Author Topic: diesel battery? (Read 12706 times)

Vincent Waldon · « **Reply #15 on:** January 05, 2008, 05:03:55 pm »

Quote from: "burn_your_money"

Quote from: "wikipedia"
Cold cranking amps (CCA) is the amount of current a battery can provide at 0°F (−18°C). The rating is defined as the amperage a lead-acid battery at that temperature can deliver for 30 seconds and maintain at least 1.2 volts per cell (7.2 volts for a 12-volt battery). It is a more demanding test than those at higher temperatures.

I don't see how this can be fudged

You'd think not, wouldn't you, but every year Consumers Reports does real-lab testing of the current suite of batteries from various suppliers (like oil filters there are only a few actual manufacturers, btw) and every year they find pretty big differences between everyone's "rated" capacity... usually more so in the CCA area than the CA area.

And... every year, "Eliminator" batteries are way down at the bottom... ;-)

I'd like more than 650 CCA (group 41) but everyone tells me that's already the biggest battery that will physically fit in my Jetta. If anyone ever finds a new group number with more capacity than a 41 which fits in a MK3 Jetta I'll be eternally grateful !!!

Having said that, back in the day 650 CCA used to start my 82 Caddy (5W30 dino oil) at -40C without more than two glow plug cycles.... good starter, good cables, so-so compression, glowplugs unknown !!

jtanguay · « **Reply #16 on:** January 05, 2008, 05:14:52 pm »

i'm going to do a large battery install in my trunk. i won't have any probs after that. :wink:

i think the size of the battery has quite a bit to do with it as well. i think my battery is an eliminator... maybe i should eliminate it? :lol:

burn_your_money · « **Reply #17 on:** January 05, 2008, 05:27:22 pm »

Quote from: "Vincent Waldon"

You'd think not, wouldn't you, but every year Consumers Reports does real-lab testing of the current suite of batteries from various suppliers (like oil filters there are only a few actual manufacturers, btw) and every year they find pretty big differences between everyone's "rated" capacity... usually more so in the CCA area than the CA area.

I consider that blatant lying rather then "smudging" the results

boostaholic · « **Reply #18 on:** January 05, 2008, 05:42:11 pm »

well i bought one today.. 850 CCA AND 1000 CA started up no prob warmer today.. will see what happens when it gets back down to -20

thanks for the info guys

clbanman · « **Reply #19 on:** January 05, 2008, 06:30:14 pm »

From my personal experience and testing we have done at work, I wouldn't hesitate to recommend Interstate batteries. We had Exides and Interstates tested head to head. Both batteries were the exact same group and rating, but the Interstates were far superior. We did a test with the Exide batteries having the cables disconnected and leaving the Interstates connected, and the Exides were completely drained while the Interstates would still easily start the truck. So yes, ratings are only a small part of the equation.

commuter boy · « **Reply #20 on:** January 05, 2008, 11:37:01 pm »

I've got a PG65-875N 1000 CCA Energizer from Wal Mart in an A3 Golf which fills the tray.

flash319 · « **Reply #21 on:** January 06, 2008, 06:09:50 am »

A battery is for storage, so selling it based on current draw in a particular situation does not seem right to me. You must look for AMP hours (how many amps can it draw for an hour) or (Ah) which is hard to find for a car battery (wounder why.....) or just look at the physical size as it is usually a good indication.

For a diesel with lots of power requirements you need to be able to draw a lot of current for a sustained period. This is where size matters. More or larger plates means more power storage which means more power available which means more current draw when you are cranking for 30seconds to get the thing going.

I am an Electrical Eng but by no means a battery expert so this is my 2 cents.

BejamminR · « **Reply #22 on:** January 25, 2008, 08:53:47 am »

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I'm running an Eliminator 10-4900-0, 850CCA, 1050CA, 120Min Reserve Capacity. It is HUGE, and looks like it shouldn't fit. The Canadian Tire guys swore up and down that it was for a truck and wouldn't fit in my car, but it fits just fine. Measure to be certain. With this thing, I can start at -10 without glowplugs (Did it yesterday just to show Giles

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Quote from: "flash319"

A battery is for storage, so selling it based on current draw in a particular situation does not seem right to me. You must look for AMP hours (how many amps can it draw for an hour) or (Ah) which is hard to find for a car battery (wounder why.....) or just look at the physical size as it is usually a good indication. For a diesel with lots of power requirements you need to be able to draw a lot of current for a sustained period.

No, not really. You're right that size and weight of a battery is roughly proportionate to the storage capacity of a battery. You're wrong that this is relevant to automotive applications in a starting context.

An automotive battery, even for a diesel, is a starting battery. It needs to deliver a large amount of current for a short period of time, which means that it doesn't need to be an effective storer of energy. It would be great if it were, but you have to bear in mind that there is a compromise between automotive / "starting" batteries and deep cycle batteries, and you can't have both. So no, you do not need to look at the Amp-Hour rating of an automotive battery unless you plan to sit in it, running the lights and radio, for hours on end. As far as that goes, Amp-Hour ratings ARE easy to fudge, in that people don't understand or care about the rating system used. What I mean is that Amp-Hour ratings have to go along with a time - a battery rated 20 Amp-Hours at a 20-hour rate (i.e. 1 amp continuously for 20 hours delivers 20 Amp-Hours) will only deliver a few Amp-Hours if you pull it over the space of one hour. Similarly, a battery rated at 5 Amp-Hours at the 1-hour rate could provide well over that if you draw it out over 20 or 24 hours. So a battery rated simply "20 Amp-Hours" doesn't have much meaning without the time scale used. "20 Ah @ 20h rate" means something, as does "20Ah @ 5h rate". Amp-Hour ratings are not typically present on automotive batteries because they are not relevant to the battery's main purpose, not because of a conspiracy.

The main factor determining whether a battery is a "cranking / starting" battery or a deep cycle is the thickness of the lead / calcium / antimony plates used inside of it. The thicker the plates, the slower the discharge, and the longer it can maintain a continuous low (relatively speaking) load. The thinner the plates, the faster the battery can delivery its maximum amount of energy, which is critical if you want to start a motor quickly, while using a minimal amount of space and weight.

Quote from: "flash319"

This is where size matters. More or larger plates means more power storage which means more power available which means more current draw when you are cranking for 30seconds to get the thing going.

I am an Electrical Eng but by no means a battery expert so this is my 2 cents.

You are incorrect, or at least mixing terms here. More or thicker plates does not mean more power. It means greater ENERGY storage, which is power sustained over time, with length of time being the more important factor. It also means conversely LESS short-term power output potential, which means LESS current draw when you are cranking to get the thing going. In energy storage / discharge terms, 30 seconds is not a sustained load, it's a very short-term load - just not "instantaneous". 3+ hours is continuous, 20+ hours is "sustained" or long-term, in the context of a purpose-built storage battery.

You cannot mix these two attributes (barring some genuinely new technological breakthrough) - a battery can either discharge a massive amount of current relative to its size quickly (High power, low energy storage, Automotive Cranking), or it can discharge a minimal amount of current for its size for a long time (Low power, High Energy Storage, Deep-Cycle for Solar / Telecom), or it can do a poor compromise of the two (Medium Power, Medium Energy Storage, Marine / Cranking). Size and weight definitely do roughly correspond to the energy storage ability of a battery, but in an automotive cranking context, what we are mainly concerned with is short-term cranking, hence the availability of cold cranking amps and cranking amps, and "reserve capacity" rather than Amp-Hours.

Batteries tend to be pretty poorly understood, and often the materials taught in electrical engineering programs either ignore them or propagate some of the misunderstandings. I was only able to learn what I know about them from my experience working in the solar industry, and even then only because I got to work unusually close with some engineers who specialized in batteries and inverters. I'm also not a battery "expert", but I have enough experience and have worked closely enough with the experts to shed some light on this one.

KTMAuto · « **Reply #23 on:** January 25, 2008, 10:02:40 am »

Nice write up. battery companys are staying below 1000 amps 'cause the plates are to thin, less longivity. Interstate is phazing out the group 42, replacing with saab battery group 91. -7F on top of this mountain, no block heaters all my cars started. Trust Interstate. The only good battery in the junk yard says interstate. Was exicide dealer, they didin't hold up to abuse. Now interstate dealer. Timing is everything below 0 F. Have mornings 25 below zero. Every car in my driveway is diesel. Wal-mart sucks...

Ziptar · « **Reply #24 on:** January 25, 2008, 10:13:23 am »

My $0.02 adjusted for inflation, err umm deflation... I mean recession?? what ever the heck is going on... :wink:

I did some checking around about batteries before I bought one. I didn't want a generic Walmart or Autozone cheapie. It turns out a Company called Douglas Battery a division of Exide has the contract with Varta to produce new OEM replacement batteries here in the U.S. for BMW, Mercedes, Audi and VW Dealers. They are also sold under the brand name "Werker" through Batteries Plus. The Group 41 Battery is a perfect fit in my A2 Jetta and has the proper venting so hopefully battery acid won't slop all over my newly POR-15'd battery tray. At $89.99 the price is decent too only $10-$20 more that Generics. Sticker says it's 660 CCA.

Cranks the 1.6TD over plenty good enough.

jimfoo · « **Reply #25 on:** January 25, 2008, 10:32:29 am »

The longest lasting and best battery I have used(not in a Diesel though) was an Optima. I could crank and crank, drained it a few times, which usually seems to destroy most batteries much quicker, plus it can't leak acid. And probably more importantly for a Diesel, they are very tolerant of vibrations.