Easy Lithium Upgrade?

[davewil@mc.net]

Looking for an explanation of amp hour rating versus watt hour rating.
For example two different lithium battery assemblies, both state 60 Ah. But one is 3200 Wh and the other 6400 Wh.

[Volt_Ampere]

Different voltages. Watts are Volt_amperes (Volts times Amps) (my last name is Watt so I know! Watt Hours are Amp Hours times Volts.

[davewil@mc.net]

Looking for an explanation of what these mean as related to golf cart use.

[yurtle]

Originally Posted by Volt_Ampere

Different voltages. Watts are Volt_amperes (Volts times Amps) (my last name is Watt so I know! Watt Hours are Amp Hours times Volts.

VA and Watts only are equal on a purely resistive load. A controller/motor has an inductive and capacitive component, so isn't "exactly" equal, but close enough.

[JohnnieB]

Originally Posted by impaper

If you purchase the DIY Assembled, it comes all put together an ready to plug in. The BMS is in the price. I added the Wifi to the BMS, charger, L brackets and Anderson connector. You could build an enclosure to put it in, but may not need it if only used on paved streets/sidewalks like me.

Contact Nick using the contact us link. He will help answer your questions.

The pack I got was not listed on his web site but is similar in price. The modules are new generation 2016 leaf modules that are 82Ah and a total of 12 cells. The one you are looking is about 60Ah with 14 cells. The trade-off between the two is volts and runtime.

The 12 cell pack will run longer because of more Ah. The 14 cell pack will have more torque and speed because of more volts.

For all battery types.

The correlation between AH and run-time is only true if the nominal pack voltage is the same.

When the battery packs have different voltage, you have to use Watt-Hours (Volts x Amp-Hours) to compare run-times.

For example: A 6V-225AH-36V battery pack has roughly the same run-time as a 8V-170AH-48V battery pack. (36 x 225 = 8100 and 48 x 170 = 8160)

More Watt-Hours gives you more run-time.
More voltage gives you a greater top speed.

[agpfl]

Originally Posted by davewil@mc.net

Looking for an explanation of amp hour rating versus watt hour rating.
For example two different lithium battery assemblies, both state 60 Ah. But one is 3200 Wh and the other 6400 Wh.

I think I know what you are asking here. If both assemblies state 60Ah, then why does one say 3200Wh and the other 6400Wh?

Each cell (2 cells in each module) is 3.8 volts and can store 60Ah. So 2 cells x 3.8 volts in each cell x 60Ah = 456 Wh per module.

7 modules x 456 Wh = 3192 Wh for the 7 module pack
14 modules x 456 Wh = 6384 Wh for the 14 module pack

So this will lead you to another question. The 7 module pack is 53.2 volts ( 14x3.8 ), so would the 14 module pack be 106.4 volts ( 28x3.8 )? Yes it would be if all the modules were wired in series. The 14 modules will be wired like (but not exactly) two 7 module packs in parallel. So two 7 module packs x 3192 Wh = 6384 Wh.

Hope this helps some instead of adding additional confusion.

[davewil@mc.net]

I think I am getting closer to understanding. Am I correct that a 6400 Wh pack will operate the cart for double the time of a 3200 Wh pack (under same operating conditions).

But what happens when two packs are both rated at 3200 Wh, but one is 60Ah and the other 82 Ah?

[jmauld]

Originally Posted by davewil@mc.net

I think I am getting closer to understanding. Am I correct that a 6400 Wh pack will operate the cart for double the time of a 3200 Wh pack (under same operating conditions).

But what happens when two packs are both rated at 3200 Wh, but one is 60Ah and the other 82 Ah?

The 60Ah pack has an output voltage of 53v
The 82Ah pack has an output voltage of 39v.

[agpfl]

My 12 cell pack with 82Ah cells is 45v.
12cellls x 3.8v = 45.6v
45.6v x 82Ah = 3739Wh

The 14 cell pack (7 modules) with 60Ah cells is 53v.
14cells x 3.8v = 53.2v
53.2v x 60Ah = 3192Wh

[davewil@mc.net]

Originally Posted by impaper

My 12 cell pack with 82Ah cells is 45v.
12cellls x 3.8v = 45.6v
45.6v x 82Ah = 3739Wh

The 14 cell pack (7 modules) with 60Ah cells is 53v.
14cells x 3.8v = 53.2v
53.2v x 60Ah = 3192Wh

They also offer 14 cells at 82Ah. 53.2 volts X 82Ah = 4362Wh.

My bigger challenge is getting them to where I live on Maui, HI. Nick is looking into whether it can be shipped. Federal Express will not do it.