Battery testing, attempt at simplification ..?

Testing batteries was a whole lot simpler when I were a lad (queue the Hovis music) the only batteries found in cars were of the lead acid type and they had reasonably predictable issues when it came to fault diagnosis, add to that the simplicity of car electrical systems that had zero loading on the battery when the car was not in use, making battery assessments a whole lot simpler.

In Porsche terms I think the SC was perhaps the last to have the advantage of "simple" electrical systems..... But even then I suspect the primary cause of battery Porsche and other related electrical faults even in those with simple electrical systems may be down to LACK OF USE.

Neither automotive machinery or batteries were designed to lay dormant over the average of time spans that many Porsches experience today, either as garage queens or just recreational vehicles taken out on the road or track for an occasional BLAST.. Though there are batteries more suited to the task for stand-by generators etc.etc.etc. which are not suitable for use in vehicles..

Boat batteries suffered similarly irregular usage and then periods of high demand thus battery manufacturers created DEEP CYCLE lead acid (and perhaps gel..?) batteries to increase dependability in such situations. Whether deep cycle lead acid batteries might have a place in Porsches as opposed to ORIGINAL spec batteries, I leave that to those with a deeper knowledge of battery construction and use than I to determine.

It would seem that it is cheap enough to buy a "meter," but that does require an element of understanding to accurately assess the readings obtained, not only in terms of volts, ohms (resistance) or amps (current) but what part those readings play in the grand scheme of things relating to the that which you seek to understand..?

I have an old battery condition tester that has been very handy and is probably older than some of the folk reading this (if any) (-: I will try to post a couple of pics to give you an idea of it`s simplicity... handy for 356/912/early 911 owners up to the and including the SC models which had far "simpler" electrical demands.

My old battery condition tester operates by taking very accurate voltage readings during a predetermined series of SIMPLE tests during which a series of LED`s (light emitting diodes) will illuminate to provide the result of the test.

As has been typed here on many occasions battery voltage readings can look just fine but the battery fails under load, thus there seems to be much room for confusion...? It seems that to better understand the actual CONDITION of the battery the ideal is to perform a number of tests.

The LOAD TEST would seem to be perhaps the best indicator of battery condition..... ? Looking at the pic of my tester you will no doubt note that the wires to it are thin, and thus not at all suitable to carry the load that would be involved to assess the loadings a battery would be exposed to when trying to fire up a Porsche, however if you read the instruction set (a pic of which I hope to post) it can be seen that the LOAD in use during the test is that of the starter motor associated circuitry and components required to effect a real time start, the condition of the battery during that test is indicated by a LED being illuminated.

Thus it seems for many owners of older Porsches, a BATTERY CONDITION TESTER might just be a more suitable option than a "meter"....?

Testing has moved on from simpler tests used for lead acid batteries where a hydrometer could test the specific gravity of the electrolyte and give an indication of the state of charge. Many batteries are sealed these days, and some are gel filled consigning hydrometer tests to the bin... There are still available relatively cheap testers that can apply an actual LOAD directly to the battery to determine it`s CONDITION relative to expectations of it`s expected duties note the larger clamps and thicker cables.. It also seems there are still available testers similar to my old one, this link might be handy..?

https://www.eurocarparts.com/batter...MI2uyz0Y7_4gIV-ArTCh0f7ATIEAAYBiAAEgJbkPD_BwE

With later Porsches and their far more complex "intelligent" electrical systems, testing batteries while still connected to those systems is far more complex not only that but to disconnect the battery to simplify battery assessment can create a series of issues relative to creating fault codes and perhaps the loss of programming relative to personalised settings and accessory add ons, requiring a degree of re programming..as Kurlykris alluded to in his recent post 23rd June 19. Also notable from that posting is that it is recommended to pull the fuel pump fuse, perhaps to prolong the LOAD test by inhibiting start up..?

Of course "intelligent" chargers go some way to offsetting the seldom used syndrome that many batteries seem to suffer these days, but it seems the condition indication LED`s on these chargers can mislead at times too... ?

When I type of the complexity of modern systems, consider if you will Iain`s (Demort) also recent contribution 22nd June 19, where he informed us of the situation where an input to the electrical system is initiated by just operating the door handle to enter the car which then automatically energises the fuel pump to pre-pressurise the fuel system in preparation for the expected start up process... Thus from that it can be seen that battery loadings of modern vehicles differ significantly from those of earlier Porsches thus assessing battery condition is also potentially a more complex issue when even to open the frunk to gain access to the battery terminals in a bid to test the condition of the battery, you have already drained a measure of potential from the battery....?

There are non-professional (cheaper) battery condition testers still available that measure voltage to assess the condition of the battery while using the vehicles on board systems to provide the very necessary LOAD TEST.. though I have no experience of them... however as with all test regimes it is important to follow the instruction set to the letter in order to obtain an accurate assessment.. it might be worthwhile to look at this link..?

https://www.amazon.co.uk/s?k=batter...827852&tag=googhydr-21&ref=pd_sl_4r1g56h4su_e

If interested, to give you an idea of more professional kit you might like to beam up :-

https://www.rotronicsbms.com/produc...MI2uyz0Y7_4gIV-ArTCh0f7ATIEAAYAiAAEgIsmfD_BwE

As ever I am just passing time thinking in type and happy to be corrected should my thinking be considered flawed.. I am no expert. :?:

Pics as promised in the post above.

Second pic

Isn't just looking at the car's volt meter in the binnacle simple enough?

I use a multifunction one that checks resistance, so gives you a calculated amp compared to new, for example new 760 cca, calculated 260 cca means its stuffed.

I have some cars that a battery will last 7 years in ( low drain , small engine fiesta 1.2 ) and and some where they last 2 years before not being dependable Grand Voyager.

I have spent hours looking at charge voltages, current drains etc and come to the conclusion unless there is a fault with the car, as soon as the battery looks dodgy, put in new one, whether its 2 years or 7 years. Because it can look ok at test, but never as good a new battery and who wants to be stuck in a morning for the sake of a battery.
My 996 is terrible for battery drain though, a brand new silver varta wont last 3 weeks unused wihout looking flat, its a combination of low charge voltage from the alternator ( set by the ECU ) and standby drain + short journeys, so a trickle charger is a must.

My new merc charges at 14.4V , whereas the 996 is nearer 14V and terms of current thats a huge difference, so short journeys kills it.

Our voyager charges at 13.8 v and when I set this to 14.2v using an external regualtor, I got hot drive belt, noisy alternator and also excessive drive belt flap due to the huge load put on it which wiped out the tensioner.

so it seems the battery life is a function of the car design and some are good and some are poor, yes I have taken un unhealthy interest in batterys.

FIL 1.4 golf was like the fiesta, small battery but you could leave a month it never let him down.

Seeking to simplify battery condition assessment can be a bit complex these days.... Catch 22..? (-:

Alex, if you use your car regularly then you are well used to it`s sight sound and smell thus you may not even need a dash mounted voltmeter to suggest there is a possible issue arising when you turn the key to fire it up if it takes a tiny bit longer to jump into life, or perhaps if the dash display dims a bit while turning over.. Yup so many little signs that something is just not quite right for someone more in tune with their vehicle as the result of their regular usage of it..?

timm996, I think battery LIFE can be a function of it`s suitability for the task is was DESIGNED to perform, and that which it might be EXPECTED to perform, as such batteries come in all shapes, sizes, capacities and chemical composition relative to their design function specification...?

It would appear that the KEY element in terms of battery failure is when it is operated outside it`s design parameters, the further outside those operational parameters relative to TIME the less likely it is to perform adequately...?

Design parameters.. may be the maximum load/discharge relative to TIME balanced against the expectations of recharge cycle and the rate thereof.

Unfortunately batteries themselves have INTERNAL losses thus even with no connection to anything they can in time loose power.

Thus in a seldom used Porsche, the battery is expected to work WELL outside it`s design function expectations, thus bound to fail relative to TIME and far more so in "modern" Porsches with electrical systems that are designed to draw power from the battery CONSTANTLY, all be it at a relatively low rate of consumption, but just like a dripping tap will drain a water tank if the tank has no means of replenishment, the battery will empty it`s self in time..?

Of course there are ways of trying to closer match the.... battery`s requirements... to improve it`s longevity if it is to be forced to operate outside it`s ORIGINAL design function specification... Intelligent chargers, may go some way towards achieving that goal, and thus extending the lifespan of the battery to SOME degree..?

Poor old battery, there are so many expectations of it which it may not be ideally specified to achieve. The battery like us is made up of a variety of chemical compounds, and like us if we were expected to operate outside our design parameters of WORKLOAD relative to rest, being fed adequately and all in temperatures that suit our personal variation in design, our lifespan may be reduced by some amount of time....?

If you can`t treat it well, or at worst treat it poorly, it might be best to expect failure sooner than later....?

I guess it can be down to a cost benefit analysis calculation as to when it seems wise to fit a replacement..against how a failure might affect your intended usage of your Porsche on any day..?

Good luck in your choices..

Claiming no expertise, just thinking in type.

Check mine everyday. Also a great way to ensure your alternator is up to scratch. Got into the habit of doing this as my battery is 6+ years old and has sounded like its on its last breath for 4 years........but whilst its never let me down I'm reluctant to change it.

Alex, using a machine in a way that the sum of it`s parts was designed to operate has the potential to pay dividends in terms of maintaining it`s efficiency to do the job, long periods of lay up or irregular usage would seem to create potential for issues to arise in batteries and much else.

That you are running an old battery equates to running a degree of risk Alex..? That being typed I guess the hope is that your battery does not totally fail with no warning at some really inconvenient moment..as has been known to happen.. I guess if one considers the cost benefit analysis of a total failure situation then replacement costs every three years or so for a modern Porsche with high electrical demands might be considered advantageous compared to possible breakdown/recovery and all the inconvenience costings associated with a total failure...? But then the digital revolution has lured business away from high end maintenance and into varying degrees of risk management in a bid to cut costs..?

Some time back on my last adventure into Southern Europe in my old sports car, my battery was at the time circa three years old and as part of my pre trip maintenance regime I replaced the battery a month or so before we left. Another well travelled friend declared that batteries can be found all over Europe...!! On the trip a few hundred miles from home an indicator stopped working, fortunately I carry spares, but I noted that the Motorway "service" station in darkest England, had zero car parts available...!!!

Further into the trip in France and seeking to to top up the oil with an equivalent grade to my then Castrol GTX, was an impossibility one of the few things I recognised on the Autoroute shelves was a can of STP, so I fired that in which curtailed my engines (Rover V8) usual thirst for oil for the rest of the trip, How that might work in an air cooled Porsche, I know not, perhaps Baz would have a thought..?

One other consumable on such a trip is that my old car has need of is grease. I fully charged my grease gun before leaving but underestimated the amount of grease it would consume on the trip, and by the time I reached Pisa, I hoped a city service station with a maintenance bay would have a shelve full of grease tins... Nope..!! Using my best pigeon Italian I went into the service bay to try to ascertain what Italian grease was called from the mechanic working within... GRASSO... Great back into the service station "shop" with the correct word, the guy behind the counter disappeared into a store room and reappeared with the most expensive tin of grease in the world.... who ever herd of ripping off tourists.. Sure I could do without a £20 ice cream cone in Rome, (circa 2003) but my old car NEEDED greased and semi regularly..

Sorry as ever got off track a bit..as ever..