Batteries

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Whether your classic is stored over the winter, or used daily, Rob Marshall explains how you can prolong battery life, as well as considering the best buying and upgrading options

That dull thud and groan of the starter motor trying in vain to turn the engine over greets many classic car owners at some point and none more so than during recommissioning it after a winter lay up. Battery RIP.

Thanks to modern technology batteries last longer than ever – up to a decade in some cases. What’s more, according to The Battery Council, at least a third of all that are scrapped are in fact perfectly fit and healthy – once they have been expertly recharged… So don’t instantly throw yours away until you get it tested first!

However, the inevitable will rear its head one day so be prepared and think about what sort of battery is best for your classic – now!

How it works

Whether your car employs either six or twelve-volts, most classic car batteries rely on lead-acid technology as a means of storing and releasing electrical energy.

The positive plates within the battery consist of lead dioxide; its negative plates are made from porous lead, both of which are bathed in a sulphuric acid electrolyte solution and are separated by non-conductive synthetic sheets to prevent short circuits. The plates are arranged to form six cells, each of which should produce just over 2V (Volts).

Electrons flow through the various consumers of electrical power and pass from the negative to positive plates, as the battery is discharged. Lead sulphate also builds on both plates as the sulphuric acid’s strength weakens. During recharging, the lead sulphate dissolves back into the electrolyte and the acid’s water content decomposes into hydrogen and oxygen.

This is why a battery ‘gasses’and necessitates that it is situated in a well ventilated area during charging.

Maintenance matters

Starter batteries are designed for brief and intense discharges, followed by prompt recharges, unlike other types of lead acid battery, such as ‘Leisure’ types used by caravanners.

The acid also corrodes the lead material used on the plates naturally, a process that is accelerated in high temperatures, meaning that even the best maintained battery will not last forever.

A 12-volt battery should not display voltages below 12.4V, because ‘permanent sulphation’ will occur, which reduces battery life dramatically, unless you restore it to a 90-100 per cent charge level. If left for longer, the lead sulphate crystallises onto the plates and becomes harder to break down and turn back into the acid. This reduces the battery’s CCA (Cold Crank Amps) and, therefore, its state-of-health.

As sulphation increases, so does the battery’s internal resistance. This ‘tricks’ your car’s battery regulators (that tend to be solid state for alternators and mechanical for generators) into presuming that the battery has reached its optimum charge state.

The current is, therefore, reduced to prevent harmful overcharging. Yet, the battery becomes undercharged instead, thus encouraging further sulphation and hastening the downward spiral. Both over and undercharging can be caused by a faulty charging system, including its regulator.

Therefore, ensure that battery voltage readings do not deviate above, or below, 13.5 and 15.0 volts, with no electrical accessory load and the engine running above idle speeds (especially with generators) but prioritise any voltage specifi cations that are provided by your car maker.

Enhancements within modern batteries have reduced the regular need to top-up the electrolyte with distilled/deionised water dramatically, unless overcharging and unduly high underbonnet temperatures (especially those encountered in hot summer weather) are experienced.

Check seasonally, or more if you suspect the box of sparks is failing, that the acid level for each cell sits just above the plates – top up with de-ionised water. Many classics batteries have access plugs but note that sealed batteries are not designed to be topped-up (although certain types, by peeling away the maker’s sticker, you can gain access to cell’s plug-ed).

Charging tips and wise health checks

Measure battery state-ofcharge, by checking that the voltage is above 12.4V. The state-of-health involves assessing the available cranking amps. The modern method involves measuring the battery’s internal resistance and calculating an ampere figure that is compared with the CCA (Cold Crank Amps) figure that is stated on the battery label. Some advanced DIY smart chargers (such as Ring’s RSC612) can perform this computation accurately but a battery retailer should be able to do this for you. Therefore, consider that it is possible for a ‘dead’ battery to display a seemingly good voltage but have a low state-of-health.

Eventually all batteries will die a death and apart from regular checks as described above there’s not much you can do although many motorists swear by Granville’s Batt-aid; small pick-me-up pellets that you pop into the cells before giving the battery a slow charge to activate them and dissipate the build up of lead sulphate. We’ve used them for yonks and while no substitute for a new battery, can prolong the inevitable for a few months for under £5.50.

Buying and upgrading

Sooner or later, you will need to replace the battery. Check that any replacement unit possesses the same dimensional sizes (don’t forget height-ed) and terminal post designs of your original. Even if MoT exempt, a loose battery is dangerous and will render your classic as unroadworthy, so ensure that it is secured.

You can upgrade your battery, by retaining the same voltage specification but prioritising a higher amperage (CCA) replacement. In theory, a higher capacity battery will last longer, because it will be able to supply the required cold-start current to get your car started for longer as its state-of-health deteriorates.

Chemically, the exact battery content is fairly complex and some makers use technical terminology for marketing reasons. Silver calcium batteries, for example, can possess a 10 per cent increase in cold-start performance and can tolerate a slightly higher charge rate but this is not especially relevant for historic vehicles, in particular. EFB (Enhanced Flooded Battery) are not damaged as much as traditional lead acid batteries, when operated in a reduced state-of-charge for long periods, and they can offer a greater lifespan, compared with ‘standard’ flooded types.

They may be dearer but can prove the most economical long-term upgrade choice. Advanced Glass Mat (AGM) batteries are intended to work with modern vehicle stop/start and regenerative braking systems, for example, and can accept extremely high currents for short periods.

They are not really suitable for classic cars which is a relief as they can be pretty costly…

So that you do not buy a new battery that has a reduced state-of-health, make your purchase from a trusted retailer that follows the battery manufacturer’s charging and storage advice. Beware of fakes, too; online sellers are known to be rife with counterfeit parts and it is not unknown for battery bases to be filled with concrete to restore weight lost from reduced lead content!

Check that the voltage is above 12.5V before fitting and, after the battery has been used for several weeks, check its state-of-health does not fall significantly below the figure stated on the CCA label.

Most modern household waste sites will dispose of old batteries for you but consider that, as virtually all of it can be reused, scrap metal sites tend to pay at least a few quid for your knackered old battery.

That classic touch

Classic batteries are a bit like classic oils insofar you can have the best worlds, in this case a period-style exposed lead bar between the cells box of sparks that packs up to date technology and starting power.

Okay to be fair, ultimate technology is not the same as today’s advanced batteries so you cannot expect quite the same performance. However, a good classic battery is still a lot better than they were back in the 1960s and 70s!

In the vast number of cases just a straight forward like-forlike replacement is adequate but you can go one better and opt for extra plates: nine plates were standard but you can go to 11 or 13 to improve cold starting performance. This is a very good idea because classics often sit around for long periods.

Originally they used a rubber casing but moved onto plastic during the 1960s. With rubber, you inevitably get some impurities in the case which does not happen with plastic – you can get a higher self-discharge as a result.

If your classic has a real rare battery type that’s virtually unobtainable then fear not; most leading classic battery makers can even rebuild your existing one. This may be case for old Fords with their unique square post terminals as hardly any modern batteries cater for them, meaning you have to change the battery leads to suit or fit adaptors.

Current affairs

Any battery is only as good as the charging system and environment it is connected to, so spend some time and money here before simply fitting a new box of sparks.

Ratty old battery leads will create high resistance and lead to poor battery performance; MGBs with their quirky six volters mounted at the rear are prime candidates – change them if they seem suspect.

Have the generator checked if you feel it’s not doing its job. On dynamo systems, a separate voltage regulator is usually fitted. These can fail but sometimes just a simple re-adjustment and cleaning the contacts helps. You can also boost the charge rate but overdo it and you’ll cook the battery; see a good old fashioned auto-electrician first.

Battery chargers and jump packs

Buying a modern ‘smart’ charger is an especially good idea. As batteries discharge naturally at, around, 0.1 volts per month at 10 degrees Celsius, (the rate of which increases with temperature), an optimum charge is ensured, without overcharging. While old-fashioned tricklechargers reduce their current input as the battery’s voltage increases, they tend not to stop charging fully, heightening the overcharging risk.

SC Power is a designer and maker of technically advanced battery chargers and conditioners. Using Microprocessor controlled charge management it ensures the correct charge at the right time, it claims.

Many smart chargers feature other maintenance modes, including a ‘De-sulphation’ facility that pulses a high voltage into a discharged battery that is designed to dislodge the lead sulphate crystals from its plates. The success rate depends on how long the battery has been in a discharged state. Should you use your classic everyday, use the smart charger to give your battery a re-fresh charge once every three months.

Portable jump starter packs are proving popular, not only with used car dealers but also motorists as it does away with the inconvenience of jump leads. Like mobile phones, they are becoming smaller; we’ve been testing the British made pocket-sized Energiser that’s endorsed by Edd China (see picture). Capable of firing up a 4-litre petrol engine several times on one charge, they’re pretty good value at around £90 and fit nicely in the glove box.

Acid, you and law changes

As a result of acid attacks, new laws restricting battery sales and home use are in force. You can no longer buy batteries (including leisure types) supplied ‘dry’ with the acid added separately by the end user unless you hold an EPP (Explosions, Precursors and Poisons Certificate) costing £39.50. As a result only ‘wet’ batteries will be sold – possibly bumping up the prices. Since November, anybody not holding an EPP licence is breaking the law to be in possession of any sulphuric acid at all – even emptying out an old battery in your garage can lead to a prosecution.

With thanks to:

GS Yuasa Battery Sales UK for help with the heading shot, and GSF (The Parts Alliance) for supplying a battery for one of our project cars – we’ll report back later on it