What chemistry do you use? (Ver. 2)

[CoffeeLuke]

I use both a 36V 8Ah NiCad, 5C Max Rate and a 17Ah led acid gell at the same time(I have a one way split I got from Justin at ebikes.ca)

[MrKang]

I use all LiPo batteries 22.2V 4000mAh 15C and 7.4V 4000mAh 15C
My first pack excists of 5 parallel packs which are configured out of 22.2 and 3 7.4 in serie
I just ordered some new 22.2V because of the space. instead of 3 x 7.4 which also is 22.2

Here is a photo of the chage section. It consists of 3 LiPo balancers which can charge my LiPo's in 1 hour!!

[Reid Welch]

Look, this year it's LiFePo4 for various reasons.
Here's my mount, at the moment *until tomorrow*

it is not secured, not yet, with an invisible strapping system just devised.


That battery will not go anywhere but stay on the bike, upside down, dropped from a cliff.

LiFePo4, pop tart packs, for now:

http://i244.photobucket.com/albums/gg28 ... 090327.jpg

[sprocket]

I have three different setups at the moment:

1. 24 V SLA (18 Ah), 0.45 Ah/mile (top speed about 16 mph, flat no pedaling)
2. 36 V SLA (6.5 Ah) ) 0.5 Ah/mile (top speed about 24 mph, flat no pedaling)
3. 48V 20Ah ping LIFEPO4 (not measured precisely yet, but >30 mph)

For my commute and my setup, I have WAY too much capacity with (1)&(3). I can charge at work and have an 8.6 mile ride on a mostly flat bike path with exactly 7 stops for road crossings. I pedal with the bike contributing about 100W.

What have I learned? 24 mph is too fast for me to feel comfortable on my bike path (minuteman trail in boston). 6-8 Ah is perfect for my situation, and anything more just adds weight. At night, I need a better way to see the road without blinding other SLOWER bikers.

spkt

[Reid Welch]

Oh Man, MrKang, thank you, but MOST ALL ebike newbies have no idea of what happens when/if defective lipo goes up in self-fueled flame hotter than an oxygen-acetylene torch.

Just a short, just a bad charger, just a tiny error in assmebling, and Mr. Newbie has just lost his home or his life or both.

LiPo for those who KWYADAWYADI, and manganese or ferrite lithium for we others.
Cheeful advocation of liPo, without warnings, is a cheerful invitation for blithe, incompetents, to die =because you did not tell them bettter= how vital it is that the battery, not a single cell, ever short.

500 million at least, of miniature lipos are in "safe" service: with big corporate names behind them. There are tons of no-name chargers and defective, bare cells. Build cheap. Good luck, probably nothing will happen to the home brewer of budget, obsolete but so-light and wonderful old LiPo explosion tarts.

My leanings; I am not a battery eggspert.

[Link]

KWYADAWYADI

Um...don't tell me..."Know what you are doing and why you are doing it"?

[torqueon]

Sounds like the why to go, also sound complcated, I want plug and play, you know a daily driver, I do not want to fart around chargers and batteries every evening

[SpeedEBikes]

I've been using lithium ion cells (cobalt) for 7 years. Most of that time I've been running without protection, ie no BMS. I tried using BMS's for a couple years, several years ago, but the units I tried were marginal, most failed, some burned up and one nearly caused a fire.

I ride daily, year round in Chicago in all weather.

I had one fire early on where I lost 2 cells and damaged another pair when slush built up on an improperly sealed connector and eventually penetrated it and shorted out a couple wires. This was on a pack of Thundersky 10 ah cells where there were wires for charging every cell individually. I had a fuse on the battery for the main discharge tap, but incorrectly assumed the small gauge charging wires would function as fuses themselves.

I stopped using the Thundersky connectors and got rid of the separate charging wires, simplifying my pack construction to only have the two main power wires entering each pack. I also changed the design of my pack cases. Originally I made enclosures from thin aluminum sheet for good cooling. I glued in strips of closed cell foam to keep the cells and wiring out of contact with the conductive case but felt nervous about it. I switched to making boxes out of coroplast. It seems cheesier but has worked well enough. Coroplast offers decent protection against vibration and impact although it does retain a little more heat. I've managed the heat issue through careful matching of my batteries, controllers, motors and loads.

I switched to anderson power pole 45 amp connectors. Those aren't waterproof so I had to take care to make sure all connections are in protected places where they don't get wet. For the batteries that meant putting the connectors inside the battery cases instead of outside them which is a little more awkward but has worked out well enough.

Without the separate charging wires I had to stop using the Thundersky chargers which I didn't much like anyway and I switched to using variable DC power supplies which I still use to this day. The downside was no more automatic balancing. For a while I carefully checked each cells voltage with a multimeter before and after every charge. For day to day use where I would charge more frequently but only up to about 4.1 volts per cell and terminate discharge before hitting 3.65 volts.

I switched to larger capacity packs, 20+ ah to minimize heating and to allow for extended all day weekend rides. Before those I manually balance the packs while doing a full charge using a multimeter, light bulbs with alligator clips and a kitchen timer. I kept a log of manual balancing and always knew the weakest cell in my packs. For a long while I had a mini pocket multimeter mounted on my handlebars but eventually switched to a self powered mini panel digital voltmeter attached to the weakest cell so I would know when to ease up and when to stop.

While this has worked for me, it hasn't been 100% foolproof. At times I've cut corners due to the tedium or inconvenience of frequent manual monitoring of each cell with a multimeter. Over the years I've had a few incidents and mishaps.

I'm currently running packs built from 18650 liion cells. They are 3 years old. Within a couple years I'll rewire them as a massive 12 volt pack and keep using them for a couple more years to power a big trailer mounted sound system. The liions currently powering the sound system are now 5 years old and in a couple more years will likely be unfit for even that and I'll have to look into recycling/disposal.

While I've managed to get by for a long time on the cheap I am looking forward to the advances in batteries and electronics. A couple years ago I added using a WattsUp meter and switched from power poles to bullet style connectors used by RC modelers. I've just ordered an iCharger 208B and the cell-log8 which I expect will make it easier than ever to take good care of my batteries.

I' m not sure what batteries I'll try next. I like the idea of moving to a safer chemistry with a more gentle aging curve but my guess is energy density and cost factors may still override that.

[vanilla ice]

Same Lead from '08 here. Cheap robust safe ,and um cheap. Checked prices today on ebay- $70 for 420Wh shipped.. 10 pack of 7ah 6v's. Yeah yeah heavy bulky saggy and peukurt, I know.

Am playing around with a lipo booster pack to get a feel for it though.. will go life when the time comes.

Still curious what pixie dust DS put in his sla electrolyte.. then mebbe I can do it too and be a DS wannabe.

[52rockwell]

Hi ,
New guy here.
I chose NiCad batteries 36v 8 ah when I bought my E-zee conversion kit from ebikes.ca,because, after reading all I could about batteries I felt that if a cell went bad in my pack I could troubleshoot it and replace it myself. I was in the market to build the best rocksolid commuter I could for my daily 8 mile one way ride, and my more infrequent 32 mile commutes. I have put about 800 miles on the bike so far in various weather, and been very happy with it so far,although
Never more pleased than today,with wind gusts to 35 ,and light,intermittent snow/icepellets .

[filbert]

36v 8ah nimh pack going on its third year. Capacity is dropping off so I am not sure what i will replace it with.

[kevo]

Lithium Manganese Bosch Fat Packs and for lighter roadbike Zippy LiPoly.

[e-bike-is-fun]

LifePo4
Headway 16ah

[kevo]

Started with LiMn (Bosch 36V tool batteries). Reliable but a bit heavy and bulky. Still great for the tools Evolved to very many Zippy LiPos, not always the best cared for. Very portable and constantly improving in capacity and lower prices. Like the US warehouses HobbyKing now stocks regularly.

[The fingers]

Year-old SLA are still going strong, 2500 miles, 250 cycles; available funds will determine replacement chemistry, I am fine going with SLA again. Easily recycled, ease of use and charging, rugged, predictable, safe, and cheap! (I am an analog person in a digital world)