Search found 56 matches

by arber333
Sun, 19 Jan 2014, 03:07
Forum: Batteries, charging, management and monitoring
Topic: Low cost BMS
Replies: 443
Views: 73213

Low cost BMS

Good, we are doing different things! I have reduced my bypass current to about 0.2A. I have heard on this forum and elsewhere that once balanced, LFP cells don't need much bypass to stay balanced. At 16A my charger is also delivering a lot less current than yours. We'll be able to see the differenc...
by arber333
Sat, 18 Jan 2014, 03:49
Forum: Batteries, charging, management and monitoring
Topic: Low cost BMS
Replies: 443
Views: 73213

Low cost BMS

Excellent work! Error codes are just the thing i wished my modules to report. Specially the info which cell the fault originated at. Can i PM you for the source code of the fault reporting? I havent made much programming other than just trying to sync my charger to the BMS. And it works. Charger now...
by arber333
Thu, 26 Dec 2013, 03:33
Forum: Batteries, charging, management and monitoring
Topic: Low cost BMS
Replies: 443
Views: 73213

Low cost BMS

Hi 4springs First of all you should start numbering your cells in some way. I start from first + terminal. This is how the modules have to be connected. So you should connect module no. 4 with module no. 5 and then from 5 to 6 and out. I guess the output from the module is not isolated, hence the ne...
by arber333
Fri, 08 Nov 2013, 01:49
Forum: Batteries, charging, management and monitoring
Topic: Low cost BMS
Replies: 443
Views: 73213

Low cost BMS

Wery well!

This could be done with xx command Neville uses. 01 is used to command balancing, so i could change it to 11, 12, 13 etc... so cell could read command and perform. Excellent thought, i like simple solutions :).

A
by arber333
Thu, 07 Nov 2013, 03:14
Forum: Batteries, charging, management and monitoring
Topic: Low cost BMS
Replies: 443
Views: 73213

Low cost BMS

I was thinking of coding PIC12F with independent PWM. What do you know, the port to control the mosfet is by chance PWM port :). Coincidence? I intend to use cca 50kHz switching freq. Maybe set a few steps controlled by ADC cell voltage data: 3,45V 30% duy, 3,5V 50% duty, 3,6V 70% duty, 3,7V 99% dut...
by arber333
Thu, 07 Nov 2013, 01:50
Forum: Batteries, charging, management and monitoring
Topic: Low cost BMS
Replies: 443
Views: 73213

Low cost BMS

Would you mind sending me your version of code? I am still modifying mine and would like to see some different solutions, maybe i am too fixed on my goals.

Specially i would like to make PWM cell balancers. Like i said i am still experimenting...

tnx

A
by arber333
Tue, 05 Nov 2013, 04:47
Forum: Batteries, charging, management and monitoring
Topic: Low cost BMS
Replies: 443
Views: 73213

Low cost BMS

I read the post you mentioned. That is different BMS, working under different conditions. The conditions set in the code of this BMS are to always balance when over the preset value, until a cell is under this. That would mean your pack would fill to some 3,7V average and BMS would need couple of ho...
by arber333
Tue, 05 Nov 2013, 04:18
Forum: Batteries, charging, management and monitoring
Topic: Low cost BMS
Replies: 443
Views: 73213

Low cost BMS

Well my own observation have history of bottom balancing. So from the start with top balancing i had to convince 200A cells to match on the upper side of the curve. Finally i did it by making my BMS balance at 2A and connect my charger at 2A. This held higher cells at bay while the rest had to catch...
by arber333
Fri, 25 Oct 2013, 02:10
Forum: Batteries, charging, management and monitoring
Topic: Low cost BMS
Replies: 443
Views: 73213

Low cost BMS

Yes i know. But the complexity... The sensors. You could just use RTC module and program it to cycle at predetermined time. I thought more of regular maintenance tool. I would come close to my car with the phone and connect. It would show the batteries graph and i could press record button and leave...
by arber333
Thu, 24 Oct 2013, 08:10
Forum: Batteries, charging, management and monitoring
Topic: Low cost BMS
Replies: 443
Views: 73213

Low cost BMS

I will try to glue them at the next regular maintenance in about 5000km. That should be in about two months. I make abou 140km/day. I will check then for any damage due to vibration. I must say i am very pleased with the system now. Neville has done wonderfully simple design. No unnecessary stuff. I...
by arber333
Wed, 23 Oct 2013, 04:17
Forum: Batteries, charging, management and monitoring
Topic: Low cost BMS
Replies: 443
Views: 73213

Low cost BMS

Anyone willing to make their own BMS, but not fiddle with design... I prepared my iteration of files and documentation on Nevillehs BMS on my website. Files are meaningfully named, though user manual is still written in Slovenian language. For english speakers i suggest you check Nevillehs original ...
by arber333
Sat, 29 Jun 2013, 11:52
Forum: Batteries, charging, management and monitoring
Topic: Low cost BMS
Replies: 443
Views: 73213

Low cost BMS

To anyone it might concern In preparation for top balancing BMS software change i got the batteries out the car and balanced them in parallel so they shared potential for 2 days. I then tested all PCBs with mosfet and 3R3 5W resistor. 1,1A is drained for cca 30min so in the end i was sure the PCB wi...
by arber333
Sat, 22 Jun 2013, 23:18
Forum: Batteries, charging, management and monitoring
Topic: Low cost BMS
Replies: 443
Views: 73213

Low cost BMS

I've even turned off the RS-232 error detection in the s/w now. Maybe that would be the problem... I connected the bluetooth module to serial O/P and connected it with my PC. At first the data was streaming ok but i noticed a lot of FF operators too close apart. Not on the display... Then after a w...
by arber333
Sat, 22 Jun 2013, 11:57
Forum: Batteries, charging, management and monitoring
Topic: Low cost BMS
Replies: 443
Views: 73213

Low cost BMS

OK now we re talking. I made the RC filter, and connected the charger-off O/P as failsafe. So it trew charger off in case of 12V fault. But now i got constant glitches while driving. Once every 2 seconds, regular. I tried to disconnect the charger-off line and sure enough - no glitches. I then went ...
by arber333
Thu, 06 Jun 2013, 14:43
Forum: Batteries, charging, management and monitoring
Topic: Low cost BMS
Replies: 443
Views: 73213

Low cost BMS

The nature of the comms is such that it won't introduce errors as you either receive data or you don't! You can get errors with corrupt data, but they will generally be values of 3.99 V or 2.21 V. That is exactly what i see. Comms is stable troughout the envelope. I see 3,99V now and then mostly at...
by arber333
Thu, 06 Jun 2013, 06:28
Forum: Batteries, charging, management and monitoring
Topic: Low cost BMS
Replies: 443
Views: 73213

Low cost BMS

Yes!!! I am pleased too http://forums.aeva.asn.au/smileys/smiley16.gif . I expected my optos to work BECAUSE of the lower current demand. I didnt count on the interference though. The optos are SFH6186-4 model and have ctr to 300% so the ones on the cellPCBs should be good. You think the PCBs may ha...
by arber333
Wed, 05 Jun 2013, 12:41
Forum: Batteries, charging, management and monitoring
Topic: Low cost BMS
Replies: 443
Views: 73213

Low cost BMS

Hi guys I solved my problem of the jumpy comms. After msg with NevilleH about his input RC filter i tried as he did. I got one 0,01uF(103) ceramic cap and soldered it across input resistor R1 (2,2K) pads with R1 in the middle. The first try was a dud. The disturbances were even higher. After brief m...
by arber333
Sat, 01 Jun 2013, 11:59
Forum: Batteries, charging, management and monitoring
Topic: DIY Battery Cooling
Replies: 29
Views: 4805

DIY Battery Cooling

I guess i am in luck. After cleaning, retorquing the contacts and two cycles now the batteries remain steady and now the cell to disconnect charger (first full) is not no. 22 or no. 23! Thank you Weber/Coloumb for the advice. http://forums.aeva.asn.au/smileys/smiley41.gif I guess i noticed the probl...
by arber333
Fri, 31 May 2013, 23:41
Forum: Batteries, charging, management and monitoring
Topic: Low cost BMS
Replies: 443
Views: 73213

Low cost BMS

I figured my motor is throwing heavy EMI, but also the comm lines are going along the power cables. I had to reduce EMI pickup so the BMS could process voltages correctly. First thing i did was put 12V 1W isolated power supply on the input side. Didnt work. http://forums.aeva.asn.au/smileys/smiley12...
by arber333
Tue, 28 May 2013, 02:37
Forum: Batteries, charging, management and monitoring
Topic: DIY Battery Cooling
Replies: 29
Views: 4805

DIY Battery Cooling

Yes i can measure cell values trough rs232 port Neville has set up on one of the mosfet o/ps. However i havent tried it yet. I intended to install bluetooth module to simplify connection. I belive he is top balancing now. Do you think i should be doing that. I expected all my cells will come down to...
by arber333
Tue, 28 May 2013, 00:19
Forum: Batteries, charging, management and monitoring
Topic: DIY Battery Cooling
Replies: 29
Views: 4805

DIY Battery Cooling

OK, my controller pulls 40A with transmission in neutral running only flywheel at 185Hz. Would that be enough? So i calculate Rload=Vpack/Aload and then compare voltages free and under load. I will also turn on lights and ventilation for additional DCDC load. Would that do it or should i press on th...
by arber333
Mon, 27 May 2013, 11:31
Forum: Batteries, charging, management and monitoring
Topic: DIY Battery Cooling
Replies: 29
Views: 4805

DIY Battery Cooling

Thank you I will search for that compound. Meanwhile...I tried to measure voltage drop, like we used to with model airplanes. 4R7 resistor across terminals and measure voltage drop (V1-V2)*R/V2 to get Ri which is internal resistance of the cell. DOH! I remember it used to be simpler. It seems the 5W...
by arber333
Sun, 26 May 2013, 01:55
Forum: Batteries, charging, management and monitoring
Topic: DIY Battery Cooling
Replies: 29
Views: 4805

DIY Battery Cooling

Hi arber33, I think we need more information to help you properly. Can you give us a link to your EVAlbum page or other web page with your car's specs and photos? At least tell us what brand, quantity and capacity the cells are? How old are the cells? How long have you been doing this daily commute...
by arber333
Sat, 25 May 2013, 11:57
Forum: Batteries, charging, management and monitoring
Topic: DIY Battery Cooling
Replies: 29
Views: 4805

DIY Battery Cooling

Sorry double post by accident. Edited...

:)

Arber
by arber333
Sat, 25 May 2013, 11:50
Forum: Batteries, charging, management and monitoring
Topic: DIY Battery Cooling
Replies: 29
Views: 4805

DIY Battery Cooling

Hi Can you help me with a problem? I am using Nevilles DIY BMS modules to assist with bottom balancing. I discharged the pack to 2,8V and charged untill one cell hit 3,6V couple of times and they went together untill full discharge quite nicely. I drive 65km to work and 50 of those are highway. Spee...