Coss Posted November 8, 2019 Report Share Posted November 8, 2019 When I bought my Kayak, I found, it, just a little low in the water for my 112Kgs. So in an attempt to raise the waterline I'm stripping weight from my setup.I need to know about using Li-ion batteries from power tools etc, to power fish finders.So I found a lot of these recycled 18650 Li-ion batteries on the interweb, that are the recycled good ones, from dead, power tool battery packs, tested and working and - wait for it - cheap!I've previously repacked two laptop battery packs, with these and they work just fine.So I got some more, to solder together, to make a pack, for my fish finder. Using a weighing machine I found that I'd save about 2.5Kg if I used these, and not my current (geddit?) lead acid batteryI'd completed the soldering and then I put the battery charger on the pack and the needle shot off to the right, > 7 Amps, a dramatic orange glow started to come from the inside of the charger. I quickly disconnected everything to prevent fire, danger, or a fission event.I am hesitant to plug in my expensive fish finder to see if it works.Then I got to thinking. When I repacked the laptop battery packs, there was a little circuit board in them, that I assumed, did a bunch of things including, perhaps - provide some resistance in the circuit.My 12 V battery charger is one of the old ones - transformer, plug, clips, needle/meter, switch, nothing in the way of electronics. Do I need to provide some resistance in the circuit with these 18650 cells ?It may be that my fish finder will have the necessaries to do this, if I connect it straight to the battery pack. But then how to recharge? I am hoping that someone here will be able to give me advice on this.Some specs ::18650 Cell Features and Technical Specifications Nominal Voltage: 3.6V. Nominal Capacity: 2,850 mAh. Minimum Discharge Voltage: 3V. Maximum Discharge current: 1C.Garmin Striker plus 7sv specifications Transmission power: 500W (RMS) Voltage range: 10 V to 28 V input voltage. Help please ! See diag. below for the arrangement I made. Link to comment Share on other sites More sharing options...
Coss Posted November 9, 2019 Author Report Share Posted November 9, 2019 Belay that, I'm an idiot. I put on two pairs of close-up reading glasses and re-examined my soldering work. Underneath one of the connecting wires, on the +ive terminal of one of the cells, a stray piece of solder had melted through the cell's plastic covering and allowed the +ive terminal to be connected to the -ive metal casing of the cell, i.e. a short circuit. After I remedied that, everything works as desired. Shit hot ! Link to comment Share on other sites More sharing options...
baa99 Posted November 9, 2019 Report Share Posted November 9, 2019 Maybe going on a diet would be more beneficial! Link to comment Share on other sites More sharing options...
Coss Posted November 9, 2019 Author Report Share Posted November 9, 2019 That's enough from the cheap seats... I was 120Kg, the Kayaking is my fitness drive, after the stroke Link to comment Share on other sites More sharing options...
Coss Posted November 10, 2019 Author Report Share Posted November 10, 2019 Well, I ran the fishyfinder on Simulator all day, connected to the Li-ion pack. It started out at 16.8 V and after 10 hours it got down to 14.4 V This has exceeded my expectations. It maybe a different story when the transducer is connected and it's pumping out watts, but I reckon it should go for a while, and I'm not likely to be running it for more than about 6 hours on the water. Link to comment Share on other sites More sharing options...
radioman Posted November 11, 2019 Report Share Posted November 11, 2019 The thing transmits at 500 watts? 😳 How does this thing work? If it runs on 12 volts, and puts out 500 watts and is 100% efficient (it's not!) that's about 41A !!! eek !!! I'm guessing this is some sort of pulse device so fairly minimal average power. Curious Link to comment Share on other sites More sharing options...
Coss Posted November 11, 2019 Author Report Share Posted November 11, 2019 Yes, Sonar pulses. Sonar Features & Specifications DUAL-FREQUENCY (50/200 KHZ) SONAR CAPABLE DUAL-BEAM (77/200 KHZ) SONAR CAPABLE FREQUENCIES SUPPORTED Traditional: 50/77/200 kHz CHIRP (mid and high) ClearVü and SideVü 260/455/800 kHz TRANSMIT POWER 500 W (RMS) If you're really interested, heres the Garmin support/Sales video Link to comment Share on other sites More sharing options...
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