# controlling trailer genset output?



## m38mike (Dec 27, 2008)

I think you'd have a hard time regulating your generator to keep from overcharging your pack. I'm not sure what you could use to do it automatically, and if you did it manually, I think you'd be sure to damage your pack. 

In my generator-trailer build I opted to go with a high-voltage, high-amperage charger. It's programable, it's consistant in what it needs to produce, it's intelligent in performing it's task, and it relieves me of the responsibility of always watching gauges to protect my pack. 

I've got a 13kW gen-set in my trailer, and if it simply went through a bridge, since most of my driving will draw well below the generator capacity to produce, I think I would easily burn up my pack. So the charger will manage the recharge for me.


----------



## Zak650 (Sep 20, 2008)

Lately I'v been thinking about using a 240 volt industrial single phase scr control. Something that is used to control a heating element. They are relatively cheap and available. It seems that if you restricted the voltage to around 75% of your pack voltage and only ran it while you were underway you could avoid damaging your pack. A 65 amp unit might run $80-$100. Keeping things as light weight as possible is important. A Harbor freight trailer runs $220, Costo has a 7kw-9kw generator for $700 both are pretty light weight.


----------



## m38mike (Dec 27, 2008)

The 240v scr control is an interesting idea. I'd be interested in hearing if it would work. But I still think that an automated charging system is the best way to make it work. And at 20-30 lbs, they aren't prohibitively heavy.


----------



## Zak650 (Sep 20, 2008)

The 10kw / 60a DIY open source charger is an consideration. I think you can set it up with the power output to be a bit lower than your generator's output.


----------



## bjfreeman (Dec 7, 2011)

Most geneerators, use field excittion to adjust the volts.
the simplest is to use a rheostat to feed the field with a manual control to adjust speed.
the other end is to use a micro that also has an ADC. you can get fancy controlling the field and speed. the Micro also has Canbus and your can use the RVc codes to monitor and control the generator.
then as you said just pass it through a diode bridge and filter.


----------



## Zak650 (Sep 20, 2008)

bjfreeman said:


> Most geneerators, use field excittion to adjust the volts.
> the simplest is to use a rheostat to feed the field with a manual control to adjust speed.
> the other end is to use a micro that also has an ADC. you can get fancy controlling the field and speed. the Micro also has Canbus and your can use the RVc codes to monitor and control the generator.
> then as you said just pass it through a diode bridge and filter.


Thanks, that was my original inclination but being electronically challenged I wasn't very sure about that as a possibility.


----------



## bjfreeman (Dec 7, 2011)

Zak650 said:


> Thanks, that was my original inclination but being electronically challenged I wasn't very sure about that as a possibility.


I use the micro way.
I would need the diagram and support email for the generator to get the data i need to provide the hardware list and code.


----------



## Zak650 (Sep 20, 2008)

I'm not sure if this is the same as my local store has but this manual has a wiring diagram in it and the generator has a remote control too.


http://www.costco.com/images/content/misc/pdf/613053.pdf


----------



## bjfreeman (Dec 7, 2011)

Zak650 said:


> I'm not sure if this is the same as my local store has but this manual has a wiring diagram in it and the generator has a remote control too.
> 
> 
> http://www.costco.com/images/content/misc/pdf/613053.pdf


I will look it over next couple of days. Component 49 (AVR on schematic) is what the miro replaces. the micro uses a RC servo to control speed, unless the Stepper motor does that. it can monitor and control the generator, as will as use the can bus to give you remote monitoring and control.
I will have to go to Costco and look at it.
what is your Pack voltage?


----------



## Zak650 (Sep 20, 2008)

Thanks, the pack will have 32 groups of A123 pouch cells and top out at 116 charge voltage.


----------



## bjfreeman (Dec 7, 2011)

Zak650 said:


> Thanks, the pack will have 32 groups of A123 pouch cells and top out at 116 charge voltage.


I assume you will have a BMS with Canbus ability to get Pack voltage, then a Master Canbus module that will communicate with the BMS and the Generator.
This will allow the Generator to kick in when the pack gets low and and shut down when the pack is at a preset voltage. it will also regulated the Generator output to charge the pack correctly.


----------



## Zak650 (Sep 20, 2008)

I have a Sevcon Gen4 controller that uses Canbus but I am not planning on running a bms. I'lI bottom balance the cells and have a cell log8 breakout board that mounts 4 celllog8s to monitor all the cells and has relays that can operate signal high or low voltage on indvidual cells. I also have a voltage meter that can output high and low voltage signals, these can be sent to the Sevcon controller.


----------



## bjfreeman (Dec 7, 2011)

Zak650 said:


> I have a Sevcon Gen4 controller that uses Canbus but I am not planning on running a bms. I'lI bottom balance the cells and have a cell log8 breakout board that mounts 4 celllog8s to monitor all the cells and has relays that can operate signal high or low voltage on indvidual cells. I also have a voltage meter that can output high and low voltage signals, these can be sent to the Sevcon controller.


maybe my solution is more advanced than you want.
The generator output needs to know the state of your batteries. so either you need a interface in the car to manually control the Generator, or you need an integrated system that you set parameters and let the system work.
I would pick the second way since I doubt you want you attention distracted with alarms, while driving.

I have a bms central distribution board that I use. I can remvofe the Shunts and you can use it in parallel with the celllog8.s. It does the same thing your celllog8, except it uses can bus and does not have a display.

you will still need the CanBus (odbII) monitor to set your parameters, independent of the sevcon.The monitor can display and control all the Canbus activity. I also believe there is and EV Display on the forum that can be used for this.


----------



## Zak650 (Sep 20, 2008)

I've seen a few posts that talk about using an arduino to control a generator it seems an interesting route.

On a seperate path theoretically if you interupted the voltage sensing point in the circuit that leads to the AVR and added voltage to what is sent to the AVR would the net result be a lower voltage output from the generator?


----------



## bjfreeman (Dec 7, 2011)

Zak650 said:


> I've seen a few posts that talk about using an arduino to control a generator it seems an interesting route.
> 
> On a seperate path theoretically if you interupted the voltage sensing point in the circuit that leads to the AVR and added voltage to what is sent to the AVR would the net result be a lower voltage output from the generator?


theoretically if you put a resistor in the FW path it should lower the output voltage.
the problem is the AVR will try to compensate. it will say oh the sensing voltage on EXW or MW1-R is low so provide more to the FW path.
this might also cause a over current shut down.


----------

