Battery charging from shore power?
Stock, do most trailers charge the batteries when they are hooked up to shore power? Or does that occur when the trailer is hooked up to the tow vehicle?
Forum Discussion
BFL13 wrote:
"You don't need to be unsure here at all. If the supply can't provide the current that the load wants, the voltage at the load goes down.
You are trying to make it too difficult: A higher voltage applied to a battery will charge it more. If the charger cannot supply the necessary current to do that, the voltage will not BE higher"
Now that I do not agree with at all! The battery voltage will rise as it is being recharged even if the recharging current is less than the battery's "acceptance rate" at the time.
You can recharge with a 20 amper even if the battery would accept a 40 amper.
If it is a 20 amp charger doing 20 amps, making it a higher voltage 20 amper won't make it do more amps. However, if the charger is only doing 15 amps at 14v, then raising its voltage to 14.8v could make the amps go up to its 20 amp limit (as long as the battery acceptance rate for that SOC and 14.8v is 20 amps or more)
You do need to have the charger's voltage higher than the battery's or no current will flow at all, but that is not the issue.
Vulcan Rider (Edit: this was an incorrect attribution prevously) has it correct. The "higher voltage 20A charger" will not actually be producing a higher voltage at the battery (given the same SOC, etc.) if both are limited by current.
Current and voltage are not independent of each other at the battery. If you apply a certain charging voltage (again, assuming a specific SOC, temperature, etc.), then a specific current will flow. If you have a certain current, the voltage will be a specific value.
Similarly, with a specific hose nozzle, if you supply water at a specific pressure (at the nozzle), you'll get a certain water flow rate. If you have a specific flow rate, the pressure at the nozzle will be that value. You can't independently set the pressure and the flow rate--they depend directly on each other for a specific nozzle setting. Changing the nozzle setting will, of course, vary this relationship, just as the relationship between electric current and voltage will change as the battery charges.
