5/2/2023 0 Comments Battle born batteries![]() ![]() The connections, with 18650s’s, are almost always spot welded to end boards that make up the individual cells. (32650 cells are available in bolted or spot weld versions) If the manufacturer uses 5Ah 32650 cells, and some do, we then only need 80 cells total, and 160 spot welds or bolted connections to potentially fail or work loose. Positive & Negative Connections Inside The Battery = 728 Hows that math work?ġ8650 Cell = 1.1Ah (An Ah rating for an 18650 cell above 1.1Ah should be considered suspect)įour 3.2V Cells Make Up a 12.8V 100Ah Battery In a worst case, a 100Ah LFP battery, built from 18650 cells, would need a grand total of 364 cells with two connections per cell. #2 Vibration – Many of the cheaply sourced drop-ins are using 18650, 26650 or 32650 cylindrical cells inside the battery case. Here's a hint" If a manufacturer is trying to sell you a "marine" LFP battery and suggests not using it to start the motor. What you’ll often find is some wimpy 50A continuous rated MOSFET switch installed inside a 300Ah LFP battery! Ouch. Companies re-stickering streetlight pole batteries, or simply copying them, do not use this type of contactor. Companies building “marine specific” LFP batteries know what boats need. What you’ll often see are 500A continuous rated Gigavac, Blue Sea ML Series, Tyco or other similarly rated contactors being used. Look at the contactor ratings companies such as Lithionics, ex Genasun, Victron & Mastervolt use/used for “ marine specific” LFP batteries. These are exactly the devices many boat owners are hoping to see a gain in performance from when switching to LiFePO4. On board devices such as a bow thruster, windlass, large inverters, electric winches, electric cook tops, massive alternators, starter motors or chargers are very very common on-board cruising boats these days. These batteries routinely use multiple tiny little MOSFET switches that often can’t handle the loads imparted by many cruising boats. ![]() #1 Current Handling – The current rating of the internal switch that protects the battery is often too small for the task. When they have improved the engineering it will definitely get mention on MHT. Sadly for boaters this can mean the low grade “orphaned” cells wind up in batteries that may look the same but are sold on Ali-xxxx, eBay or through other less reputable sources.ĭrop-ins will likely be the future of LFP, and there are currently a few good manufacturers working to improve the shortcomings but, in my opinion, they are still not prime time ready. ![]() Most of the “A” graded LFP cells used in these Chinese drop-ins are sold into the street lighting industry. The application of a “ marine” sticker, and perhaps even a well marketed brand name, on the plastic box, does not always denote a product that is well engineered for a cruising boat. I know many boaters assume we are a large market but we are not and no, many of these drop-in manufacturers are not specifically building “marine” batteries for us, though they may be “marketing” them to us. The demand for this type of battery, especially in third world countries, is staggering. These batteries, as a class, were originally designed for telephone pole mounting where light weight and “drop-in” replacements for lead acid were critically necessary for the solar powered street lighting industry. Wheredrop-ins often fall flat is in marine specific engineering. All LFP batteries that claim to be Made in the USA are using Chinese made cells (Except Lithionics) so they are really just "Assembled in the USA". Most of the drop-in batteries have been Chinese in origin and this is not necessarily a bad thing. and they lack any external communication between the internal sealed BMS and the vessel. Excerpt from: LiFePO4 on Boats:ĭrop-In LFP batteries are often sold in standard lead acid case sizes eg: group 27, 31, 4D, 8D etc. ![]()
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