Dual Battery

**DeanoH** · 18th February 2010, 09:49 PM

Sorry Drivesafe, you're not right.

Originally Posted by drivesafe

Sorry DeanoH, but until recently, most vehicles ran at around 14.v to 14.4v and on average they got much better than 2 years out of the cranking battery and more from their auxiliary batteries.

Absolute rubbish! eg. my 86 RR runs at 13.4 v, my 95 P38 ran at 13.6 v and SWMBO's D2 starts at 14.2 and runs at 13.8 v.

The biggest killer of batteries is Shopping Trolley Syndrome, where the vehicle is only driven for short time periods meaning the battery is never charged properly.

Yes! we agree, see previous post. It's called sulphation.

Vehicles used on regular basis and driven for decent periods of time are actually far less likely to shorten the cranking batteries life span but if we were to go by your theory, the longer we drive for the more likely we are to cook the battery.

Now you're talking dual battery systems. With a separate controller/regulator ? and yes, the more you overcharge a battery the shorter its life. QED.

This is just not what happens.

Sorry, Yes it is.

My 03 RR did 180,000kms in 5 years and and run at a constant 14.3 at all times and it still had the original starting battery in it when I sold it.

I'm pleased for you, (seriously), but meaningless in this context, what sort of battery(s), what sort of alternator, what sort of controller, what sort of use?. Too many unknown variables for me to say why.
Rons comment....................The batteries don't seem to last very long either -- may be one year to two maximum before they need replacement. Again too many unknown variables for me to say why.
But two totally different outcomes.

I havn't set out here to have a debate or a slanging match. I respect your views I just don't agree with them.

I've spent a lot of time over the last 30+ years maintaining DC power installations from 12 volt to 130 volt with battery capacities from 100 AH to 2500 AH and all the associated gear that goes with them.
I may be guilty of over simplifying some explanations, to make them more understandable, but I do have the knowlege and experience to make the statements and give the advice I do.

So setsuna, back to your original question.
.............is there any issues with charging??--overcharging, or undercharging using batteries of different sizes/types?

Yes!

But as you seem to have an older style alternator and a conventional lead acid battery and a calcium type auxiliary (with or without an external controller/regulator), not the most optimal setup but you should be OK.

Deano

**Blknight.aus** · 18th February 2010, 09:55 PM

Originally Posted by p38arover

Can one buy a conventional flooded lead acid cell battery any more? They all seem to be calcium these days. At least, when I have bought the last 3 batteries for my Rangie and Disco. They never seem to charge fully in the Range Rover and Disco - at least the green fully charged indicator never comes up.

Even if I charge with a four stage charger the same applies and I wonder whether the charger is not designed for calcium cells.

The batteries don't seem to last very long either -- may be one year to two maximum before they need replacement.

yes you can.

Its topping charge wont be high enough so you might be missing out on as much as 30% of your total chargeability.

thats what happens when you dont store batteries in a fully charged condition or repeatedly put a high amps charge onto a battery.

my rough rule of thumb.. (excluding gel and some other exotic acid batteries) from dead flat and compared to say filling a sports stadium

0-50% easy the electrons just walk in
50-75% they need a little bit of encouragement but not much
75-95% gotta start to push them a little all the good seats are gone and the little buggers start tripping over each others eskies
95-100% they're getting busy reshuffling around themselves trying to stay in groups with their friends and families so it takes longer to get the few late stragglers in through the turnstiles and when they get there they've missed half the game, some of them get crowded and just leave as soon as they can.

**drivesafe** · 18th February 2010, 10:09 PM

Originally Posted by DeanoH

I've spent a lot of time over the last 30+ years maintaining DC power installations from 12 volt to 130 volt with battery capacities from 100 AH to 2500 AH and all the associated gear that goes with them.

And I’ve spent the last 35 years designing and manufacturing automotive electronics for the industry.

And for just over twenty years, I’ve specialised in designing and manufacturing dual battery systems for the RV industry.

I base my info on hands on experience in this very industry, not on generalized DC applications.

With over ten thousand dual battery systems out there and working with the feedback from many of my customers, your theories are the exact opposite of reality and the problem with your theories are that there is no smoking gun to back them up.

**Blknight.aus** · 18th February 2010, 10:30 PM

Originally Posted by setsuna

I guess running it dead flat is OK if it is deeeeeeep cycle =)

no, bad man, goto crank handle, do not pass electric starters, you must use a magneto ignition or a diesel.

50% capacity is about the safe limit if you want any sort of decent length of life out of the battery.

call it 10.5volts on the terminals with a 4 amp draw on the battery. (an old school engle)

**DeanoH** · 18th February 2010, 11:10 PM

Originally Posted by drivesafe

And I’ve spent the last 35 years designing and manufacturing automotive electronics for the industry.

Excellent

And for just over twenty years, I’ve specialised in designing and manufacturing dual battery systems for the RV industry.

Again excellent, and we havn't even discussed controller/regulators.

I base my info on hands on experience in this very industry, not on generalized DC applications.

DC theory is the same never the less. A lead acid battery is still a lead acid battery regardless of where it is.

With over ten thousand dual battery systems out there and working with the feedback from many of my customers, your theories are the exact opposite of reality and the problem with your theories are that there is no smoking gun to back them up.

What theories?

1/ Overcharging batterys reduces their life.
2/ Undercharged batterys don't hold their full capacity.
3/ Different types of batterys have different characteristics and work best in systems designed for them.

Nothing too radical here I would have thought.

As I said earlier, I havn't set out here to have a debate or a slanging match. I respect your views, I just don't agree with some of them.

Query. Are we at loggerheads here because you're assuming an external multi-stage controller/regulator and I'm not?

At the end of the day setsuna and others can read this thread and make up their own minds.

"Akuna matata"

Deano

**drivesafe** · 18th February 2010, 11:57 PM

Originally Posted by DeanoH

DC theory is the same never the less. A lead acid battery is still a lead acid battery regardless of where it is.

DC theory is one thing, practical application is a totally different kettle of fish.

What someone can do with batteries in a RAPS set up can’t necessarily be done in an automotive situation, so your theory of “A lead acid battery is still a lead acid battery regardless of where it is.” just doesn’t hold water.

There are huge differences and some one setting up a dual battery system, as is the subject of this thread, needs genuine information based on sound operating practices, not unsubstantiated theories.

**Blknight.aus** · 19th February 2010, 06:03 AM

Originally Posted by DeanoH

DC theory is the same never the less. A lead acid battery is still a lead acid battery regardless of where it is.

you joking right?

thats like saying a tdi is the same as the puma engine just because its a 4 pot diesel with a turbo.

scott oz · 19th February 2010, 07:20 AM

Great debate.

Curious I’ve got an “IBS” (?) controller. Had it a number of years and it just sits there, I think, doing its job.

My average drive would be 40 minutes to work each day in city traffic and 40 back. I avoid the short trips.

So my question is how long “generally” does it take to recharge the cranking batter after starting?

**DeanoH** · 19th February 2010, 08:16 AM

Originally Posted by Blknight.aus

you joking right?

thats like saying a tdi is the same as the puma engine just because its a 4 pot diesel with a turbo.

Not what I'm saying Dave.

The electrical /chemical characteristics of a lead acid battery are the same regardless of its application. Though in automotive applications heat and vibration play a greater part than in a static situation. Just as electrolyte stratification is a real issue in static instalations but not in automotive. But the battery's characteristics are the same.

A bit like saying, the Puma and TDi engines are the same in respect that they both require the same fuel/air ratio to compress for maximum combustion efficiency. I'm not a diesel mechanic so hope that's a reasonable analogy?

Deano

Deano

**DeanoH** · 19th February 2010, 08:19 AM

Originally Posted by scott oz

Great debate.

Curious I’ve got an “IBS” (?) controller. Had it a number of years and it just sits there, I think, doing its job.

My average drive would be 40 minutes to work each day in city traffic and 40 back. I avoid the short trips.

So my question is how long “generally” does it take to recharge the cranking batter after starting?

I'll leave this one to the experts, don't know anything about dual battery controller/regulators, not my thing.

Deano

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