Electric vehicle batteries and chargers

The VRLA batts that will be in the bike I've ordered have a max charge rate of ".3C20A" There are five in the pack for 60V.

The vendor supplies a 5A charger.

I have a general purpose charger already that can go 2, 10, and 100 amps.

I'm tempted to think the batts can handle 20 amps, so if I figure out the connection types, 10 amps would be fine and quicker. But, that ".3C" I do not understand.

Sorry to be such a noob, but can someone expound on this?

Hi everyone this is my first post so yea here goes...

i rember hearing a couple years back about ppl taking the DeWalt battery packs for the A123 cells inside as well as the VPX 7v batteries... and i just found out that the Yuasa battery is pretty much dead/wont hold a decent charge. so i was thinking about using A123 cells in a 4S (and later when i get more funds a 4S2P) to get roughly 13.2 volts

i got my inspration from these two sites
http://www.rcgroups.com/forums/showthread.php?t=975066
http://www.zxforums.com/forums/zx-6r-forum/29563-a123-lightweight-battery.html

but in order to keep things simple is that i wanted to keep the VPX battery pack intact and hook two up in series and then wire it up to my 200cc scoot. only to keep things cheap and simple so i can plug it into the stock charger with no modifications, or if i wanted i can use the battery for the VPX tools n stuffs.

im just not too sure if the 18650 cells would provide enough amps for the starter motor as opposed to using the bigger 26650 cells

what do you guys think?

thanks in advance
Mark

Just want to bounce around an idea here.

It's based on these general "impressions" which I have gained from my 2 year peek into battery technology:

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Impression A) People want more range than what the currently available batteries can provide.

Impression B) Batteries last much longer if they are being cycled in many shallow cycles, rather than frequent deep cycles.

Impression C) Batteries get damaged by heat caused by a variety of "mechanisms". The worst damage is probably done by heating up excessively from the inside out, particularly by exceeding maximal charge and/or discharge rates, and over-charging and over-discharging.

Impression D) You need high voltage batteries to keep cable sizes and resistive losses low in the overall system. More volts generally mean more "Ooomph" and more speed. Unfortunately, this also makes it very dangerous.

Impression E) To get more Ooomph you need many cells and that means a complex and expensive Battery Management System (BMS).

Impression F) Batteries generally like it to be used to no more of 50% of their capacity, for both peak current draw and total Ah drain.

Impression E) There is always one cell that bites the dust first - depending on circumstances, it may then take the others down with it...
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Now to the conclusions from these impressions:

1) Combining A) + B) +F) ===> In order to get good battery-lifetime range, the available trip range needs to be reduced even further - by about 50% ! Not a popular idea, I'm quite certain...

2) Because it is always one cell that goes down first, you might as well make sure you know exactly which cell this will be. If you can be certain that this cell will be the one that gets over-charged or over-discharged before all others and that it suffers more heat damage than all other cells, then you only need to monitor this single cell! That's the idea. Quite simple.

The proposed solution (possibly hogwash!):

Place a sacrificial cell into the battery string, monitor only this cell. The operating conditions for all other cells should then always be within the parameters conducive to maximising the lifetime energy delivery of the battery.

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Here is an example to illustrate the idea:

Imagine a 40s 40Ah battery.

Instead of monitoring every cell, place just one 25Ah cell into the series and monitor this cell constantly.

When it dies (and die it will!), replace it with another 25Ah cell, again and again and again, until the pack has deteriorated down to maybe 30Ah.

Once the pack capacity has deteriorated significantly, despite the very gentle treatment it is receiving, you could either get a new pack or use an even lower spec sacrificial cell to keep it going.

Needless to say, older cells of the same product line might be perfect sacrificial cells. Down-cycling at it's finest!

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What say you?

For anyone who might be looking for chargers, please evaluate them yourself.

In My latest e-bicycle build I posted this picture of the battery pack I'm meaning to put in the bike

The pack as shown is a 16s2p (48volt 20ah) pack of Headway cells. The cells were bought last year via a group purchase deal ... There has been a continuing issue with this pack where cells are dying and I've never gotten to use any of it to power a vehicle. Well, until today that is. It arrived with funky packaging and one cell pair dead and some of the BMS wires were loose (bad soldering). I eventually bought another cell pair and by the time (months later) I got it rearranged other cell pairs had died. I bought some more cells and also redid all the BMS wires to have better connection. FWIW The resulting pack has cells with manufacturing dates spread out over the last 1+ year.

A couple weeks ago the pack came together as shown in the picture. All the cells were full (3.2-3.3 volts) and I left it sitting. Then yesterday I wanted to mount it on the bicycle and started checking the cell voltages. Some of the cells (2 pairs) were dead. I'm really getting tired of this.

I took off the BMS completely as I'm totally not confident in it. I've heard from others that BMS may be problematic.

Unfortunately I don't have enough cells for the 48v 20ah pack. So I redid it to a 10ah pack (16s1p) w/ no BMS at the moment. It was enough to put it on the bike and take it around the block a couple times. The bike is great, powerful, etc. I think there's only one kink left - the lights aren't working right. But this is about the pack.

My options are:-

a) get a few more cells to get it back to a 48v20ah pack - PLUS - get the fetcher/goodrum BMS (I found the place that sells assembled BMS boards)

b) leave the 48v10ah pack as is and use some of the cells to make a 24v10ah pack for another of my bicycles, that bike has a 24v10ah pack already but that pack isn't quite strong enough for the discharge on that bike and adding another 10ah of cells would make that bike more useful

b.1) also get the fetcher/goodrum BMS board

c) forgo the BMS entirely and just be careful on the monitoring

One thought is maybe these headway cells I have are just bad anyway. They keep dying and maybe throwing more money at them (buying a this other BMS board) is just throwing good money after bad. Option (c) is my frustration plan.. I just use the cells as is until they all die (assuming they're all going to die) and "later" buy a real pack from a reliable manufacturer. Basically I have no idea whether to trust these headway cells at all.

In January , 2010, our company, Shandong Hipower new energy group, send 48V100 AH LifePO4 Battery Pack to Shanghai for battery performance tesing.
With testing data automatic generated by testing machine, I could make offer some pictures, the original Excel documents is about 25M,
With the whole Pack discharging, Testing machine logged all 16 pcs of 3.2V 100A cells discharging status, which marked with different colors, to show the consistency of wole battery pack, curves are automatic generated from data in EXCEL,
3 pictures I could offer, in continuous discharge of 3C, 2C, 1C,
That means battery pack continuous discharge current is 300A ,200A , 100A.
3C continuous discharge curve (3.2V 100AH, in 22'C temperature)

2C continuous discharge curve (3.2V 100AH, in 22'C temperature)

1C continuous discharge curve (3.2V 100AH, in 22'C temperature)

For any details, could directly contract with me, infohipower@chinabatteries.net
or visist www.chinabatteries.net http://chinahipower.en.alibaba.com/

At end I also put discharge curves comes from datasheet, that means if the battery performance can not match those curves, customer could directly asking for replacement or send it back with total free.
0.5C discharge curve from battery pack datasheet(48V 100AH battery pack, in 22'C temperature)

battery performance in different temprature(3.2V 100AH, 0.3C Discharge )

Hi everyone,
Generally re-charging a battery takes between 2 to 5 hours depending on the type of the batteries.What factors deal the re-charging time of a battery ?
How can we reduce the recharging time of a battery ? Can anyone help me with some information.Thank you in advance.

Srav.

I just fried my charger (my bad, it was a raindrop) and desperately need a replacement in Palo Alto CA. It was a QSC4231; 110vac, 2.5A in;48VDC @ 2.6A out. It's for an X-treme XB-600 with 48VDC lead acid (20ah). If anyone's got one to spare between San Francisco and Santa Cruz please ring my cell @415 272-1293 or email (slower for me) roblyn8@hotmail.com

An interesting manual on Lithium technology and implications at:

http://www.electronics-lab.com/articles/Li_Ion_reconstruct/

Recently Hipower updated the new BMS of ENERGY BALANCING, which applied for patent, this new technology greatly improved the LifePO4 battery pack life and performance,
Hipower BMS use energy balancing instead of load balancing, When charging the BMS begins balancing, and when discharging BMS would auto adjus energy of cells, that is BMS will auto transfer energy from high to low among cells, It keeps all cells in same status as volt, capacity, and keeps the weaked cells away from damaging with the help of other cells offering parts of current. so battery consistency becomes less sensitive and energy balancing could greatly eliminate the negative effect of inconsistence of cells after a period of usage. The whole battery pack could offer constant, stable power.

Normal fuction (introduce ) of Hipower BMS:
Monitoring and controlling the key parameters such as voltage, current, temperature, etc., during charging and discharging, and generate alarms and reaction when any of parameters become out of limits. Also Charger and controller of motor with CAN BUS could receive signal sent by BMS with CAN BUS, they would reaction just in time with the BMS indication. (For BMS with CAN BUS type)

Fast reaction as one whole power system:
Advanced Hipower BMS can offer signal transport and display function, the signal which follow the CAN BUS protocol will be accepted by Charger and Controller of motor also with CAN BUS. That means Charger and Controller will action just in time with the indication of BMS such as over charge protection, over discharge protection, abnormal temperature status, and other limits be set. BMS with display would offer better Human-machine interaction. Users can setting all parameters as they want. The display would show the real time data, also logging data in storage, which can be used in analyzing the whole power system, and alarm signal can also be shown on display.

There is no doubt that all of the above i mentioned means that we are helping you to prevent your battey from damaged and can have a best performence.
So,if you have any interest or inquiry please contact me by email hipowerkevin@gmail,I will provide much more details to you.