Search found 773 matches

by Nevilleh
Thu, 15 Nov 2012, 11:44
Forum: Batteries, charging, management and monitoring
Topic: Low cost BMS
Replies: 443
Views: 72833

Low cost BMS

The number of cells that can be monitored is limited by the available RAM in the PIC16F1827 and is a max of 150 with that micro. I haven't had a look to see if there are other devices in that family with more RAM, but with Microchip being what they are, its more than likely. The way it works in the ...
by Nevilleh
Wed, 14 Nov 2012, 18:14
Forum: Batteries, charging, management and monitoring
Topic: Low cost BMS
Replies: 443
Views: 72833

Low cost BMS

Nevilleh I am looking for something just like this. Where have you got your PCB's? Any chance I could buy some of them? Regards I don't have any available at present. I bought them from PCB-Cart who seem to do a reasonable job at a reasonable price. Drop me a PM with your email and I'll send you th...
by Nevilleh
Thu, 08 Nov 2012, 11:43
Forum: Members Machines
Topic: Renard's BMW
Replies: 237
Views: 35229

Renard's BMW

Your '98 model may not be much different to my '88 model! BMW have always been pretty conservative. Anyway, maybe you could send me a copy of the relevant part of the wiring diagram and I'll compare it with mine.
by Nevilleh
Wed, 07 Nov 2012, 17:46
Forum: Members Machines
Topic: Renard's BMW
Replies: 237
Views: 35229

Renard's BMW

When you get that speed control working properly, would you share it with me? Just waht I need on mine and if you can discover where to find the square wave, I should be able to add it in easily.
by Nevilleh
Wed, 07 Nov 2012, 11:27
Forum: Members Machines
Topic: Renard's BMW
Replies: 237
Views: 35229

Renard's BMW

That's good, I originally tried my pump with a couple of Li cells giving 6.4V and it had enough grunt to turn the wheels easily. Then I upped it to 3 cells and the steering was very light. My driver is set for 8V and that gives quite nice steering. I've added a switch so I can turn it off completely...
by Nevilleh
Tue, 06 Nov 2012, 19:38
Forum: Members Machines
Topic: Renard's BMW
Replies: 237
Views: 35229

Renard's BMW

Well, I saw my engineer this morning, and after having crossed his palm with silver -- or gold -- http://forums.aeva.asn.au/smileys/smiley2.gif     he didn't seem too concerned about crumple zones, particularly after I pointed out that the six-cyl. engine left so little space anyway. Measuring agai...
by Nevilleh
Mon, 05 Nov 2012, 18:58
Forum: Technical and conversion discussion
Topic: FWD, RWD, AWD considerations
Replies: 26
Views: 13313

FWD, RWD, AWD considerations

I avoided FWD in my choice of vehicle because of the inefficiency of retaining the gearbox and its pretty much impossible to do a FWD car without doing so. I have to say that direct drive to the diff in a RWD car is pretty neat, but the torque requirements are a bit higher if you want reasonable per...
by Nevilleh
Tue, 30 Oct 2012, 18:17
Forum: Members Machines
Topic: Ian Hooper's RX7 Conversion
Replies: 102
Views: 27288

Ian Hooper's RX7 Conversion

Well, they're not actually!
NZ regs now require all bms sense wires to be fused and that is one of the main reasons I went to a cell-top module for my BMS. OK for prismatic cells, but a bit difficult for Ian's ones, I admit.
by Nevilleh
Thu, 11 Oct 2012, 12:54
Forum: Batteries, charging, management and monitoring
Topic: Low cost BMS
Replies: 443
Views: 72833

Low cost BMS

Have a look at my BMW forum to see the latest version of the cell module pcb, extended to fit 81 mm terminal spacing.
by Nevilleh
Wed, 10 Oct 2012, 19:45
Forum: Members Machines
Topic: TheMechwarrior's - Road Motorcycle EV Project
Replies: 48
Views: 6554

TheMechwarrior's - Road Motorcycle EV Project

Yes, you could strap a generator to the wheels, but you will only get something useful out of it when going down hill. At all other times it will take more power out of your battery than it can put in! If you use a brushless motor, you get regenerative braking which is the same thing. Remember the 3...
by Nevilleh
Wed, 10 Oct 2012, 18:54
Forum: Members Machines
Topic: TheMechwarrior's - Road Motorcycle EV Project
Replies: 48
Views: 6554

TheMechwarrior's - Road Motorcycle EV Project

I see the Zero S ZF9 still only goes 100 kms at 100 kph with 7.9 units available, so you still can't do what you want and you're $15,000 out of pocket. Better go back to the Prius! I don't think you can carry enough cells even with the best/most expensive battery technology available to do 150 kms a...
by Nevilleh
Wed, 10 Oct 2012, 17:46
Forum: Members Machines
Topic: Nevilleh's BMW
Replies: 337
Views: 65576

Nevilleh's BMW

I'm to blame for that constant, not Woody! He just put it in because I told him to and a comment saying "Neville said" would not be helpful. Actually, it comes from 1023 *1235 which is Vref in mV x the ADC max count. My upside down use of Vref and Vs, plus the compression of the 10 bit ADC count dow...
by Nevilleh
Wed, 10 Oct 2012, 14:43
Forum: Members Machines
Topic: Nevilleh's BMW
Replies: 337
Views: 65576

Nevilleh's BMW

Many thanks to Woody for writing a Perl of a program that converts my raw cell voltage data into a csv file that can be opened in Excel and hence graphed to show how the cells perform under load or charging or whatever. For example, here's a single sample of 45 cell voltages in my compressed, raw fo...
by Nevilleh
Mon, 08 Oct 2012, 22:29
Forum: Members Machines
Topic: TheMechwarrior's - Road Motorcycle EV Project
Replies: 48
Views: 6554

TheMechwarrior's - Road Motorcycle EV Project

If you use prismatic LiFePO4 cells, you'll need nearly 120 kg for 10 units of electricity.
A123s?
Someone work out the weight!
by Nevilleh
Fri, 05 Oct 2012, 23:05
Forum: Members Machines
Topic: TheMechwarrior's - Road Motorcycle EV Project
Replies: 48
Views: 6554

TheMechwarrior's - Road Motorcycle EV Project

I think you'll need about 6 kW to do 100 kph, maybe a bit more if you are heavy, but if you lie flat on the tank, maybe ..... So, 100 kms is an hour and 6 kW means 6 kW Hrs of capacity. 24 CALB 60 A Hr cells is 24 x 3.2v x 60 = 4600 A Hrs - a bit short, but you are limited by what you can get into t...
by Nevilleh
Fri, 05 Oct 2012, 21:42
Forum: Members Machines
Topic: TheMechwarrior's - Road Motorcycle EV Project
Replies: 48
Views: 6554

TheMechwarrior's - Road Motorcycle EV Project

I've recently imported an eRider motorcycle from China and it has a 72V @ 50 AHr battery pack with a brushless hub motor of around 4 kW. They claim a top speed of 100 kph with a 75 kg rider, but with me on board (92 kg) it will only do 90 kph Accelerates to 80 kph quite nicely and has regen braking....
by Nevilleh
Thu, 04 Oct 2012, 18:42
Forum: Members Machines
Topic: TheMechwarrior's - Road Motorcycle EV Project
Replies: 48
Views: 6554

TheMechwarrior's - Road Motorcycle EV Project

Couldn't help noticing your comments about my BMS and I thought I would point out that the cost of the cell modules, if you source the parts and build them yourself, is about $US6 each. The $15 is what I charge to supply fully assembled, programmed and tested ones. I have it installed on my electric...
by Nevilleh
Thu, 27 Sep 2012, 17:07
Forum: Members Machines
Topic: Nevilleh's BMW
Replies: 337
Views: 65576

Nevilleh's BMW

Will do, look for a PM.
by Nevilleh
Thu, 27 Sep 2012, 13:44
Forum: Members Machines
Topic: Nevilleh's BMW
Replies: 337
Views: 65576

Nevilleh's BMW

I haven't tried field weakening yet and I'm not sure I'm going to bother as the performance is quite adequate as is. I have collected quite a bit of data on the cells now, via a serial port from the bms master and I'm trying to format in a way that conveys useful information at which time I will sta...
by Nevilleh
Sat, 22 Sep 2012, 13:08
Forum: Members Machines
Topic: Renard's BMW
Replies: 237
Views: 35229

Renard's BMW

I made my sheet metal boxes to be a snug fit so the cells are hard against each other and the box walls and didn't I have a job and a half getting them in! I tried to remove some about six months later and it was too difficult so I just removed the whole box and did my tests with the cells in place....
by Nevilleh
Fri, 21 Sep 2012, 12:25
Forum: Members Machines
Topic: Renard's BMW
Replies: 237
Views: 35229

Renard's BMW

How neat is that? Well done!
I don't see how your battery boxes clamp the cells though, or are you not concerned about that?
by Nevilleh
Tue, 18 Sep 2012, 23:32
Forum: Batteries, charging, management and monitoring
Topic: Low cost BMS
Replies: 443
Views: 72833

Low cost BMS

Go for it guys! Buy your programmed chips direct from Microchip. If you want to purchase assembled, programmed and tested cell modules, the price is $NZ18 ($US14.75) each, plus gst if applicable. The master controller will cost you $NZ65 ($US53.30) also assembled in a small plastic case, programmed ...
by Nevilleh
Tue, 18 Sep 2012, 14:29
Forum: Batteries, charging, management and monitoring
Topic: Low cost BMS
Replies: 443
Views: 72833

Low cost BMS

I've just bought 20 x 12F1822s from element14 at $NZ1.97 each plus gst, a total of $2.27 which works out at about $US1.80. But free shipping! Dearer than Microchip and you still have to program them. Convenient though and they arrived next day. I'm going to fit my bms to my electric motorcycle, henc...
by Nevilleh
Tue, 18 Sep 2012, 14:18
Forum: Batteries, charging, management and monitoring
Topic: Low cost BMS
Replies: 443
Views: 72833

Low cost BMS

You can order the pics pre-programmed. https://www.microchipdirect.com/programming/FAQNew.aspx?mid=5 Then you don't have to program or solder. Shame on you for not using an AVR http://forums.aeva.asn.au/smileys/smiley23.gif I didn't know they offered that service, pretty reasonable at only 10 or 11...
by Nevilleh
Tue, 18 Sep 2012, 14:08
Forum: Batteries, charging, management and monitoring
Topic: Low cost BMS
Replies: 443
Views: 72833

Low cost BMS

Its the battery voltage with respect to the negative terminal (of the battery). If you have both positive and negative isolated from the chassis, as you should, then there is no problem. I put that warning in there so users would be aware that the comms cable is connected to the battery positive. It...