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Hi Guys

I live in London in the UK.

I have recently converted a 20ft fishing boat to electric power. I am hoping to get a little extra range out of it by using a small 3000W generator as a range extender. I have had a look at some of the forums already but haven't quite found out the answer to feel confident to do it.

My set up is as follows


Motor: Lynch motor LEM200: 200A (400A peak)
Controller: Alltrax ax7245 (450A)
Batteries: 6 x 12V Valance XP 130AH Batters: approx 10KWH
Charger: TSM2500

Although the valance batteries are suppose to be absolute monsters in terms of cycle life, they already have 1500 cycles on them when I brought them, and i am
keen to keep them in shape for many years.

At the moment the Boat runs really well, happily plodding along the river Thames however it eats through the available energy in the batteries quickly.
I currently stop every hour and either use solar energy stored in two lead acids (via an inverter) or a small generator to charge the batteries and dump
a KWH or two into the main bank. during charging the batteries are isolated from the controller which is what I Intend to change if safe to do so.

Ideally I would like be able to run the charger straight into the batteries while the batteries are supplying the motor. The charger I have is a TMS 2500
pumping out 2500W. I can program the voltage and current on the fly with this charger which is a bonus. On average the boat needs only about 3500W to move at a suitable speed, it does however require peaks of 15KW at times

My hesitation comes from balancing the charger and batteries and where power is drawn from when the boat demands more than the 2500W the charger can supply.
Will it just automatically draw the additional 1000W or more from the batteries or will it blow out /trip the charger ? I have read a few articles on voltage
droop balancing which I get in theory but i feel this might be complex to implement and would prefer a simple solution.


Any knowledge or tips on how I might get over this problem, or if it is even a probelm would be much appreciated.

Regards
Nick
 

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Holy shit, I wrote a lot of words. I deleted most of them since it was verbose.

I wanted to say, this depends on your charger. If your charger is a very simple CC/CV charger you should be OK under one condition: You probably want a very beefy or multiple beefy schottky diodes on the output of the charger. In series with the positive lead of the charger.

The condition I'm concerned about is backfeeding into the charger when the load is high and the battery becomes higher voltage than the charger due to foldback protection on the charger.

I would love to see if someone more knowledgable says whether the schottky diodes are required or not. They might not be. And they do have an efficiency cost depending on your total pack voltage (0.2/72 = only 0.27% loss but non-zero)
 
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