60V charger for 40AH LiFeP04 pack.... please help

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wheelie's picture
Joined: 11/15/2008
Points: 82

I need a charger for a 60V 40AH LiFeP04 pack (well 18 x 3.2V 40AH Thundersky Batteries)

Can anyone please give me a few suggestions on which charger to buy, or which one might suit.... will a 72V charger fry the batteries or BMS???

...please help

Mr. Wheelie.

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Jeffkay's picture
Joined: 07/16/2007
Points: 90
Re: 60V charger for 40AH LiFeP04 pack.... please help

Go to this company and check out the chargers. I have TS in 48v pack. I use the 48-15Amp charger that was $165. It ends the voltage at 58.2 volts. Or look at the other models for your needs. I have needed no BMS as the charger slightly undercharges the TS cells--perfect: http://elitepowersolutions.com/products/product_info.php?cPath=9&products_id=63

Hmmm, I just saw you have 18 cells--that's kind of an odd number...

Jeff K.

Joined: 12/13/2008
Points: 1
Re: 60V charger for 40AH LiFeP04 pack.... please help

I have been using lead acid batterys because of cost of LI, and the charge discharge/cycle life problems. The batterys have to be well balanced as to their capacity in their pack, as the other poster stated it is best to slightly under charge for longer cycle life- On another forum a LI user killed his batterys in a short time by drawing more than their rated current rating in not many cycles- wrong use causes the growth of crystals that lead to a internal short.

The best chargers that I have read about use a by pass system when the single cell reaches the maxium allowable voltage, as to not over charge that cell in the string. In order to accomplish this the chargeing system has a voltage monitor connected across each individual cell that will, in this case connect a device across the cell when it has reached it's fully charged voltage, to shunt around the current until the correct chargeing voltage in string is reached, before turning off.

As to each cell, over charge fatal, cycle to below recommended voltage fatal, or at least the cycle life will be reduced to a few hundred cycles, as to the optmum charge/discharge cycle up to around 3000 cycles. The recomended storage and shipping voltage is around one half charge.

With the cost of your 40AH pack I would invest in the charger that will give the maxum life of your batteries even if it costs in the hundreds of $. Make shure that your controller (to motor) will do a low voltage cut off, or have a digital volt meter to look at to allow you to not discharge below the 3V~? X (number of cells) or what the total recommended voltage is for the pack.

My 2 Cents worth, jeb

wheelie's picture
Joined: 11/15/2008
Points: 82
Re: 60V charger for 40AH LiFeP04 pack.... please help

..Thanks fellas...

18 Cells - 3 lots of 6 cells - fits my trike battery box perfectly... I didn't think this would be an issue...

Have sussed out many chargers, and written to numerous suppliers - Sunday here in Australia - so I won't get replies till Tuesday - as the USA is a day behind us...

Kelley (controllers) sell a 60V charger - kind of expensive, have not been able to find too many other 60V chargers (under $2500).

I have checked out Elite Power Solutions stuff too - their chargers are for 16 or 20 cell units - and not sure if the number of units is the important thing - or the voltage??

Have a good BMS on order for the Thundersky pack - so hopefully discharge issues won't be too much of a problem.. Plan on running two 1500W hubs - with dual Kelley controllers...

Joined: 07/07/2007
Points: 1675
Re: 60V charger for 40AH LiFeP04 pack.... please help

Gday Wheelie,

good to see a fellow aussie on the forums :D
which part of Australia you from? Perth myself.

i have a 15cell 40AH TS pack on my emax.
i charge it with this charger:

and this BMS:

a few things to note,
for true 60v, you need 20cells.
18cells will only give you 54v at 40A, whereas 5xagm 12v batteries would give you a fulll 60v under load.
i found this out the hard way, and had to add a second set of cells of get ym top sped back above 60kmh.

as far as charge voltage goes, it just has to be between 3.4v and 4.2v until curent falls below 0.1A.
testing on my dumy load puts the difference in discharge capacity between 4.2v and 3.4v at 0.5AH.

on my scooter i charge to 3.89vpc until current falls below 2A.


PS. do you have an evablum page?
mine is here: http://www.evalbum.com/1499


Daily Ride:
2007 Vectrix, modified with 42 x Thundersky 60Ah
Vectrix 60Ah Lithium Tyres Fuel Registration Insurance cycle analyst 2 x TC Charger & MC
Spent so far: $5800 + $7000 + $2040 + $1200 + $425 + $800 + $140 + $3000
Cost to do it again: $1000 + $3800 + $2040 + $1200 + $425 + $800 + $140 + $1500 (lasts longer)
Cost for a Petrol bike:$6000 + + $1440 + $7560 + $1000 + $1600 + $4000 servicing
Total spent: $20405
Total to do again: $10905
Total to have used a petrol bike: $21600
Total distance travelled so far: 102'120km

Other vehicles:
2008 Mazda 2 conversion
2009 Blade Electron
1997 Prius - plugin hybrid mod

wheelie's picture
Joined: 11/15/2008
Points: 82
Re: 60V charger for 40AH LiFeP04 pack.... please help

Hey Matt..

I'm from Perth, living in Tas now.... Have been designing my tilting trike for 3.5 years now - time to build!! it will be my first elec...of many I hope. Bit reluctant to post my design images at this point - applying for a grant for this - will post some pics when I exhibit.

looking at the space I have again (slim-line frame) - taking into account BMS and two controllers - will have to go with a 48V 40AH LFP pack... ok for the prototype I guess... cheaper too.



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