Batteries & Battery Charging

Welcome

• In this presentation we try to give you:

• An overview of lead acid batteries and how they work.

• An overview of Hawkins battery chargers and how they work together with some charging curves.

• Some common battery charger problems.

All Devices Using Lead Acid Batteries Need a Battery Charger

• Regular supplementary charging with a battery charger extends battery life substantially.

• This results in an economic benefit to the end user

for which he will pay.

Our Battery Charger Range Covers

• Domestic & Recreational Chargers• Professional Chargers used commercially in all the

Automotive and Agricultural sectors• Fully Automatic Chargers used for standby and

sealed batteries

Battery Types

• We deal with rechargeable Lead-Acid batteries only.

• 2 Fundamental Types– Engine Starting – Quick bursts of high

current for a few seconds.– Deep Cycle – Prolonged discharges of low

current

Battery Construction

• 2 Basic Types depending on plate construction

– Flooded Cell - Usually allows water addition • Low Maintenance (Lead-Antimony)• Maintenance Free (Lead-Calcium)

– Valve Regulated (VRLA) - Always Sealed • Gel Cell• Absorbed Glass Mat (AGM)

Amp Hours - A Useful Battery Term• Ah – Amp Hours

• This indicates the battery capacity. If a battery is rated at 100 amp hours, it should deliver 5 amps for 20 hours or 20 amps for 5 hours, etc. This is useful for deep cycle batteries.

• An old rule of thumb is to choose a battery charger capable of delivering in amps, one tenth of the battery capacity in amp hours. eg For a battery with 100 amp hours capacity, choose a charger capable of delivering 10 amps. Some modern batteries may use C/5 & even C/3 & high tech batteries ask for 3 x C.

How Lead-Acid Batteries work

Battery Life

• In general, only 30% of lead –acid batteries sold attain a 4 year life.

• 80% of all battery failure is due to stale sulphation of the plates.

Stale Sulphation – the Silent Killer

• Stale Sulphation is caused by

• Storage without some energy input• Deep discharging an engine start type battery• Undercharging a battery • Heat - increases internal discharge• Low electrolyte level. The exposed portion of the plates

will sulphate• Incorrect charging levels – cheap chargers cause

problems• Parasitic drain – the load put on the battery in a standby

mode – see below

Parasitic Drain

• Parasitic drain is a load put on a battery that has been switched off

• Most vehicles today have clocks, alarm systems, engine management computers etc all of which may be operating without the engine running or when it is idling. This is parasitic drain.

• The constantly low or flat battery caused by excessive parasitic drain will have a dramatically shortened battery life.

Battery Charging

• If you don’t put the energy used back into the battery soon after use, it will commence to sulphate which affects life and performance.

• The vehicle’s alternator is a battery charger. It works well if the battery is not deeply discharged.

• The alternator will usually maintain the battery’s state of charge at somewhere around 80% - see the following diagrams & charts.

• Full state of charge is best achieved by using a separate battery charger when the vehicle is at rest.

Battery State of Charge vs Regulator Settings

Typical RegulatorSetting+/- 73%

of capacity

Driving PatternsAlternator Current Delivery ex Bosch SA

Engine idling= battery discharging

Driving PatternsEngine Speed : Idling as % of Driving Time

What is a Battery Charger ?• In simple terms, a battery charger is a device

that applies a d.c. voltage across the battery terminals.

• If the applied voltage is higher than the battery voltage, energy flows into the battery.

• This continues until the two voltages are approximately equal. At this point the battery has been charged up to the capability of the charger.

Battery Charger Construction• Good quality battery chargers should have

the following fundamental components– Some type of transformer to reduce the supply

voltage down to the nominal battery voltage– Some type of rectifier to turn the a.c. into d.c.– Some type of control over the output of energy to

the battery– Some type of device that will fail safe & limit or

prevent damage to the battery or the charger

Battery Charger Types

• Battery Chargers are divided into three broad types:

• Non-adjustable• Adjustable • Automatic.

How to Select a Battery Charger - 1

1. Establish the battery’s capacity in Amp Hours Ah.

2. Look at the output current data on the back of the range of chargers (use the lowest current rating.)

3. Choose a charger capable of delivering a MINIMUM current in Amps equal to 10% of the battery Capacity. Eg for a 50Ah battery, choose a charger that can deliver at least 5 Amps

4. Is the battery sealed or refillable?5. If it is sealed, you MUST use an

automatic charger.6. If it is refillable, you can use an automatic,

a manually adjustable charger or a non-adjustable charger.

7. A non-adjustable (trickle) charger cannot be left on a battery permanently.

How to Select a Battery Charger - 2

How to Select a Battery Charger - 3

8. A non-adjustable (trickle) charger will continue to trickle current into the battery as long as the battery voltage will allow this.

9. Over time, this trickle is quite capable of taking the battery in to the gassing stage where it will lose water and may suffer permanent damage.

10. All battery chargers except the automatics have to be monitored to prevent overcharging.

11. If the battery is not used very often – eg leisure application, boating, biking etc – leave it connected to an automatic charger permanently.

12. The automatic charger will keep the battery at optimum voltage for years if need be, ready to go at a moment’s notice.

How to Select a Battery Charger - 4

Hawkins Non-Adjustable Chargers

• These chargers include the Power 4, the Power 6, the Power 8 and the Power 10.

• These chargers all have similar charging profiles.

• They are taper chargers which rely on the rising voltage in the battery to reduce the current into the battery.

• They use fuses &/or thermal cut-outs for protection.

• The charging operation must be monitored from time to time to check on the battery’s state of charge.

Power 4 Non-adjustable Taper Charger

Power 4 charging 50Ah Raylite BatteryThis taper charger must be monitored

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Time Hours

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olts

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ps

Current tapering off but still delivering over 1a after 45 hrs

Eelectrolyte gassing but voltage still rising

Power 10 Non-adjustable Taper Charger

Power 10 charging 12V Exide 628 50 Ah BatteryThis taper charger must be monitored

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0.0 0.3 0.7 1.0 1.3 1.7 2.0 2.3 2.7 3.0 3.3 3.7 4.0 4.3 4.7 5.0 5.3 5.7 6.0 6.3

Time (H)

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Voltage well into electrolyte gassing stage: stable at +/- 15V

Current tapered down and still delivering +/- 1,3A

Hawkins Adjustable Chargers

• These chargers include the Pro 15, Pro 30, Pro 615, the Pro 224, Pro 324 & Pro 524.

• All these chargers have operator controlled switches for both voltage & current. These allow the operator to charge multiple batteries if desired and vary the charging current to obtain the best charging profile.

• They use fuses &/or thermal cut-outs &/or circuit breakers for protection.

• They use toroidal transformers – a very efficient design• The last 3 are combination engine starters/battery

chargers and are able to boost start a vehicle with a flat battery.

Current Selector

Voltage Selector

Overload c/b

Hawkins Pro 15 Operator Adjustable Taper Charger

Pro 15 Charging 50 Ah Exide BatteryThis charger has manually operated switches to

control the output current

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Pos’n 3 on current selectorVoltage rising, current

tapering downCurrent low..

Pos’n 4 selectedCurrent increases &

voltage rises

Hawkins Regulated Chargers

• These chargers include the Classic 6, the Smart 6, the Smart 15, the Auto Pro 5, Auto Pro 10, Auto Pro 20 & Auto Pro 50.

• They subdivide into 2 types, voltage regulated and fully regulated.

• The Smart chargers are voltage regulated only• The Auto Pro chargers are fully regulated and

conform to a precise charging profile. They self adjust their performance with ambient temperature change.

• They all use fuses &/or thermal cut-outs for protection

3 indicator lightsRed – Power on

Yellow – ChargingGreen - Charged

Hawkins Smart 6

Voltage Regulated Automatic Battery Charger

Smart 6 charging Exide 628 50 Ah BatteryThis automatic charger is voltage regulated

only

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Time (Hrs)

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Voltage reaches top limit &

charger switches off. Current falls

Voltage decays to bottom limit & charger switches on. Current & voltage rise

to top limit and cycle repeats.

Hawkins Smart 15 12-24V Fully automatic 3 - Stage Charger

3 indicator lightsRed – Power on

Yellow – ChargingGreen - Charged

12/24V Selector Switch

Min/Boost Selector

Smart 15 12/24V fully automatic 3 Stage charger charging 1 x 12v 105 Ah Battery

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Smart 15 12/24V charging 1 x 12V 105Ah battery

Bulk Charge

AbsorptionCharge = 1/3 BulkCharge

FloatCharge

14.4V14.9V

13.8V

0.6A

Bulk Charge

Absorption Charge =1/3 BulkCharge

FloatCharge

Sealed, Maintenance Free Batteries

• There is an accelerating trend to sealed, maintenance free batteries particularly in hard-to-service applications.

• Such batteries demand an automatic charger.• The more intelligent the charger, the better

the result.• Time constraints for charging dictate the

rating of the charger and thus the turn round time of the battery.

Common Battery Charger Problems

• A damaged or sulphated battery will result in little or no current flow. The customer then complains that the charger does not work. Check this by connecting the charger to a known good battery.

• An automatic charger needs a minimum voltage in the battery of about 10v before it will switch on. An extremely flat battery may not allow this to occur.

• Customers short out the clamps to see if the charger is working. This will result in blown cable fuses or rectifiers.

• Badly corroded clamps mean a poor connection between charger and battery. Poor maintenance of clamps can mean no current flow and/or heating at the point of contact i.e. the battery terminal.

 

Typical Battery Charger Applications

• Home Use – Unsophisticated customer generally topping up batteries – suggest Smart 6, Smart 15.

• Leisure/Recreation – Biking, Boating, Fishing, Golfing, Caravanning. Wants battery always ready to go. Suggest Smart 15, Auto Pro 10,Auto Pro 20.

Hawkins Manufacturing (Pty) Ltd

• Thank you for watching this Presentation.• If you have any queries or comments please

contact us• via our website www.hawkins.co.za

or email info@hawkins.co.za

• or telephone/fax 031 579 2813 (Tel)

031 579 4642 (Fax)