[KS] The original battery was made by Panasonic. When you buy an original replacement battery at the dealership, it’s packed “like the crown jewels,” as they told me, unlike any other battery they had seen.
Based on the responses to my question, it appears that the original battery lasts four to six years. (Some owners replaced it after four, and Harry still has the original in his ’91. I suppose that means one could last eight or ten years, and we won’t know for sure until Harry’s battery dies.) Any battery will normally last longer if it never gets fully discharged (over the winter or by leaving lights on).
FWIW, my battery died when the car sat over the winter of ’91-92. The dealer covered it as a warranty item when they replaced it in April ’92 (and told me they would only cover it that one time). I had them install the Schumacher charger at the same time and have had no problems since. Based on these responses, I’ll plan on replacing mine first thing in Spring ’98 unless it dies in ’97.
[AC] Mine just died after two weeks on jack stands while awaiting new wheels. At least it died in my garage. I took delivery of the car in April ’91 so 7+ years ain’t bad.
[LE – 99/2/9] Allowing a lead-acid battery to discharge is not good for it’s life. If someone lets their battery run way down a couple times a year it may very well only last a couple years. Keeping it well charged or removing and properly storing it during periods of low use should give you 5+ years of service unless it’s treated harshly another way (running a huge stereo, mega wattage lights, excessive vibration, etc.)

What Battery Chargers Are Recommended?

[KS, JT] I have the Schumacher SE-112S battery charger which I had installed in April 1992. It works exactly as prescribed – charges the battery if the voltage drops, shuts off when it’s fully charged. I plug the car in in October, and it starts like a charm again in April.
It’s mounted alongside the battery, on the right side of the car, i.e. it’s on the left of the battery if you’re standing in front of the car looking at the battery. One of the nice things about the NSX is that, unlike the rest of the car, under the hood there are open areas in the floorpan. So just leave your extension cord on the floor of the garage, down the middle, with the end about where the spare tire would be. Pull the car in and remove the spare tire and you should be able to reach down to the floor, grab the end of the extension cord, and plug in the charger. I then leave the spare tire off to the side of the car. Don’t forget to unplug the charger before you go anywhere.
Schumacher’s number is (in Chicago) (312) 973-1600. I bought the charger from Bass Pro (1-800-BASS-PRO). I think it was $40 or $50. Similar charges are the “Battery Tender” or Sears model 71202. I had never heard of Bass Pro but I think they have something to do with boats and fishing. I think the charger is made to be used on boats as well as cars. Battery Pals cost about $30-35 and have been used on NSXs with excellent results.
Be very careful with any charger that is not made to turn off automatically. You DON’T want to overcharge your battery – a prescription for disaster.

What About A Battery Disconnect Switch?

[LL] This is sort of a follow up on the Black Panther battery installation. The idea is that with the deep discharge dry cell battery and a disconnect switch one will able to simply close the switch in the fall to put their NSX to sleep and then return in the spring opening the switch and driving away. No charging involved. I spent some time researching switches and thought I’d pass a bit on.
Most of the switches available at the local parts stores or even at high perf shops like Jegs are not big enough for total battery disconnects. Most switches are dual rated for continuous amperage and for intermitent amperage. We need one good for a minimum of about 110 cont. and 700 intermitent. I did find several by going directly to the switch mfgr’s. The boating industry offers a few also.
Taking reputation, size and weight into consideration, I chose one made by the Joseph Pollak Corporation. It is a zinc die cast body unit rated at 180/1000 and weighs 12 oz. It is offered with either a key or simmply a throw lever. The lever model no. is 51-302 and the key model no. is 51-316. To find a distributor call Pollak direct at 617-282-9550. I paid around $36 for the lever model.
The above switch is a single pole single throw design to only switch the main power or ground lead. This is all I wanted. If this is tripped when the engine is running however, alternator damage may occur. Another model is offered that is double pole single throw that also disconnects the alternator circuit. I didn’t opt for this because IMO the extra wiring hassle wasn’t worth it. If by chance I need to use the SPST switch because the car is on fire, I’ll just write off the alternator also. Many of course use these switches on the starter circuits as security devices. You might want to have Pollak fax you info on all their switches and mull over them with your mechanic. There are several ways to wire them, all with pros and cons.
After talking with Hawkers top man and a few local auto electrical experts, this switch can be installed either in the positive or the negative at the battery. Theres a lot of theory mostly dealing with the corrosion potential which is unlikely with our well protected rides. I planned on putting it in the ground lead to the body, that was Hawkers preference.
There are several disconnects that bolt directly to the battery. One source of these can be obtained by calling 1-800-215-5527 and asking for their “Gizmo’s and Gadgets” catalog. You can just use one of these manual thumb nut type disconnects(also available at some NAPA’s), but they are actually heavier than the more convenient conventional type switches. The conventional switch however will require a fabricated bracket to mount.
Regarding the Black Panther installation itself, I noticed that the Honda terminal clamps didn’t tighten down on the terminals until the last half of turn of the wrench, not enough safety margin for me. I called Hawker and they stated that the terminals were exactly to SAE specs. Of course Hawker has a nice knurling on them for extra bite. I haven’t had time to mike them, but I think they took that knurling into account. Bad idea. Never ceases to amaze me how someone can design a top notch product and not even know about a major problem with it, especially in light of how well designed these posts are otherwise with their breakaway torque feature, helicoil inserts and all. The knurling is so sharp that it’s bite is saving them. If the knurling gets worn down a bit, it will be a problem.
I placed a small brass .015 thick shim about 1/2 high and 3/8″ wide in between the clamp and the post. I know it’s sounds tacky, but it’s an old racers trick and IMO we have little choice. Don’t run the shim all the way around the post though, this would negate the nice knurling bite. I would recommend to those that had another install their battery that they add this shim before they hit the track.
Now ready for the laugh? After all this I decided not to install the switch and just manually pop the negative lead off the battery instead. Why add 12 oz I don’t need?
I may still add it in the future as part of a security system I’m starting to think about.
BTW I fabricated an aluminum 4oz skelotonized battery “pan” and a 4 oz hold down bracket. The stock plastic battery box weighs 1# and the stock steel hold down is another 8 oz, so I netted a 1# savings. This brings the total BP800 weight savings to 8.1 #. Argg-Argg!
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