Super capacitors for starting, bowthruster, and windlass circuits

[ngmayo]

Has anyone tried adding the cheap supercapacitors in the in-rush circuits of the starter, bowthruster, or windlass to reduce strain on the batteries?

something like this?

https://www.amazon.com/Farad-Capacit...737091&sr=8-15


I've had eight 100 amp battleborn batteries system for 4-5 years without issue on a previous boat (I know they now suggest only 4 parallels and battery balancing and no inrush now. Years ago there was never all this guidance). I'm looking to do better (cheap Chinese Lipo4 and four larger batteries)on next boat so was curious.

Another side note, I'm honestly confused how the capacitor balancing circuit board could handle the large current for even a short time, but am curious if anyone has tried.
thanks!

Thanks!

[SailingHarmonie]

I don't understand what problem you are looking to solve? What are you hoping to accomplish?

Starters, bowthrusters, and windlasses are used by the tens of thousands every day without the need to put super capacitors in the circuit.

Of course without careful management the capacitors will have in-rush currents that far exceed those of the motor every time they are connected to the battery.

[ngmayo]

Essentially looking to prolong battery life.

[Cwens]

Originally Posted by ngmayo

Has anyone tried adding the cheap supercapacitors in the in-rush circuits of the starter, bowthruster, or windlass to reduce strain on the batteries?

something like this?

https://www.amazon.com/Farad-Capacit...737091&sr=8-15

"About this item" looks to me like utter ********.

• 1. Reduce the starting time of the car, reduce idle jitter and make it more stable.
• 2. Increase engine power to make throttle response lighter and more sensitive.
• 3. Reduce clutter distortion and improve sound quality of vehicle audio system.
• 4. Protect the battery and the circuit of the original vehicle, reduce the load and prolong the service life.
• 5. The spark plug supplies power to each cylinder evenly to make the engine run more smoothly. Improve the phenomenon of low-speed driving and make the shift more stable.

[SailingHarmonie]

Originally Posted by ngmayo

Essentially looking to prolong battery life.

Why do you think this is a real world problem? And how would you know if this approach fixed it?

I personally think you are wasting your money buying one of these, and wasting your time worrying about it. If the "starting inrush" to your windlass motor is the biggest thing affecting your battery life, you are managing your batteries far better than anyone I know.

Take this money and buy real Li batteries with a proper BMS and external contactor instead of the cheap and fragile FETs used in "drop-ins" and you'll come out way ahead.

But, if you are sure, go ahead and try one. They come back when you can tell us you get 19 years instead of 15 from a pack of drop-in Li batteries.

And while "super capacitors" and soft start circuits are a real thing, that Amazon product you listed is total crap. If reading the advertising copy for it doesn't have your BS meter running off scale, said meter needs a serious recalibration.

[jamhass]

Besides, I didn't see a post suitable for a 2/0 starter cable ...

[S/V Illusion]

PT. Barnum was right. We all know that so there is no need to provide more evidence by buying crap like this

[ngmayo]

Originally Posted by SailingHarmonie

Why do you think this is a real world problem? And how would you know if this approach fixed it?

I personally think you are wasting your money buying one of these, and wasting your time worrying about it. If the "starting inrush" to your windlass motor is the biggest thing affecting your battery life, you are managing your batteries far better than anyone I know.

Take this money and buy real Li batteries with a proper BMS and external contactor instead of the cheap and fragile FETs used in "drop-ins" and you'll come out way ahead.

But, if you are sure, go ahead and try one. They come back when you can tell us you get 19 years instead of 15 from a pack of drop-in Li batteries.

And while "super capacitors" and soft start circuits are a real thing, that Amazon product you listed is total crap. If reading the advertising copy for it doesn't have your BS meter running off scale, said meter needs a serious recalibration.

I know (don't think) this is a real world problem based on the LiPO4 manufacturer guidance from companies such as battleborn. Refer back to any of the forums topics on LIPO4 as a starting battery. What makes you think it isn't an issue? I don't know if this approach will fix it. Hence the question here if anyone had any facts associated with the topic....

[ngmayo]

Originally Posted by jamhass

Besides, I didn't see a post suitable for a 2/0 starter cable ...

because a 2/0 vs 4/0 wont change the fact that that Lipo4 such as battleborn and dare I say it chino will lose life more rapidly if used on a circuit with an appreciable (diesel starter, windlass, bowthruster) DC motor in-rush.

[markcouz]

I built a 24V engine start supercap using 10x [Maxwell 2.7V 3000F 3.0Wh] supercaps in series to replace 2x 180Ah Silver Calcium batteries. This is to start a huge and heavy Perkins 6.354.

I charged the caps using an MPPT charge controller using my 48v lithium house bank as source - the MPPT programmed to charge at 25V (bulk, absorb and float) at a max rate of 20A (it is critical not to exceed the 2.7V per cap rating, I was charging to 2.5V per cap).

The caps charged with no issues and started the motor quickly and powerfully with a scary amount of torque - I could get 3 or 4 starts out of the original charge before recharging was required.

After the initial test, I connected the MPPT permanently so that the caps would charge immediately in between starts. It seemed to work flawlessly with the recharge taking a minute or 2 after each start - considering that I could get 3 to 4 starts with no recharge at all, it seemed to be a great system with huge space and weight savings.

Soon after this I started the engine and on releasing the key switch I heard a loud Crack - the MPPT was converted to smoke!

A bit disheartened, I replaced the MPPT and tried again - the system again worked flawlessly for several starts over several days until..... Crack!

I disconnected the supercap system and reconnected the lead acids. I have no idea what was causing the failure but couldn't afford the cost of continued testing and couldn't live with the lack of reliability - but if anyone would like to know if it is possible to start a big marine diesel using supercaps, the answer is a definite yes, so long as you can resolve the recharge issue.

[SailingHarmonie]

Originally Posted by markcouz

I built a 24V engine start supercap using 10x [Maxwell 2.7V 3000F 3.0Wh] supercaps in series to replace 2x 180Ah Silver Calcium batteries. This is to start a huge and heavy Perkins 6.354.

I charged the caps using an MPPT charge controller using my 48v lithium house bank as source - the MPPT programmed to charge at 25V (bulk, absorb and float) at a max rate of 20A (it is critical not to exceed the 2.7V per cap rating, I was charging to 2.5V per cap).

The caps charged with no issues and started the motor quickly and powerfully with a scary amount of torque - I could get 3 or 4 starts out of the original charge before recharging was required.

After the initial test, I connected the MPPT permanently so that the caps would charge immediately in between starts. It seemed to work flawlessly with the recharge taking a minute or 2 after each start - considering that I could get 3 to 4 starts with no recharge at all, it seemed to be a great system with huge space and weight savings.

Soon after this I started the engine and on releasing the key switch I heard a loud Crack - the MPPT was converted to smoke!

A bit disheartened, I replaced the MPPT and tried again - the system again worked flawlessly for several starts over several days until..... Crack!

I disconnected the supercap system and reconnected the lead acids. I have no idea what was causing the failure but couldn't afford the cost of continued testing and couldn't live with the lack of reliability - but if anyone would like to know if it is possible to start a big marine diesel using supercaps, the answer is a definite yes, so long as you can resolve the recharge issue.

The problem is that an empty (or significantly discharged) capacitor presents to any power source connected to it as a dead short for a finite amount of time. Hundreds of milliseconds? More in the case of a limited power supply like your MPPTs. Maybe much more in the case of these huge beasts. Some power sources can handle this, others need a current limiter so the cap charges more slowly. I would suggest that evidence suggests that your MPPT units are squarely in the second category.

What would you expect to happen to those MPPT's you were using if you directly shorted across the output terminals???? I expect a nice SNAP-CRACKLE-POP would be the result, along with the escape of the magic smoke.

[markcouz]

I would expect the voltage to collapse in order to maintain the programmed max 20A output as should happen with a CC/CV power supplu, but I was probably expecting too much of the el-cheapo MPPT[emoji848]

The

[ngmayo]

Originally Posted by SailingHarmonie

The problem is that an empty (or significantly discharged) capacitor presents to any power source connected to it as a dead short for a finite amount of time. Hundreds of milliseconds? More in the case of a limited power supply like your MPPTs. Maybe much more in the case of these huge beasts. Some power sources can handle this, others need a current limiter so the cap charges more slowly. I would suggest that evidence suggests that your MPPT units are squarely in the second category.

What would you expect to happen to those MPPT's you were using if you directly shorted across the output terminals???? I expect a nice SNAP-CRACKLE-POP would be the result, along with the escape of the magic smoke.

Sorry to hear about your MPPTs. That is very good information. Thanks so much! After reading your experience, I'm actually rethinking a setup. Maybe putting a 13.2 volt isolation solenoid on a LIPO4 that is a starting circuit with supercap. Have everything on the house battery bank until the voltage goes below 13.2v. essentially an emergency start circuit that isolates. When the circuit is above 13.25 the capacitors recharge off the house. Use 16v capacitors or such. All charging circuits (alternator and inverter/charger) to the house. This is really helpful.

[AKA-None]

So. If I understand correctly you want to replace the motor inrush with a capacitor inrush
The capacitance you are considering is greater than a small capacitor for something like a fridge or ac unit

[markcouz]

Originally Posted by ngmayo

Sorry to hear about your MPPTs. That is very good information. Thanks so much! After reading your experience, I'm actually rethinking a setup. Maybe putting a 13.2 volt isolation solenoid on a LIPO4 that is a starting circuit with supercap. Have everything on the house battery bank until the voltage goes below 13.2v. essentially an emergency start circuit that isolates. When the circuit is above 13.25 the capacitors recharge off the house. Use 16v capacitors or such. All charging circuits (alternator and inverter/charger) to the house. This is really helpful.

Go for it, but just read the Cap spec in my post carefully, note that the F (Farads) and not uF (micro Farads) wasn't a typo!

They are each the size of a deodorant can with bonus filling, the experiment cost me around $600 and I shed a tear when I called it quits.