I now have the Z3 parked in a secure underground car park where I work.
It means it keeps clean
and I can swap cars whenever I like and drive the Z3 more this year
The downside is that I don't have access to a power point to connect a trickle charger and on Friday when I came to drive the car home the battery had died (I think its on its last legs anyway). It was no problem as I had another car to drive but frustrating
So I've spent the weekend doing some research into car batteries.
I was looking for something I could leave connected up for as long as I liked with no fear of it dying. Unfortunately no such battery exists as ultimately the constant drain from the alarm, radio, etc... will flatten any battery. However, endurance batteries do exist which basically cram more lead into the battery and hence they can hold their charge for longer. The downsides being cost and weight (up to twice the weight of the standard battery).
Other factors to consider are form factor (ie would fit the Z3 battery box, the OEM Z3 battery is a BCI Group 48 size, other sizes will fit though) and SAE connection posts with the +ve and -ve the correct way around (so no need to extend wires).
I narrowed the possibilites down to 3 batteries in preferred order all of which have long reserve capacities (how long they can maintain a sufficient charge to start a car after constant drain) and more than sufficient cranking power (how easily they start an engine especially in cold weather, not really an issue for me as its a summer car)
1) Odyssey PC1500RT
2) Braille B7548 Endurance Race
3) Bosche S6008
The Odyssey is generally regarded as the best of its type but I could not source a UK distributor who could do the RT version (with +ve/-ve posts on the correct sides). This is the most expensive (c£250)
The Braille is fitted to many Ferraris as upgrades (standard to some of the newer models) and is proven to work with cars that can be stood for a long time between uses and require a high cranking power. Mid priced (c£200)
The Bosche is the cheapest (c£135) and probably the sensible choice.
So I ignored the sensible choice and went for the Braille
I also decided to be ultra safe and buy a backup battery as I did not want to have the worry of taking the Z for a long run and being stranded. For this I chose a proven solution used in track prepped cars. These are not bothered about reserve capacities but light weight but I still needed something which I could just leave in the boot and not have to worry if it had been charged recently.
So I went for an Odyssey PC680. This is a high end motorbike battery but is proven to work in race prepped cars. It stays fully charged for years (when no drain ie not connected) and is small and lightweight. Its no good as a permanent solution as its reserve capacity is low so it would go flat easily under constant drain but is ideal as a backup power source in an emergency. I really needed the PC680T version (with SAE mounting posts) but ended up sourceing the PC680 without posts and sourcing those seperately.
So I should not need to worry about the Z not starting over the summer
. I may also fit a battery cut off so that if I know I won't be using the Z for a month or so I can easily disconnect the battery (my car park is very secure and I have a CCTV camera pointing at it so I'm not bothered if the alarm is on as I fit a thatcham approved steering lock and can lock the doors manually
I'll post up pics next week when everything is installed but here are some stats on the batteries:Braille Auto B7548 - Braille Endurance Race Series Battery
•Highest cranking power and longest run time in their class
•Patented sealed valve regulated technology delivers no spill, no corrosion and no maintenance power
•Longer battery life and green manufacturing help to preserve the environment
•Backed by a 5-year warranty
For performance power that delivers the audio, racing and street muscle that you’re looking for, Braille Endurance Batteries are a great choice. These high-quality batteries are designed to be direct-fit replacements for your existing OE part. This means that you can get the increased power and run time without a complicated installation. Plus, Braille Endurance Batteries have the highest cranking power and longest run times in their class.
Your new Braille Endurance Battery features the patented sealed valve regulated technology, which means no spills, no corrosion and no maintenance to worry about. And the longer battery life and use of recycled materials means that your new volts are easier on the environment. Even better, you know that your new battery is up to the challenge. Braille Endurance Batteries have taken several performance race cars across the finish line in first place. And, they’re backed by a durable 5-year warranty.
Voltage: 12 volts
Full Charge Voltage: 13.8 volts
Short Circuit Current: 3800 - Estimated
Cranking Amps 30 sec @ 80F: 1560
Cranking Amps 30 sec @ 32F: 1285
Cold Cranking Amps 30 sec @ 0F: 945
Reserve Capacity: 120 min
Capacity (C/20 rate): 75 amp hr
Life Cycle @ 10% DOD: Up to 3000-3500 cycles
PLEASE NOTE: ALL RATINGS ARE TESTED AND CONFIRMED PRIOR TO SHIPMENT USING A MIDTONICS 400XL BATTERY TESTER
Unique Features: Durable Virgin Poly Casing, Horizontal & Vertical Mounting
BCI Group: Group 48
Minimum Weight (lbs): 45 lbs
Post Type: SAE Automotive Posts Odyssey PC680T
680 cranking amps for 5 seconds
595 cranking amps for 10 seconds
525 cranking amps for 20 seconds
17 amp hours
Short circuit current over 1800A
25 minute reserve capacity with 25amp load
Female brass terminal w/M6 SS bolt
Length 7 1/16"
Height 6 9/16"
Weighs less than 15 lbs
2 year full warranty
Rugged Drycell sealed design
60% more starting power
Deep discharge reserve power
2 year storage life
8-12 year design life
Can be mounted flat or upright