does anyone know whether we can feed common esk8 bms units with slight overshooting voltages of common solar panels? say I have a couple 12V / 120w panels, specs say they go up 21V when no load is connected, and deliver with a max of 17,3V when a load is draining, say an esk8 battery. will the bms handle this correctly, or do most skates need the very specific ac/dc charger, or else…
anyone already charging their boards with the sun already?
actual example: 12s battery charges with 10 amps top from the charger, ends at roughly 50.7V. say I take 3 modules, wire them in series, so I get 51.9V max charging voltage from the panels, while also delivering close to 360w, will it get full or will the voltage drop off too soon? do I need 4 panels in series? if so, will the bms handle the potential overvoltage, like, uh, it will need to pull the voltage down when the charge gets close to completion, right?
It would probably be better to find the appropriately sized MPPT controller instead of hoping the BMS will take care of the varying strength of the panels
No time to read all those posts but mostly agree with the last big one. Why disable balancing though? Just disconnect when you want to (if doing 4.15V charging).
Hard to keep all the cells at 4.15V too if not balancing whenever you can.
there’s programmable MPPT controllers (Tracer comes to mind as a brand I’ve used before) that are capable of charging up to 48V (configurable) lipo packs. You need to do some research and program in proper voltage thresholds for each stage of charging, and that won’t happen in just a day of reading. Teach yourself the implications of using something that really has no idea how to charge lithium packs, to charge lithium packs. If you want something more turn-key, I bet products exist, but if you’re already going off-grid, get some big-ass lifepo4 packs, a good MPPT inverter, and as much solar as you can afford for whatever overnight current draw you might need over the hottest days of summer and the coldest days of winter, add 10-20% for safety factor, and use a DC powered lipo charger for charging your toys. Solar panels hooked directly to lipo packs will not be pulled at efficient ranges. Half-assing a setup has a lot of safety and longevity implications you may come to regret long-term.
absolutely, been thinking it would be best to just focus on the general off-grid situation, and then worry about whether I save some % in efficiency skipping the dedicated ac charger to a dc one. the idea to hook the panels directly was too naive. already in the process of ordering about 4-5kwp of panels, similar range of kwh in battery, and still undecided about whether to get a hybrid inverter/charge controller which can still hook and sync to the grid, or whether to completely ditch the energy supplier. will try out different setups I guess…
For what it’s worth, some of the auto-switching grid tie systems can work without battery. The grid-tie-in part is where things get super murky however, as you need a device that is certified and an electrician to sign off on the installation. Not because it’s safe or not safe, but because your housing and code regulations are going to require it.