for my kon tiki old lead acid 12 V 7 AH sealed batteries are getting old &she aint got the range she had 3 years ago they are run until dead flat then fully charged , so thinking of using 2 x pairs of 6 volt 7Ah in series then paralelled up they will just fit in , would that give me double running time . other idea was using nicads would they give better range ?
ronaldo8,
Jan 5, 10:08pm
Yes double the runtime, 6V 7Ah+6V 7Ah series= 12V 7Ah, then in parallel with another bank the same= 12V 14Ah.
The battery technology will only affect the amount of space they take up and weigh. The final Ah rating is all that matters re your runtime (on shore), the amount of energy stored regardless of storage technology used. Lithium ion is king of energy density, I.E the amount of juice per unit mass.
That said I'd add that a lighter battery with the same amount of energy available as a heavier one will also increase your runtime because your prop won't be working as hard and the motor drawing as much current given your kontiki will be lighter. That will be a not insignificant difference between say a lipo and lead acid.
there is a fairly large markup there but it gives you an idea how its done, look at the cost of those same battery packs and the BMS here, eg. Listing #: 2920932365
running Lead acid dead flat is a extreem bad idea when they are flat at 12.2 volt. Running them lower is burning up its lifespan quite massive. So what i would have is a cut-off voltage trigger as the voltage will rise above again after a while And you would know the battery is flat when it starts to drop out like this. With lithium its ultra more difficult you get a larger range but you also must control that -range- or you have non chargeable cells. or you have fire on lithium.
intrade,
Jan 6, 8:36am
Short Story i keep telling people things that i know is correct. They only seem to believe me when they find out exactly what i told them. cheap vibrater tool mate has charges 3 minutes runs 3 minutes i told him and you all the battery need balancing . There is 3 cells 18-650 in there and its cheap so they just set lower voltage and highes voltage to prevent fire. So one cell is now fully charged and 2 are almost flat because they dont use expensive balancing charge circuit as that would cost like 100 bux just for the electronics as example on a tool that only cost 80 bux. now this one cell is full and tells the controller to stop charge the others are near empty .= they wont ever be charged The capacity runtime is now just based on the 1 cell . because the pack is so much out of balance. Quite similar how a $hitbox Leav Looses massive range on 1 bad cell. jehu-garcia has tons of videos and he made diy controllers to try and keep the cells balanced . Cheap jump-starters have 3 lithium pouches and 2 sensors on 2 cells and one is uncontrolled . it will go out of balance and puff up and die . The reason why i just explained. lithium cells have to be the same voltage and charge at all time and if not Well you will find out the hard way.
skull,
Jan 6, 8:37am
I think #4 is the way to go unless you want more range than you had when it was brand new. Seems rather a significant price leap to double the range as in #3.
intrade,
Jan 6, 8:43am
the battery in #3 is made up of 32-650 you would want to have a charger that can charge 1 cell if the pack does not balance all cells and that pack could last 14 years as that is the predicted livespan under best conditions of them batterys . . it would also depend how easy you can get to a bad cell. Worst case you need a few and make your own battery pack out of a few bad packs.
ronaldo8,
Jan 6, 10:39am
Correct, The additional wires coming out of that pack are for monitoring each cell, they attach to a balance charger whose job it is to balance each cells charge level by throttling the charge rate. That functionality might also be duplicated in the BMS, the battery management system. MIGHT be, some manage discharge rate only.
elect70,
Jan 6, 3:50pm
Need to get maximum run time the fish are in deeper water this season down here 1500- M out at least , clam dredge been through the shallows & ripped up all the shell fish beds so battery life is c sacrificed they are cheap anyway
elect70,
Jan 6, 4:00pm
ronaldo8 wrote: Yes double the runtime, 6V 7Ah+6V 7Ah series= 12V 7Ah, then in parallel with another bank the same= 12V 14Ah.
The battery technology will only affect the amount of space they take up and weigh. The final Ah rating is all that matters re your runtime (on shore), the amount of energy stored regardless of storage technology used. Lithium ion is king of energy density, I.E the amount of juice per unit mass.
That said I'd add that a lighter battery with the same amount of energy available as a heavier one will also increase your runtime because your prop won't be working as hard and the motor drawing as much current given your kontiki will be lighter. That will be a not insignificant difference between say a lipo and lead acid.[/quote ok other idea is to run it on 18 volt using 12 v & 6 v batts gives prop lot more speed t get out past the breakers . .
ronaldo8,
Jul 11, 7:28am
Heh yep that too
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