Bob & Holly Wilson wrote:
>
>> . . .
>>
>> My inverter (true sine wave) has an inrush thermistor, but I'll add your
>> suggested RF toroids.
>
> I use the toroids to block higher frequencies from feeding back into the
> 12 VDC bus. I didn't want inverter noise to feed back into any of the
> ECUs. The inverter vendors advises against toroids but they are there to
> protect the $0,000 car, not the $00 inverter. So far, I've had no
> problems.
>
>> When drawing more than a kW I don't see the voltage drop that you
>> reported. It could be internal resistance because conversion to 18650
>> Li-ion cells affects both energy-density and energy-flow. Thoughts? (my
>> car is an '04)
>
> Did you rig up a separate LiON pack as an energy storage buffer? Do you
> have a skematic and/or photos somewhere?
>
> I've racked my brains to figure out an affordable, power isolation
> approach. Sure I can put in a 100A diode so current flows one-way but
> there would be a 1.2 VDC forward voltage drop, 120 W.
>
> The only way that makes sense would be a power MOSFET with a current
> sense amplifier for the gate. This would provide a fractional forward
> voltage drop. Properly designed, it could limit maximum current draw
> from the car and thus protect the fusable link. But there lies the path
> of madness.
>
> The next thought is to build a switching power supply with
> ultra-capacitors as the energy buffer. The advantage is no battery
> chemistry risks. But once I start that path, when do I stop? <grins>
>
>> My inverter is heat-sunk onto a thick (0.5") Al plate, battered into a
>> shape such that it attaches to the car's sheet metal at several points
>> and becomes a heat pipe. It stays pretty cool for short-term use, but I
>> added a 12V computer fan to keep air moving over the outer finned case.
>> It vents into the car with no problems, but I've been thinking of
>> running the air to the outside. If I make the system more automated like
>> yours, heat may become an issue. What do you think?
>
> In my case, I lower the hinged panel to access the inverter. This puts
> it in one of the prefered mounting orientations. The unit already has an
> internal fan and it is thermally protected. Since I still need to run
> the power into the house, I simply keep the trunk cracked open and any
> heat easily escapes.
>
>> Also, as I understand your diagram, the traction battery charges the 12V
>> circuit when the 'ignition' is ON, and you've added an automatic switch
>> to the 'ignition' circuit. Can you provide details of that circuit?
>
> Not quite. I modified my inverter to provide a remote ON/OFF switch.
> This allows me to use the inverter when traveling to provide 110 VAC for
> laptops or other light duty devices.
>
> It is very important that the vehicle be ON and in "READY" when using
> the inverter. The 12 VDC battery does not have enough power to run long
> and you need to let the Prius engine cycle as needed to maintain
> traction voltage. So my remote switch is powered by the cigarette
> lighter circuit. This circuit is only on when the car is in "READY."
>
>> We just bought a 2.5kW gas generator for backup purposes, so the Prius
>> solution is less important. I may restore the original battery, freeing
>> up the Li-ion pack for other uses.
>
> Only because I'm leary of LiON batteries due to their notorious
> temperature sensitivity and constant current charge-discharge
> characteristics. I'd probably replace them with NiMH if only because
> NiMH are less finicky and don't have a reputation for self-destruct. But
> it sounds like a clever approach to handling surge loads.
>
> Bob Wilson
This thread stimulated me to pull the system apart (before the game).
Tomorrow I'll put the original battery back in the car. The Li-ion pack
simply replaced it, but it will return to its role powering a scooter.
For my purposes, the original lead-acid battery will handle the load.
btw, pin 2 of the leftmost connector of the block under the steering
wheel is always-ON, and sufficed for light loads and a small inverter
until I got carried away.
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>> . . .
>>
>> My inverter (true sine wave) has an inrush thermistor, but I'll add your
>> suggested RF toroids.
>
> I use the toroids to block higher frequencies from feeding back into the
> 12 VDC bus. I didn't want inverter noise to feed back into any of the
> ECUs. The inverter vendors advises against toroids but they are there to
> protect the $0,000 car, not the $00 inverter. So far, I've had no
> problems.
>
>> When drawing more than a kW I don't see the voltage drop that you
>> reported. It could be internal resistance because conversion to 18650
>> Li-ion cells affects both energy-density and energy-flow. Thoughts? (my
>> car is an '04)
>
> Did you rig up a separate LiON pack as an energy storage buffer? Do you
> have a skematic and/or photos somewhere?
>
> I've racked my brains to figure out an affordable, power isolation
> approach. Sure I can put in a 100A diode so current flows one-way but
> there would be a 1.2 VDC forward voltage drop, 120 W.
>
> The only way that makes sense would be a power MOSFET with a current
> sense amplifier for the gate. This would provide a fractional forward
> voltage drop. Properly designed, it could limit maximum current draw
> from the car and thus protect the fusable link. But there lies the path
> of madness.
>
> The next thought is to build a switching power supply with
> ultra-capacitors as the energy buffer. The advantage is no battery
> chemistry risks. But once I start that path, when do I stop? <grins>
>
>> My inverter is heat-sunk onto a thick (0.5") Al plate, battered into a
>> shape such that it attaches to the car's sheet metal at several points
>> and becomes a heat pipe. It stays pretty cool for short-term use, but I
>> added a 12V computer fan to keep air moving over the outer finned case.
>> It vents into the car with no problems, but I've been thinking of
>> running the air to the outside. If I make the system more automated like
>> yours, heat may become an issue. What do you think?
>
> In my case, I lower the hinged panel to access the inverter. This puts
> it in one of the prefered mounting orientations. The unit already has an
> internal fan and it is thermally protected. Since I still need to run
> the power into the house, I simply keep the trunk cracked open and any
> heat easily escapes.
>
>> Also, as I understand your diagram, the traction battery charges the 12V
>> circuit when the 'ignition' is ON, and you've added an automatic switch
>> to the 'ignition' circuit. Can you provide details of that circuit?
>
> Not quite. I modified my inverter to provide a remote ON/OFF switch.
> This allows me to use the inverter when traveling to provide 110 VAC for
> laptops or other light duty devices.
>
> It is very important that the vehicle be ON and in "READY" when using
> the inverter. The 12 VDC battery does not have enough power to run long
> and you need to let the Prius engine cycle as needed to maintain
> traction voltage. So my remote switch is powered by the cigarette
> lighter circuit. This circuit is only on when the car is in "READY."
>
>> We just bought a 2.5kW gas generator for backup purposes, so the Prius
>> solution is less important. I may restore the original battery, freeing
>> up the Li-ion pack for other uses.
>
> Only because I'm leary of LiON batteries due to their notorious
> temperature sensitivity and constant current charge-discharge
> characteristics. I'd probably replace them with NiMH if only because
> NiMH are less finicky and don't have a reputation for self-destruct. But
> it sounds like a clever approach to handling surge loads.
>
> Bob Wilson