Another charging option I haven't seen mentioned on the forum is using both pack and bank charging together. I know sounds crazy at first but stick with me. Most bikes have a pack charger already. Most pack chargers voltages can be adjusted internally as well. The idea here is to turn down the voltage on the pack charger to the float level for the pack. Then by adding some small 2amp or less (for small physical size and low cost) soniel chargers (1 for each battery) you have your bank charging advantages.
Charge profile looks like this:
Initiate charge and you have bank charger plus pack charger max amperage as your charging amperage. As the voltage increases the pack charger pushes less and less as it is set to float voltage. Once the pack passes float voltage the only charging amperage is coming from the bank charging chargers. The soniels are small and reliable (fairly easy to find room onboard for them) have a nice charge profile. The soniels do a nice gentle finish charge on each individual battery. Charge times generally work out the same as the pack charger alone before it was turned down. Wiring and mounting is simple. Charging is plug and play since all the chargers AC feed can come from one source. Nothing to change or reconfigure for each charge cycle, just plug one cord into the wall and the rest is automatic and also onboard for opportunity charging. The pack charger can't overcharge or undercharge any batteries because the soniels take it out of play automatically once the pack voltage rises past where it is set.
One other side benefit is partially avoiding the biggest drawback to bank charging. The case where one bank charger has failed to charge and you take off with 4 full batteries and one dead one. Dead one (permanently) becomes the operative word for that battery in this situation very quickly. With pack plus bank charging at least the battery served by the failed bank charger unit is about 80% charged by the pack charger.
Aerowhatt
Hey, I like it! Especially since I went with 7 2.5 amp chargers for my CB-750 with 75Ah batteries - supplementing them with a higher amp pack charger makes a lot of sense. Many thanks for the idea. Have you done this in practice - or is this just theory at present?
This all certainly sounds like it should work just fine - does anyone else have any thoughts?
John H. Founder of Current Motor Company - opinions on this site belong to me; not to my employer
Remember: " 'lectric for local. diesel for distance" - JTH, Amp Bros || "No Gas.
I've been using the concept for some time. I did some data logging of a few charge cycles to make sure that I wasn't overlooking some bad side effect in the thought experiments. It works really nicely as long as the pack charger is tuned to the right voltage (float).
Aerowhatt
Add in a few relays that turn a BattEQ off whenever the chargers are on, and add a timer and a spike arrester just to be sure to be sure...
Mr. Mik
This information may be used entirely at your own risk.
There is always a way if there is no other way!
Thanks guys - this is what I'm going to try for my CB-750. Any recommendations for an easily tunable 84V pack charger?
BTW - I'm not going to do a BattEQ - I figure it's not worth it if I'm doing bank charging.
John H. Founder of Current Motor Company - opinions on this site belong to me; not to my employer
Remember: " 'lectric for local. diesel for distance" - JTH, Amp Bros || "No Gas.
I agree with you about the BATEQ, redundant for your set up. Not that redundancy can't be a good thing.
You sort of crossed the line going over 72 volts. Chargers are more limited and more expensive above 72V. My choice for you would be a Zivan pre programed to your specs. Decent charge rate, very reliable and a good value.
What kind of range do you get with that battery pack? 84Volts and 75AH is some serious WH for a motorcycle!
Aerowhatt