Quote:
Originally Posted by babock
Well, the max charge rate of your batteries should be C/4 which would be 50A although good luck getting that unless the batteries are severely discharged. If you just trying to get from 50% to 70%, that may be doable in a little over an hour. It's from 70% to 100% that takes a long time. Of course, you really want to keep your batteries at 100%. Leaving them at 70% is going to cause sulfation big time. You aren't going to get that amount of current from the tow vehicle unless you put in welding cable!
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An alternator is never going to give you the charging rate of a dedicated battery charger plugged into a generator.
Here is the charging curve of the OEM 3 stage battery charger. ALL 3 stage battery chargers of 50 amps or so will follow this curve.
Look closely at the voltage vs time to full lines.
Remember that Bulk Mode ends at 50% capacity.
From the attached WFCO manual:
All WFCO power converters are automatic three-stage switching
power supplies. The converter senses which mode it needs to be in by
checking the RV system voltage.
The three modes/stages of operation include:
Absorption mode/Normal operation
Nominal battery charge and supplies power to appliances
Bulk mode/Charge mode
Fast battery charge and supplies power to appliances
Float mode/Trickle charge
Trickle battery charge during storage
Absorption Mode: During this mode, the converter output is in the 13.6 Vdc range. This is the normal operation mode. This mode provides the 12 Vdc and current required by the 12 Vdc RV appliances, as well as
slow charging the battery.
Bulk Mode: When the converter senses that the RV system voltage is less than 13.2 Vdc
(equivalent to less than 50% of battery charge) the converter will automatically go into the “Bulk mode.” In this mode, the output voltage of the converter will switch to 14.4 Vdc
for a maximum of four hours. If the converter cycles between “Absorption and Bulk mode,” there could be a shorted battery cell or other issues.
If the output voltage drops below 13.2 Vdc, the converter automatically changes to a “Bulk mode” 14.4 Vdc (unless the converter is in overload condition).
There are two signs of an overloaded converter:
Low output voltage, and full converter fold back or shutdown. In both cases, the converter will automatically turn ON, once the complete load is removed. For low output condition, removing the extra (over the current rating) load will be sufficient. If it is impractical to remove all the load, resetting the main breaker will have the same effect.
Float Mode: If the RV is not being used for approximately 48 hours, with a “no load” condition and the shore power is plugged in, the converter will automatically go in to the “Float mode.” In this mode,
the converter is charging the battery with a trickle voltage of 13.2 Vdc.
When the converter senses a demand (by turning on lights), the converter automatically returns to the “Absorption mode” 13.6 Vdc.
Linear Mode
