Well so far the batteries are working out fine. I am going today to pick up a set of 25A diodes to install to prevent the main pack from discharging through the smaller pack.

Ken Finch

Hello Ken
Really appreciate the updates on this project.

Do you have any way to verify (meters, whatever) what is happening with the 2 different aH-rated packs in parallel?

• That the main pack now is indeed discharging into the smaller pack when the bike is not being used?
  
• That this no longer happens after the diodes are installed?
  

Well diodes are an electrical version of a one way check valve. They allow the electricity to flow freely in one direction. But the prevent the electricity from flowing in the reverse direction. This way the electricity can flow out of the small pack and into the main pack which then feeds into the controller. But the main pack will not be able to discharge into the smaller pack.

Ken Finch

Thanks again.

I'm no expert on this stuff, but I was thinking about this some more and was wondering why it's a problem if the large pack discharges into the small pack. If the small pack has been drained somewhat and is at a lower voltage, wouldn't it just accept a charge until both packs were at the same voltage? Which seems like it would be OK and in fact desireable? Same logic applies to charging when the two packs are cascaded -- should work OK? If so, would eliminate the need to charge the two packs separately.

Again you guys know a lot more about this than me, so let me know where I err.

Well the problem with the larger pack discharging into the smaller pack is that is discharges in a uncontrolled manor and will overcharge the smaller pack and charge it with too many amps thus boiling the electrolyte in it and eventually ruining the battery pack. Plus even after the smaller pack is fully charged the main packs discharging will continue until it is fully discharged thus damaging that pack. And this can occur within a couple of hours. I do not want to park and go shopping for a couple of hours and come out to my Condor with two dead and ruined battery packs.

I have found in my stuff at home two good 10A diodes. So I paralleled them together to create a 20A diode then soldered it in between the positive terminal of the smaller pack and the power output cable. So now power should be able to leave the pack, but no power should be able to flow in reverse along the power output cable. I made sure the smaller packs charge cable was not connected to the diodes so I can still charge the pack.

Ken Finch

Well I rode my Condor from my house today at York Mills and Victoria Park area to 1000 Finch Avenue West. I then rode from there to Yonge Street and went southbound to Gerrard Street. Went East on Gerrard Street to Mobility Unlimited at 1007 Gerrard Street East to start work. I would not have been able to do this distance with only my 48V 20A SLA AGM pack in this cooler temperature. I even had some battery power left. But I did notice the diodes that I had wrapped in electrical tape got hot enough to melt the electrical tape. Should I add another diode in parallel to make a 30A diode pack or is the diodes running a little warm normal?

Ken Finch

It's tricky paralleling diodes...

`Cause they are almost never identical. A voltage drop differential of mere mV will cause the diodes to share unequally. As the one sharing the larger portion of the load heats up, its voltage drop will decrease, increasing the unequal load sharing. My guess is that the electrical tape was melted around one of the diodes more than the other.
tks
Loc

Hey Ken. I am really considering adding a second battery to add more distance and for adding overall battery life. The bike I have is built for 2 batteries. I have the Motorino XPh.

Got a few questions for you.

-Do you know if after I added a second battery, would I also need diodes to prevent the large batteries power form leaking over to the new smaller battery?

-Would adding a second battery for me be the exact same as you adding another battery (in my case the space under my seat already has a cord to plug the second battery into)?

-How does your new battery pack compare to say buying a second battery pack which is already to go?

-How much extra distance are you getting?

Your Motorino's design for a second battery includes a switch to choose the main battery or the secondary battery. But not both together at the same time. Motorino and Daymak uses this setup because it is easier and cheaper to design and implement. My design is more complex, requires more parts and chargers, but it has much better performance and range output then their design. I just have to work the bugs out of the diodes. I say I am getting an extra 10 to 20 kilometers. But the torque improvement is much better. In your E-Bikes design you will not have a torque advantage, but you will get a little extra range. But remember when you switch from one battery that is discharged to the other charged battery. You are now pulling the weight of the discharged battery thus reducing the range of the charged pack. My design both batteries contribute to the power for the E-bike. Both batteries discharge at the same time and same rate. Thus when one battery is discharged the other is discharged as well. That means pull over and recharge for at least an hour or two then continue on your ride.

Ken Finch

Your Motorino's design for a second battery includes a switch to choose the main battery or the secondary battery. But not both together at the same time. Motorino and Daymak uses this setup because it is easier and cheaper to design and implement. My design is more complex, requires more parts and chargers, but it has much better performance and range output then their design. I just have to work the bugs out of the diodes. I say I am getting an extra 10 to 20 kilometers. But the torque improvement is much better. In your E-Bikes design you will not have a torque advantage, but you will get a little extra range. But remember when you switch from one battery that is discharged to the other charged battery. You are now pulling the weight of the discharged battery thus reducing the range of the charged pack. My design both batteries contribute to the power for the E-bike. Both batteries discharge at the same time and same rate. Thus when one battery is discharged the other is discharged as well. That means pull over and recharge for at least an hour or two then continue on your ride.

Ken Finch

Makes complete sense. Luckily my bike has amazing torque. The rating is higher than any other bike in its calss that I have seen on the market. The externar real wheel motors like the one on your Condor are better than the
small luyuan hub motors so I imaging with your extra power your bike might be on par torque wise with mine.

I would still like to maximize as much as I can since I plan to cart my fiance around a fair bit so I'd still love to add more power and torque the way you have. How would I go about adding battery power in the manner that you have?

By chance are you able to answer the other questions?

Good job btw. Doing what you are doing is not an easy task.