Hi from a frequent poster from the past! I have a 2001 NFR S2K with only 37K on the ODO. Since I moved to Colorado, there are months in the winter when driving it isn’t smart due to snow on the road. So it sits in the garage along with our Mercedes SLK, while we drive our two other cars that have 4WD. The S2K is unique, as just being garaged (not driven) runs down the battery. The SLK has no such problem. So, for the S2K I have a trickle charger I use to keep the battery up. My question is, what could be draining the S2k’s battery that is not draining the SLK’S battery during non use? I have had the S2K checked out about this by competent techs, and they had no answer. So I am just wondering if any other seasonal S2K users have this problem.

 

Small battery and an alarm,its normal and needs a battery tender plugged in all time,if not would last 2,3 or 4 weeks max and be flat.temp related.

 

Not unique to the S2000. Every one of my cars will do the same thing. The remote locking system is listening for signals all the time. The radio memory is keeping those stations in storage and using power all the time. Easiest solution is a battery tender. You can seek out parasitic draws by connecting a ammeter in between the negative battery pole and the wire that is normally connected to it. Tell us what you get. Even a few milliamps will add up 24/7 for weeks at a time.

-- Chuck

 

To elaborate, since electrical is not well understood by most, the procedure to measure leakage current would be:

1. Remove one of the battery terminals. Best to use the negative terminal.

2. Place your meter between battery and terminal. One meter lead to now empty battery terminal, other meter lead to now loose cable.

3. Make sure battery is setup read DC current. Typically this involves both setting dial to DC Amps, as well as moving the red lead to different plug in meter, specifically for reading SC Amps.

4. Make sure key is off. Car at rest like how you'd store it.

5. Take current reading.

This reading would be your at rest power consumption. Normally just what it takes to maintain ecu memory, radio presets memory, and for ecu to listen for key fob radio signals. Possibly for alarm too. So not much.

But if there is a component drawing power when its not supposed to, this test would recognize that.

 

Yeah, I compared the physical battery size in the S2K with that in our Mercedes SLK. THE ONE IN THE S2K is physically smaller. I don’t know how battery physical size relates to storage and longevity, but it makes sense that it does.

 

Battery voltage after the battery has been at rest for 24 hours is a good test. Fully charge the battery for 24 hours then disconnect the negative cable from the car and let it rest for 24 hours. A good battery will show 12.6vDC.

Ordinary car lead-acid battery capacity is directly related to size and the amount of lead. These batteries seldom have a capacity more than 80 amp hours and a 100 milliamp (0.1a) draw will suck nearly 20 amphours out of the battery every week. These small draws are insidious as they'll pull the battery voltage down to the point the battery is damaged and won't recover.

Testing for parasitic draws: Once the meter is connected start pulling fuse one at a time to isolate where the draw is coming from.

Our cars don't like sitting without driving (at least mine doesn't). I'm on my 3d battery in the past 10 years.

-- Chuck

 

Another thing to consider: Have you replaced your bulbs with LEDs? I have seen where LEDs can partially light up even while the car is off. Most likely, they are cheapie ebay LEDs, so be sure to use quality units if you decide to replace the original bulbs. A good test would be to close the garage door (or test at night) and just look at your bulbs to see if they are dimly lit. I saw this on my interior cabin lights once when parking the car in my garage. Check ALL bulbs you have replaced -- don't forget the trunk light or any headlight/taillight/sidemarker bulbs you may have forgotten about.

 

the 51r is one of the worst batteries ever.

 

Actually, I don’t think I gave ever replaced a light bulb in that car, so all the bulbs are OEM. Lots of good info here. The battery is not OEM but it is OEM specs. I never considered battery size, so I compared it to my other three cars. The S2K battery is tiny by comparison. Another thing is that the garage where this car is kept in the winter is semi-heated. It is in a walk out basement. The temperature never falls below 50 degrees.

 

I have this same issue. But I don't think its drawing any more juice from battery than incandescent. In fact, likely less.

The only way led can be lit is if there is actually voltage present, and a path for conductivity. This path and voltage had to be there even when bulbs were incandescent. The bulbs in fact conducted current then, just not enough to see any light. That is merely because incandescent so inefficient. They make more heat than light.

So your old school bulbs were flowing more current, wasted as heat, and you didn't know.

Meanwhile led actually producing some light just because they are so efficient. They're barely flowing any current compared to incandescent, but making some light anyway.

Yes, better led would be smart enough to not draw any current when voltage well below 12v, thus zero current flows. But its like shutting off a dripping faucet (poorly constructed led) vs an open garden hose (incandescent).