Battery Life
 

i have too many benzes, i suppose. what astonishes me is how fast batteries go south. and i store my cars in a climate controlled garage[60-80]

i put my e320cab up in the spring love bug season in early april, wanted to take it out today. dead. dead. dead. this battery was new in april 2002. all cells were still to the brim.

and the interstate battery would not take a charge. and the griot's garage jumper pack 400 wouldn't fire it up either. by the way, this is a lousy product - don't buy one.

it loved the new battery, though. fired right up. radio wanted the code re-entered, but all presets had been remembered[how did this happen?].

and all the window presets had been remembered.

sometimes, after encountering this situation, i think of replacing the standard batt with one of the optimas. but, when i examine them, i ask myself, how can i secure them in the benz batt comparments? they have no foot for clamping them. and they are too tall.

if the optima product is such an advance, why don't those design engineers configure it to fit into the envelope of a standard automotive battery. if they did that, it would be a "no brainer". if they are better, more long-lived, than the conventional auto batts.

any comments?

Deep discharge is death to lead acid batteries. I looked up the Optima on the web and although they make the claim that it can be stored for 12 months at controlled temp, when you open up the pdf datasheet, it makes no such claim and does not address self discharge at all. It does give a spec for recommended float charge, however. I am not convinced that the Optima is much of a revolution in battery technology. I am happy with my Mercedes 100A OE battery (For 130.00 I ought to be happy). Even if the Optima could survive a year with no charge, I think this would cause some harm to it. I think that is an advertising gimmick if it is even true. If you store a lead acid battery, you should keep a trickle charger on it. A lead acid battery that is kept charged up will last a long time. Only thing to watch out for is that you don't have a trickle charger that is a little "over vigorous" (too high voltage) that "boils" off the electrolyte. The fancier ones are self adjusting, or you can just keep an eye on the electrolyte levels.

Mike

Do you take the batteries out of the cars and keep them on a trickle charger? If you just leave a battery in a car it will be drained quickly and the plates will oxidize and ruin the battery. My old SDL draws constant current I would imagin the newer ones are worse! MB makes a good battery, I know of a few coming up on 10 years old that are still fine.

tkamiya just keep an eye on the water level in the battery. I know people you have ruined $1k worth of batteries for their boats by just throwing them on a trickle charger for 6 months and forgeting about them! :eek:

How much juice does startup take?
 

Say for a 95 E320, the owner manual gives these specs

Alternator 14V / 90A
Starter Motor 12V / 1.7kW
Battery 12V / 62 Ah

Is there any formula to calculate how many startups such a fully-charged battery can sustain? Assume the startups are 'normal' (i.e. car fires right up), and that each time the vehicle is driven too short a distance to recharge the battery back to the state before ignition.

I know it's a hypothetical question, but have been very curious about this. Thanks.

The manual also states that batteries must be trickle-charged every three months minimum if the car is in storage. I know from working with battery engineers that a car battery has a finite number of deep discharges until the battery is used up.

Hence, the need for "deep-cycle" batteries for applications where batteries sit for long periods and are allowed to discharge, requiring several recharges over its lifecycle.

Typical car batteries can survive no more than 5 or so full charge-discharge cycles before they give up the ghost.

My light-duty vehicles (once or so a week driving) get about six years of battery service before replacement is required. The daily driver averages about three years per battery.

The VW (which rarely moves from its storage position) would require a fresh battery every season! So I:

1. pulled the battery out and left it on a (supervised) trickle charger, and...

2. stopped buying expensive batteries for the car. No point getting the "Super Ultra Power 1000" if all you're doing is a once-a-season Sunday cruise on a battery that will have to be replaced in a year!

We all have a drawer full of those little transformers that used to power a calculator or other such long discarded gadget. Most of the 12V versions put out very little current and could easily keep your battery in good shape with no expenditure for a fancier "trickle charger".

if you have done this, shoot us a pic of the device hooked up to you batt.

I have done this myself but the problem is that it takes a little electronics talent to get it right. First there is the issue of AC output vs DC. Assuming you have DC then there is the ussue of regulated output vs unregulated. Most adapters are unregulated but not all. An unregulated "12V" adapter will put out about 18v maybe. I have made good trickle chargers out of unregulated adapters that were marked 8 or 9 volts. Just depends on the adapter and what it actually puts out. Then there is the mA capacity which affects how much the voltage will load down. Usually I have to watch the charge voltage for awhile (days) and then put in a dropping diode or 2 if necessary to get a good float voltage around 13.7 or 13.8.

Mike

Batteries
 

I have an interstate battery in a 1989 420 SEL. How long can I expect it to last? I had an 'energizer' it only lasted 3.5 years. Up here in Canada, you do not want to have a weak battery in winter. The best I have found up here is the Canadain Tire eliminator.