Since I just got my 430, and since she'll spend much of the next five months waiting in the garage for warmer weather, I pulled the old battery in favor of a new one and I hooked up my battery tender as I have done on previous "Sunday summer" vehicles. Oddly it was taking longer than I thought for the 1.5 amp tender to reach maintenance mode on a new, fully charged battery. So, I thought I would check to see what the parasitic draw was on this car to see how long it would take to "top up" the battery. .96 amps? What? That's huge. Checked it three times. Maybe my multimeter is bad? No wonder the 1.5 amp tender was taking so long with a net 0.5 amps going in.

Much information is out there about the parasitic draw the SC430's seem to have and dead batteries after a few days of sitting. Has anyone EVER narrowed it down to anything we may have in common? I see much written about maybe the ML amplifier staying on or possibly a bad ECU, or the security system, but seldom are threads completed past how to diagnose the draw. We don't seem to get to the bottom of it past "put a battery tender on if you don't plan on driving for a few days". So now, when I have several spare hours, I guess I will try and narrow mine down and promise to report back.

 

Mohrd,

Something is not right with your reported measurements.

A Battery Tender Plus is rated for max 1.25 Amps. Once it goes into float mode (fully charged battery) there is no way it will remain in float mode (solid Green) with a parasitic drain of 0.96 Amos. Float mode puts out much less than 0.96 amps and if the parasitic draw was that high the battery tender would not be able to maintain voltage in float and would go back into full charge mode with Red light on.

I have measured my battery tender JR (0.75 amp max). Once fully charged and in float mode the tender puts out less than 50 ma (0.050 amps) to maintain battery voltage. I've monitored current and voltage over several weeks with consultant results.

Best way is to insert an ammeter in line with the charger and see what current is being supplied by the charger after the battery is fully charged and voltage is stable.

JR

 

I have had battery problem on and off since 2002. Now I simply unplug the battery before I fly away for more than a week.

 

Thanks JR. I gave it some more thought. Tender was definitely cycling between charged and charging last night. This AM it is steady on maintaining. Possible when I was taking my measurement on the neg cable there is a phantom draw as the pos lead to the tender was still attached although the unit was unplugged? Still, there has to be a common cause of all the parasitic drain measurements of near 100 milliamperes, that many owners are finding.

 

I've done that but with my 07 and 08 SC430 it's a pain because I loose memory seat positions and the GPS goes back to default region and settings. I'm not sure what you loose with a 2002.

After reconnecting the battery I have to;
Reset memory seats and mirrors for position 1 ( my wife) and position 2 ( me). Wife is #1 of course.
Change GPS Region
Change GPS speed settings for hyway
Change GPS settings to NOT ignore toll roads etc.

Besides. Lead Acid batteries seem to last longer when they are kept fully charged..

JR

 

U R right, things need to be reset, the seats, radio, clock, Gps, but takes only few mins. For me it is a practical solution because that's not more than once or twice a year!
I am not good with tools, I have fear of breaking something while fixing.... so I bought a 'Lexus'
I think Lexus should recall for this flaw, but its not a safety feature!
I remember my friend with old Honda Accord saying all his car lights (circuit) shuts down after few mins locked until he key back in, like our head lights

 

What timing, as batteries go! My experience with auto and motorcycle batteries runs true to everything being said. Use to be, we needed to maintain our batteries, now maintainence free has taken over because that's is what we wanted, so now we complain about those. Batteries fail, always have always will, at what time in life, well thats the secret. Weather or not we have a constant draw or not, its just a fact of battery life, hence, battery warranty!!!

My 02 SC had started to show weak battery tendancies for the past month. Jumped, charged, tested....all signs were that the battery was slowly dying. But having said that, during this period it sat for 2 weeks during a motorcycle vacation, started right on our return, go figure.

Batteries for the SC are a rather odd size, or so it seems. During my search on a Sunday afternoon for one in stock at my local stores, no joy for a named brand. Did not want a Duralast or other off brand. Otima did not show an appcation for the SC even if I was willing to wait a couple of days for an Amazon delivery for $150, Odyesse wanted $350, still had to wait a week. I wanted it fixed,,,,NOW!

Of all places, AAA of SoCal, the current battery was branded as an AAA battery, never saw one of those before, internet showed a price quote of $130, Called for a Roadside Assistance call, the local AAA contractor was at my house in 45 minutes with a new battery for the SC.BAttery tested bad, new battery in, UNDER WARRANT, in 15 minutes. I had to do NO WORK AT ALL. But to sign the paper and say Thank You very much.

AAA batteries are made by Interstate, big name brand, AAA warranty which includes roadside service for the battery so my Roadside card is not charged, win, win, win, very happy. The constant draw, dont know dont care, I just maintain the car, Battery Tender....swear by them!

 

Would it be more cost efficient to replace just the voltage regulator or the entire alternator?
How difficult is it to perform either of these procedures....anyone have a write up or procedure.....not seeing results using the search.

Also........which brand of alternator do most folks here recommend?

Thanks

 

I think that most modern alternators have the voltage regulator built into it??

If you think that shot diodes are causing the alternator to draw current (trying to behave like a motor, that is), then the parasitic amperage should drop when you disconnect the alternator. Interesting idea - but I haven't heard of such a problem in years, with the improved design of alternators.

 

I have the alternator charging cable disconnected now.....leaving the fuses in mpx-b1, b2, b3 to see if the parasitic draw that is causing my battery to die almost daily is from the diode pack being bad (as advance auto parts test said) or the draw being pulled from those fuses.....Ive heard that these cars are expected to have some parasitic draw and Im guessing its related to these fuses

 

I don't want to guess. I want to know. Re-checked readings again. Get between 1.30 amps and .60 amps on the negative side. 10 to 30 times to high. P/O was no help as he drove daily. A pullin' I will go.

 

The current values that are being cited here, are they from an ammeter in series with one of the battery connections (that is the battery cable connects to one ammeter lead, and the other ammeter lead completes the connection to the battery)? The draw from a tender in parallel represents the battery drawing from the tender as well, not simply the car's circuits drawing from the battery. As many here have said - hook up an ammeter in series (with no charger or current source included) with the battery, note the current that flows, and start disconnecting circuits (e.g., pull fuses). As for a bad diode pack - if the current doesn't drop when you disconnect the alternator, then the alternator isn't the source of the draw and you can move on.

I have a Fluke digital multimeter that I'll hook up to my stock 2002 (stock except radio HU) - curious about the draw when the car is fully asleep. Will post my numbers.

Kelly

 

Anyone have a DIY procedure for alternator replacement?

 

yup, in series. Haven't started pulling anything yet. Alternator disconnect was going to be my first. Then ML amp. Then fog lights, because I have none. Unless the fog lights can't be turned on independently...I know, I know, get off the computer and start pulling relays...

 

My readings were with my Fluke in series with my Battery Tender JR. It started out supplying almost 700 ma until battery voltage (as measured with a second voltmeter) reached about 14.1 vdc. Then after the battery was fully charged the voltage dropped to 13.1 vdc as the charger went into float mode. Now it's stable and to maintain 13.1 vdc the current supplied by the charger was 47 ma.

Of course I could have disconnected one of the battery cables and inserted the ammeter in series as long as I didn't have it on a charger but it was easier to use the charger clips.

JR