Anyone else wonder why we need a 50lb lead starter battery?

[drmanny3]

So this is the battery you recommended or used in your NC1? Not too cheap at $600. Was there a problem in securing the battery in the space? Or did the cable connections keep it secure? You specifically mentioned not to get the Restart which this particular battery does not have. That function limits how much the battery can be drained, stopping just short of being able to start the car. So this feature requires that you then reset either with the remote or on the battery. The remaining juice is sufficient to start the car. You mentioned in your first post that the battery would discharge while driving and then you would have to reset it. Was this the restart feature that was being invoked? I have not observed my battery voltage dropping during operation much below the 14.58 volts even after driving the car for around 45 minutes. So not sure why you say such a low voltage from your battery? While I like the idea of technology and also using a lithium battery to replace the lead acid battery in the car, I am still wondering about the need to procure a standby charger to keep the system functional. By the way, how did you determine which battery to run in the car?

 

[drmanny3]

The Shorai battery LFX36L3-BS12 can be had for about $250 via Amazon. The Charger that is specifically made for this battery is another $80. So in total this would be significantly cheaper way to go and still have a light weight battery. Does anyone know what our current OEM battery specs are? Cold cranking amps etcetera. Correct me if I am wrong, but in our cars the 12 volt battery powers primarily the accessories and also the main ECU? The traction battery (just under 2 kwh Lithium) is what turns over the electric motor attached to the ICE. That is why it starts so quickly. Isn't that correct? So one does not need a really high cranking battery to replace the OEM 12 volt. Other than capacity while sitting around. Without the 12 volt the whole system comes to a crash. My Volvo XC90 T8 Plugin operates in the same way. There is a 12 volt accessory battery that is glass mat based and it powers all the accessories plus the ECU. If it dies then the system will not operate. My old Prius behaved in the same way. The traction battery could be full but if the 12 volt did not work the car would not operate. So it would suggest that the Shorai at half the price is more than capable of operating our car's system. If someone could design and manufacture a holding system for the battery in our cars I would probably go for it. I don't want it to look mickey mouse

 

[Chawumba]

I got mine for $450 with no tax using a ebay seller and going direct to their website. I use industrial strength velcro strips to secure the battery, then put it in the battery box and then used the metal hold down, so there is no way its going anywhere.

You don't want a model with restart - it will shut itself off when you driving because of the battery management system in our cars, then when you turn the car off everything will be dead. It will happen almost every drive. Since our battery does so little in our cars, you could likely use the smaller ATX-30 non-HD model, but again, make sure there is no restart. The issue with the smaller batteries is if you needed your emergency flashers for 3 hours or some other long slow drain on the car they may not last, so I think the one I used is a nice compromise. Other problem would be securing the smaller battery model in the box, the ATX 30 HD fits reasonably well.

 

[drmanny3]

Pictures of your setup would be nice. Also what more can you tell me about the battery management system in our cars. I could not find anything that discussed this topic.

 

[drmanny3]

Chawumba, still waiting for your response. I also wondered do our NSXs have an ECU controlled battery charging system? You have a relatively new car and perhaps that is why your charging voltage is lower than mine. What do you think?

 

[Chawumba]

In the process of moving right now, will try to post pics when I have my car and camera in the same place. Again, I tried the RS-30 model and it didn't work, (battery turned itself off after every 2nd drive) and the folks at Antigravity suggested it was a problem on cars with actively managed charging systems. I doubt 2017 systems are any different, so that is why I'm advising anyone against using a restart equipped battery. I've been using the non restart ATX-30 model for over a month now and it seems fine. Biggest challenge is terminal spacing is narrower on ATX model battery (and height is about .25" taller), so you will have to get artistic with a grinder and cut up the lid of the battery insulation box, then tape it up to seal the old openings.

 

[drmanny3]

I paid for a subscription to the Honda Service Express and tried among other efforts to lean more about the 12 volt battery and battery system. As far as I can tell we do not have a built in battery system that adjusts to the age of the battery in respect to charging. There are sensors that measure the temperature of the battery and will turn on the fan if supplied to cool down the battery. Also there is feedback to the dash so that problems can be communicated. I did not see anything referencing an age based battery charging program. I did find that Honda offers a light weight battery for this application. It is a sealed Pb based battery that is relatively small. There is even an adaptation kit for the battery. It turns out that the battery is the one that is also used for Honda's inverter generator EU7000i. The battery is a relatively small battery that is used to start the motor in the inverter generator. It has around 200 cranking amps. The battery is only used for accessories and not for starting the engine so you really don't need as large a battery as you installed.

 

[RyanRA]

Thanks for sharing

 

[Chawumba]

I paid for a subscription to the Honda Service Express and tried among other efforts to lean more about the 12 volt battery and battery system. As far as I can tell we do not have a built in battery system that adjusts to the age of the battery in respect to charging. There are sensors that measure the temperature of the battery and will turn on the fan if supplied to cool down the battery. Also there is feedback to the dash so that problems can be communicated. I did not see anything referencing an age based battery charging program. I did find that Honda offers a light weight battery for this application. It is a sealed Pb based battery that is relatively small. There is even an adaptation kit for the battery. It turns out that the battery is the one that is also used for Honda's inverter generator EU7000i. The battery is a relatively small battery that is used to start the motor in the inverter generator. It has around 200 cranking amps. The battery is only used for accessories and not for starting the engine so you really don't need as large a battery as you installed.

Good research, and while I agree the battery I got was "overkill" in terms of CCA, I went bigger at Antigravitie's advice because the real issue is slow parasitic discharge on cars not driven regularly. Sadly, mine sits for 2-3 weeks sometimes, and full discharge is bad for lithium batteries, so I went a bit bigger hoping it could survive longer intervals. Was only a little more $$ and only 1-2lbs more weight for the peace of mind.

 

[Chawumba]

I went with the size I selected not because we need massive CCA to start the car, but because mine is a bit of a garage queen and sits for up to 2-3 weeks at a time. Antigravity suggested going with the more powerful version as it will last longer with passive drain from the car sitting for prolonged periods. Also, should you have a roadside emergency or other situation where emergency flashers or lights are needed for a longer period of time, the larger battery helps.

 

[drmanny3]

Don't forget pictures.

 

[Chawumba]

Forgot to take pics during install, but here you can see the finished install - not particularly pretty, but all hidden under a panel anyways. The antigravity terminals are much closer together, so I cut the top of the battery box lid with a grinder then sealed with black foil duct sealing tape (not regular duct tape).

 

[Ignition_Key]

Did a long write up on this with pros and cons, but it seems lost in moderator land and won't post. in short, with a fair amount of work customizing the battery cooling box, I was able to fit a ATX-30-HD - and be sure to get the one WITHOUT restart.

I’m a bit confused about the battery compatibility. From my research the NSX takes the H5/Group-47 battery. Like you, I want to ditch the AGM battery and go with Lithium to save weight.

According to my search the AntiGravity battery that is a direct OEM replacment is the Antigravity H5/Group-47 Lithium Car Battery:

https://antigravitybatteries.com/products/starter-batteries/automotive/ag-h5-rs/

 

[drmanny3]

So, form what I understand the purpose of the ACURA Lead Battery (Part# 31500-T6N-AGM100M) is to only supply voltage to the internals of the car?. If that is the case then what specs do, we need to match the lightweight battery with the OEM, is it the Cranking Amps, Amp Hours (e.g. 15Ah, 30 or 40Ah) or somethjign else.
The OEM battery is an H5 with 600 CCA, so to me it does indicate to be starting the car? Do we have any @NSXTech here?

The owner's manual states the following:

Battery TypesThere are two types of batteries used in this vehicle; a standard 12-volt battery that powers the airbags, the interior and exterior lights, and
other standard 12-volt systems; and a High Voltage battery that is used to power the propulsion motors and recharge the 12-volt battery.

From the initial press media release:

The Direct Drive Motor, packaged between the twin-turbocharged V6 engine and the 9DCT, provides additional torque and power assist to the rear wheels.
NSX Direct Drive Motor
To help eliminate the response delay typically associated with turbocharged engines, the Direct Drive Motor acts directly on the engine’s crankshaft which, together with the front-mounted TMU, helps the NSX realize immediate, high-output and high-torque acceleration. The effectiveness of this design is particularly noticeable when accelerating from a standstill at low engine speeds.
The NSX utilizes its Direct Drive Motor to start the engine instead of using a conventional 12-volt engine starter motor. Eliminating the 12-volt starter ring gear reduced weight and layout complexity.
To help improve fuel efficiency, the NSX comes equipped with idle stop capability. Using the powerful Direct Drive Motor as an engine starter ensures that engine restarts are smooth and quick. Engine idle-stop is also fully integrated into the operation of the Automatic Brake Hold system.
Additionally, the Direct Drive Motor acts as a generator, helping to maintain the hybrid batteries at full charge to consistently support driver demands under almost any condition—even while lapping a track at full bore.
The Direct Drive Motor has a liquid cooling passage that provides consistent cooling, even when the system is being pushed to the limit, such as on a track excursion.


I am really confident that the 12 volt battery is used only to power all the ECUs and the various accessories and NOT the Direct Drive Motor attached to the engine.

As for why a 600 CCA 12 Volt Battery: You need high output so that in emergencies things like emergency flashers can work for hours, etcetera. A lithium battery has power but only for short bursts. A lithium battery cannot supply a steady current as does a lead acid battery like our 12 volt battery. So keep in mind if you replace the 12 volt battery with a lithium battery you will need to keep a special tender on the car. Not a big deal. I have also enclosed the 12 volt battery system that shows how it works in the car.