I've found several 36v lithium ion BMS (10S2P) packs originally made as replacements for hoverboards. They only have 4.4Ah. I was wondering if anyone has tried using these for a cheap lithium battery upgrade.
We have helped a customer design a scooter which uses those 4.4Ah hoverboard lithium battery packs. The important specifications to match up are the maximum continuous discharge rating of the battery pack and the controller's current limit. The controller's current limit should not be higher than the battery packs maximum current limit otherwise the lithium battery pack could overheat with possibly catastrophic results.
On the project that we helped out with we found a lithium battery pack with a 15 Amp maximum current limit and matched it up with a controller that had a 12 Amp maximum current limit.
Sorry, some of my last post got cut off.
So for the battery above I would need a controller that pulls less than 30 amps?
Does overvolting the controller (24v) with this 36v battery increase the amperage pull through the controller? I rather like my legs and just want to be extra careful.
When a controller is overvolted its factory specifications are no longer valid or known.
For a battery pack with a maximum continuous discharge Amperage of 20 Amps, a controller with a current limit that is below 20 Amps should be used. A controller's current limit is what it can supply to the motor so what it can demand from the battery pack will always be slightly higher due to its inefficiency. The battery pack's rated discharge Amperage is what the manufacturer recommends the controller's current limit is rated at. Two battery packs could be wired in parallel to double the ratings so a more powerful controller could be used.
Ah thank you very much for that info! One more question for you: Is there any issue with charging a lithium ion battery pack through the stock 3 prong inline port > controller > battery vs directly from charger to battery?
The charger port does not need to go through the hoverboard controller to charge the battery pack and only does so to let the controller know when the battery pack is being recharged so the controller does not allow the hoverboard to be ridden.
There is no problem at all with charging the battery pack if the charger port is wired directly to it. All good quality hoverboard battery packs have a battery management system (BMS) board inside of them which regulates the charge to the individual batteries in the pack and stops the charge if a battery in the pack gets too hot.
Most electric scooter controllers have a charger port connector that the charger port can plug into to recharge the battery pack. If the controller does not have a charger port connector then the charger port would need to be spliced into the wires running between the battery pack and controller.
Each manufacturer has slightly different discharge ratings for their SLA batteries and some SLA battery manufacturers do not list their batteries discharge ratings at all. We have an SLA battery discharge current chart at this link https://electricscooterparts.com/battery-maximum-discharge-current-chart.html which shows the average 7 and 30 minute discharge current for most SLA batteries.
Unfortunately no. There's some issues with wiring lithium ion packs in parallel. Theoretically it would work but if one of the BMS fails while charging, the other battery will get overcharged and potentially burst into flames. I would have had to charge both batteries separately (2 chargers) and disconnect the power out to the controller every time I needed to charge it. It just wouldn't have worked for my setup. I ended up getting a bigger battery (24v 8ah) so that it doesn't need to be disconnected at all. One charge wire plugs in and that's it. Good luck!