4x4 Action Group

Some light reading regarding lead acid charging.... (actually an interesting site regarding batteries in general)

https://batteryuniversity.com/learn/art ... id_battery

My std TD5 alternator is 120Amp output and my Mad-Man generally indicates charging voltage at about 14.2V.
So I’d assume on reasonable runs, say 1/2 hour twice a day, that the starter draw-down is replenished as is the glow-plug draw (20A*4 mind you !) and the fuel -pump load is a running load as would be other minor electronics leaving plenty to top up both my cranking and HCDP connected aux battery (no load) on any shortfall....but I will put my smarty charger in and check.

Many lesser cars of course only have 85A or 100A alternators ...

Maybe that will create some other dark holes. Smart chargers go through analysis paralysis before deciding what to do.

But a good idea to play with. Will try it and see.

Thanks

Henri, after my long tirade earlier I’m embarrassed to disclose:
I put the Optima 6 charger on at 17:50 it ‘desulphated’ for 15 mins and then charged at ‘0.5 to 5 Amp’ for at least 2 hrs but , only now, peeking through the LR window, I see its still on reserved Test Mode
and not giving the ‘All Charged & Clear’ signal

‘Test Mode’ is where it waits for the battery to discharge sufficiently to warrant yet another cycle after let's say ?4 hrs from connection ?

(I question whether any charger can detect
sulphation let alone redeem it! )

Battery is 1 maybe 2 years old but still kicks the engine over easily. I will use my Boomers Hydrometer to check it out tomorrow.. !

Chas, it is to Woolf you should be apologising.

Woolf is the one who said that the alternator never fully charges the battery so he uses a smart charger and feels that may be giving him longer battery life.

The other things we've learnt on this Thread are;

Most batteries are from the same manufacturer.

Buying a 'posh' pricey battery doesn't gaurantee you longer battery life.

Forty months is considered an above average battery life.
In fact, anything over 36 months is good these days.

There are a lot of factors that can influence a batteries longevity. Some of those are related to the design, manufacture and materials used and others are related to the vehicle they are used in.
We don't have much control over materials used. Here we are limited to buying a brand that has a reputation as "good". However a lot of the time we are stuck with what we can get at the time when we need it.

On the vehicle the charging system is one of the most overlooked and under serviced systems. We generally ignore it until the car does not start or we get a warning light pop up, but very seldom do we actually have the system "serviced". Maybe some agents do this as part of the service schedule but I have not seen it in any of the vehicles I have owned over the years.

Woolf is right. Batteries in cars almost never see a 100% charge. A lead acid needs in the region of 6 to 10 hours of constant charging to get to 100%.
Most of us never drive that many hours in one stretch even on a long trip. A daily driver will not ever get there.

Having a monster alternator is also not going to charge the battery any faster. A high current alternator is useful if you have large current draws while the engine is running but the charging of the battery is limited to around 2A to 3A @ 14.4 to 14.7V while the initial charging cycle starts and this will drop down to less than 1A @ ~13.6V once the battery reaches above about 90% of its charge. Charge a lead acid to fast and it boils or worse.

Other things to take into account:
1/ Lead acids do not like to be discharged more than about 20 to 25% of their capacity. Discharge the Batt more than this and you can kill it quite quickly.
2/ If battery connections are not kept in top notch then the batt will not charge as well as it should making a bad situation worse.
3/ Modern cars have higher parasitic drain on the battery even when the ignition is off, leading to higher over night battery discharges
4/ A malfunctioning voltage reg/rectifier on the alternator could over-charge / undercharge or supply a whole bunch of AC to the battery
5/ Flooded lead acids don't really like being shaken about all that much. In our 4x4's beings used off road this is a given fact of life and will hasten the demise of a battery. More off road the shorter the battery life.

3-5 years is a good life expectancy. I usually get about 5 years but then I do check the charging system and clean battery connections every 6 months or so.

Thanks Wooky,

I simplistically understand that a battery is fully charged when a voltmeter test shows 12.6 V.

Given all the above you have explained very well, if I switch my car off and the voltmeter settles at 12.6 V after a short while all should be good?

Cheers

What you are talking about is "resting voltage"

To measure resting voltage you need to leave the battery ( disconnected from the car) for 12 to 24 hours to let the voltage settle to a proper resting voltage.

A new battery ( at 100% charge) the resting voltage should be around 12.9V to 13.2V ( 2.15 to 2.2V per cell X 6 cells in a 12V battery) - this is full capacity
A resting voltage of 12.4V (2.07V per cell X 6 cells in a 12V batt) the battery is about 75% capacity.
A resting voltage of <12V (<2V per cell X 6 cells in a 12V batt) the battery is about fully discharged.

Using resting voltage is only an approximation of actual charge state @ ~ 25 deg C

Best way to test resting voltage is:
1. disconnect batt from car
2. Charge fully using a decent charger
3. disconnect the charger and let it sit for 24 hours
4. Measure resting voltage

If, by doing this, your batt cannot get close to 12.7V to 12.9V then it is getting old. It could last for a while longer but could also die on you come a cold morning.

Please note resting voltage is only an estimation of charge capacity.
To test the the battery for high current draw, like starting the car, you will need to actually "load" the battery.

It is easiest to go to your local battery place and ask them to do a load test for you.

Interesting stuff Wookey.

Great Thread...

Now I really am edumacated on batteries!

Thanks Wooky

Hey I am by no means any sort of expert on batteries.
Just been around the block sorting out charging issues on too many old vehicles

Nice info here!

I'm going to Battery Centre today to swap out the crap deep cycle they sold me, and then I'm going to start charging my batteries more often.

I have never really dealt with charging of deep cycle batteries so not sure if the charge parameters would be the same.
What I have posted relates to what I could find / learnt over the years regarding vehicle starting (cranking) batteries and their charging systems.

I have a thingy, attached to my dash (aftermarket and I can also use ORRA radio frequencies on it...) that gives me a voltage reading from my main battery any time I want one by just pushing the on button.

My main battery has never been below 13.2V in the Ford, and never below 12.8V in the 76. I have it that the Ford has a smart alternator, and charges at a constant 14.6V, the 76 charged at 14.4V.

How does the smart alternator's charging map, differ from an "analog" alternator and are they more battery friendly?