Yeah and matter of fact I have seen that battery used in large motorcycles. Keep in mind you want good copper lugs on those terminals. You also want a wire gauge which will handle the ampacity you want. If any switching is involved you want a switch or contactor which will handle a high enough DC current load.

Ron

 

Do I really need copper? I know it is better than steel or aluminum, up to 2x as conductive, but it is far more expensive. Could I not just use some bolts and thick pieces of steel, along with 1/0 gauge CCA?

And it said it has 102% capacity at 100F. It seems to rise with temperature. At 0F, it has only about 60% of the capacity. So I should light it on fire for optimal capacity? Actually though, should I try and cool as much as possible it when drawing large currents, or just so that it does not get really hot? Or would it not heat up too much anyways? Because 10-20mOhms at 100A causes a 1 volt drop. 1V*100A = 100W of power to dissipate. But it is across a 7" by 6" by 7" battery. So that's less than 1/2 a watt per cubic inch.

I need decent undervoltage and short circuit protection. Is there a commercial option that allows you to set the maximum current and minimum voltage? Ideally one that would take into account the fact that there may be an unloaded voltage 1V higher than the loaded voltage at maximum current. It should work for 12V and 24V. I have only found circuit breakers and relays. I guess a 120A or 150A CB will protect against shorts that will damage the battery, but there could still be other very dangerous overcurrents if the wires are long and thin enough. I suppose I could use an additional fuse or something, but it would be nice to be able to adjust it easily.

For undervoltage, I do not want it tripping at higher loads due to internal drops of up to 1V. But I also do not want the risk of it being discharged to a dangerous no load voltage. So one cutoff voltage may not be a good option here, unless you only get a small advantage discharging it one more volt. I have looked at a few commercial options, and they cannot handle the current. I also really don't want oscilations because of the difference. I have an idea for a circuit to pulse it, make up for the off time with a capacitor, and measure the battery voltage while the capacitor is supplying it. But I have little real life experience with those types of circuits, and it would not be too reliable. So what do you recommend?

 

I suggested copper lugs and copper wiring simply because my own choice would be copper and yes, I am aware of the cost difference between copper and aluminum.

I have no clue what your intended application is for batteries or what will draw the currents you mentioned. I now also have no clue as to why there would be concerns with freezing temperatures. Batteries used in extreme cold normally have small electric blankets wrapped around them.

They make high DC current breakers, EATON comes to mind but they come with a price the home hobby enthusiast is not about to pay.There are also literally dozens of DC under and over voltage solutions out there. You want to measure battery voltage under load and oscillations are a function of load.

Tomorrow morning early I am out of here for about two weeks of beach time with kids, grand kids and family. I may visit my forums briefly but plan more time for enjoying food. Any number of forum members here are willing and very able to address questions you may have but I won't be around much.

Ron

 

Battery blanket lol. You’re almost freezing to death but then you wrap the blanket around the battery or get an extra one and make sure it is nice and warm. I was more asking about what I should do for heat dissipation at higher loads, if anything is needed. I do not plan to use it in very cold weather.

 

Tomorrow morning early I am out of here for about two weeks of beach time with kids, grand kids and family. I may visit my forums briefly but plan more time for enjoying food. Any number of forum members here are willing and very able to address questions you may have but I won't be around much.
Ron

I hope you have fun.

 

I was more asking about what I should do for heat dissipation at higher loads, if anything is needed. I do not plan to use it in very cold weather.

Batteries are rated for the temperature extremes they should give normal performance in. I guess if the need were there you could heat sink a battery or cool it using any number of means. I guess if I wanted I could run a battery in an ice bath or refrigerate it. Anyway if I were that concerned I would just monitor the battery temperature.

On the bright side vacation, as always was sweet.

Ron