My Honda battery seems to let go every 2 years. Any suggestions as to why???🤔

[Pride]

That's a fair point goldnsx, I might just as well try another make and see what happens over time, nothing to lose I suppose as they will also be under warranty.

Does anyone have a favourite make and type preference for reliability??

I do between 2-3000 miles a year.

What type??
Lead acid, spiral wound, gel cell, recumbent gas..........all I would really like is reliability at the end of the day.

[havoc]

Have you still got an old CTEK - if that is showing the battery fully 'conditioned', yet it's still weak straight after unplugging, that would point to a fault with the charger...but you say it's been happening for the last ~4 batteries which presumably is more than one CTEK in that time...which points back to the alternator, maybe?

(I don't know enough about the innards of an alternator to comment further, but that's arguably the one common component here)

[Pride]

Have you still got an old CTEK - if that is showing the battery fully 'conditioned', yet it's still weak straight after unplugging, that would point to a fault with the charger...but you say it's been happening for the last ~4 batteries which presumably is more than one CTEK in that time...which points back to the alternator, maybe?

(I don't know enough about the innards of an alternator to comment further, but that's arguably the one common component here)

Cheers for your input Martin, over the years I find CTEK charges do not like being dropped or knocked about particularly when at full working temperature and as I'm pretty clumsy I have had to replace a few in my time.

I have also had to replace the alternator twice. The first time it just stopped charging, so I replaced it with an identical casing style Denso alternator which went up in a huge ploomb of white smoke during a very high revving, spirited drive, that was about 6 years ago, so I decided to buy a second hand origanol on EBay and no such problems since.

I believe the voltage regulator is built in the alternator is it not???

[Hagasan]

As your car likes to talk its head off just ask it what's wrong ��. Apart from that, check good earths, terminal connections on battery etc. Everything else I'd suggest has been mentioned unless your car just doesn't like going "north" ��

[dcnsx]

I had a similar problem with a previous car. New battery that would be flat in two weeks if left standing. It turned out to be a bad connection with a fuse, I took everyone out and put back in problem solved. Although it was an Alfa so there you go...

[NSX100]

I had a similar problem with a previous car. New battery that would be flat in two weeks if left standing. It turned out to be a bad connection with a fuse, I took everyone out and put back in problem solved. Although it was an Alfa so there you go...

Same with me and mine is an NSX.

If I leave it for more than 2 weeks without the CTEK the battery will go flat despite how new is the battery. In almost 10 years I am on my 5th battery. Kaz and others have been all over the car and cannot trace any fault. Or maybe it is intrinsic to NSXs?

[Heineken]

I've made the experience that vehicle batteries tend to be optimized towards typical use. That is being kept fairly well charged, driven every few days, etc.
What I would try is an Optima Yellow. They are gel batteries which are much less sensitive to unusual using patterns (like less charging, low charge level and others), otherwise they are compatible.

My NSX is equipped with the Optima YT R 3,7 YellowTop 48Ah since autumn 2017 (well, not enough for a long time test) and all I've done so far is disconnecting the battery after driving and even though it was not connected to any charger from October to April it started up flawlessly (due to very little self-depletion).

The other Yellow Top is in my Honda Jazz since November 2016 and shows no sign of weakness. The original Honda battery regularly died after about one year due to the auxiliary heating discharging it too much (not really low but a typical car battery is not cycle proof and dies early if recharged too often, instead of keeping it on a steady high charge). In this case the gel type battery offered a big improvement as it's specifically rated as cycle proof.

Although these use cases don't directly apply to your problem but it would be worth a shot, from my point of view.

[goldnsx]

If I leave it for more than 2 weeks without the CTEK the battery will go flat despite how new is the battery. In almost 10 years I am on my 5th battery.

This is NOT normal.

Years ago (or when the batteries were of good quality) it took about 3 months to deplete a battery of a standard NSX. If you added electronics like theft-alarm things look different. Sometimes an aging relay is powering all the time and draws current when it should not. This is highly likely in an older car.

For all of you with much shorter depleting time please check how much current the car draws from the battery when it's just sitting around (no interior lights on of course). 30 mA is around ok for the NSX in standard form. If it's more try to pull fuses/relays by watching the multimeter. If it drops significantly you're on the right track.

The ADAC found out over the years that the battery makers use less and less lead in their batteries and welcome to "brave new world" shortened the life cycle of their product in general. This is induced by the dictat to lower costs. OK, enough of the conspiracy theory...

My last OEM Honda battery died after 4.5 years (one cell bad), that's ok but I'm usually using Banner or Varta and they're good (as well). What really kills a battery is it's laying around for more than a few days fully empty. 1 month fully depleted and it's shot.

[Kaz-kzukNA1]

All nice/interesting advice so just supplement…

Voltage, capacity, internal resistance, dark current, number of discharge/charge cycle, type of battery, driving mode, driving environment, car storage environment especially the temperature, etc.

The ordinary green/red/black indicator on the battery relies on the specific gravity measurement.
Can't detect increased internal resistance.

Basic/mid range battery conditioner from CTEK, Accumate, etc uses constant current control circuit with voltage sensing.
It does test for the sulfation/sulphation and load test to a certain level but unless you pay extra, it doesn't have enough absorption capacity for heavy load test and thus, can't detect some of the failure modes.
Partially because of the above and the way they use voltage sensing, even if it shows fully charged, your battery will fail cranking the engine.

Internal resistance changes depending on the capacity level so must be tested under the same condition.

Over 12V doesn't mean 100% charged capacity as well as 0.0V doesn't mean 0% empty capacity.
Depending on the type of battery, even just about 11V would mean 0% empty status and fail to crank the engine.

If your battery conditioner has desulfation/desulphation mode, try it after you had flat battery issue and if it is of ordinary lead acid type battery like Honda one.
It may prolong the life of battery if used once a year on low annual mileage car.

With ordinary lead acid battery, even if it happened just once, making it flat will never recover the full capacity. The damage has been done.

If jump starting the car, please pay extra attention to the surge current when removing the cable from the donor car/battery pack.
It could damage your ACG, controllers, etc and on modern cars, even could kill the ECU.

Drive regularly.
My Honda battery is 6 years old and still healthy.
I only connect it to the battery conditioner a few times per year when doing desulfation or top up the charge after doing some electrical testing without running the engine.

In Japan, many car owners tend to replace it every two - three years because of their driving mode/cycle and heatwave during the summer.

Many classic MX-5 owners are reporting battery life of well over 10 years including mine.
It sits inside the boot so away from Eng/Rad and even in the winter, it's in better condition than being exposed to outside atmosphere.


Kaz

[goldnsx]

I believe the voltage regulator is built in the alternator is it not???

Yes, it is.

I'd go with a standard Varta or Banner.

Without anything connected a lead battery is between 12.2 (empty) and 12.8 V (full). You can easily check your CTEC by measuring the voltage while it's connected to the battery, it should be 13.5-14.5 V. If you disconnect it and let the battery sit overnight it should have near 12.8 V if it's good. As you have a power ampere tester you can gain even more data. A good battery should not go down below 9 V under 100 ampere.

Your blowing alternators are a little mystery (to me). The regulator could be not working (well not if it's showing 14.5 V above 1500 rpm) or it's cooking the batteries, so they die that way. Unknown to me is also the added stereo system. How much load does it ask from the 12 V system? I could only imagine only if you listen very loud in traffic jam that the battery gets depleted. The alternator only offers full current at 1500 rpm or higher. At ldle with everything switched on (lights, windows defogger etc.) it is not able to deliver that amount of current and gets the extra juice demanded from the battery.

Did you also check for leaking ampere while the car sits? Something around 30 mA is normal in the NSX. The silly clock module draws the most I've heard. If you have a working CTEC connected the parasitic current draw is compensated by the CTEC.

Just as an info: my Odyssey 680 is always tricklecharged by a CTEC and it's in its 13th year now! That's what I call quality. I've also power tested it (100 A) and it's still perfect.