Netsniper
25.04.2021 12:22:54
Next, it really depends on your battery:
See full version: How long to charge batteries at idle
Next, it really depends on your battery:
****Gel accept charge at 25% of their rated amp hours more
First - what size and type is it. A series 31 AGM is a very strong battery that's easy to charge. A series 31 Thin Plate Pure Lead AGM is (for non NASA applications) THE beast of charging
Besides, such types of batteries are easily portable as they are small in size and light. This feature also allows you to store the battery effortlessly.
Also, a gel batteries are safe to use because it’s sealed and carries a viscous gel that is spill-proof. more
On the other hand, an onboard charger is pricier than a portable one. And you have to install it with wiring permanently in your boat. [links]
Do you know all these? Maybe not.
Now, you'll probably never actually run all of your electrical appliances at full amperage load at the same time, much less for a protracted amount of time. But it's still important to add up the demands of all your gear, first of all the appliances that the ABYC defines in their E-11 standard as "mission critical." These would be safety-related items like running lights, navigation equipment, and VHF radios. Things like anchor windlasses, cigarette lighter power sockets, cabin lights, and other gear only operated intermittently are considered less mission-critical. Then there are systems like electric refrigeration that are not mission-critical, but that run constantly and draw significant amounts of electricity. here
It’s important to understand the different ratings used to determine battery capacity and also to understand that sometimes battery manufacturers will use specifications that may do more to confuse you than actually help in making the right choices.
However, with much of the new technology available and in growing use by boaters today, recharge acceptance rates are considerably higher, approaching the 60% rate in many cases. So, this means that larger, higher-output battery chargers can be employed, and can recharge high-acceptance-rate batteries much quicker.
The bottom line with all of this is to use the C-20 rate as a point of comparison with any claims of deeper discharge capacity and cycle-life predictions to establish which battery can give you the longest potential service. Don’t forget price either. I like to calculate this using a cost-per-amp-hour value, which takes all of the metrics discussed here into consideration. here
Modern battery technology can mean a higher acceptance rate for charging, which in turn means that buying a higher-output charger might be a smart decision. However, bear in mind the other elements in the system that might also need upgrades. Photo courtesy of ProSport.
To obtain a reasonably good capacity reading, manufacturers commonly rate alkaline and lead acid batteries at a very low 0.05C, or a 20-hour discharge. Even at this slow discharge rate, lead acid seldom attains a 100 percent capacity as the batteries are overrated. Manufacturers provide capacity offsets to adjust for the discrepancies if discharged at a higher C rate than specified. (See also BU-503: How to Calculate Battery Runtime.) Figure 2 illustrates the discharge times of a lead acid battery at various loads expressed in C-rate.
When discharging a battery with a battery analyzer capable of applying different C rates, a higher C rate will produce a lower capacity reading and vice versa. By discharging the 1Ah battery at the faster 2C-rate, or 2A, the battery should ideally deliver the full capacity in 30 minutes. The sum should be the same since the identical amount of energy is dispensed over a shorter time. In reality, internal losses turn some of the energy into heat and lower the resulting capacity to about 95 percent or less. Discharging the same battery at 0.5C, or 500mA over 2 hours, will likely increase the capacity to above 100 percent.
Charge and discharge rates of a battery are governed by C-rates. The capacity of a battery is commonly rated at 1C, meaning that a fully charged battery rated at 1Ah should provide 1A for one hour. The same battery discharging at 0.5C should provide 500mA for two hours, and at 2C it delivers 2A for 30 minutes. Losses at fast discharges reduce the discharge time and these losses also affect charge times.
The battery capacity, or the amount of energy a battery can hold, can be measured with a battery analyzer. (See BU-909: Battery Test Equipment.) The analyzer discharges the battery at a calibrated current while measuring the time until the end-of-discharge voltage is reached. For lead acid, the end-of-discharge is typically 1.75V/cell, for NiCd/NiMH 1.0V/cell and for Li-ion 3.0V/cell. If a 1Ah battery provides 1A for one hour, an analyzer displaying the results in percentage of the nominal rating will show 100 percent. If the discharge lasts 30 minutes before reaching the end-of-discharge cut-off voltage, then the battery has a capacity of 50 percent. A new battery is sometimes overrated and can produce more than 100 percent capacity; others are underrated and never reach 100 percent, even after priming.
A C-rate of 1C is also known as a one-hour discharge; 0.5C or C/2 is a two-hour discharge and 0.2C or C/5 is a 5-hour discharge. Some high-performance batteries can be charged and discharged above 1C with moderate stress. Table 1 illustrates typical times at various C-rates.
Table 1: C-rate and service times when charging and discharging batteries of 1Ah (1,000mAh)