Search found 773 matches

by Nevilleh
Tue, 14 Aug 2018, 14:45
Forum: Renewable Energy and Storage (Non-EV)
Topic: Low Cost BMS for Home Storage Batteries
Replies: 61
Views: 6470

Re: Low Cost BMS for Home Storage Batteries

Oh well,the hard part is usually working out what you want to do rather than doing it. I'm sure you'll get it going once you do that. If you want any help, let me know. I still have all the original files.
Neville
by Nevilleh
Sun, 12 Aug 2018, 17:14
Forum: Technical and conversion discussion
Topic: Reverse-cycle (heat pump) heating
Replies: 20
Views: 4938

Re: Reverse-cycle (heat pump) heating

I admire your tenacity! Hope you get it working satisfactorily. My old BMW E30 had air con and I got my brother, who is an air con specialist, to help me retrofit it. We drove the compressor off a v-belt pulley mounted on the front end of the drive motor and used the electromagnetic clutch to operat...
by Nevilleh
Sun, 12 Aug 2018, 12:42
Forum: Renewable Energy and Storage (Non-EV)
Topic: Low Cost BMS for Home Storage Batteries
Replies: 61
Views: 6470

Re: Low Cost BMS for Home Storage Batteries

Hi Chris,
I haven't looked on here for years, been busy with other stuff, but i am wondering if this project ever got off the ground? Nice to know my old BMS stuff still has relevance!
Neville
by Nevilleh
Sat, 11 Jun 2016, 21:22
Forum: Batteries, charging, management and monitoring
Topic: Low cost BMS
Replies: 386
Views: 54146

Low cost BMS

Had a query the other day about how the temperature is calculated in this and I thought maybe it might be of interest to some of those who have built this thing: For the thermistor, Delta R = K Delta T over a small temperature range, ie its linear. The ADC reading is proportional to the thermistor r...
by Nevilleh
Fri, 17 Apr 2015, 15:42
Forum: Batteries, charging, management and monitoring
Topic: Amp-Hour meter
Replies: 10
Views: 1705

Amp-Hour meter

Sorry to not have replied sooner, I haven't looked on here for a while.
Yes, I have the plans for the AH meter. Drop me a PM with your email and I'll send them to you.
by Nevilleh
Tue, 13 Jan 2015, 14:23
Forum: Batteries, charging, management and monitoring
Topic: Amp-Hour meter
Replies: 10
Views: 1705

Amp-Hour meter

Back in 2013 designed an AH meter which was covered in the forum forums.aeva.asn.au/wanted-an-amp-hour-meter_topic3368.html. Jonescg bought a couple to use on Voltron and found it not totally satisfactory as it didn't handle regeneration, so I thought I'd modify it to make it bi-directional. With a ...
by Nevilleh
Wed, 15 Oct 2014, 16:07
Forum: Batteries, charging, management and monitoring
Topic: Low cost BMS
Replies: 386
Views: 54146

Low cost BMS

Glad to see such good work! I did build an ammeter using a Hall sensor and a spare master board modified to do it and wouldn't be that hard to make a new master pcb incorporating those additions. The 4 line LCD could display current as well as the other stuff. I also counted amp-hours and the 1847 s...
by Nevilleh
Sat, 19 Jul 2014, 14:24
Forum: Batteries, charging, management and monitoring
Topic: Low cost BMS
Replies: 386
Views: 54146

Low cost BMS

I have heard some quite bad reports on the Golden brand - poor quality, lack of support and warranty are just some of them.
Mars have a very good reputation though.
You might also look at the EMRAX 207 - might be a bit more power than you are looking for though. Its priced at around 2500 Euros.
by Nevilleh
Tue, 15 Jul 2014, 22:23
Forum: Batteries, charging, management and monitoring
Topic: Low cost BMS
Replies: 386
Views: 54146

Low cost BMS

You haven't disappointed me, I already calculated that it is not practical with current battery technology - no pun intended! The thing uses 80 kw for take-off for about 3 - 5 minutes and then needs about 48 kw to cruise at 160 kph. With Boston Power batteries, I can get about 40 kwh of storage and ...
by Nevilleh
Tue, 15 Jul 2014, 13:24
Forum: Batteries, charging, management and monitoring
Topic: Low cost BMS
Replies: 386
Views: 54146

Low cost BMS

I'm not sure what car I would use, but it would be something fairly new, as light as I can find and rear wheel drive with no transmission (except diff) much as I did with the BMW. But I'd use an ac motor, perhaps something like an AFM 140 or even the new EMRAX 268 with probably a Tritium controller....
by Nevilleh
Fri, 04 Jul 2014, 14:30
Forum: Batteries, charging, management and monitoring
Topic: Low cost BMS
Replies: 386
Views: 54146

Low cost BMS

The AH meter I built was designed to complement the bms and so it has its own lcd. I had room in my car to mount the two displays, one above the other, so I could see battery voltage, motor current and remaining battery capacity all at once without having to push any buttons, just a quick glance dow...
by Nevilleh
Thu, 03 Jul 2014, 16:19
Forum: Batteries, charging, management and monitoring
Topic: Low cost BMS
Replies: 386
Views: 54146

Low cost BMS

I must say I'm enjoying reading this thread! Almost moved to do another car conversion. The SD card might be a good idea, but not so easy to find enough port pins. There is the RS232 o/p pin and maybe the ISP pins could do with a re-look. The thing has I2C and SPI as well, but I'm not sure what the ...
by Nevilleh
Tue, 01 Jul 2014, 17:23
Forum: Batteries, charging, management and monitoring
Topic: Low cost BMS
Replies: 386
Views: 54146

Low cost BMS

Ah well, you must've read this:
viewtopic.php?title=wanted-an-amp-hour-meter&t=3368
Send me a PM and I'll send you all the details so you can make your own. And develop it into something new.
by Nevilleh
Tue, 01 Jul 2014, 05:20
Forum: Batteries, charging, management and monitoring
Topic: Low cost BMS
Replies: 386
Views: 54146

Low cost BMS

You can, you know, get too carried away with this stuff. In nearly 2 years and some 6000 kms of running my car with my bms I never had a comms failure once. Also, the error rate was insignificant and when it did get the odd bad value, the poll rate was so high that a new, good value appeared almost ...
by Nevilleh
Mon, 30 Jun 2014, 19:43
Forum: Batteries, charging, management and monitoring
Topic: Low cost BMS
Replies: 386
Views: 54146

Low cost BMS

Yes, that would be right. The arrays are initialised to 00 (default)upon startup and this corresponds to 3.99V, so if no comms the master thinks the cells are at Vmax. If you set the shunting voltage below that, the master will send the shunt-on command. If comms is restored, it should sort itself o...
by Nevilleh
Mon, 30 Jun 2014, 02:06
Forum: Batteries, charging, management and monitoring
Topic: Low cost BMS
Replies: 386
Views: 54146

Low cost BMS

Coulda sworn my original module code turned the shunt off if no comms received within a certain time, so it WAS fail-safe! Independent of the master.
Pity the LM385 makers produce all those variants! Keeps you on your toes though.
by Nevilleh
Fri, 27 Jun 2014, 17:36
Forum: Batteries, charging, management and monitoring
Topic: Low cost BMS
Replies: 386
Views: 54146

Low cost BMS

Yes, the 1st master had a missing pull-up because I read the chip specs and they said that port a (or whatever) had internal pull-ups, but when I figured out why my s/w didn't work I discovered that that pin was the only one that didn't! I was more used to AVR at the time. Note that the voltage is m...
by Nevilleh
Mon, 23 Jun 2014, 18:06
Forum: Batteries, charging, management and monitoring
Topic: Low cost BMS
Replies: 386
Views: 54146

Low cost BMS

For my original version, I used the CCS C compiler which has functions delay_us and delay_ms built in and accessed by #USE DELAY() I note that 4springs converted it to use the XC8 compiler and the functions _delay_?? are part of that. There is probably an include file that is needed to access them a...
by Nevilleh
Thu, 30 Jan 2014, 14:13
Forum: Batteries, charging, management and monitoring
Topic: Low cost BMS
Replies: 386
Views: 54146

Low cost BMS

Your circuit looks fine. I did use a pwm output when I originally thought about the bms as I had no idea what the charger would be then and I thought I could always control any sort of charger with a mosfet-in-a-box controlled by a pwm signal - a bit like what you are doing. Then when I bought the P...
by Nevilleh
Thu, 23 Jan 2014, 20:48
Forum: Batteries, charging, management and monitoring
Topic: Low cost BMS
Replies: 386
Views: 54146

Low cost BMS

Hi Nevilleh. Although it is clear now, thanks to 4Springs' measurements, that it is not a clock speed problem, you seem to have failed to understand both of the points I made in my previous message. Is that an insult? Maybe I'm too sensitive. But I didn't fail to understand, I just didn't bother re...
by Nevilleh
Thu, 23 Jan 2014, 20:13
Forum: Batteries, charging, management and monitoring
Topic: Low cost BMS
Replies: 386
Views: 54146

Low cost BMS


What is it they say about teachers?
by Nevilleh
Thu, 23 Jan 2014, 16:39
Forum: Batteries, charging, management and monitoring
Topic: Low cost BMS
Replies: 386
Views: 54146

Low cost BMS

Plus or minus 5% makes a 10% spread. And the rise and fall times don't eat into it much - as long as the voltage is past the threshold, the input (Schmitt, probably) will see it as a 0 or 1. The RS232 spec says something like 3-15 volts , + and - but I've found it works very well using logic levels,...
by Nevilleh
Thu, 23 Jan 2014, 12:05
Forum: Batteries, charging, management and monitoring
Topic: Low cost BMS
Replies: 386
Views: 54146

Low cost BMS

Your waveforms look pretty good. RS232 is very tolerant and doesn't care too much about rise and fall times and even the clock rate can be nearly 10% out without causing many errors. Remember that a "byte" is 10 bits long and it syncs off the first edge of the start bit, waits 1/2 bit period and the...
by Nevilleh
Wed, 22 Jan 2014, 11:39
Forum: Batteries, charging, management and monitoring
Topic: Low cost BMS
Replies: 386
Views: 54146

Low cost BMS

Can't see any reason why the thing would reset with that value. The voltage can go as high as 3.99v without over- or under- flowing. I don't think I put any range checking in there, but it shouldn't cause a reset no matter what. I wonder if it is a watchdog reset? In which case maybe a s/w bug, but ...
by Nevilleh
Tue, 21 Jan 2014, 11:54
Forum: Batteries, charging, management and monitoring
Topic: Low cost BMS
Replies: 386
Views: 54146

Low cost BMS

Pleased to see this topic is still alive and well! I may have mentioned that I sold my car last year and so haven't been at all involved with EVs since,but I had a PM about my AH meter so I thought I have a look on here as well. Good to see lots of advances and improvements. Keep up the good work! I...