Quote:
Originally Posted by Hotdam
Btheo - yes, please elaborate! I purchased a 200 AHr LiPO4 battery for my 2720 thinking that I could simply drop it in and switch the jumper on my newer, lithium-capable converter. Then I decided to add solar and an inverter. Been researching for a while now, and may have a case of ‘analysis paralysis’.
My understanding is that a fully-charged lead acid produces about 12.9V, LiPO4 tops out about 13.8. You’re saying that the propane detector is sensitive about its supplied voltage? How did you address this? (Not sure what you mean by “12v converter”) Any other components you found sensitive?
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I will assume that you meant "LiFePO4", and I will refer to that as an "LFP battery pack.
Many "Lithium Capable Converters" are programmed to run at a single high voltage all the time, that fixed voltage value can be as much as 14.6 volts. In many cases, that will cause the built-in "Battery Management System" of a packaged "12v" to shut down charging and maybe discharging as well, due to reaching or exceeding over-voltage limits.
Correct charging of a "12v" LFP battery pack should be done in two stages. In the initial "Boost/Bulk" mode stage, there is no appreciable advantage in charging above a maximum voltage of 14.4V, and most experts use values of 14.2 Volts and lower (3.55 volts per cell). Many experts never use a "bulk" stage at all, instead floating at 13.7 volts (and even lower values) at all times. But these experts all have access to control parameters of their BMS units, and they make sure that "balancing" is initiated at a lower voltage. And, while providing a charging voltage of 13.7 volts, most will prevent charge current from being accepted after the highest cell within the pack reaches 3.50 volts , allowing only "balancing" to occur after that limit is reached.
When the "12v" battery pack reaches about 13.5 volts, the BMS should have already starting a process to balance the voltage among the 4 individual cells inside. The battery pack (per attached chart) is already above 99% State-of-Charge. Charging the cells to still-higher voltage provides you with almost no additional usable power, but tends to cause significant damage within the cells.
In my expert option, "Lithium-Capable" Converters which present Constant Voltage above 14.2 Volts are horrible products, which will tend to greatly damage the lifespan of the cells being charged at abusive voltage levels. My own power converter is such a model, I resolved the problem by setting the DP jumpers into the positions specified for "AGM batteries". That setting critically avoids high voltage "equalization" cycles, and also provides for nearly correct values "boost/bulk" and "float".
IMO, your LFP battery pack should never be charged to reach a balanced voltage above 13.5 volts. If your BMS is configurable from a bluetooth connection, I can advise you on its paramter settings.