Trolling Motor powered by lithium ion 18650's?

[sikeston34m]

I took this setup for it's first run today.

First, a watt meter was connected to the SLA batteries to get an idea of what was going on there. I was shocked.

On high, the trolling motor was pulling 27 amps, but the voltage was sagging to almost a flat 9 volts. Sheesssh......

I'm not sure if my wiring sucks or if the SLA batteries are in that bad a shape.

But then came the better results.

After being hooked up to the converter array, Running the trolling motor on high resulted in alot more power.

Todays run on the watt meter produced the following results:

12.64 voltage minimum
50.11 amp peak
633 watt peak
65,500 mah consumed for the day

The single packs of 18650's performed very well. Their voltage sets right now at:

#1 - 3.77
#2 - 3.76
#3 - 3.77
#4 - 3.76
#5 - 3.77
#6 - 3.76

Very balanced and quite powerful. The end of the day's run being just as powerful as when the pack was topped off.

My wife and I ran all over the lake today and the battery still has alot of juice left.

This pushes the boat with alot more power and top speed is much better too.

[J57ltr]

Wow, cutting it a little close huh? Those are great results

Jeff

[sikeston34m]

Originally Posted by J57ltr

Wow, cutting it a little close huh? Those are great results

Jeff

Thanks.

a little close? Oh. The 65,500mah consumed? Here's something strange.

Since that's on the low voltage side of the setup, you can divide that by 2 to get the mah drained from the 6S pack.

Total pack mah came out to be a little over 72,000mah. I used some new 2600mah cells also.

She should be good for about 126,000mah+ on the low voltage side considering efficiency losses.

I want to add a true sine inverter to use this as a backup battery for power outages also.

The charger has added 27,000mah back to the pack so far and cell voltage is just now up to 4.0 volts per cell.

I'll get the total and figure up the eff. loss percentage. It should be 10% or less.

[sikeston34m]

The 180 cells that make up the 6S pack, took back 45,000mah to become fully charged again.

Whew! I need a bigger charger. LOL

This means all day fishing used 63% of the pack's total capacity.

Now we have enough data to figure efficiency losses.

The watt meter measured 65,500mah worth of useable energy going to the motor.

On the high voltage side, this translates into 32,750mah of energy

Hmmmm..........73% total efficiency. That's not very good really.

I think a large amount of the losses came from the wire that I'm feeding with. 10Ga. Silicone does get warm when feeding 50 amps continously for extended periods of time. The wire was probably 95 degrees on a 70 degree, fairly windy day.

Traxxas High Current connectors are used to attach the silicone leads to the trolling motor lead. I noticed the trolling motor lead was a little warmer than the silicone portion of the lead Entire lead length is about 7 feet.

Hmmm........perhaps replace the entire harness with 8Ga. Silicone.

I could detect very little heat coming from the converters.

This pack does still serve a good purpose and I'm looking forward to the fact, this setup could live and give for 10 years.

[sikeston34m]

I forgot to show the almost completed version.

This picture shows the 5 - 200 watts Vicor Converters wired parallel. 1000 watts of power at 13.8 volts DC.

The parallel hookup was interesting. One of them is the brain of the operation and the rest are booster slaves.



I still intend to add a true sine wave AC inverter to help things when the power goes out.

I did add an outlet to the outside of the box which will channel AC power to the outside. The switch you see, disconnects the 6S pack from everything.