I connected 2 22.2Vac 4Ah batteries in series giving me 46.3Vac at full charge. Hooked the trolling motor up to the converter output. Plugged the batteries into the input of the converter. Voila it worked. Rather than try to make the Rad Power batteries work I ordered 2 new 48Vac 16Ah LiPo batteries from EBay which have a BMS and charger but only 2 power leads to an XT60 connector. Hopefully they work OTB like new Rad Power batteries would and come with a circuit diagram for the BMS. Wish me luck.

Thanks again,

The 2 batteries were recently fully charged. One was at 53.7Vdc the other at 53.8Vdc. Also remember I hooked only 1 battery to the convertor and it still went to zero volts.

I have 2 matched 22.2Vdc 4Ah Heavy Duty r/c batteries I am going to try with them in series.. I need to get some connectors first.

The trolling motor has 86lbs of thrust is 24Vdc Has 5 forward and 3 reverse speeds, it draws 48Amp max.
So that's about 1200 watts and the 2 batteries in parallel are about 1300 watts capable.

The converter
Specifications:
Input Rated Voltage: 48V DC
Input Voltage Range: 30-60V DC
Output voltage: DC 24V 60A
Output Rated Power: 1440W
Efficiency: 97% (half load); 95% (full load)
Ripple: 200mVp
Line Regulation: ±0.2%
Load Regulation: ±0.2%
Voltage Accuracy: ±1.5%
Enclosures: IP68
Case Operating Temperature: -40~85°C
Weight: 2200g
There is an external resettable 50 amp circuit breaker supplied on the output of the converter

I will buy a Datex2 as suggested is a 60Amp rating on that good enough?

Also I do have a Tektronix Oscilloscope I haven't used in 15 years. I know I have a set of probes still hanging on the wall. I hope I can find the manual. I'll give that a try to see if I can see a current spike.

Thanks again for the help.

Thanks for the reply,

The batteries shutdown without any load on the output of the converter.

I have leads from the neg. and pos output on each battery. I then connect both neg leads to the common lug on the convertor and both pos leads to the pos lug on the converter. It doesn't matter if I connect one or both batteries, they shut down in both cases.

I am a little surprised that the 3 little connectors go nowhere. There are 3 little pins in those spots on the connector. I was betting they were for that 3 button switch on the handlebar that turns the power on, selects the PAS setting and other switching functions. Oh, well. That's why I am asking you for help because guessing just gets me into a lot of trouble.

Yes his older one matched my part number.

I'm inserting myself into one of your answers to someone else because it appears you know a lot about these batteries.

I want to use my 2 RadCity 4 bike batteries as power for the Trolling Motor on my kayak. They are 48V 14 Ah each. The Trolling motor is 24V 48amp max. current or 1152 watts. So the 2 bike batteries in parallel should work nicely. I have made 2 3D printed connectors I found on Thingiverse that hooks up to the 48v power terminals on the battery. I have to connect them to a converter to reduce the voltage to 24Vdc. When I meter the output of the battery I get 53Vdc with the key on. When I then connect it to the input of the convertor I get 0 volts when I turn the key on. Someone who has done a similar project found the same issue with connecting to the converter. He previously purchased a spare replacement battery. Because it looked different in a few non-functional ways he tried that battery and it worked great! Finally to my question why is the older battery going to zero volts under load and can I make that function go away? Do the 3 small connection points on the battery connector have something to do with it?

Thank you.

I did check this out. He had the same problem I do on an older battery of the same size. He did purchase a spare battery and it is different. The power stays HIGH when he hooks the new battery to his convertor. I would rather understand why the older battery goes LOW when a load is applied so I can use it to power my trolling motor when kayaking. It is 24 Vdc. So, 2 new high Amphour batteries would be very expensive.

I am trying to use the bike battery off-line to power a trolling motor for my kayak. It is from my RadCity bike 48V 14 Ah. I can connect to the power output and get a 53V output when the key is on. When I connect the battery to the convertor input this voltage drops to zero at the convertor. This of course doesn't happen when the battery is on the bike. Are the 3 smaller connections on the battery used to control the batteries power on and off?