Tuesday, Dec 05, 2023 at 02:17
Its truly a land
mine out there, I just brought a DCS 180AH, and as impressive as its energy density is, I have no way of knowing what its quality is. Other DCS reviews of poor life under bonnet suggest their cells are average so I'm worried.
Generally you buy a cheap battery its overall crap with average quality but non the less fairly good for shorter periods, you buy a top brand and ~40% of the price is in overheads with some possible awful design flaws, thats just how the world works. I could never spend the money on a red arc or victron without knowing exactly the quality of cells.
They all pretty much have the same internal engineering and quality of cells, none I have seen strike me as stand out. I have used alot of dropins over the years from torture testing various monitors.
At some point you realize these batteries are a liability, they work
well but when they pack up your left stranded with a warranty worth as much as the paper its printed on.
For me as a guide, I look for energy density, being backed by a large mob, giving some indication the battery is intended for outback use, price per ah, "warranty" period LOL,
Parallel use requirements:
1- each battery must be able to deal with the bank's max draw. the cells in each 12v batt must be limited to 1C discharge (dont listen to the nonsense of 2-3C), the bms must be able to handle the max draw on the whole bank, with mosfets as switches that means they need to be programmed right.
2- each batterys bms must be able to handle the transient on long inrush currents and disconnect/reconnects. as a battery reconnect at low soc the others might discharge heavily into it for a short period, the bms may see this and keep disconnecting as it thinks its too high, so a delay in shut off would be needed.
3-all the pos and neg cables from each battery must have same resistance (balanced), ignore some unscrupulous li battery installers who tell you lithium in parallel is bad, they spread lies.
Enerdrive made an embarrassing video once saying you cant parallel which showed their misunderstanding of how solid state switches work.
4-the crucial overlooked point is the batteries must be top balanced! which means simply charging them all to ~14.4v taper current 0, this means they will all get to the bottom perfectly. Again some li battery installer goes around saying they each deliver different amps, that is exactly what they are suppose to do! You dont worry about them all giving different amps, you worry they all have the same soc (voltage) which is obtained by top balance. be carful of unscrupulous people who dont really understand electrical theory and physics.
li is easy, but some basic knowledge is needed.
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