Battery Vehicle Society

As reported in the Range Thread I achieved 63.2 miles

I recon the batts have settled in nicely now, just goes to show how long its taken to get them back into the idea they are designed for cyclic opperation, rather than being sat about.

Must admit they react totally different to lead acids and they are totally new beasts to me and they are teaching me things all the time

ChrisB

Update time :

Well over the last couple of days since my massive 63miles it does seem to have upset the energy meter somewhat
Currently its refusing to charge to 100% now I dont think its the fact the batteries arnt getting charged to 100% but more the fact that after my discharge down to 0% and it was still running meant the puter started to have negative numbers turn up regarding amount of energy left and hence has been using these negative numbers to to calculate where the energy meter should sit.

Currently it wont charge ( show that its charged) to above about 95% but this has improved as the first time it only made it to 90%

I think it just goes to show how rubish the energy meter is and while it gives an indication of battery state you really shouldnt rely on it for any accurate measurements.

A project that I intend to carry out is the fitment of a pack volt meter and an ammeter into the dash which will hopefully give me much truer readings of the packs mental state

ChrisB

Chris,

You may find it easier to fit a voltmeter to the weakest cell in the pack rather than total pack voltage. That way you know your weakest Cell voltage and can protect it from going under voltage.

A few weeks ago one of my 12v batteries failed to charge properly due to PEBCAU (Problem existing between charger and user). I drove the car and it appeared to be fine until I realised that while my two fully charged batteries were quite happily sitting at aout 11.5 volts under load the duff one was going way down to 8.5!

By monitoring your weakest cell you should also prevent yourself from going under voltage on the rest of the pack and help extend the battery life. I know quite a few people do it on Lithium Ion Packs and as long as you regularly balance and check the cells you should be fine!

A lovely thought Nikki but sadly one thats not that practical due first off the 27 batteries in the pack, and the fact dropping the packs down isnt a 5 min job

I know what you mean though and I suppose in hindsite then when I swapped the packs around it might have been prudent to attach loads of sensor wires out of the packs to do such a thing.
But then also I quite like to keep the clean lines of the vehicle inside and out, you start adding loads of this and that to it and people then look at it as a geeks vehicle and I dont think it helps the whole EV image .

I personally dont think theres any charging issues and I think its more the fact the energy meter can only read what data its given by the puter and then attempts to calculate a percentage of energy left. If its given duff info then it calculates duff info

The saft nicads do seem to be very robust units and can cope with very low discharge levels and even dont mind going reverse polarity from time to time ( not great but they can cope with it )
They are certainly far tougher than lead acids from my experiences so far

ChrisB

Maybe a job for future swaps then?

A pack voltmeter is actually what I have in my car. I brought a 2 inch bezel LED design which I was able to calibrate. Anacrocomputer helped build a 5v regulator circuit which the meter runs off (constantly) and it's a great thing. I know instantly what my pack voltage is without having to go clambering around in the back!

I'm "hoping" I wont have to do a future swap ( touch wood, famouse last words etc etc )
There are people out there with 70k + on packs so with luck by the time this lot die there will be an alternative out there in vehicle form.

ChrisB

WOW. I'm just jealous now!

While I remember here's the details for the display I brought:

Panel LED display by Lascar

aminorjourney wrote:WOW. I'm just jealous now!

While I remember here's the details for the display I brought:

Panel LED display by Lascar

Thats a nice little display there I may well have to look at something like that, I do sometimes prefer an analouge view though, also I need to look in my box of bits .......called the garage as I've got piles of stuff kicking about so why buy when I might already have something I can use here

I'm surprised you havent thought of looking at a set of nicads for the city, I wonder how it would cope with them weight and size etc

ChrisB

It's been done, but then I am just about to put some Lithium Ions in there so

(They're only second hand but should help out with the range if properly installed and looked after!)

aminorjourney wrote: but then I am just about to put some Lithium Ions in there so

Thats just not fair your not playing the game fitting Li-ions into it

I recon that will make for a very interesting vehicle, dont forget to document it all

ChrisB