Battery

[bullen727]

as u can see im a newbie lol. just curious how big of a battery can i get because i have a sound system in the car. i see the space for a bigger battery than what im using now. where do i get those from?

[RDM]

A battery? you buy them at any auto parts store. Pretty self explanatory.

As far as size, the physical dimensions aren't your concern, it's the output of the battery. OE is around 600CCA, you want the most available in your size battery, probably can find something 950-1000CCA.

[1990LS400]

Check your owners manual but I'm pretty sure that battery size 24F is the correct size for LS400's of all model years. If you have extra space around your current battery, maybe it is the wrong size. If a decent 24F battery isn't enough with your sound system, maybe you have a problem with alternator output or something else is wrong with the charging system.

[CUMan]

The 24F(or 24R - they are the same) will work; however, the 27F (or 27R) will fit in the battery holder. The 27F is about 1" longer than the 24F. My thinking is that the bigger the battery, the better. The problem one might encounter is that the 24R is commonly in stock at most auto parts stores, while the 27 size is not.

[curiousB]

Not sure why you think a bigger battery will make any difference. The battery is sized to crank the engine for 1-3 seconds. Current output of say 400-600 Amps. At 12 VDC that is 5000-7000 Watts. Unless your audio system is in that range of power output then battery isn't your primary concern.

Now you may find the alternator is a concern. I believe these cars have alternators sized around 900 Watts power out. That is for everything electrical. So if you have blower motor on, headlights, wipers, ... there might not be much power budget left for the audio. That means while the car is running the battery is gradually discharging rather than charging. Not really a good situation if driving somewhere you find you can't restart the car later.

We're talking averages here not peak power however. I would doubt the human ear could sustain 500 Watts of continuous power in such a small air volume as a car cabin. The sound pressure level would surely damage the eardrum.

[killerFatty]

My two amps put out 580 RMS continuous watts. Not a big deal. Upgrade that alternator before the battery.

[bullen727]

My two amps put out 580 RMS continuous watts. Not a big deal. Upgrade that alternator before the battery.

well 2 me more specific i was just wondering the size and cca everyone has currently. however this is the second alternator i have put in. battery is fine but i guess im looking for a 27F someone mentioned. Where do i get those? i got 2 use a bungee type thing 2 hold the battery in place lol.

[VBdenny]

I'll add my thoughts on replacing a battery on these LS400's. For some reason, these cars need a lot of juice to start well. My choice of course would be an Optima Redtop. Seeing as how your car is a 94 I figure it has at least another 10 good years and the Redtop will last just about that long. Here is the deal, at Costco you can buy a Kirkland battery (which I have done) and they last about 4 years. The warranty should they go bad is excellent. I had one go bad after 2 1/2 years and got a new one for $30. In my truck I put a Optima Redtop in and couldn't be happier. $139 at Costco (and elsewhere). One night I left my lights on all night in the garage and in the morning when I went in the garage and saw them on, I said "oh sheet" but they were still bright. The truck cranked right over like there had been no strain. Needless to say, I was happy about that.

I told my brother who has sold industrial DC batteries for years and he said Redtops use a different construction and that they last forever.

If money is the issue, go with the Kirkland because they are great and cheap. If money is not an issue, easy choice for the Redtop. The application size is really easy to find but you will find the Redtop will be slightly shorter (in height) than the standard size but without issue.

Yeah, Wal-Mart, Target, JC Penney, Pep Boys, Sears, Advance and everyone else sells batteries but Costco (and maybe BJ's) beats them all. Just my thoughts and good luck.

[VBdenny]

and oh yeah, tough loss for the Hokies Monday night.

[curiousB]

Maybe you need one of these 200Amp alternators instead of the stock 100A unit.

www<dot>ebay<dot>com/ebaymotors/93-2000-LEXUS-LS400-SC400-HIGH-OUTPUT-ALTERNATOR-190A-_W0QQcmdZViewItemQQhashZitem255b067b3eQQitemZ160440941374QQptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAccessories

[bullen727]

i see. thanks for the good suggestions. last thing i do know there is a draw draining my battery. only thing is, would the alarm system be the cause? just wondering because b4 i put in my sound system and changed the alternator the first time i noticed my lights were dimming on the cluster. not bad but noticeable. so after a while got a new alternator again when it went bad. still i notice the dimming lol. i did the light test but how accurate would that be if i pulled out the fuses? also would a capacitor for the sound system help out?

[curiousB]

i see. thanks for the good suggestions. last thing i do know there is a draw draining my battery. only thing is, would the alarm system be the cause? just wondering because b4 i put in my sound system and changed the alternator the first time i noticed my lights were dimming on the cluster. not bad but noticeable. so after a while got a new alternator again when it went bad. still i notice the dimming lol. i did the light test but how accurate would that be if i pulled out the fuses? also would a capacitor for the sound system help out?

Capacitors are generally to filter out alternator ripple which shows up as a whine tone through the speakers and the pitch varies with engine RPMs. This is a low frequency noise (pitch) coming into your power amp via the +12VDC.

This is a separate matter from sizing an alternator. You need a bigger alternator if with all these electrical loads the current alternator can't recharge the battery and keep up with the drain. Before you spend a bunch of dollars chasing solutions you might be advised to see if you need them. Get yourself a digital multimeter and probe the DC voltage at the battery. Should be around 12VDC. Then start up the car. Voltage should rise to around 13.5 or so. Then start turning on electrical items along with your ear drum shattering, sure to produce early onset deafness, sound system and measure battery voltage. If it stays north of 13 VDC you probably don't need a bigger alternator.

[wanderson]

I have a gizmo that plugs into your cigarette lighter and displays your DC voltage on an LCD display, picked it up from an auto accessory website to monitor a 12v gel cell battery I use for my telescope, but it also comes in handy for diagnosing charge/drain auto issues as well. Not as accurate as my Fluke multimeter but easy to leave in the car to monitor. Last time I saw one was on the Scopestuff.com website. Current draw is almost nonexistant as I leave it on my scope battery all the time and it rarely needs a charge up.