if I’ve learned one thing from my madness build it’s that bigger is not always better.
I mean it’s awesome to have massive range available, but on most rides I go on, I don’t even use a quarter of the pack.
If i had my time again, i would make a smaller battery with a range extender battery as an option for longer rides.
I keep thinking about this. building a charge-n-ride lunchbox for the top of my mid range boards. still trying to learn if say 8s with cccv boost converter or 14s with cccv buck converter or anything else might be the right way to go.
when you say range extender are you talking portable charger or parallel pack?
I’m still thinking about which is the better way to have a range extending pack. .
Personally I would prefer a parallel pack. I don’t really like the idea of charge and ride.
I’ll have to go with Al… Mostly because my charge n ride setup caught fire 
That was my plan before selling Morpheus. Good thinking mate.
I don’t understand parallel pack yet. how close do they have to be in voltage before connecting them? is it like cells in pgroups where people seem to want 0.02v or so deltas?
seems like charge and ride would be safer? or at least for the lazy.
the other feature for me is using it on either 10s or 12s boards. given the one I was thinking of would have a adustable cccv circuit to act as charger.
but at some point I’ll probably standardize on 12s so maybe all that extra electronics isn’t worth the complexity and parallel packs is the way?
and you didn’t figure out why.
I don’t fully understand it yet either 
i’ve never properly looked into it.
However from what I do know, I would probably want to be running a discharge BMS on the auxiliary pack and ensuring that the aux pack is of lower capacity than the main pack. Or just running a discharge BMS on both packs. Or just have a low voltage alarm on both packs… I don’t know the best way to do it
bonus like. 
From my understanding, you’ll want a max diff of 0.05v/cell. That’s how I calculate it when I connect all my lipos. I tell myself I have .3v of wiggle room (6s packs
But something tells me going with a mppt would be so much simpler
why mppt vs some other simpler boost or buck that does cccv?
my understanding of mppt is they are about maximizing the pull out of a solar panel. i got a bit lost trying to see the reason it’s picked for this application.
For this I love me my top mount packs.
I can make X 6p packs and just swap when one is empty.
Optional for enclosure packs would be to top mount the escs and just route a xt90s out of the enclosure which can be disconnected when the pack in the enclosure is empty and plug in the new top mount extended pack.
With it you do not have any troubles with same voltage in p groups and what not ever.
I guess it would be duable like this also with escs in the enclosure, just would need a plug to disconnect the escs.
Mppt are more efficient as they will find the best possible combination of input voltage and current to maximize output at any given temperature.
Puh ha that’s quite close.
Not sure if I ever had my cells so close 
Mine are almost on the dot.
can you explain further? cause I don’t understand.
does it mean instead of cccv charging the main pack off the charge-n-ride pack it’s varying output voltage and current for some reason?
Was just jk. Think mine are on point as well, but there is always a bit of drift after the charger stopped charging.
I remember that hummie experiment with totally different voltages of two cells and than connected them. As far as I remember they barely got hot.
Sure it’s good to have cell voltages close to each other, but as long as you not fully drain the pack till 2.5V per cell I think it’s fiiiine if different packs a bit out of balance (like 0.1-0.2V)
Disclaimer: just my opinion, not meant to follow that thoughts.
No its going to vary the input depending on temperatures to minimize energy losses during the charge.
Example: a dcdc will pull x amps to give you y amps, during this time, it heats up and start losing some of the energy to ensure a constant current.
On the other hand, the mppt will detect temp as it goes and notice its heating up and slow a bit down to let itself cool down and minimize heat losses.
I have also heard it’s no a concern. that the initial current spike settles quickly.
but I can imagine 50amp spikes at 1v difference and quickly being minutes? so seems like an issue to me.
I agree. But that is a “before you ride” scenario. If you wanted to plug an external pack in the middle of a ride, you’d be fucked
hmm. ok. i guess that would be varying the input and the output?
I will look more into this. is there an mppt people use for this app that you can point me at?