Series connections for duct tape batteries

C

Christobel931

100 mW
Joined
Apr 10, 2009
Messages
44
Location
RSM, CA
Hi all,

So I am considering getting a ping 24V 15ah, battery to connect to my 36v15ah HTB lifepoe in series for 60v nominal ... both have a BMS, can this be done with out heavy mods to the batteries? I will be changing to a 24-72v controller and CA to limit thinks and keep an eye out.

Lots of experience going fast on two wheels, so I'm ok with too much power, its how and when you use it, ya? The hill terrain performance is good, but, I'd like better... I thought of switching to a good old 5304, but hate the weight and cogging effects. any opinons?
 
when the packs are in series, then you need to have the same discharge limits on each one. otherwise it will shut down when the current limit is exceeded on the smaller width.

make sure your controller can handle the higher voltage too. i did not know there was a controller capable of 24-72V operation. you could use a regular 36V controller, such as a shenzen or infineon, and increase the input resistor to keep the input voltage to the voltage regulator within spec. that's cheaper than buying a new controller and more interesting. you can solder up the shunt too, and solder up the shunts on the battery BMS if you wanna really go fast. or bypass the output FETs, and use the CA to keep track of the current.
 
Your ideas on the mods are most interesting, if not a little intimidating.. :lol:

ebikes.ca has 20 and 30amp, 24-72V contollers for sale, Justin says he sets the LVC for 19V and lets the CA and user set the rest. I can see ending up with my current controller modded and running on a townie or a second bike later... not sure. I don't mind trying a few mods, but this bike has become my main transpo, so plug and play, to an extent, is what I'm looking for. I should add that the quest for increased torque and power are with the idea that this bike may become an xtracycle at some point not too far away. A stokemonkey setup would be awesome, but out of my range.
 
Ideally, the return trip is downhill, or at least mostly. I did way too many return trips uphill last summer, till I figured out what was going on with my charger, leaving me undercharged for the trip home. It was real fun when it was 105 , and the hourly bus just went by 10 minuites ago. That motor cogged a lot, so I'd try to get the battery going so I could at least trickle some power to make the cogging go away.

Do post a thread on how the aotema brushless does overvolted. How hot does it get etc. Personally, I wouldn't be keen on a front hub, 60v motor. For that reason alone a rear 530x would be a good idea. I believe the battery connection can be done with diodes, but if you go for the big motor, can they handle that high amp motor is the question. Maybe overvolt a 9 continents from amped, or a clyte 400 series rear motor?
 
you could put a new 36V ping in parallel too, save the cost of a new controller that way. what kinda controller is it now? is it the shenzen controller with 12 FETs? easy hack.

that gets you to having lifepo4 side by side and you should be able to live without the schottky diode to combine them because they should drop in a reasonably balanced proportion, dependent on the sag of either.

but the volts give you more speed, the controller hack for the power resistor is easy. but it would be the same current going through both BMS, so the one with the lowest current control limit will determine how much you get from the packs, in parallel it is different because the current will be through each BMS for that pack, so combining is simpler.

this is how the CA can be such a powerful tool. if you go series for the speed, you can solder up the shunts on the 2 BMSs, and then let the CA control the current so you could overamp a little (in an emergency of course) by setting the CA high enuff to cover you and still know how hard you are treating the batteries just by monitoring them. that helps keep the current through the controller lower too, so you should be able to solder up the controller shunt a little too, enuff to clear the higher pack current.
 
Return trip is ALWAYS uphill, so yeah, a nice reliable setup, with more than enough power is the goal. What I got is good, if I lived in a flatter area, my bike would be done, but, I'm not so lucky in that regard. :cry:


The controller is a WE brand but the same one that is pictured here, in Dogman's review:
viewtopic.php?f=4&t=8361&start=0

I agree about the CA as a great tool, I understand that the rule of thumb is volts = more speed, however, I'm sure I would see a nice torque increase at 60-72volts nominal, yes? :D
My pack as it is now, is rated for 30A continuous, 40 amps peak discharge, and the ping would be the same or better. So my idea is to run at the higher voltage and like was said, limit my amps to 20 or so, so that would be around 1400W at peak? Right now, I see just under 1000W up my grades and the motor doesn't even get warm to the touch on a 75 degree day, so I think there's more to be had out of it.
At this point I would have a bike capabale of going very fast, but, I wouldn't be blasting through the McDonald's parking lot at 35mph! :lol:
I would, for the most part, use partial throttle except on my hills, and on some of the smooth, 6 lane, 50mph roads we seems to have a bunch of around here. The other option would be to just get a big 48V pack (what I shoulda done first eh?) but, then my other 36v pack would either sit, or maybe I could sell it here...
 
of course you could get another 36 or 48V pack and add in series. i think the controller you have is the shenzen, i have one here that has the p75n75 FETs which are capable of 72V lifepo4. but the caps are 63V and you would need the 100V1000F caps like i did on the 9FET infineon.
http://www.endless-sphere.com/forums/viewtopic.php?f=2&t=10222

you could use the current controller, upgrade it to 72V fro $2 and use the money saved to buy the bigger battery. or you could just buy the big battery and sell the 36V like you said. then someone else could get another battery. hard to get good money for used batteries though.

i should go list the ebay capss i bot on the sales page, 30 cents each plus postage,
they are the 100V1000uF like the nichicons.

i should upgrade this shenzen controller too. the problem with getting all the caps to the input on the shenzen are the 3terminal regulators which take up some of the space needed by the new caps. i was thinking they would fit underneath along with the power resistor and i may have to move the shunts down there too. and add a switch for the controller current, so i could leave the packs connected while parked.
 
I'm not sure there would be room in this controller... the caps might fit but not much room under the board...

FYI, I'm an electrician, so I get most of the theory, but, the board level stuff can cause some mind melting on my part.. :oops: :wink:

Edit: Mr Ping advises using diodes in parallel with each series connected battery with BMS. I thought this was only the case for Paralleled batteries. Perhaps the paralleled batteries need the diodes in series with each battery....
 
You must log in or register to reply here.
Back
Top