But…But….you left out the critical line…….
“Not sure how the motor and simple vacuum circuit would like that extra voltage”.
One way to find out…
One big problem with those Efest cells, Zebretta, is they're low drain. Big no! If the vacuum cleaner really pushes current a couple 7+A continuous cells in parallel is going to be required (extra rpm requires extra torque).
Not sure how the vacuum cleaner circuit will deal with the extra voltage? What :-D circuit?
All I had to deal with for my hairclipper mod was, essentially, the removal of some cell recharge current limiting components and rewiring plus resistor value adjustment for a power-on red led. ;-)
Originally posted on Mon, 10/30/2017 - 06:44; little fix.
Yeah, but he’s trying to use 2 Tenergy Blue NiMh to power it. I seriously doubt those cells have a lot of amp output. I’ve got some OLD ones (very old so very tired), but they are lousy. I had some NEW Tenergy Blue D-cells and they were lousy too.
yea, blue cells are not that good, premium or lsd centura are better.
there is no need for any circuit with nimh cells, assuming your cells can supply current needed. when voltage drops below 1v they supply almost no current, and your device simply wont work.
also if you need to pull 7A from aa cells forget about tenergy, you need elite
A little story worth being told:
For my hairclipper initially I replaced its dieing stock low capacity AA NiMHs, but there was a catch: the stock AAs were rugged overcharge tolerant industrial cells, the lack of a true charging circuit inside the appliance killed the newer high power Tenergy AA 2500mAh cells I stuck inside at first FAST (overcharging). 
If Zebretta's vacuum cleaner does not have proper -dV/dt Ni-MH charging logic inside, the newer AA cells' life is going to be rather short.
If high voltage is a concern, another alternative could be using two 14500 LiFePO4 cells in parallel, there are 1S BMS circuits available for this (a couple of these would do for ≈10A combined).
Example: Soshine 14500 LiFePO4 700mAh (gray) @ lygte-info.dk
Above 500mAh of capacity even if discharged at 5A, with more than twice the voltage output of the best Ni-MH AAs when discharged at 10A. Sounds like a noticeable performance increase, even if the effective capacity would only hover between 1000 - 1100mAh.
FastTech has Soshines and Powerlions in stock, Soshines with a lil bit more capacity and Powerlions with a tad better discharge rate if I do remember right, the long ago published review in this regard on the forum is now missing the graphs: Test / Review: Coolook, Powerlion and Soshine 14500 (AA) LiFePO4
Hope this is of help.
Cheers :-)
Thanks for ALL the replies !
Ok, today I actually measured the current draw.
So, my “HIGH current drain vacuum” uses………
1.5A startup
0.7A running
lol
“the sky is falling”….“the sky is falling”…… :person_facepalming:
Sry guys, I was estimating. I thought it would be more.