Battery Maintenance

System

Terry98 wrote: »

. I only do about 3000 miles a year and quite a few short journeys of about 10 miles in total each trip. I know that puts a strain on the battery but if the alternator is working properly isn't 10 miles good enough to recharge it?

Not even remotely enough, especially at this time of year when you have heaters and lights on. Most of the time the alternator is charging on the types of run you're doing it'll be barely putting anything back into the battery as it'll not be generating much more than the vehicle electrics require when running.

Yes but the link I put in my first post thinks most batteries these days go in 1 to 2 years. Perhaps you get what you pay for!

The battery on my car is the original. It is coming up to 7 years old and the car has over 115,000 miles on it. The difference between you and I is my car does two 30 mile journeys 5 days a week going to work and back. The problem you're having is because the battery is going flat. Once they get to around 11 volts they've suffered internal damage. Down to 10V and they're definitely damaged. Whilst you may not notice it in a car that does a decent journey every day the damage has been done and it is mostly likely going to show up in a dead battery the first cold weather we get.

My advice is to get a battery charger and every few months give the battery a charge with it.

System

Strider590 wrote: »

Typical alternator is going to kick out 90A +

The full output is only reached once the alternator reaches a certain RPM. During tickover and low speed urban driving, much of the time it won't be.

Headlights = 8A
Tail lights = 4-8A
Ignition coils = 6-12A
Heater blower = 10A
Wipers 15-20A
Electric Windows = 10A (when in use)

Fuel pump = 3A to 17A depending on flow rate and pressure.
ECU and other onboard computers = 2/3 amps per unit.
Electric Power Steering = 8A-10A.

Strider590

Tarambor wrote: »

The full output is only reached once the alternator reaches a certain RPM. During tickover and low speed urban driving, much of the time it won't be.

Which is why short journeys are bad, despite claims to the contrary.

Tarambor wrote: »

Fuel pump = 3A to 17A depending on flow rate and pressure.
ECU and other onboard computers = 2/3 amps per unit.
Electric Power Steering = 8A-10A.

EPAS equipped vehicles usually have a larger capacity alternator and the current is dependant on how much torque it's having to apply. Manufacturers don't like having anything that uses a constant high load as it screws with fuel consumption figures. You'll never exceed the capacity of the alternator unless you've got aftermarket additional loads, like a huge car stereo/amp, they're designed for the vehicle maximum load plus a given percentage (depending on the manufacturer) and if you do exceed the maximum load, the alternator is going to !!!!!! kittens.

Alternators typically need 2k rpm to achieve maximum power output and this drops of rapidly below 2k, so at idle it's doing very little.

parking_question_chap

Probably alternator or pulleys.