David's 2001 Civic EV (80-100 mile range; 65+ MPH; 8 second 0-60)

[TheSGC]

Originally Posted by Daox

What do you have to detect low state of charge? What about if a single cell goes low?

The MiniBMS does cell level monitoring. I have a unit for each cell and it detects LV and HV and will shutdown the charger when HVC is reached or will buzz and reduce throttle when LVC is reached.

It's a nice simple BMS that didn't cost too much. I am going to be building an AH counter and have it run a small LCD and the original gas gauge. I am also working on my 6 KW charger, but that's on hold until my EV is fully running.

[Daox]

Great to hear. I do think an Ah counter is an absolutely necessary item to have with a minimal BMS system like that. Unfortunately, voltage can't be used as a low SOC indicator with lithium which really makes things more complicated.

[MetroMPG]

Haven't been commenting, but I wanted to let you know I'm following the updates & enjoying the progress.

[TheSGC]

Originally Posted by Daox

Great to hear. I do think an Ah counter is an absolutely necessary item to have with a minimal BMS system like that. Unfortunately, voltage can't be used as a low SOC indicator with lithium which really makes things more complicated.

Yeah, I've had a lot of experience with lithium over the past year, voltage can really only be used to High/Low cut-offs, not SoC.

To start I will be using the AH counter in the Zilla, since I am hooking up my laptop to log my drives I might has well use the AH counter in the ZillaConfig tool.

I just got my batteries in, but I don't have enough wire to hook up the MiniBMS so I am going off to work to get loads of it and to browse the MiniBMS documentation to make sure I know every little bit of it.

It looks like I am on track for a Friday test drive, I expect the BMS installation to take about 2 hours, which I may do most of it tomorrow night.

[Daox]

Good good, I'll stop buggin ya then. Just would hate to see that beauty of a pack get ruined!

[TheSGC]

Originally Posted by Daox

Good good, I'll stop buggin ya then. Just would hate to see that beauty of a pack get ruined!

Oh yeah, I have $12k into this battery pack, charger and BMS. I stopped myself from test driving the EV this morning, I have everything ready except the BMS! I was SOOO tempted to, but instead I forced myself to go to work and pickup new wire.

I still need to install the charging plug receptacle. I am starting off with my 110v adapter but I am thinking about J1772 soon. I want to use the ChargePoint stations in MA and I want 110/220v access. My Elcon is 1.5 KW when plugged into a 110v outlet and 2.2 KW when plugged into 220v.

[Cobb]

Good for you. I met a guy who makes EVs from conversions of gasser vehicles. He said the reason you see so many EVs for sale used that needs new batteries is the fact no one knows how to care for the batteries and instead of parking the car and calling for a tow, they will drive the car on a low battery to dead battery therefore ruining or throwing the pack out of balance rather its lead acid, agm, lifepo4, etc.

Most people look at the voltage, vs what the voltage of a dead pack should read, but that is only half the story in regards to capacity.

For example 10.2 volts on a lead acid battery is considered dead, but if you got 12 + of them in series you will read a 122.4 volts and think you got a while to go before its really dead and needs charging.

[QUOTE=TheSGC;328970]Oh yeah, I have $12k into this battery pack, charger and BMS. I stopped myself from test driving the EV this morning, I have everything ready except the BMS! I was SOOO tempted to, but instead I forced myself to go to work and pickup new wire.QUOTE]

[davismltc]

This is an awesome thread...Glad I tuned in !!

[TheSGC]

Here's a picture of what my trunk currently looks like:


I've gone through all of the MiniBMS documentation and I've decided how I am going to wire it all up. These new style Elcon chargers have a BMS input that will shut off the charger if Pins 1 + 3 are disconnected from each other, on the 7 pin control plug. The plug was included with the charger with wires only for these two wires, so that makes this really easy.

I really don't know how much temperature affects these batteries compared to lead acid. I know it's a heck of a lot better, but I really oversized my pack for my daily needs so I'm not worried. I will be insulating it in the coming months, and building a nice frame/top for it.

I've already tested the low voltage wiring and it looks good. I do have to program the Zilla for the higher voltage and the speed sensor, but I will do that when my laptop for logging is setup. I am on track for a test drive tomorrow, after the BMS is installed and the battery pack all charged up.

[mechman600]

Are you going to charge each individual cell with a small charger before the first "big" charge? The guys on diyelectriccar.com seem to recommend this.