New saxo owner

[Bentzon]

Hello there from Denmark

Since the danish EV forum seem to be quite dead and the norwegian one is closed I turn to you Berlingo drivers

Just got hold of a 9 year old saxo, done 3000km and looks like it just left the factory.

Ive done 60 km on it today and the energy meter was at 30% so the battery pack is in good condition. Will do a watering when i get hold of a evlite.

Got the idea of building a 40cell 60Ah lifepo4 sky ernergy pack with seperate charger and voltblocher or similar simple bolt on BMS. Have a relay seperate the lifepo4 pack from the nicds under charger and incase of any cell hitting the low volatge cutoff.
This will fit right into the trunk, add about 100kgs and a guess about 50km extra range.

Now the question is could the lifepo4 pack be connected directly in parallel with the nicds without damaging one of the batteries(nicd or lifepo4).
My guess is the higher voltage battery pack will charge the other all the time. The lifeo4 is smaller Ah but will hold a more steady voltage during discharge than the nicds so I would quess the Ah difference wouldnt be much of a issue.
A 100Ah lifepo4 pack would be ideal but its too expensive for me, heavier and would be harder to fit.

Another way to do it was to have a relay for both the nicd pack and the lifepo4 and basically use one pack up at a time then switch to the other.

Does the ernergy meter just measure battery voltage or is it more sophisticated keeping track of Ah used, voltage during discharge etc.?

You think this is a crazy idea and should just save up more money and dump the whole nicd pack at once

[ChrisB]

Welcome along didnt realise they did a saxo version

It never a good idea to mix different types of batteries to be honest, and yes you will find that I think the LiFePO's will try and charge the Nicads all the time and they will be flat fairly quickly.

The energy meter is more a Ah capacity meter, and thus looks at discharge and volts etc and then works out what % of charge is, some peoples energy meter appears to be very linear but I've found that this can change dependant on driving style between one charge and another.

Have a look at Tim Pootles thread regarding his Li-ion conversion.

ChrisB

[arsharpe]

I agree connecting 2 different types of battery directly is probably not a good idea.

(I have been thinking about something similar for myself, so that we can easily get to my parents which is just out of range for our 106)

I don't like suggesting something that I haven't already tried and this may need a little more thought, but I think you may be able to use a break-before-make 2 pole contactor to select which battery set you want. You would probably need to stop to do the switch-over, but that should be ok.

The other thing is that you may want a 300v, 300a diode in series with the lifepo4 pack to make sure that NiCd charger does not charge the lifepo4s if you forget to switch back to the NiCds before charging the NiCds from the mains.

Obviously
a) the battery voltages need to be similar (150-200v) and
b) the energy meter may become seriously confused.



Has anyone invistigated injecting current into dc input at the back of the charge lead while moving. The energy display may then work properly.

I have been waiting for Evan to complete his 106 upgrade. Evan - any news on this ?

[The normal disclaimers apply. Only do this if you have the abilities or get a qualified electrician to do it.]

[Bentzon]

Wow thats alot of lithium in one berlingo really hope he finish that project.

Thats exactly what I was thinking for a 2nd option arsharpe. Either the break-before-make contactor or better two relays. The relays mechanically and electronically block each other if engaged, plus a break-before-make switch to control it.
In addition to the diode a relay controlled by the nicd signal for the charger mains or just run them through the same relay as the nicd pack.
This should be bullet proof.

Just measured resting voltage of the nicds after a full charge and its 140V. 40 lifepo4 sky energy cells in series is resting at 136V if I understand their specs, so voltage shouldnt be a problem.

Yeah the energy meter will probably be very confused. Do you know if it gets any signals from the charger or measure Ah going back into the pack?

[arsharpe]

Ok - sounds like you know what you are doing

The working assumption is that the energy meter measures AH in/out and can calibrate itself to a certain extent - so it assumes that the batteries are of good quality. The low battery light is probably a voltage detect.
I don't know what exactly happens when the low charge light comes on, so I guess you want to avoid that happening and size the cells accordingly.

Good luck.

[Grumpy-b]

The amber low power light is voltage triggered. Its something like 140+ volts on a berlingo. It also triggers a sequence of controlled slow down to deliberately limit current drain and hence damage to the batteries. One of my vans would pretty much shut down after a few minutes. Re-booting the computer would re-set this.

Grumpy-b

[Bentzon]

Okay so as long as I dont run it down to the low voltage limit it should work but with risk of energy meter not working properly.
When hitting 10-20% of first pack pull over, turn the car off, switch to the other pack, then continue.

Will keep you updated once I launch this project, got 3 cars in the garage now with the saxo so need to get rid of one of the ICEs first

[EVan]

I have been waiting for Evan to complete his 106 upgrade. Evan - any news on this ?

Done!

[ChrisB]

............and ?

ChrisB

[EVan]

Nothing really to report yet, here's what I posted elsewhere-

I converted my Peugeot 106 - http://www.evalbum.com/2406 - to use
LiFePo4 cells (which arrived back in August!). The first trip out on
the road, today, had to be to the MOT centre - it had expired while the
car was out of service.

The car benefits from the reduced weight and greater available power
(over the wrecked Saft nicads that were in it) and I was able to run
it "wide open" on the motorway at around 110A, with the cells giving a
solid 3.2V. I hope with a bit of aerodynamic improvement to get
that down to 90A, just 0.5C. 62MPH if you're wondering.

Used about 80AH for the 45 mile round trip, can I hope for 100 miles?!

Anyway it failed the MOT due to a badly split tyre so I can't play any
more until it goes back on Monday...