I've been reading and learning about batteries and charging systems for small power equipment and learned something interesting regarding my 12500 watt Briggs and Stratton portable generator. I'm posting this for anyone who is interested in the topic and for feed back on whether I am understanding things correctly.
The first thing that I learned was that the AC output from the generator is regulated only by the engine rpm so it is important to adjust your running throttle to give the desired output of 220 - 240 VAC.
Then more interestingly I found that after adjusting the rpm to 3600 as per the service manual and 225 volts at the outlet the battery voltage was 16 vdc. At this I decided to look at a wiring diagram and found that the unit does not have a voltage regulator. It does have a rectifier which is small component which rectifies AC current to DC current but I found no voltage regulator. I can also see the DC battery voltage varies with engine rpm as does the AC outlet voltage.
Long story short I called Briggs and Stratton tech support, got escalated to second tier (yes I have too much time on my hands) and the technician agreed that the DC battery output is regulated only by the engine rpm. So what this means is that the charging system is designed to overcharge lead acid batteries.
My question is about this rectifier. I have learned here in the past that a diode will cause a fixed amount of voltage drop so I assume that this rectifier in addition to converting the voltage from AC to Dc is also dropping the AC voltage by a fixed amount from ~120vac to something close to12 volts DC. Close but not close enough to do a good job of charging the battery.
So if you have a portable generator I would love to hear what the battery voltage is at full rpm and if you are familiar with a portable generator charging system please enlighten me becasue I find it a little hard to believe that I am understanding this correctly. Why didn't they just put a regulator on the unit?
I am considering disconnectiing the battery from the charging system. Then I will take a battery minder, plug it into the AC outlet on the generator and hook it to the battery. Presto, when the machine is in use the battery minder will charge the battery properly.
Mike.
The first thing that I learned was that the AC output from the generator is regulated only by the engine rpm so it is important to adjust your running throttle to give the desired output of 220 - 240 VAC.
Then more interestingly I found that after adjusting the rpm to 3600 as per the service manual and 225 volts at the outlet the battery voltage was 16 vdc. At this I decided to look at a wiring diagram and found that the unit does not have a voltage regulator. It does have a rectifier which is small component which rectifies AC current to DC current but I found no voltage regulator. I can also see the DC battery voltage varies with engine rpm as does the AC outlet voltage.
Long story short I called Briggs and Stratton tech support, got escalated to second tier (yes I have too much time on my hands) and the technician agreed that the DC battery output is regulated only by the engine rpm. So what this means is that the charging system is designed to overcharge lead acid batteries.
My question is about this rectifier. I have learned here in the past that a diode will cause a fixed amount of voltage drop so I assume that this rectifier in addition to converting the voltage from AC to Dc is also dropping the AC voltage by a fixed amount from ~120vac to something close to12 volts DC. Close but not close enough to do a good job of charging the battery.
So if you have a portable generator I would love to hear what the battery voltage is at full rpm and if you are familiar with a portable generator charging system please enlighten me becasue I find it a little hard to believe that I am understanding this correctly. Why didn't they just put a regulator on the unit?
I am considering disconnectiing the battery from the charging system. Then I will take a battery minder, plug it into the AC outlet on the generator and hook it to the battery. Presto, when the machine is in use the battery minder will charge the battery properly.
Mike.