Right here is an article that you’ll completely by no means see on another regular ebike weblog web site. For the final yr or so I’ve experimented extensively with charging ebike batteries with a reasonable Variable Voltage Energy Provide (also called a lab energy provide). This text is about how and why I’ve executed it and why you must in all probability by no means ever do that.
Most ebike chargers cost batteries to 100%, there are a number of exceptions just like the Luna Advanced ebike chargers which let you cost to 80% or 90% and the Grin Cycle Satiator which lets you cost to any voltage however they’re the exceptions to the rule. All lithium chargers that I do know of cost with a Steady Voltage Variable Amperage model. Which means the facility provide places out a steady quantity of voltage and the battery sucks up no matter amps it may well tolerate for the state of cost it’s in. This creates a charging profile which expenses at most amps as much as about 75 % after which slowly tapers off to zero. Typical ebike chargers have some inbuilt protections like
- If there is no such thing as a voltage detected they won’t begin charging (not like virtually all lead acid battery chargers)
- It would shutoff if there’s a over-voltage situation on the battery
- It would shut off if there’s a brief
- If the polarity is reversed most lithium chargers won’t cost
A lab energy provide has none of those security precautions which makes it extraordinarily harmful to make use of, particularly if you’re operating with a BMS that doesn’t have a excessive voltage cutoff or charging a battery with no BMS. When you hook up a lab energy provide to a battery with the polarity reversed the battery and the lab charger will play tug of warfare and ultimately one of many two shall be destroyed, in all probability in a fiery show. Principally don’t do that.
I purchased a variable voltage energy provide as a result of I purchased a big 80lb LifePO4 battery from China that was all types of tousled from transport and I made a decision to waste a few hundred hours of my time attempting to repair it. I wanted to cost particular person cell groupings at odd voltages and so I simply broke down and acquired this 5 Amp Lab power supply on Amazon for $79. There are different 10 Amp Lab energy provides which are a bit dearer. After some time I made a decision to attempt to cost my ebike batteries with it and I used to be pleasantly shocked at how nicely it labored. Though you need to use the alligator clips to hook up with XT60 feminine connectors, this isn’t advisable. You probably have XT60 male connectors in your battery you actually shouldn’t use the alligator clips as a result of if you happen to by accident contact the 2 contacts (very straightforward to do) then you’ll make a number of sparks and harm the connector. You should purchase a spare set of probe wires for $10 and wire on a everlasting XT60 or barrel connector (constructive tip polarity) which is the most secure factor to do. When you do that be certain that to double verify the voltages to be sure to don’t mess up and reverse the polarity earlier than plugging in your battery.
With a variable voltage energy provide you possibly can cost an ebike battery to any voltage rapidly and simply. Simply set the goal voltage you need on the facility provide earlier than hooking up the battery after which plug it into the cost port of your ebike battery. Wish to cost to 80%? No drawback. What to cost it to 50% for long run storage? No drawback. The probabilities are countless. Ensure you know what the nominal voltage of your pack is and the utmost voltages to securely cost is earlier than you hook up the facility provide.
Now the draw back, you don’t need to set the voltage of the facility provide greater than the utmost charging voltage for the pack you might be charging. Batteries charged to even 101% of most might be extraordinarily risky and may overheat or explode. NEVER depend on the Excessive Voltage Cutoff(HVC) of your BMS to guard your battery. When you set the dial flawed or your cat bumps up the voltage by rubbing its physique up in opposition to the dial whereas charging then you possibly can have actual issues in your hand. By no means depart lithium batteries charging unattended, the most secure place to cost Lithium batteries is outdoors your home or in a woodstove.
Simply since you CAN do one thing doesn’t imply you SHOULD. I’m recommending in opposition to utilizing variable voltage energy provides to cost ebike batteries, however for folks like me who spend their life tinkering with lithium packs (and know what they’re doing) you completely can do it and it really works fairly nicely in a pinch.