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theFREElaker
03 February 2015, 1243
Trying to figure out the best way to turn on the motorcycle:

Here's the problem:
So You have a big battery pack and a DC-DC step down converter. In order to turn on the DC-DC step down you need to turn on the high voltage system, but turning on the high voltage system requires a low voltage system to trip a relay.

Here's the solution?
1. Use an auxiliary 12V battery to control the 12 volt relays and power the necessary systems before the Highvoltage/DC-DC are active.

2. Connect a portion of the main battery pack to the DC-DC via a mechanical switch. This requires additional contractors in order to properly control connection between battery packs and systems.


So my question is, what did you guys do?

Hugues
03 February 2015, 1331
My 12 volts DC-DC is always on, my BMS needs it, and some other stuff. But maybe this is not you're asking.

theFREElaker
03 February 2015, 1401
My 12 volts DC-DC is always on, my BMS needs it, and some other stuff. But maybe this is not you're asking.

So in normal use, assuming you were going to ride or charge it that would be fine. But if you need to store it, what do you do?

frodus
03 February 2015, 1409
Or get a dc-dc with a built in enable/disable, or something like a sure power that has an always on and a keyed on. They're good up to 96v packs and are 400w.

I can get them if needed.

__Tango
03 February 2015, 1744
My DC-DC is connected almost all of the time. The circuit that runs from the B+ to the DC-DC +In runs through an anderson connector that's accessible on the side of the bike. So whenever I want to do long term storage, I just disconnect that one connection. I wanted a switch of some sort, but finding a 120V DC switch was hard, and anyway a simple connection was the least hassle.

Stevo
03 February 2015, 1903
x2 for the Anderson connectors.
I'm also going to try one of these: 400A Emergency EV Disconnect Switch (http://www.electriccarpartscompany.com/200-400A-Emergency-EV-Disconnect-Switch-br-USA-Stock_p_627.html)
It's quite robust and should work fine for my app. I wouldn't use one for anything over 90 volts pulling more than 400 amps (stated good for 1000 volts however)

theFREElaker
03 February 2015, 2122
Or get a dc-dc with a built in enable/disable, or something like a sure power that has an always on and a keyed on. They're good up to 96v packs and are 400w.

I can get them if needed.

So correct me if I'm misunderstanding you, but don't you need the contractor to close in order to power the DC-DC?

What is this sure power? I found an all in one battery jumper that I was thinking would be easy to use as 12 volt auxiliary power: Amazon.com: PowerAll PBJS12000R Rosso Red/Black Portable Power Bank and Car Jump Starter: Automotive (http://www.amazon.com/PowerAll-PBJS12000R-Rosso-Portable-Starter/dp/B00D42AFS8/ref=sr_1_5?ie=UTF8&qid=1422993392&sr=8-5&keywords=car+jumper+battery+pack)

theFREElaker
03 February 2015, 2136
My DC-DC is connected almost all of the time. The circuit that runs from the B+ to the DC-DC +In runs through an anderson connector that's accessible on the side of the bike. So whenever I want to do long term storage, I just disconnect that one connection. I wanted a switch of some sort, but finding a 120V DC switch was hard, and anyway a simple connection was the least hassle.

I didn't think about how slowly it would drain just in standby. I will look into this option.

What is your option about the post above this one? its an all in one 12V car jumper. so the idea would be charge it up from the battery pack while the bike is charging, then use it to start the bike. I think really the only advantage of this system over yours is being able to just use a 12volt switch to start the bike and also to be able to power/test the low voltage system without engaging high voltage.

frodus
03 February 2015, 2300
So correct me if I'm misunderstanding you, but don't you need the contractor to close in order to power the DC-DC?

What is this sure power? I found an all in one battery jumper that I was thinking would be easy to use as 12 volt auxiliary power: Amazon.com: PowerAll PBJS12000R Rosso Red/Black Portable Power Bank and Car Jump Starter: Automotive (http://www.amazon.com/PowerAll-PBJS12000R-Rosso-Portable-Starter/dp/B00D42AFS8/ref=sr_1_5?ie=UTF8&qid=1422993392&sr=8-5&keywords=car+jumper+battery+pack)
No.... The contactor is for the controller.

You would have a dc-dc that is connected direct to the pack via a fuse of course. You can get one that allows you to enable and disable it so it's not on all the time.

Surepower is a company that makes a 71030i that has an always on output (for things like bms that always need power) and a switched output for the rest of the 12v system. You would just use a normal switch like the key to turn the dc-dc on, then have the switched 12v close a relay that would turn your controller on.

Sure Power 71030i DC-DC Converter 72/96V to 13.5V, 30A 400W (fits GEM Cars) - DC-DC CONVERTERS - EV PARTS (http://www.electricmotorsport.com/ev-parts/dc-dc-converters/sure-power-71030i-dc-dc-converter-72-96v-to-13-5v-30a-400w-fits-gem-cars.html)

I can get them for much cheaper if you need one.

theFREElaker
03 February 2015, 2358
No.... The contactor is for the controller.

You would have a dc-dc that is connected direct to the pack via a fuse of course. You can get one that allows you to enable and disable it so it's not on all the time.

Surepower is a company that makes a 71030i that has an always on output (for things like bms that always need power) and a switched output for the rest of the 12v system. You would just use a normal switch like the key to turn the dc-dc on, then have the switched 12v close a relay that would turn your controller on.

Sure Power 71030i DC-DC Converter 72/96V to 13.5V, 30A 400W (fits GEM Cars) - DC-DC CONVERTERS - EV PARTS (http://www.electricmotorsport.com/ev-parts/dc-dc-converters/sure-power-71030i-dc-dc-converter-72-96v-to-13-5v-30a-400w-fits-gem-cars.html)

I can get them for much cheaper if you need one.


duh my bad, wasn't thinking on the contractor

Didn't even think to check if the Dc-Dc converters have an on/off switch. It looks like that particular model has an input voltage range that is too low for my battery pack. My pack will see a voltage swing from 110Volts to 156Volts. Do you have anything along those lines?

Also, I haven't calculated out yet, but what is the typical power demand for the low voltage system, just off the top of your head?

Stevo
04 February 2015, 0011
If you use LED's for all of your lights, you'll use less than 100 watts.

theFREElaker
04 February 2015, 0016
If you use LED's for all of your lights, you'll use less than 100 watts.

hmmm, we will have the usual headlights and turn signals, we will also have a charger for the tablet display, pump for liquid cooling, arduino, orion BMS (250mA), 2 motor controllers

Stevo
04 February 2015, 1055
Check these out... they will help considerably: Led Headlight Kit at Cycle Gear (http://www.cyclegear.com/motorcycle/Led-Headlight-Kit)

Only 24 watts compared to 55-60 watts halogen

frodus
04 February 2015, 1234
What's your budget and a guesstimate of all loads? (if you could, look up all the data sheets for your equipment.... I unfortunately won't have time the next few days).

Stevo
04 February 2015, 1347
Frodus, it appears your website needs some work.. there are no products when I click on any of the product links. Don't take that observation in a bad way, just that, an observation.
Having built a website myself, I know how time consuming these things are. Then keeping it up-to-date is a full time job in itself. How much on-line business does it generate?

frodus
04 February 2015, 1404
Yeah, I intended on having a full eCommerce website, but sales have slowed the last few years for the DIY market. I haven't added anything because it ended up that most people want very specific quotes. Best to email me and ask... E-commerce software that is freely available isn't really meant for a quote based system and drop shipping.

But I did just update the website to make it more simple with just an About me and Contact. Thanks though.

podolefsky
05 February 2015, 1201
I use a Vicor DC/DC converter. It has an enable/disable pin. Floating is on, connected to ground turns the unit off. It's normally always on. I have my stock key switch wired so that in "park" it disables the DC/DC converter.

frodus
05 February 2015, 1327
+1 on vicor. They sometimes need external components like a cap or trim resistor, but they're pretty solid.

Skahle
05 February 2015, 1846
I have the same setup as Noah. I bought a different DC:DC first (still have it sitting) and then bought the Vicor which floats or pulls down so I could use my stock ignition switch. My homemade BMS AFE is powered straight off the pack and uses less than self discharge rates, always powered.

theFREElaker
05 February 2015, 2123
I use a Vicor DC/DC converter. It has an enable/disable pin. Floating is on, connected to ground turns the unit off. It's normally always on. I have my stock key switch wired so that in "park" it disables the DC/DC converter.

So I assume its got a tiny battery inside or some kind of stored angry to use as a signal when that pin is grounded?

frodus
05 February 2015, 2240
No. Its got some circuitry inside that turns the internal electronics on when you touch the GATE IN input on the Vicor to ground. Once that happens, the internal electronics of the DC-DC energize, and you get output at the output terminals.