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Thank you. I'm a newbie and considering building my own packs for my RV and a small pack for a Scout trailer. There is a ton of information scattered all over the site, and these works of "collected wisdom" are indispensable for learning and staying out of trouble. I look forward to seeing how this evolves over time.
I'm wondering if the SOC should really be attributed to Ah capacity or were these charts/table created using Ah capacity with voltage measurements? If so, does Ah capacity of the cell matter for the SOC compared to voltage? Do we only care about cell voltage to figure the SOC?
Steve_S
Steve_S
AH depends on the specific cells being used. Cell Voltage & combined battery pack voltage determines SOC for Lithium Based cells.
Very complete, including wiring in series/parallel for different voltages.
This is awesome! I've been searching for a way to configure my bank without it becoming a 40 inch long string.
One question, can I take your squarish shape 2p8s configuration, make it a 3p8s configuration and wire it up the same way???
Thanks for taking the time and providing this great resource!
FilterGuy
FilterGuy
Yes, you can make a 3P8s. I am not exactly sure which layout you are referring to in the deck, but any of the 2PxS layouts can be extended by adding a 3rd cell to each of the 2p Parallel cell groupings.

Please take a look at the page that talks about bus bars.... As you get larger parallel groupings, you need to pay attention to minimizing the voltage drops across the bus bars.
Firstly, this spreadsheet is gold, thank you so much for this resource.

Secondly, I'm a bit confused. Shouldn't the "Required Total daily Solar output (Sunny)" - cell L19 calculation which looks at the "# sunny days to recharge (from ZERO) while under load" - cell L18 (as you mention in your definitions, it is the number of sunny days required to recharge the battery from ZERO (or in this case assuming from max discharge) while you are still using power) be referencing the "Battery capacity" - L14 x "max. discharge" - L11 as well as the "Daily Storage Requirement" - cell L10)? You are only considering daily requirements and not replenishing the entire battery in your current formula.
You have: L19 = L10+ L10/L18
Should it not be: L19 = L10+ (L14*L11)/L18

If I'm wrong I may need an explanation why you are not referencing the battery's capacity in a. calculation to full recharge, where a recharge is directly dependent on how much of the battery has been depleted on not only on your daily usage.

Cheers.
FilterGuy
FilterGuy
Good catch!!! I fixed it yesterday. Sorry it took so long
really well thought out.
Very helpful. I'm pretty new to this and am confused by the top of page 5, the 24V page. It says 4S2P but to me it looks like it should be 8S2P but I could be totally missing something. Thank you for helping me earn.
FilterGuy
FilterGuy
Good Catch!! Thank you. That is a typo that has been there a long time...... I just fixed it.
Extremely helpful guide, I've already come back and referenced it several times -- thanks!
Thank you, I built and installed one based on your plans for a 200AH LifePO4 system with 48V and 3KVA inverter. No more sparks :-)
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