Hey all, with my zed heading down the path of dedicated track work and my current battery beyond being charged im chasing advice on which size battery to run. Thinking of a fairly small battery 360-400cca? as they are cheaper and lighter. Has anyone done testing to find out what the minimum CCA is? I know the weather can affect the batterys power but more looking at temps above 15-20 (first start of the day can be by jump pack) Any other factors I need to consider? No stereo, high output alternator (180 off of memory) Thanks Ben
If it remains easy to start after track engine mods. You can get away with a very small battery 250-350 CCA, You would want to place it in the passenger rear area
http://www.google.com.au/url?sa=t&r...9-XQDoVcMgIqkL-uw&sig2=cxzil4txgFRKHKRlLBQnhQ ^^ This is what I ran before 425cc at 7kg in weight I WOULDNT GO ANY LESS IN CC I now run a 2kg lithium battery at about 900cc ...not cheap though .
Problem for the OP is the gorilla spec alternator which is only EVER necessary for 4wd idling around in the bush with half a dozen 100w spotties blazing away into the dark. Why such high capacity alternators are routinely fitted to round-town-clown cars is a mystery to me. Its like fitting a pair of 044 fuel pumps and 1000cc injectors to a bone stock boost engine....Like.... WHY? The stock alternator is specified to do the job required and going bigger achieves NOTHING. Alternators are rather stupid and dont take into account the size/capacity of the battery they are looking at and will bash stupidly high charge rates up the batteries bum regardless. This is why modern car battery , in a regularly driven urban chariot is so short in comparison to, say a battery fitted to a VW or an old Holden grey motor with a lower amperage generator that are particularly "soft" on the battery during recharge. The fundamental design and construction of a "traditional" wet cell lead acid battery hasnt changed much over many years and they dont take particularly kindly to being overcharged repeatedly as is the case with an alternator...ANY alternator. And the problem gets worse. The bigger the alternator you go combined with the latest generations of funky sealed calcium/AGM/gell and ad-nauseaum funky-assed batteries that take a very dim view to being repeatedly overcharged which occurrs EVERY start! Just saying is all! E
I went with this lithium-iron 440CCA option. Has no problem turning over a VG: http://www.lithiumax.com.au/#!product/prd1/4070510491/lithiumax-400cca-blue-bms-series-battery Made a bracket for it out of a photocopier and popped it where the back seat used to live. It's unbelievably light too. 1.8kg by itself and 2kg including the bracket, which is roughly a 14kg weight saving compared to the old sealed battery I had previously.
That's not quite right -the charging amps will increase with load on the electrical system (eg lights on, stereo, etc). If you have an inductive meter you can measure.
Man the lowest CCA I've had the car running on was 370 I think -it didn't seem to mind. Seriously though unless you are going to use the car regularly you will be changing batteries more frequently with a smaller battery compared to OEM size. If you can save kgs in other areas you'll make your life easier...
Originally got the high output alternator to cope with twin thermos, stereo and normal electrics in the zed. And it was cheaper then a stock one. To my knowledge isnt that what the voltage regulator is for? Only bad thing I can see is it will charge faster (which isnt ideal for battery maintenance) Ben
Blackbeast and Instamatic Thanks for the advice but both might be a bit on the costly side landed expecially with the dollar atm. Might look at stealing a friends battery till I can afford one of these. The insanely light batterys are not the main factor in buying one but I would hope to get 3-4 years out of the battery (for the cost) as long as it is kept charged
The retailer I bought my battery from (see link) is Australian. No currency woes there! Take care of it (don't let it run flat), and it'll last forever. That, combined with the massive weight saving - I can lift it with thumb and forefinger - means it's money well spent. Lithium-iron FTW.
THAT is exactly my point. Which a few have clearly missed above. The alternator isnt "smart", like a good battery charger, it only looks at battery voltage. It has no way of determining a specific charge rate based on the battery fitted. If the alternator looks at the battery voltage after a hard cold start with a small battery, which will be pretty low initially, it will "think" the same as if there was a bloody great bank of truck batteries when it sees low battery voltage and chuck a huge chunk of amperes down the batteries throat. The batteries will only accept a given max charge rate and over that is dissipated as heat within the battery. This results in warpage and eventual failure of the plates, inner terminals and a "dead" (open circuit) battery is the worst result and at best vastly reduced battery life. I still submit that these monster alternators are largely a woftam on a road car, in the longer term, even with the additional draw of (circa) 15 amps for a pair of aftermarket thermos and a rockbox.
Yes but that assumes that amperes are the same regardless of the load on the electrical system. Ie that a 180a alternator is going to put more current through the battery than a 90a (for example) alternator under the same conditions. If you measure the two you'll see that is not the case. Also modern calcium batteries are by design better suited to high current applications, as are AGM batteries (compared to a traditional lead/antimony battery).
Alternators will put into the battery whatever they can based on VOLTAGE alone. They are not "smart". if new generation batteries are so wonderful, why are their specific charging regimes so peciliar in comparison to wet cells of old then? Additionally, why is it that these fantastic plastic wonders of modern science last on average, half as long as their traditional counterparts of old run on old fashioned generators? You sound like a salesman Im afraid. E
Have you actually measured the charging amps? I have, tens of thousands of times, on a variety of vehicles. Of course the alternators work via difference in voltage. However the current will vary according to the load on the electrical system; it will not run at 180a all the time (or 10 or 20 or whatever other number), it will rise and fall with load on the system. Again you can measure this if you're really interested. They're not... a modern lead/calcium battery is simply designed to give a lot of starting current, then accept a lot of charging current. If you put a calcium battery in an older car due to low charging amps it does not last long and vice-versa. Half as long is a bit of a stretch. Besides which you're comparing components that are on average smaller and lighter, working in a much more demanding environment. The average battery life in this country is 36 months (that's an industry average) and of course this varies greatly depending on servicing, application, useage, etc etc. The right battery in the right application should last 4-5 years. Yes we've all had (or know someone that did) a battery that lasted ten years or more blah blah blah but this is not indicative of the norm. Funnily enough roadside battery replacement is exactly what I did for about ten years. That's around 1000 dianosis and replacement myself per year, and overseeing 3500-5000 jobs per year that my vehicle attended. Every job involved checking charging volts and current in various running conditions with various electrical loads. Take that with a grain of salt but as I said what you are suggesting doesn't hold up in real world testing.
I know exactly what you did Rob so your self-riteous horn blowing holds no sway with me and many others. Your first comment is irrelevent as your talking alternator output current. Of COURSE the current with vary with electrical load..derrrrrrr! Thank you for actually confirming one of my suspicions and actually undermining your own arguments!! That was too easy!!!! But since it seems your the bright star auto electrician around here then you have the best grasp of what happens here yer? In my case, i will listen long and hard to the words of wisdom of a pair of qualified auto electricians of many years experience, both of whom I admire greatly and have known for over 35 years. The kind of electricians who will actually diagnose, find and fix a fault rather than string a red bypass wire alongside a loom. Guys who will re-co alternators, starter motors and wiper motors to as good as new, for close to peanuts rather than just parts swap out off the shelf. Guys who also run roadside breakdown service for over 40 years within a successful autospark business. Guys who KNOW the theory and who can determine the difference between battery seeking and alternator seeking alternator outputs!!!!!! And thats a compliment I rarely bestow upon anyone, least of all a battery fitter of all of 10 years who knows how to use a meter, but thanks for your input anyway, its always appreciated!!!! E
These are the figures recorded starting a stock Z32 TT fitted with a stock alternator & the battery fully charged. This is a cold start (the engine had not been run for at least 24 hours). The voltage of the battery was 12.8VDC prior to starting. The minimum voltage whilst starting was 9.76VDC. The voltage increased to 14.2VDC once the engine started. The maximum amps drawn were 592, this being the inrush current to get the engine turning. The amps then decreased to approximately 500 & continued to decrease to around 200 on the compression strokes. Once the engine started the alternator supplied 22.4 amps. The amps continued to decrease to 5.9 at idle, with the voltage at 14.28VDC.
