Why is the Prius traction battery so incredibly inefficient?

Chuck mentioned the IMA can't do EV practically. Perhaps the one motor replacement for IMA can. I believe it can declutch the motor from the engine. The current two motor system in the Accord hybrid is also the one in the Accord PHV, so it can do EV mode well. The PHV availability appears Honda was only interested a compliance vehicle, and the hybrid uses a parallel mode at higher speeds for efficiency, but I haven't seen anything preventing the system from being used full EV in a PHV if it had a large enough battery.

 

I think the series EV at low speeds makes a lot of sense. Sure there are losses BUT the power required is so low the losses are insignificant. But as the power requirements increase with speed, we start to see a better match between the engine-efficient mode and the power needed at speed. So a parallel approach makes sense with the EV part providing passing and climbing energy beyond what the engine can provide.

I haven't looked but I suspect we'll see some impressive numbers with non-IMA Honda Accord. I'm just not sure what model year it began.

Chuck,

Have you considered 3d party the D-cells for an Insight pack? The 10 Ahr cells look pretty attractive.

Bob Wilson

 

Bob,

Is it something like this?

Honda Insight IMA Battery | Bumblebee Batteries (this is 8 Ahr - factory battery pack is 6 Ahr AFAIK)

 

I was thinking more along these lines:


Bob Wilson

 

I was not intentionally trolling, just in case I was suspect.

 

Bob,

Again, I intend to replace my Insight traction pack. The cheapest way is the time-consuming pull batteries out and refurbish as many as possible - replace the heat-damaged ones. Some aftermarket packs are under $2K, have 25% more power than the Honda OEM pack, AND run cooler (important in the Sunbelt)

I'm open to suggestions

 

Sorry, you are not qualified to be a troll. <grins>

I don't know enough about the Insight traction battery characteristics to have an opinion. The key would be using welded tab cells that were pre-balanced but I don't know if the battery management system has any other sensors on the batteries. For example, the NHW10 used D-cell tubes and has a 3d sensor electrode in each string.

Bob Wilson

 

A more efficient battery would either cost a lot more, or have a much shorter service life. Military-spec rechargeable batteries use advanced technology to provide maximum efficiency and durability, and to prevent electrode degradation, but the costs are multiples of that of consumer-grade products.

Cell-phones have more efficient batteries due to weight considerations, but the penalty comes in a much shorter service life. You might not kick about having to replace a cellphone battery after 18 months, but in a Prius, that would be enough to make you swear-off the brand. The good news is that as technology marches forward, newer and better batteries are coming out all the time.

 

Short answer to the question posed is cycles.

Every battery chemistry has its applications. Lead acid is well suited to float service such as backup where weight has no penalty. The volumetric efficiency of lead acid is actually pretty good. Use it in short bursts, keep it charged, and don't cycle it you've got a good battery.