Nimh HV battery and discharge 40 amps

[Flying White Dutchman]

what i don't get is the following

the prius HV battery is 201 volts and 6,5 ah = 1,3kwh
but when i drive with my canbus monitoring on i get a electric consumption of 40 amps on 207 volts
is the battery not being discharged to a extend it can not handle?

When i look at the plug in prius with lead battery's the recommendation is 20 x 12 volts -20ah because when you go lower the battery;s Will not provide enough amps...
and the prius battery is 6,5ah???

[archae86]

Originally Posted by Flying White Dutchman

what i don't get is the following

the prius HV battery is 201 volts and 6,5 ah = 1,3kwh
but when i drive with my canbus monitoring on i get a electric consumption of 40 amps on 207 volts
is the battery not being discharged to a extend it can not handle?

Try rephrasing your question.

On first read to my eyes, you appear to be comparing Cumulative current (6.5 Ah) and Cumulative power (1.3 kWh) to instantaneous current (40 Amperes).

Actually the instantaneous traction battery discharge current can go several times higher than 40 Amperes. My ScanguageII displays readings broadcast on the CANbus that say there are very brief peaks well above 100 Amperes at the onset of acceleration from a stop. Sustained full-throttle acceleration can also reach current well above 40 Ampere. Your battery can handle that and more--has to in fact in order to get the specified maximum power out of the electric motors MG1 and MG2. But it cannot do so for very long at all-which is the point that your comparison with the time integral numbers makes.

Again, if this response was misoriented to your actual question, please try rephrasing it a little.

[Flying White Dutchman]

ok

what i wonder wy a lead acid battery can nog provide this because then i simply put in a 7ah 12 volt x 20 lead battery pack and parallel it and i wil double the ev range!
OR CAN Nmih handle more higher discharge amps?

[kohnen]

Originally Posted by Flying White Dutchman

what i don't get is the following

the prius HV battery is 201 volts and 6,5 ah = 1,3kwh
but when i drive with my canbus monitoring on i get a electric consumption of 40 amps on 207 volts
is the battery not being discharged to a extend it can not handle?

When i look at the plug in prius with lead battery's the recommendation is 20 x 12 volts -20ah because when you go lower the battery;s Will not provide enough amps...
and the prius battery is 6,5ah???

Don't confuse Amp-Hour with Amp!

Amp-Hour is how many electrons the battery can hold.
Amp is how many electrons per second the battery can put out.

If you have 6.5 Amp-Hours, you can spit out 6.5 Amps for 1 hour, or 13 Amps for 1/2 hour, or 1 Amp for 6.5 hours or 65 Amps for 1/10 hour or 650 Amps for 1/100 hour.

Does this help?

(A simplified explaination - I know that an Amp Hour really is 3600 Coulombs, and that the charge on an electron is 1.60217646 × 10-19 coulombs, and that the definition of an Amp is a coulomb per second.)

[Flying White Dutchman]

a 12 volt 20ah lead battery can only put out 1ah ( a hour ) because the 20ah are based on a 20hours discharge rate.

so a 12 volt 20ah battery wil not provide 1 our of 20amps or 40 amps for 30 min
so i think battery chemistry is needed to take in to account.

maybe a 12 volt 20ah battery wil provide ( if you take 1ah ) 2 amp for 30 min
and not provide 40 amps in 30 min.

if the prius battery is 6,5ah then in your calculations its 390 amps per min.

[Patrick Wong]

Consider a regular automobile that has a starter motor. The 12V battery in such a vehicle may be rated around 50-60AH. However, for a few seconds while the starter motor is running, the battery has to deliver several hundred amps to power the motor.

In any event, it is true that the Prius traction battery can receive and deliver current in the high two-digit ampere range for brief periods of time. I also noticed this when using the Ecrostech scanner on my 2001.

[David Beale]

The amount of current a battery can deliver is not related to its' Amp-hr capacity. It's related to the design intention. In the Prius battery case, the battery is designed for this application, so it can deliver up to around 100-150 Amps short term.

Many gel lead acid batteries are designed to power remote electronics, so cannot deliver much more than 5-10 Amps without internal damage. You -can- get gel cell batteries that are designed for high current discharge, but they are not as common as the lower discharge type.

It's related to the size of the internal cell plate connectors and cell interconnects, as well as the fine adjustment of the internal chemistry.

[kohnen]

Originally Posted by Flying White Dutchman

a 12 volt 20ah lead battery can only put out 1ah ( a hour ) because the 20ah are based on a 20hours discharge rate.

so a 12 volt 20ah battery wil not provide 1 our of 20amps or 40 amps for 30 min
so i think battery chemistry is needed to take in to account.

maybe a 12 volt 20ah battery wil provide ( if you take 1ah ) 2 amp for 30 min
and not provide 40 amps in 30 min.

if the prius battery is 6,5ah then in your calculations its 390 amps per min.

Nope. It doesn't make sense to use the units Amps per hour.

You're right - the "real world" case of the Amp-hours of a battery is you have to define it at a certain discharge rate. If you have a 20 Amp-hour battery defined at a 1 Amp rate, then it will have a somewhat lower Amp-hour rating if it's discharged faster. As an example, I have a 12V, 7Ah battery (lead acid) that puts out 4 Amps for an hour. It has a lower (in this case, 4 Amp hour) capacity rating because the current is higher.

[Flying White Dutchman]

Originally Posted by David Beale

The amount of current a battery can deliver is not related to its' Amp-hr capacity. It's related to the design intention. In the Prius battery case, the battery is designed for this application, so it can deliver up to around 100-150 Amps short term.

Many gel lead acid batteries are designed to power remote electronics, so cannot deliver much more than 5-10 Amps without internal damage. You -can- get gel cell batteries that are designed for high current discharge, but they are not as common as the lower discharge type.

It's related to the size of the internal cell plate connectors and cell interconnects, as well as the fine adjustment of the internal chemistry.

thats wat i was looking for
a 12 volt 7ah lead battery x 20 wil not be able to discharge 100 amps and the design of the prius Nimh battery is able to.
i was hoping a 12 volt 7ah x 20 = 240 volts 7ah setup wil have the same capability as the prius battery of 201 volts 6.5ah battery

[kohnen]

Originally Posted by Flying White Dutchman

thats wat i was looking for
a 12 volt 7ah lead battery x 20 wil not be able to discharge 100 amps and the design of the prius Nimh battery is able to.
i was hoping a 12 volt 7ah x 20 = 240 volts 7ah setup wil have the same capability as the prius battery of 201 volts 6.5ah battery

No, but...

(disclaimer: _YOU_ need to make sure that you know what you're doing and don't either electrocute yourself or damage your car or its surroundings. This should be in no way considered advice on what to do or how to do it nor should it be considered an endorsement thereof.)

If (presuming it can be done) you put a lead acid battery pack in parallel with the NiMH pack, the lead acid will have a lower peak power capability (fewer amps) than the NiMH pack. But, it will have a similar energy (amp hours) as the NiMH pack. Under peak acceleration, most of the energy will come out of the NiMH pack. Then, when you're cruising, the lead acid pack will be charging the NiMH pack. So your idea still might work well.

This is similar to the idea of putting a battery with an ultra capacitor in an electric vehicle. The battery has the energy in it, but can't provide that energy quickly. The capacitor stores less energy, but it can release it VERY quickly so you can get good acceleration.

Good luck, but be careful: You don't get second chances with 300 Volts.