Low or Dead Battery condition

[cwirtz703]

The following is a suggestion for a specific use case:
Condition:

• dead or low battery (so low/dead that the NanoEFI will not operate or will power up but not enough to power the injector &/or fuel pump)

• engine can be turned over with kick or pull starter

• engine electronics are connected to other systems such that NanoEFI shares power with these other systems

Suggestion:

• NanoEFI has a micro-usb or usb-C power connection that would not feed power back into the normal power in terminals but could power the NanoEFI and the injector and fuel pump.

Provides:

• Ability to kick or pull start the engine from dead battery condition using a phone charger, battery bank, or from a cell phone directly (in power supply mode)

Thoughts?

[cwirtz703]

BTW, I did try searching to see if this has been addressed previously. I wasn't able to find an answer hence this post/thread.

[Travis Nano]

Hi @cwirtz703 , thanks for your support! This is an interesting suggestion.

There are a few challenges I see... the first to mind being that the fuel pump consumes a lot of power in order to produce usable fuel pressure. Micro USB wouldn't be able to handle the current, however some USB-C cables are able to handle up to 100w and 20v max. As much as I love USB-C though, I'm not planning to add USB support in order to keep prices down and keep the enclosure watertight.

Something similar could perhaps be partially achieved by back-feeding 5v through the sensor power pin on the ECU. It's normally an output, but a clean 5v source tapped in at this pin would provide power to both the 5v/3.3v components of the ECU, as well as any sensors.

The injector(s) and pump are still a problem though. These typically require a 12v power source. And more importantly, high current components like injectors and pumps are typically wired directly to positive post of the battery (through a suitable relay and fuse). The ECU doesn't actually "send" power to the injector/pump, rather it switches the grounded leg of each high current component. This is because of the way the MOSFET NPN transistors work inside the ECU. So there isn't a good way to provide power to injectors or pumps without other components of the electrical system wanting their cut of any available source of current as well. Not saying it can't be done, but the additional board complexity and costs necessary would probably be the prohibiting factors.

If I can offer an alternate suggestion for very low / dead battery conditions: There are small handheld li-ion based 12v jumpstart packs designed to be carried along in a backpack or even small trail pack. I won't link to any particular one, but I've seen them range from $15 to $99 USD. Personally, I've had good results from the lower priced models starting small and mid-size powersports vehicles.

I'll be thinking more about this scenario. Thanks again for asking!

[cwirtz703]

I recently saw that Stihl is releasing a new chainsaw that is fuel injected. Their animation (seen here: https://www.youtube.com/watch?v=bpA1xwVWJ-M) is interesting regarding this discussion thread. They use a manual primer bulb to "prime" what looks like a pressure accumulator attached to or integrated with the injector.

In the scenario I painted, if there's enough power for the nanoEFI (or the solution you suggest might work) to trigger the injector and spark a manual primer bulb with a small pressure accumulator might be enough to get a few ignition cycles before the engine can power the fuel pump and take over the electrical power supply requirements.

Thoughts?
Definitely an issue to be solved in a v2.0 but one that I wouldn't want precluded by design aspects in v1.0.

[cwirtz703]

Oh, and keeping a small LiPo jump start pack around is a great idea for anytime you NEED to be able to restart your engine but we all know everyone isn't that smart or will have the ability to carry such a device at all times (or have the tools around to access the batter terminals).

In the world of carbs if you can spin the engine you can start the engine (gravity rolling start, push start, kick start, pull start, etc.). It'd be nice if, in a v2.0 or with specific options (i.e. manual primer bulb), the NanoEFI could accommodate that same functionality.

[cwirtz703]

You know, if the pressure accumulator had a switch in it that told the pump not to turn on (and thus draw lots of valuable amps at a time when there is little or no power) for the first couple injection pulses then what little power is available from the dead or depleted on-board battery (or power from a USB plug) might be enough (pure guessing here) to get everything going until the engine's rotation is enough to maintain operation.

[Travis Nano]

I like the idea of an accumulator for manual priming, as well as maintaining a bit of reserve which may have other benefits. I think it would be a great as an addon or optional upgrade. I say this because development for the main kit is always under a lot of pressure to keep the final price as low as possible. Ultimately, I'd love to see a community of NEFI modders and hackers making custom modifications using the NanoEFI core and implementing this kind of thing. I know it'll be way too much for me to handle by myself when it comes to design, machining, etc., but I'll be able to support these kinds of mods in software for sure.

If you can get the engine spinning, either by kick or clutch drop, that should provide enough juice from the stator->regulator to get the ECU up and running. There's very little startup time for the processor, the ECU goes straight into monitoring for trigger signal within milliseconds.

[RC-PPG]

How much pressure is needed for the injector?