High amperage 12V socket install

[ball_socket]

Figured I'd share my accessory socket install.

I went with the 12V "cigarette lighter" socket instead of USB because it is versatile. You can plug a USB charger into it, a tire inflator, camp light, AC inverter, etc.

The OE Honda 12V socket doesn't have a matching power connector in the USDM headlight bucket. This thread will give you some tips on which OE connectors you can use to tap into the factory harness to get low amperage power (thanks for the Sumitomo part numbers!): https://hondatrail125.com/index.php?threads/installing-the-honda-12v-acc-socket-on-a-usa-ct125.361/

I decided to tap into the factory ignition switch wiring with a little pigtail, and use that to trigger a relay with +12V from the battery. I used the connectors from the link above to get into the ignition switch without modifying the harness, and also to connect to the Honda 12V socket without modifying it. I also used a Sumitomo mini fuse holder that is the same as the "Sub" fuse next to the battery, and in fact clips onto it just like an OE piece, and switched the power through an Omron mini relay rated for 30A @ 12V. I used 14awg TXL wire for the power and 20awg for signal, and wrapped it in Raychem DR-25 for protection.

This combination of wiring, relay and fuse should provide enough power to run a 300W AC inverted if you ever wanted to do so. It's also switched so you don't have to worry about forgetting something is plugged in and draining your battery.




Links to relay and fuse holder:

https://www.amazon.com/dp/B079QVDRGZ?psc=1&ref=ppx_yo2ov_dt_b_product_details
https://www.corsa-technic.com/item.php?item_id=1515

 

[SneakyDingo]

Ok, I'm gonna ask.




I'm trying to think of a situation where I'd need the full capacity of a 300W inverter short term (like under 60s of usage), or a long term scenario that wouldn't kill the battery super fast. I'm not questioning the cigarette lighter attachment, I have an adapter for that myself, just the effort to do 30A.

On my bike I paired everything to wiring intended for safe 10A sustained use and an expected 99% scenario of 7.5A or less (to the point that it uses an appropriate inline fuse). That's because 1) the only thing that would pull that much power for me is my portable air compressor, which I only use for about 30s at a time; 2) the battery on this bike is tiny and 3) the excess stator output on this bike is also tiny.

Are you going to replace the OEM battery with something higher capacity?

 

[ball_socket]

When I went to buy the (originally 16awg) wire and (cheap Chinese 10A) relay I realized, why not just use 14awg wire and a better relay? It only costs about $10 more. I may not ever use 30A but it takes zero additional effort and negligible expense.

BUT, now I'm curious about your "excess stator output" comment as I assumed that the running bike would keep the battery charged, but that really is just an assumption. I am going to have to test that. On my old CT90 I had to hand-wrap the stator with more coils just to keep the battery from draining when the headlight was on (this was with an aftermarket motor and 12V power).

Do you have any information I can look at about alternator output vs consumption?

 

[SneakyDingo]

BUT, now I'm curious about your "excess stator output" comment as I assumed that the running bike would keep the battery charged, but that really is just an assumption. I am going to have to test that. On my old CT90 I had to hand-wrap the stator with more coils just to keep the battery from draining when the headlight was on (this was with an aftermarket motor and 12V power).

Do you have any information I can look at about alternator output vs consumption?

I'll answer this in two parts, because you get one definitive number and one wishy-washy one.

Alternator output, the definitive number: 190W @ 5000 RPM
Page 1-11 of the Honda Trail service manual, under Alternator Capacity. This number drops if you're just idling the bike since it's related to RPMs, and since we're discussing "excess" you understand this is for everything.

If you weren't using 300W for a long period of time, a sufficiently large battery would likely offset the effect. For a Lenovo laptop, for example, assuming a very good inverter rate and an upgraded battery, your depth of discharge from 0 to full is likely to only be about 1/3 of the vehicle's battery capabilities. I wouldn't want to do that repeatedly, but for every other day on a yearly trip lasting 2 weeks, that's probably ok.

Excess stator output - the wishy washy number:

Alternator/Stator Output?

Tony, did you use a wiring diagram to find the 12V trigger source in the headlight housing? Or is it obvious? I like the voltmeter aux pwr socket. If I attempt to use my 20 year old Gerbing on a test ride, it should tell me if/when my battery is draining. At least that's the plan. Someone posted...

hondatrail125.com

There's also a few other search engine terms like, "current available", "alternator output", "available amps", etc. that you can try, but they all link back to this information.

We've also been warned that if excess stator output = 74W, running the bike at 70W (i.e. at ~99% of stator capabilities) is not a good idea either. That being said, 1) replacement stator is only $52, and 2) it's an opportunity to upgrade. It's a bit harder to find the quote, but someone, somewhere in the forum stated 1/3 stator output being available for accessories on these kind of bikes is generally considered a good start point estimation; I've found that to either be roughly accurate or way overestimating for various bikes, but it's usually well documented when excess wattage for accessories is low on a particular bike.

 

[SneakyDingo]

When I went to buy the (originally 16awg) wire and (cheap Chinese 10A) relay I realized, why not just use 14awg wire and a better relay? It only costs about $10 more. I may not ever use 30A but it takes zero additional effort and negligible expense.

I forgot to mention - to be honest, this here is the best kind of reason: "because I could, and because I wanted to."

 

[Shoot870p]

I honestly have not wanted to ask “why” on so many adds and mods. I do not want to be surprised in the dark hours by someone moving MY bike though! I like to see some of the things done here for sure. Probably will not get around to doing the vast majority of them but continue on my brothers and sisters.

 

[ball_socket]

Alternator output, the definitive number: 190W @ 5000 RPM

So what you're saying is, I'm going to have to bounce it off the rev limiter to use the hair dryer?

 

[SneakyDingo]

So what you're saying is, I'm going to have to bounce it off the rev limiter to use the hair dryer?

Because of the electrical principles in play, the power generation is non-linear, so it's more like you'll need to turbocharge it and THEN bounce it off the limiter.