My new LiFePO4 battery and charger
I am a newbie to the Forum and also a bit of a dummy regarding electrification of bikes?
Give me an old V8 Chevy small block and I´ll strip and rebuild, no problem. To each his own!!
Long story short, I bought a Giant Cruiser beach bike, fitted with a Crystalyte Phoenix 5303 Racer rear hub motor (48 volt, 40 amp.= 1920 watts) and an absolute rubbish Chinese LiFePO4 battery, the size of a truck SLA, that collapsed after two weeks!
I then went the route of 4x12 volt SLA´s, that gave good service for a couple of years but were so heavy (each weighed some 10lbs.) that I decided to go to a LiFePO4 again, because modern technology appears to have moved on.
I was advised, because I only do a few miles a day, at low speeds (plus my wife has a Dahon ROO EL folder, that struggles a bit but she is happy)to buy a 48 volt x 12 amp. LiFePO4 battery, together with a 3 amp. charger.
This I did. It arrived yesterday, WOW!! Weight only some 10lbs. in a little rear rack bag. I then noticed the charger stated 5 amp.
So guys, I have three questions, if I may?
Will the battery handle my Phoenix Racer motor OK?
Should I buy and try to learn the intricacies of a stand alone Cycle Analyser?
Will a 5 amp. charger reduce my battery life by much?
Thank you in advance for any help and advice.
Who is the maker of the battery pack?
What was the specs they gave for the battery pack, especially the rated discharge capacity?
The deal is - your crystalyte motor is powerful for a bicycle (48v 40amps = 1920 watts, or almost 3x the legal rating of an electric bicycle in the U.S.). The key number is the 40A discharge rate. Assuming you got a 10AH battery pack, that means your peak discharge rate is 4C, and depending on the cell maker a 4C discharge rate may be too much.
The battery pack should have come with a specifications sheet listing max discharge rates as a peak discharge you can do for a few seconds, or a continuous discharge you can maintain over time. What were those numbers?
The spec sheet should have also listed the max charge rate. And if you bought the charger from the battery vendor, presumably they mean for the two to go together.
12A helps a little .. still depends on the ratings of the cells.
As for the Cycle Analyst question -- they are EXCELLENT. I have Cycle Analysts on all my electric vehicles, from bicycles up to my electric car.
I agree with everything reikiman says - I just wanted to add that I'm 90% confident you'll be fine and wanted to address the charging side a little more.
1. Will the battery handle my Phoenix Racer motor OK?
2. Should I buy and try to learn the intricacies of a stand alone Cycle Analyser?
3. Will a 5 amp. charger reduce my battery life by much?
1. I expect the pack will be fine - given your stated "low stress" riding. If you can take a picture of any markings on it we can probably help identify it. Amp draw will peak during acceleration (especially from stop on an uphill). The advantage of an e-bike is that it has pedals :-) You don't need to pedal it up hill but even just an initial push on the pedals should help reduce the peak load. Oh, and no burnouts!
2. YES. I've actually never owned one of these but from what I know they are one of the best aftermarket devices. More data is always a good thing. :-)
3. I very much doubt the peak current of the charger (5A) will cause you any grief. The question is more to do with "how smart" the charging system is. And how smart it needs to be is dependent on the pack construction (number of individual cells) and pack usage (how low do you drain it? how often do you charge it?). On the usage front: seeing as you only go a few miles every day and you have a fairly big pack you're not draining it very deep and if you get in the habit of charging it after every use you should keep the pack happy. One caveat being if you're going to store the bike for a long time you want to store it with the pack about 60% full. On the "smart" front: do you have a BMS? I don't know if David runs a BMS on his e-bike? It's essential on large packs that get worked hard (for example in a maxi-scooter)
Enjoy your ride and raise a glass of Sangria for us... (but not while actually riding ;-))
are you finished this? I thought the battery is ok. Please let me know your process on this battery,I would like to know this also
I'm sorry to have taken so long to respond.. in any case the specs on the battery pack are approx what I thought they'd be. If I understand it right, the max discharge would be 35A which would be not quite enough to satisfy the max demand from your controller. But my experience with this sort of battery is if the BMS turns the system off, you simply unplug the battery then plug it back in. On my bicycle the connector for this is near the seat tube, and I've been able to unplug then plug it back in while riding. And over time you'll learn to not hit full throttle .. ;-)