Cheap-E build. SLA to LiFePO4 not working. Need help.

[CH300]

48V 10AH. Total SLA build including bike and accessories - $450. Works great since 2019, however I'm going thru rear wheel tread every 2yrs, heavy to load in my SUV, plus I'm sure the cheap chinese bearings aren't going to last much longer. Saw on Amazon LiFePO4 batteries are now under $40 each, so I bought 4 and changed out the heavy SLA's with these. LiFePO4 batteries are same 12v 10ah. Each one was delivered over 13 volts. After installing, batteries showed 4 bars out of 5 on my battery monitor. As soon as I gave it some juice, bike stopped and battery monitor showed empty. I measured each battery and each one was still over 13 volts so I'm stumped. I'm guessing the BMS on 1 or all batteries can't take the load and shuts off? I put the SLA's back and everything works.

Anyhow, is there a 12V, 24V or 48V LiFePO4 batteries under total of $250 that will work in an on and off road environment? I'd like to use four 12V in series. Thanks for any help.

[stts]

Yikes, yea those are pretty inadequate. Those are not the greatest high current terminals. That's the first red flag on sight. Second, that chinese battery label is more cause for suspicion. Third, it's only 10Ah and on an unknown chinese label, its probably no where near that. Just like their 100,000 candle power flash lights are bright but in no way near that number. So these batteries may likely work, but not for running your eBike. SLA really pumps out the current, even thru chinsy terminals like that. So you can test each battery just to see if they all react the same. Hook each to your car instead of your car battery. Then turn the key on but don't start. Then just see how much stuff you can turn on and how long it stays running. Lights and inside fan motor pull some amps. So you can really tell one battery from another. You may have one especially faulty battery. But it's certain that you will have to get at least double all those batteries to run your eBike. And triple if your going farther than 10 miles. If they were name brand batteries, then they might run your bike, but under 10 miles for sure. You have the most power hungry motor you can put on a bike. So you may have to stick with SLA for economics. They have low capacity and big weight, but work come hell or high water. Yea, SLA doesn't catch fire in water, hah. Lithiums cost lots more and Lifepo are even higher. So you will be up to $320 now to get this up to a very minimum usable standard with the motor you have. Amazon is good for returns if you find problems. Or even change your mind. But double up might still be lighter than SLA and well cared for LifePo4s can vastly outlast SLAs. But you know, I have a 22 year old SLA that I still use right now. Its 35Ah and it gets used lightly once every couple of months. Certainly it is no longer 35Ah, but its still very usable for me. I use it to winch on stuff but not cars. So never say never on SLAs. Lithion is by far the most compact and light weight. And requires its own charger. So all that is food to chew on.

[CH300]

Thanks for the quick reply stts. I don't know much about this stuff. From your info and others on this site, I guess the torque required for my cheapy application is greater than what these cheap LiFePO4's can manage so I'll return them.

I don't want to be critical but shouldn't someone change the name of this website from "electricbike" to "electricmoped"? Seems a lot of people on this website never use the pedals, not getting any exercise.....soooo why have a bike? Why not just get a moped or motorcycle? I enjoy pedaling. I only use the 48V in strong winds, going uphill or crossing a busy road. I still have a little juice remaining after a 10 mile trip with my SLA's.

I appreciate your help in deciding what to do. Thank you!

[AZguy]

Outside of the sur-ron section I think a lot of folks are in the pedaling camp - some more than others... for me if the motor is making power I'm pedaling and I'm old and disabled... I'll go on runs with friends on their acoustic bikes and just leave it in PAS0 with no assist... I always like it when people ask what the "range" is on mine and I tell them it's infinite since I don't need to turn it on! ;-}

Good luck with your project... not too many use LiFePO4's due to the weight and size penalty compared to the usual Li-ion chemistries most electric bike guys are using... but if you are coming from SLA they are way better... I think most folks consider the no-name chines stuff to be risky purchases... not to say there aren't some good ones but there's so much junk even if you are buying from china best to find a supplier with some real reputation IMO...