Making own battery

(system) #1

Has anybody tried making their own battery so they dont need to lease one.
I may get a twizy. I have 16 x 100ahr Lifepo4 cells already, would consider making my own.
Does anyone know the dimensions that the batt has to fit in?

(mender) #2

I’m pretty sure that you can’t own one without agreeing to the battery hire-can’t remember, but sure this was mentioned.

I like the £53/7500 mile deal; not having to buy, finance or replace the batteries is fine by me. The only worry is they only replace them if they do not hold 75% charge-at 85% they won’t do what I need them to do. Watch this space.

(system) #3

Well even if you have to sign up on purchase they cant tie you in for ever.
Im sure when they come on the second hand market they wont be able to force you to lease.
I like the fact the Twizy is just around 50v, that is a safe voltage to work on.

I can make a 50v 100ahr pack for about £1200, that would last 5-10 years, so averages out at less than £200 a year!

(system) #4

I like the idea of your own battery.

I use a 6 amp/hr 22.2 volt 6 cell lipo @ around £70 (from a huge model helicopter) with great success on my home made electric bike.

It may be hard to hack into the Twizy electronics for connection and charging.

Presumably the charging system balance charges all cells which must be tapped therefore at each of say 14 Cells.

Lifepo cells are I think slightly lower voltage than the 3.7 now common lipo cells.

But I’m all for independence and doing your own thing which is what I like abut the Twizy:)

(system) #5

Yes Lipos are good, but LifePo4 is safer for a car, as doesn’t have the risk of combustion.
If I made my own pack I would use my own charger and balancer.
FYI if you charge cells in parallel they automatically balance.

Your lipo cells can probably deliver 100amps discharge continuous. You could theoretically run a Twizy off 5 parallel sets of 2 in series!
problem is you would maybe get only 15mins of driving time before they run out!

(system) #6

Like you I generally avoid ongoing costs wherever possible and without the battery lease issues I would probably buy a Twizy having test driven one.Can we get over all issues?If you return Renault’s battery they may recover it at your (high) expense.It is likely chipped for their tracking/research purposes.The car may not recognise any other battery. Evenwith your own charger we will want benefit of regen braking capability and the car will try to do that anyway.I know my lipos wouldn’t last long but their discharge capability is 35 c or about 200 amps - short but sweet

(osbrook) #7

It might be worth talking to [FONT=Georgia]*Sevcon design, *[/FONT]as they make the control circuits for the Twizy. You never know. It might be an off the shelf controller that you can get the specs on and see how it fits with your battery pack. Now if you can fit it with a way of dropping it out to swap it for a charged one, that would be neat. Or even build in a fast charge ability.

(system) #8

yes Im sure they can do 35c burst but pulling that current continuous will melt the wires. you may get away with 3 parallel x 2 in series.
So that would be 18amphr pack for around £400

no problem getting the controller to ‘recognise’ that, twizys use the sevcon G4 controller which is fine.

could be a project for an emergency pack. You would get about 9mile range and a lighter twizy!
Put a 5v 1amp solar panel across each cell and that would be really interesting! Could recharge itself each day in the sun!

(system) #9

Looks much more promising.
I note lifepo batts are coming in and are the way to go as you have said.
I’m not an expert at all but am keen on your idea.

Can a Twizy be acquired without batt?
I gather in Israel batts are swopped at equivalant of petrol stations on the spot.

I suppose one would have to inform insurance co of mod.?

(system) #10

I don’t see why many of these “electric cars” manufacturers don’t throw a solar panel array (flexible ones do exist) on top or on the hood, hell a translucent one from a solar calculator as a giant sunroof would be cool (sure it would almost cost as much a Nissan leaf but it would have stout.)

As for the LiFePO4 battery idea, try it out, i’m in the states here waiting for twizy’s to hop over the ocean (already planning on mods)… but not allowed to own one without signing up for the battery contract… hmmm, i understand for disposal, recycling, or replacement. But to say i can’t hack it after i pay $10k+ (usd) for it, wouldn’t be much fun. And as long as the controller is well documented and you not going to put your tongue across the contacts then cool, i say hack it, maybe even resell the ideas back to Renault.

(Bassflex) #11

“Don’t put tongue across contacts…” good job I saw that.

Surely someone on here has £500 quid to purchase the software and cable to mess with the engine mapping.

Some of you have an exstensive car history, the sportiest thing I ever had/have is my Saab.

Some of you have had Supercars, or even still have super cars. Surely that replacement brake disc and caliper could wait till the next service? :razz:

(system) #12

AFAIK that’s exactly what they do… you can’t sell a Renault EV without transferring liability for the battery lease…

(system) #13

Hmmm, currently own an '95 aspire and a '03 focus, both hit about 380/miles a tank, ALMOST bought a Saab in Maryland back in 03 (REALLY NICE TURBO). But here in Atlanta with the wife’s job at corporate its more feasible for a twizy (less than 20 miles round trip)… a solar charging option would be cool, the LiFePO4 batteries would be a lot safer though.

Be even sweeter if they sold a twizy in the states too :slight_smile:

I’m sure someone, somewhere, is/and/or violating the product secretly… Hell i’m still waiting for the turbo diesel focus to come over the pond. :frowning:

Anyway thanks guys, just was wondering if there were anyway to upgrade the battery pack to a different source, and someone had the same idea.

(system) #14

Blackross, see my posts r.e. the battery leasing thread. Main point being when you first buy a Twizy you lease the battery for min of 12 months at min £55 (IIRC).
After the 12 months you own the twizy you bought outright. The batteries have come to the end of their lease. What happens? Renault cant take the vehicle back.
They can take the batteries but at their own cost. ??You then own a Twizy with no ongoing obligation? i am unsure but would love to know.

(system) #15

Do you know if they track your location? Is there a GSM card in there? Can they disable your battery if you decide to move country?

(system) #16

DUDE sweet, didn’t even see that… that open it up to third party options.

(Faisal Khouri) #17

Here in UAE when I got my Twizy I won the battery too without any contract. The only issue is when Twizy stop working and their service charge are very high. They told me to change the 12v battery to know the issue, then they manage to put the light on but the came up with issue am facing on inverter which it took them 2 month to bring it. After they put the inverter, they inform me that am getting the charge but the traction battery is not holding the. Barge the main issue that the battery is not holding charge and the cost of replacement is around 9K USD
Currently am having the original batter which it’s not holding the charge as well I have old set of battery box belong to friend of mine which he face the same issue before he turn his Twizy to project car.
I highly appreciate if someone can help me with traction battery issue