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Charging battery

6 June 2000
Los Gatos, CA
OK, I am going to plead ignorance, but last night I thought it might be a good idea to charge my battery since I hadn't driven it in a couple weeks. As I connected the clamps to the battery posts, I got sparks galore! I would have thought that I put a spoon across the terminals! Needless to say it got my attention.

After this event, I thought it might be prudent to RTFM (Read The Manual). It clearly says that one should disconnect the battery from the entire system before charging. Hmmm, maybe this is the problem. Those of you who know me, know what I did next . . . Yes, folks, I closed the hood.

My question: Why would it be necessary to remove the battery from the car to charge it? Before the flames (HaHa) start, please know that I know the difference between red and black as well as + and -. Is there something special about the NSX's electrical system? I have charged many car batteries in the car and yes, connecting directly to terminals. Occasionally, I feel like following instructions and grounding to the engine block, but not usually.
In the future, I think I will follow the proper directions for the NSX.


Batteries sometimes emit volatile gasses, so that putting jumper cables or charging cables on the battery can actually cause an explosion. This is true of all cars, not just the NSX.

That's why the NSX includes clamping posts in the engine compartment. Just like it says in the owner's manual.

I understand that fact about battery gas, but that still would not explain the sparks after connecting the charger. They were definately SPARKS, I know, I was there!

The manual does make mention of the posts in the engine compartment (for jump starting), but it recommends not to charge from the posts.


I don't know why they tell you to disconnect the battery but I know I've dealt with the dead battery more than one time. I live in ND and it snows so I have to store my car. At frist I never took the battery out. But now I do.

I think you can leave it in the car just disconnect the terminals. Look in the FAQ if you don't know how to take it out or get to it.

The NSX electral system is well engineered. Last year I had to get a new battery so I opted to get a Optima, because I have great experience with them. I have two in my 98 Suburban and one in my 89 suburban and they perform flawlessly, starting in the coldest of temps, with no block heater. It's been about -14 this whole week and -40 with wind chill and my old 89 that sits outside starts with no problems, cranks with no hisitation. SO if you have to replace yours I suggest Optima.

But back to my little NSX experience. I bought one and eager to get it in the car I accidentally hooked it up backwards! In all my life dealing with batteries and working on cars I've never done this. So another suggestion don't but a battery in a car when your really tired! Also the Optimas have one color tops, the whole thing is RED so its hard to see the + and -. Well the horn blared and its sparked. Needless to say that woke me up. Well after asking myself WTF? I felt so stupid and I hooked it back up the right way, but the car wouldn't start. I was like OH F^%K! So I started pulling fuses and they were all fine except one main fuse. So I replaced it and it works fine. I love HONDA ENGINEERING! Just a little story.
Your instance of sparks when connecting a charger would not be abnormal. Various factors are involved, e.g., the state of charge of the battery, the impedance of the battery charger.

If you use a trickle charger (2-5 amps), you do not need to remove the battery, and you can clamp across the terminals.

Note: one reason for removing the battery is the positive post is so close to the battery tie down system that there is a possibility of a short to ground (this would cause a lot of sparks!)if you are not careful attaching an oversize alligator clamp.

As for the NSX electrical system... let's just say they appear to now have the grounding right.
If you connect a charger to the battery terminals, you will get sparks if any power is being used (for example the clock). More importantly, if you charge the battery with the terminals connected, you are forcing a high amperage current through all of the electrical systems in the car, including the engine management system!

Always disconnect at least the positive terminal. The ground terminal by itself will not cause sparks or shorts because the circuit is no longer complete without the positive terminal connected.
The Odyssey batteries (formerly known as the Black Panther) made a number of improvements over the Optima. (They were designed by folks who left the Optima company.) They're available from Dali Racing http://www.daliracing.com

If you expect to need to let your car sit for extended periods, you should look into the battery chargers that mount on the car. These monitor the charge on the battery and if it gets too low, they start charging, then shut off once the battery is fully charged again. I'm sure there's information on them in the FAQ.
Thank you gents,

If I need to charge in the future, I will disconnect, I was just feeling lazy and didn't want to reprogram the radio.
Ended up driving the car just fine this weekend, I think I just wanted to charge the battery so I could do SOMETHING NSX related during a rainy week.

Of course I could . . . DRIVE it, that would be a thought . . .