Topic: A newbie's battery questions :)

[joerg]

Hi folks,

I have just joined the community of proud C5 owners: Bought my first C5 back in February this year and successfully restored it. Photos will be posted here very soon. )

As I am still a bloody beginner, I just bought the first 35Ah car starter battery in a local store - just to get things going!

When it is fully charged, it has a voltage of around 13.5 volt - the motor works perfectly and the speed without pedaling is at around 20 km/h.
After around 15kms with pedal support at hills and at the driveaway, the voltage has dropped to 12.37 volts.
The motor support is now very week and without pedaling the C5 goes with walking speed (6km/h or so).
Another day, the voltage dropped below 12V (11.9 if I remember correctly) and the motor wasn't able to turn the wheels anymore.

Now my question: Do you share this experience? Does it happen because the voltage is too low? Or would the motor operate properly at "just" 12V if the battery delivered enough amps? As far as I know, a 12V car battery can be discharged down to a voltage of 10.5 volts...

http://www.ev-power.eu/Winston-40Ah-100Ah/
What do you think about these ones? Should I give them a try? I'd use four of them with an appropriate BMS/balancers.
What capacity would you suggest me? On long day tours with my "normal" bike, I use to make 70-100km per day. If my C5 made 70 kms without recharging, it would be perfect when starting after breakfast on a sunny sunday and coming back for a late dinner. Any suggestions and ideas?

Thanks in advance,

Jörg

[thedesigntailor]

Hi Joerg

Welcome to the forum - I'm afraid I'm not very technical so can't answer your questions.

However this is the battery I use and find really good http://c5alive.co.uk/forum/index.php/topic,2144.0.html

Lots of advice in here http://c5alive.co.uk/forum/index.php/board,13.0.html

And faults and solutions here http://c5alive.co.uk/forum/index.php/board,6.0.html

Good luck and I'm sure some of the guys who know what they are talking about will be here soon...

[radiomarty]

Hi Joerg - Welcome aboard - as far AS i can see you are getting around 10 miles out of your battery. The discharge rate and readings I think are quite normal for this battery - increasing the amps hours will improve your range slightly but not dramatically. I have no experience of the lifepo4 batteries but I understand that they are superior and very good.I think someone one here has used them and had a very good range but maybe not the range you are hoping for ! - I am sure someone will be along soon that can advise you on these type of batteries- regards Marty

[Karl]

Hi and welcome to c5alive

I agree with Marty, it sounds as though the range you're getting from the lead acid battery is on a par with what we would expect.

Very few seem to go down the lithium route mainly due to increased cost and complexity - especially as most of us tend to use our c5's for weekend events etc and seldom go for the range you are looking to get. For low usage lead acid are the best cost option.

If you do go for lithium please let us know how you get on.   

[joerg]

Hey,

thanks a lot for the fast answers.
I am basically using my C5 every day - for short tours through the country side, for shopping or just for the fun of riding this vehicle
Sure, if the C5 is more a collector's item that is only used on special occasions, it's not worth thinking about lithium at all. But I recharge my battery every night....and somehow I have got the feeling that it will be dead before christmas
As far as the specs say, a lithium battery has 3000-5000 cycles, while a lead acid battery has 300-500...

So, if I got everything right: For the price of four lead acid batteries, I'll get one lithium that gives me the fun of ten lead acid ones

But currently, I am working on two smaller projects: Replacing the original chain tensioner and making a new seat cushon!

I'll keep you updated.

Thanks,

Jörg

[thedesigntailor]

Some lead batteries come with a warrantee of several years - mine is about 3 or 4.

So if you do manage to wear it down then you might be able to get it replaced for free.

Not sure how easy this is in reality.

[kamilb1998]

Some lead batteries come with a warrantee of several years - mine is about 3 or 4.

So if you do manage to wear it down then you might be able to get it replaced for free.

Not sure how easy this is in reality.

I'm using lead acid car batteries and my C5 does 300+ miles/month.

The range on them starts dropping after about 400 miles and I have been to replace one under warranty but this made me feel bad as they weren't supposed to be used in a C5 and the guy in the shop will probably be stuck with them if the factory doesn't accept them back so I will be looking into mobility scooter/lithium batteries in the near future.

[joerg]

Hey guys,

I have news for you: Just ordered a winston LiFePo4 60Ah 12V battery pack.

http://www.ev-power.eu/LiFeYPO4-batteries-12V-1-1/Lithium-Battery-12V-60Ah-WB-LP12V60AH.html

Even though it ruins my small student's budget for now, I hope it will save me a lot of money in the long run.

At the moment, I unfortunately have a gearbox problem (see my other thread), but I might test the battery in some other C5 first and share my experience with you. )

Jörg

[Lancealot]

Hi and welcome to the forum.

Be careful to get the right charger as they are different for lithium batteries to lead acid ones.....................

Lance

[marra]

Hey guys,

I have news for you: Just ordered a winston LiFePo4 60Ah 12V battery pack.

http://www.ev-power.eu/LiFeYPO4-batteries-12V-1-1/Lithium-Battery-12V-60Ah-WB-LP12V60AH.html

Even though it ruins my small student's budget for now, I hope it will save me a lot of money in the long run.

At the moment, I unfortunately have a gearbox problem (see my other thread), but I might test the battery in some other C5 first and share my experience with you. )

Jörg

  Hi there. You need to check if it has a built in BMS or LV cut out. If not you will need to buy a separate monitor. I have used these Thundersky cells from the US and had problems with balance , thats why I now use Ping or Heinzmann for all ebikes. You will do irreversible damage if you go low volt, usually by 3v on any cell. Also these LiFeYPo4 are pretty new ( dont confuse with Lifepo4 ) and unsure of standing with the life Yttrium cells, sometimes for the C5, just having a good budget battery as Booboo said is the long term cheaper option.

[joerg]

Hi...

thanks for the hint! The C5 that will be powered by the LiFeYPo4 cells doesn't have any electronics anymore, the control box board was burned down when I got it. I'm trying to build it up from scratch now with an ATmega micro controller and a SyRen 50A PWM motor driver. The SyRen board has a lithium cut off at 3.0 V per cell, so that should all be fine.

The 12V LiFeYPo4 battery block has no BMS. The charger should be OK, I emailed the dealer (a marine shop in berlin) to make sure I get the correct one.

Jörg

[marra]

If the battery has no BMS then how can the controller detect each cell before 3v, the pack will push out 4 cells unbalanced , i.e. (peak cell 3.2 ) 3.2 + 3.2 + 3.1 + 2.6 = 12.1v (controller doesn't pic up fault if no controller line ) = knackered , this just from my past experience and others. If the retailer says OK then good. just check the warranty. can you put pics up of the project as you go. Nice to see more project posted. thanks m

[joerg]

Hi marra,

hmm, I asked the dealer twice about balancers...because that was my concern as well.
He said that I don't need them because the 12V packs contain "pre-selected" cells.

The controller will just cut off at 4*3 V = 12 V - so as you say...no single cell monitoring.

Jörg

[marra]

Pre-selected cells also known as Matched cells, all lipoly battery builders do it ( apart from HK power + V power as same company) . From what I know as the cells soften with every use ( usually by 20 discharges ) they become mismatched from one and other. I am not going to start putting down the retailer/dealer due to the numbers they sell and their experience , but in mine and others the built in BMS and balancing charger also such as Ping ( and others, I think Turnigy are also doing high amp 12v now)  batteries are far better. If you have been given the OK and there is a good warranty then thats something. Keep us up to date with the project. m

[joerg]

Hi marra,

well, we will see. It's a bit hard to talk about these things if you haven't tried it. I basically see the point that the cells should be balanced and asked the dealer about it. For me, the C5 is a hobby project - other guys restore old cars, thats even more expensive than giving these batteries a try.
Can you give me some information about the batteries you are using? What capacities, models, where to buy etc.
Have u tried one of these LiFe(Y)Po4 in the C5 already or are you just sharing your experience with ebikes?

Jörg