[Duncan]

Hi Jimmy

Would you be opening/closing under load? - why?

Battery water
I'm using water/antifreeze mix - car antifreeze has corrosion inhibitors
You can see how I got the air out on my build thread

110F is 43C
You should be looking at keeping the battery to 30C - 35C - the problem here is getting it up to that
Your garage is 43C - what is the air temperature outside?

 

[jimmyaz]

Hi Jimmy

Would you be opening/closing under load? - why?

Battery water
I'm using water/antifreeze mix - car antifreeze has corrosion inhibitors
You can see how I got the air out on my build thread

110F is 43C
You should be looking at keeping the battery to 30C - 35C - the problem here is getting it up to that
Your garage is 43C - what is the air temperature outside?

Hi Duncan,

Yes, the relay would have to be under load all time and it could be 10amps - 100amps. The idea is for these relay to shut off power from solar to solar charge controller to prevent a overcharge in case the charger malfunction. For the inverter disconnect, it's to protect the battery from over discharging. All though the inverter already have cut off that can be set, but this is a SAFETY redundancy I want.

Arizona is the perfect place for Solar, sunshine 340days a year. But in the Summer, the heat scorching is outrageous... high ambient can peak to 125F = 51C. If so, my Garage can get to 110F, mostly the garage would be between 90-105F (32-40C).

Even with water cool, I am thinking I'm going to have to run this water through something that cool it.. .otherwise ambient water temp would still be above 90F (render useless).

Currently my AGM battery box is hook up to a tiny mini fridge that run a few hours a day to keep it cool. Maybe I can do the same if the water cooling is too complicated. But I always thought having coolant flow through every single cells is much better than cooling a entire batter box space.

thanks for all the advise.

 

[Duncan]

Hi Jimmy

As the contactors are back-up they won't be opening/closing all of the time - I'm pretty sure that they are good for 10,000 + cycles at those sort of currents - the only thing I would check is for capacitors
Both the charger and the main invertor on EV's have large capacitors so they are initially connected through a resister to limit current - called "Pre-charge"

As far as cooling is concerned use your fridge and have a copper water coil inside it
I'm using one of those solar water pumps
You won't need to cool it for the heat the batteries are producing - just the heat it gets from the surroundings so some insulation will help a lot

 

[jimmyaz]

Hi Jimmy

As the contactors are back-up they won't be opening/closing all of the time - I'm pretty sure that they are good for 10,000 + cycles at those sort of currents - the only thing I would check is for capacitors
Both the charger and the main invertor on EV's have large capacitors so they are initially connected through a resister to limit current - called "Pre-charge"

As far as cooling is concerned use your fridge and have a copper water coil inside it
I'm using one of those solar water pumps
You won't need to cool it for the heat the batteries are producing - just the heat it gets from the surroundings so some insulation will help a lot

Hi Duncan,

You lost me there on the capacitor set up... I tore the contact apart and pull the two big one out. Do you think I can use it without any precharge?

So these are normally "open circuit" unless power by a 12v source to the coil right? Any idea how much power it uses and how can I know which positive and negative for the coil wire?

 

[Duncan]

Hi Jimmy
Now that you have the contactors out - look up the specs on the web to confirm direction of voltage
I think that they are just coils with no inbuilt diode so they don't care

Pre-Charge
The problem with coupling something with a big capacitor to a high voltage source is that you get a LOT of inrush current - as in hundreds of amps

This is only when you couple up an empty capacitor
The solution is to have a resistance in series
So you switch on with one contactor but with something like a kettle element in series - then after the voltage is most of the way up you use the other contactor to "short out" the resistor

You can't use an ordinary resister as you do want to charge the capacitor quite quickly so you do want a reasonable amount of current (5 or 10 amps?) and that will blow up one of those little resisters

A kettle element is ideal and you can probably rob one from a dead kettle - or water heater

 

[piotrsko]

If you have a complete volt pack there two white "power" resistors that chevy used for precharge. Probably 10 watts rated. I forget the resistance.

 

[jimmyaz]

According to this datasheet, I think the two big relays are only rated for 120A.

https://www.google.com/url?sa=t&rct.../control/relay/vehicle/catalog/mech_eng_ev.pdf&usg=AOvVaw04v3S42RRQNedT3X7ThtW2

 

[bilbo]

Has anyone had success controlling the 2 main contactors and the smaller relays in the battery header through the Can bus. Now that the charger, heater, dc-dc converter and parts of the BMS are working a complete electrical system using the stock devices is close.

Also I cannot find an off-grid 400 VDC to 120 VAC inverter (preferably in a 2kw range). If anyone can point one out I would greatly appreciate it.

 

[Duncan]

Also I cannot find a 400 VDC to 120 VAC inverter (preferably in a 2kw range). If anyone can point one out I would greatly appreciate it.

Have a look at solar power inverters - mine operates at about 400v DC

 

[aeroscott]

weberauto on youtube just disassembled the volt power inverter 1000 amp and 650 volt rating ,2 of these units in the box, overbuilt . why can't it switch at 10khz instead of 2khz making it 3 phase ups/inverter. More caps,snbubers what would it take.Drivers would be worked much harder.

 

[bilbo]

I am looking at buying a gen-2 battery to be used as a full battery pack. A number of people (ex, post 54 on this thread) have the BECM Working with a standalone complete pack by powering the connector on the front of the battery.

Will this work on a gen 2 volt battery? If so what is the pinout on the battery connector?
Finally is there a gen 2 service manual available on the web?

 

[arber333]

Weber transaxle dissassembly
https://www.youtube.com/watch?v=dqM3YXEf1js

Well since nobody is saying this...
If you got inverter and you got transaxle, batteries aside... you could use motor B to drive the wheels and just connect a Briggs&Stratton lawnmower engine to motor/generator A. Of course you would use flex coupling to dampen vibration. You simply leave clutch B off and only operate clutch A. Or weld it for that matter....

So when you run out of battery you start B&S motor and apply clutch A to bring say 8 - 10kW to inverter.
Inverter could be run off of two Lebowski brains. One only in regen mode.
Second driving motor B up to 70mph. TomDB sucessfuly operates BLDC motor using one Lebowski brain board.
http://www.diyelectriccar.com/forums/showthread.php/chevy-volt-opel-ampera-inverter-179922.html

No CAN bus needed that way and only You in control of operating B&S stinker .

5c dropping...

 

[poleguy]

So I discovered that the HPCM2 isn't necessary in order to get the cell voltages out of a standalone Volt battery.
...
but it would be awesome if someone could catch the battery balance command in the act from the HPCM2 (maybe by drawing down one cell while capturing the CAN traffic).

For now I am going to just build a system to let me see the cell voltages and alert me if any drop out of spec, then I'll go in and manually balance the cells.

I'm planning to buy a volt pack to convert a civic. Your post is very encouraging. It seems from further reading (WopOnTour) that a balance event "occurs when the BMS measured voltage of any group/triplet exceeds the average voltage for the 96 groups being monitored"

http://gm-volt.com/forum/archive/index.php/t-129417.html

So the idea here of bleeding down one cell is backwards, and wouldn't trigger a balance event, you need to charge up one cell more than the others for it to happen. And it's triggered by the 'brain' module, so the whole pack must be together for it to happen.

So probably you don't have a pack still all together, right? If you or anybody out there has a Chevy Volt (or complete pack) that you can monitor the CAN bus, would you be willing to drive the pack down a bit and then charge up one cell more than the others and post a dump of the CAN BUS?

 

[mons2b]

Sensor is lem product dhab s44 a 0 to 600 amp inductive coupled DC. Runs on 5 v ref. Darn kindle won't paste the pdf here.

I'm lusting after modifications to the mains relays after I figure out what they break. 350 amp one shot perhaps.

Also many assorted imbedded thermocouple, and looks like a 600 watt heater element

I still have my current sensor. What circuitry do I need to use it? it would be neat to see the current reading from it. Ive seen Arduino boards. Is that the easiest way to use it?