Parallel battery question

One of the big differences I have noticed going from Gen 2 to Gen 4 is the lion battery seems to charge a whole lot faster.

 

I was thinking that the engineers probably did a lot of research to arrive at the most efficient size for the traction battery.

It occurs to me now that a bigger battery would be bad for mileage for the same reason as forcing the present battery into EV mode and then making the car charge the battery from a lower SOC.

 

how different would baseball be if the pitchers mound wasn't 60'-6" from home plate?

 

I’m just happy they have instant replay for certain plays.

Don’t get the purists all worked up .

 

Ok three answers
#1yes that would work but you would need to cool the second pack just like the 1st. If the individual modules are paralelled and only the bottom pack is wired to the car no additional bms will be needed but you will have to cross match capacities before hand or eventually it will go all out of wack. i.e the stongest of one pack with the weakest of the other etc.
#2 the mpg should probably boost back towards the level of a healthy pack i.e. about 50 mpg paralelling a whole pack doesnt wirk because the bms cannot puck up the second pack properly but paralleling modules should. However unless the packs are really good the additional weight should offset any minimal gain in mpg from increased capacity after about 48-50 mpg.
#3 Reality is getting the original mpg - wearlosses and the losses due to additional weight is realistic but getting more than what the prius was designed for out of the hybrid system is unlikely because that is the way it was designed. NiMH batteries have an almost 100% efficiency to 70% soc. Of course with our currents it's a bit less so yes reduced resistance and a bit more capacity can help in some cases like freeway driving to save a bit more recovered energy a bit more efficently but overall the 04-09 prius hybrid system is pretty maxed out.
So yes doable yes but you'll have to use some plastic to direct the airflow. And well it might be a good idea for someone that is starting towards failure mode i.e. less than 30 mpg city but still gets good fwy milage.
My $.02
terramir

 

Ehhh corrections since I can no longer edit cause the op liked my post
#2 third line wirk=work 4th line puck=pick
And #4 here is one thing you might want to note the ICE is used based on what current the hybrid system thinks it can draw and this is based on soc and current capacity of the pack so if the prius thinks you have a pack with a 6.5 + Ah capacity it thinks it can draw more than if you just parallel the pack and it only detects the one batteries capacity, so yes paralleling the modules would be far superior to paralleling the packs because the current detector is around the negative wire so yeah besides the wiring nightmare it would be far superior mind you you'll need 56 copper strips a little thicker than the busbars that are at least 6 inches long that you'll have to dump in plasti-dip for safety but yeah no reason it not just wouldn't work but it would also be far superior to parallel packs.
#5 the voltage of the parallel modules would be held at the same voltage no worries there.
Again my $.02
terramir

 

You can't edit after 12 hours. Likes don't prevent editing.

 

Ok, learn something new today :- )

 

Doubling the battery like that would double the charging current frying the HV inverter or MG1. Not a good idea IMHO.

 

Ehhh no the prius would not change the current with which it will charge the HV battery nor will the generator produce more current to charge the battery, in force charge mode may take longer than the original (new) battery to charge, but only if the combined capacity exceeds a new hv battery. Rechargable batteries don't suck energy out of the generator. The internal resistance of two new batteries in parallel, might be worrisome, if there was no regulation maybe, but not with an inverter and a computer inbetween. And this guy was planning to use two aging batteries to appoximate the performance of a new one.
My $.02
terramir

 

No. 0.019 Ohms.

0.030 Ohms is high.

 

Jaron, I admire your adventurous spirit but I was curious what results were you expecting? The factory BMS is sensitive to voltage difference between blocks and bases its SOC and next function on these levels. By using 4 modules instead of 2 and bad ones at that you've modified the discharge curve and introduced multiple cascading failures, so a failure within a single module will immediately create a drain on the "twinned" module. This creates strange activity on the monitored block.

I've thought about adding two modules to the pack in series to build a 30 module pack. You just need to extend the battery cage to add two modules, no need to extend the case or bottom chassis, let them hang off the side. You will need to scoot the sensing harness down, putting the unmonitored modules close to the battery computer and extend both the positive and negative leads. As long as these modules are newer than the rest of the pack and properly matched in charge level they don't need to be monitored. Depending on how Toyota programmed the Hybrid Computer it might result in increased power and mileage or could result in overvoltage codes (which could be tricked with resistors).

 

Yes. Create modules of 4 cells instead of the current modules of 2 cells.