Mixing AGM and wet cells...

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Originally Posted by Remy

Let us look at some peer-reviewed journal articles by people who research in this area! Feel free to purchase the articles if the abstracts are not enough for you. I can access them through my work.

ScienceDirect - Journal of Power Sources : Search for an optimized cyclic charging algorithm for valve-regulated lead–acid batteries

Welcome to IEEE Xplore 2.0: Design considerations for charge equalization of an electricvehicle battery system

read the conclusion of this research

http://photovoltaics.sandia.gov/docs/PDF/caploss.pdf

I can find plenty more JOURNAL ARTICLES that have been peer-reviewed by scientists in these fields that show that these DEEP CYCLE batteries should be charged in special ways to maintain full charge and a long life.

In conclusion the specialist chargers are not just for SALES.

Now as i started saying a while back i also use my alternator to charge the deep cycle but use the charger designed for these batteries to top it up and maintain good battery condition. My deep cycle has never been full from car charging even after a 10+ hour drive from Brisbane back to home. i.e. my charger spent an hour throwing more charge into it before telling me it was finally charged.

All opinions have been valued - i hope mine is too!

No more from me - sorry for the distraction - gone for now.
cheers
Remy

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Interesting articles, but they appear to deal with solar and other power systems. They do not seem to deal with motor vehicle batteries. The question of proper charging in the articles appears to deal with increasing the number of cycles that can be obtained from the battery. Important in a power system, not so important in a motor vehicle. Due to the use of the batteries in in the article, they are attempting to squeeze every bit of power they can store in them. By the graph in one of the articles, at 14.5 volts (alternator output), you will charge them to 90% plus. To most of us, that is close enough to fully charged. It appears that you are attempting to argue fine points that are not overly relevant to motor vehicle drivers, or it might mean that your fridge cuts out an hour earlier.

Based on your articles, an alternator will not fully charge a car battery, but it will get close.

Is this true? It seems odd.

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Originally Posted by Fridge&Solar

Standard car and truck alternators are designed, for various good reasons to recharge car batteries to only 70-80%, and this works very well for normal cars and trucks, ....

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Noting most cars get used for short journeys and have a lot of start/stop cycles, wouldn't this be very bad for a battery?

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Originally Posted by p38arover

Is this true? It seems odd.

Noting most cars get used for short journeys and have a lot of start/stop cycles, wouldn't this be very bad for a battery?

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Hi Ron, this is the “Shopping Trolley Syndrome” I mentioned earlier in this thread. It is really not relevant to most people on this forum as their vehicles are more likely to be driven for quite a few hours between uses while on a trip, when the auxiliary battery is required.

As I also pointed out, the article is based more on a sales ploy than on the reality of long distance driving.

Tim, like many people who use the 'net, I've become increasingly sceptical of stuff I read.

As you know, I'm an electronics tech by training (not that I've done much in the past few years) but batteries are not my field of expertise. I rely on the experts. I don't know who to believe! :(

I'd have thought that blokes like Collyn Rivers would know their stuff (I first came across him back in the Seventies or Eighties when he was editor of Electronics Today International).

I've just been hunting around the 'Net for some of his stuff. I see he also mentions the 70% charge for car batteries.

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Originally Posted by Collyn Rivers

A vehicle charging system is deliberately designed to drastically cut back charging at 70% of full charge. The only really safe ways to approach 100% charge (90% is a realistic target) is via adequate capacity solar modules and solar regulator; or via a ‘smart’ charger – also increasing known as a three-stage charger

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I do note he says about himself (elsewhere):

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Originally Posted by Collyn Rivers

This is a field that's a long way from rocket science and I seek no credit for apparently uncovering it. Any electrical engineer would have done the same (and probably much quicker because I'm a research engineer). But there appear to be hardly any electrical engineers working in the practical side of the RV industry.

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Sorry i cannot help myself - broken promises i know!

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Originally Posted by r.over

Interesting articles, but they appear to deal with solar and other power systems. They do not seem to deal with motor vehicle batteries.

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Yes they deal with Deep Cycle batteries what i have been talking about not your standard car battery.

"By the graph in one of the articles, at 14.5 volts (alternator output), you will charge them to 90% plus. To most of us, that is close enough to fully charged. " Yes agreed - for me that is close enough too while driving. But not fully charged which is how this all started!
When i get home i make sure the DEEP CYCLE is looked after, fully charged using a three stage charger so that i get more cycles and have a full battery for my next trip.
"It appears that you are attempting to argue fine points that are not overly relevant to motor vehicle drivers, or it might mean that your fridge cuts out an hour earlier." Without a doubt i am discussing a optimised situation and maybe the extra hour of fridge life is important to ME especially when i have been charging using solar or other means because the car is stationary while i am fishing :). This may not suit all but i think it wrong to completely dismiss the research and say these chargers are just for SALES and that the alternator is perfect. I think the system that drivesafe has designed and sells appears to be great (BTW i didn't know that when i started these posts), reasonably priced and practical for an automotive application. I use a similar system! I NEVER said an alternator based charging system wasn't practical just pointed out the research about charging and care of DEEP CYCLE batteries and was told i was wrong.

"Based on your articles, an alternator will not fully charge a car battery, but it will get close." YES that is all i have said all along. We could argue about % but in the real word in doesn't really matter if you need more hours add more batteries. For ME cycles is also important because they are expensive batteries so i take a bit more care

Better go to work to earn the money for my next trip.

cheers
Remy

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Originally Posted by drivesafe

Hi Ron, this is the “Shopping Trolley Syndrome” I mentioned earlier in this thread. It is really not relevant to most people on this forum as their vehicles are more likely to be driven for quite a few hours between uses while on a trip, when the auxiliary battery is required.

As I also pointed out, the article is based more on a sales ploy than on the reality of long distance driving.

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So - stupid question.... if you'll permit me.

In between the long trips, when I don't need the auxiliary battery, should I leave it sitting in the battery box connected up, constantly being topped up by the alternator. Or should I disconnect it? Which would keep the battery in the best condition?

if left in the car, leave it connected to the charging system via an isolator.

best thing is to take it out of the vehicle a leave it in cool dry place with a trickle charger or better still a charger that monitors the battery condition and charges accordingly. K-Mart has such a charger.