Thanks for the kindness. I did say that, but I meant the entire pack was 10 amp hours. I was tired and didn't catch it on final edit. 73 Julian oh8stn
Adding capacity This question always comes up in battery builds. There is only one single thing required to do when adding capacity. For example, if we want to double the capacity, we add another stack of identical cells in parallel. There's no need for a second BMS. The parallel cells will balance each other, while the BMS will manage cell voltage of each group of cells. The BMS doesn't care how many cells are actually on each balance port, provided they are within the BMS specs. I'll write this up in the episode notes in a day or two. I think it may also be a good idea to do a video tutorial dedicated to this topic. QRO ugrade Setting it up for QRO is incredibly simple. We only replace the BMS, for one which is rated at the required amperage. I found several different BMS models for qrp to qro. They are listed in the episode notes. In hindsight perhaps I should have just spect the higher amperage rated BMS regardless of qrp or qro. 73 Julian oh8stn
So each cell is indeed 10 amp hr rated. I just looked up the specs. If you connected 4 of these together in series i guess that still keeps it at 10 amp hrs???? Doesnt make it 40 amp hrs?
Or you could just buy something like this, if feeling lazy: https://www.aliexpress.com/item/12a...lgo_pvid=2c2b662b-e58a-4de1-bb59-9c9f52331c3d
Yes, this would be called a 4S2P pack (4-series, 2-parallel). In reality the individual cells would be connected in parallel, then in series, and a cell balancer would keep all of the pairs individually yoked. Rechargeable batteries in series have the same problems as electrolytic capacitors in that they do not always charge or discharge evenly, leading to unequal voltages and states of charge throughout the series string. For a given series configuration, you have P times the capacity of a single cell. So a 4S2P pack made with 3.2V, 10Ah LiFePO4 cells would be 12.8V (3.2 x 4S), and 20Ah (10Ah x 2P). I built a pack out of 8 x 3.2V 15Ah flat cells for a total of 30Ah at 12.8V. It's handy.
Cells can be rated in WATT-HOURS. Adding more always adds more watt-hours. How the volts and amps break down depends on how you wire them.
Identical batteries in series => sum volts Identical batteries in parallel => sum amps Dissimilar batteries in series => not my cup of tea Dissimilar batteries in parallel => not my cup of coffee
There are opinions out there that connecting Li-Ion cells in parallel can cause trouble due to possible differences in internal resistance. Do you know anything about that ?
Nice work! Whats the weight of the total package? Are you saving any weight and if not, does this have other benefits that a commercial battery doesn't have? I'm a big fan as I have watched some of your videos before getting my ticket. Thanks for sharing and Semper Fi!
Just an addendum to KM4DYX comment - the watt-hour capacity goes up as a function of the number of added cells, so you do get more stored power, but as said previously, the number of amps each cell can supply stays the same. If you want more amp-hour capacity, you'd have to either get larger capacity cells, or parallel smaller cells. Since it is really a pain to try and balance paralleled cells, using larger capacity cells is usually the best way to go.
