DC outlet high voltage

[jupoa]

The battery of the scooter I tote on the back of my coach runs down after a month or so of inactivity. It is inconvenient to hook a charger or jumpers to it where it is mounted so I installed a DC connector on the battery of the scooter with a cord long enough to reach a DC outlet in a storage been. That way I can connect the scooter battery to the coach outlet whenever I what to charge it. Problem is, it works so well, it boils the scooter battery almost immediately. The voltage on the outlet is over 15 1/2VDC when the coach shore power is connected.

The voltages at my Magnetek 6345 converter are 12 1/2V at the house terminal and 13 1/2V at the battery terminal. How am I getting 15 1/2 volts at the outlet? The measurements were made with a quality meter within a minute or so of each other with the chassis battery switched off.

[jupoa]

The battery of the scooter I tote on the back of my coach runs down after a month or so of inactivity. It is inconvenient to hook a charger or jumpers to it where it is mounted so I installed a DC connector on the battery of the scooter with a cord long enough to reach a DC outlet in a storage been. That way I can connect the scooter battery to the coach outlet whenever I what to charge it. Problem is, it works so well, it boils the scooter battery almost immediately. The voltage on the outlet is over 15 1/2VDC when the coach shore power is connected.

The voltages at my Magnetek 6345 converter are 12 1/2V at the house terminal and 13 1/2V at the battery terminal. How am I getting 15 1/2 volts at the outlet? The measurements were made with a quality meter within a minute or so of each other with the chassis battery switched off.

[RV Wizard]

Unless you have two converters there is no way possible to have two different voltages from one converter. Also it is going to be important that you manually act as a charge controller for the scooter battery. The converter you have is not going to cycle down and will boil the battery dry if you let it. There are ways to charge the scooter but you will need to install a charger made for the battery system on the scooter.

[Bob (WA0MQE)]

When you say you see 15.5 volts at the outlet, is this unloaded or with the scooter plugged into it? Did you try to plug in some other 12 volt device into this connector and test the voltage to see if it's any different or the same? RV Wizard is correct, you can't have two different voltages coming out of the same converter/charger. Have you traced the supply from this connector back to it's originating point?

Also, I assume you know for sure the scooter battery is a 12-volt battery. Many scooters and smaller motorcycles typically have 6-volt batteries.

[DSouthw524]

I suspect that the outlet is being tested for voltage when the engine is running and the outlet is being powered from the battery (receiving the charge). I agree that 15+ volts is unusually high.

Why would you have a scooter on the unit for over a month without using it?

[jupoa]

OK, after some more investigating, I've discovered the following:

The DC output of my Magnetek 6345, option A, has three possible voltage sources: the converter output, the battery output and the charger output. The battery charger has a voltage sensing circuit which toggles the output between maint. and charge.

With the shore power plugged in, there are always two voltages available from various combinations of the three sources. The converter output is isolated from the other outputs by relays when on shore/generator power and available on fuses 1 thru 6. Battery output is available on fuses 7 thru 9 and is affected by the state of the battery and the battery charger. High demand on the battey fuses pulls down voltage and causes the charger to kick in yielding, guess what?, 15 1/2 VDC! There is a lag between removing the load and the voltage returning to normal. That is how I came up with three voltages, getting the timing between unplugging my scooter and making my measurements outside and inside the coach just wrong.

I removed the converter/charger section because it is majorly full of dust bunnies. There is a voltage adjustment on the charger circuit board which may need some tweeking. While the converter is out, I,m going to look into upgrading it with a bridge rectifier and a regulation circuit. Not sure how far my electronic knowledge will get me with that.

DSouthw524, we only use the scooter when we take the motorhome out because the way we park the motorhome in a tight spot in our driveway makes it very difficult to unload and load. It weighs almost 200 lbs and does have a 12V battery.

Thanks for all the replies. I'll post again if my upgrade ideas pan out.

[jupoa]

Well, after considering my options, I just bought a new maintenance-free battery for my scooter with free trickle charger included and a PD9145A converter with the TCMS accessory for the coach. The PD9145 is lighter, quieter, cooler running and outputs filtered, regulated power. With the TCMS, I can leave the coach plugged in all the time without degrading the batteries.

The 9145 with separate TCMS module is about $40 cheaper than the 9245 with the TCMS built in when you purchase from PPL. Go figure.

[RV Wizard]

jupoa, congratulations on the new gear! It sounds like your problems will soon be past tense for the scooter as well as keeping the house satisfied. Once you get some time to asses it let us know.