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?