208km (129 miles) in electric mode with a gen 2 prius

Hello, Dimitris,

You have two ways

First "High" power (Up to 25 kW)
If you add cells in your prius 2 you will need a device that will change the state of charge (soc). If not your prius will still use the 6.5Ah factory and you will only have reduced the battery internal resistance.
I still use bms+ made by Norman. But he is retired now.
This bms+ handle the soc and send a modified one to the other ecu. Simple, very reliable and independant from the cells capacity. Never add problem since 4 years.
Add extra cells (A123 in my case), a contactor between the nimh cells and the lithium one.
Always add a bms on these cells
Add a HV charger, different plugs, domestic or type 2 or type 3. Now I use à 10kW charger (Only 10kg) then I use a type 2 or 3 plug.

Instead of using bms+ and a bms you can use orion bms. Very good system but more expansive.

Second solution low power
You can send up to say 14A via a dc-dc converter. This was the "enginer" idea.
I use a dc-dc converter, but unlike the enginer dc-dc converter in high voltage between my two lithium packs.
Also reliable, this dc-dc converter is a low power and low amperage solution. Low amperage means very low heat dissipation.
With a dc-dc converter you will not charge the lithium cells going downhill.

You may have more details on my web site.

On prius chat you can find details on differents threads.

Dc-dc converter
High power

Just for fun a few example charging places where my Plugin has been:

 

Hello, Semo.pz

Here, in France there is an important price difference between electricity and gasoline.
So, since I use my plugin, the difference is more then 4300 Euros. That pay more then 50% of the 140 A123 cells, charger, bms, bms+ ...
I drive less then 15 000 km each year (9300 miles) , It is also a hobby. But what I want was to reduce my gas consumption for all sort of reasons.

We have here gen 2 prius since 2004 and they have still there nimh battery. So i think the average nimh life is more then 8 years.
8 years is the waranty.
I believe that hot temperature where you use the car is one of the main factor.
Concerning old nimh battery, you have several threads on priuschat.

 

Jonas

I use a meanwell HLG 320H and a HLG 240H. If necessary they are connected in // at both primary and secondary (connecting first primary).
When output voltage is out of range, the 320H disconnect itself and you have to inplug / reconnect this device, unlike the 240H that stay just waiting a better output voltage.