger the capacity that needs to be charged, the greater the problems these DC-DC converters will cause, to the point where their use will actually result in the rapid shortening of the batteries life span.

If you what to believe the garbage that these snake oil pedlars are spinning, so be it, but don’t come here and make out you are an expert in a field you quite obviously don’t work in and also as obvious, you don’t understand.

Newton has asked some legitimate questions and he is after legitimate answers, not misleading advertising hype.

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I did say that I wasn't referring to cutting edge 2011 technology, just AGM's that had been around for years.

Anyway, you are getting nasty now, so I will sign off now and content myself with pointing out that it is YOU, not me, who has a vested commercial interest in promoting one technology over another. I have no reason to offer "misleading advertsisng hype".

ok wilbur, if you dont like that test lets do the same one with an 85A alternator.

both batteries setup as before but all equipment (I'll be nice to your batteries, you can have them outside) must be in a 75-80 degree environment.


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.