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Ohm (YC S15) is a smarter, lighter car battery that works with your existing car

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Re: Ohm (YC S15) is a smarter, lighter car battery that works with your existing car

#121

Post by conjecTech »

murbard2 wrote: post #96

So aside from what's been said, I can get this for $200 http://www.batteryspace.com/Powerizer-LiFePO4-Battery-12V-15... and it has 50% more storage than what is being advertised. What's the difference? The supercapacitors?

Storing a lot of energy and delivering it faster are two separate problems. The batteries you linked are design to store a lot of energy, but are only rated to deliver it at 30Amps. Cranking even a medium sized sedan would take 5x that or more. Creating something that can do that reliably requires a lower energy density. LiFePO4 by itself also doesn't stand up particularly well to cold temperature. The capacitors do most of the heavy lifting involved in starting the car. Using the combination of the two also enables some other nice things like the dead battery prevention.

Re: Ohm (YC S15) is a smarter, lighter car battery that works with your existing car

#122

Post by aidenn0 »

I've prototyped similar with just 7 maxwell caps in series wired in parallel with a lead-acid battery. The caps can start an engine entirely on their own, and the lead-acid maintains the voltage when off. It works fairly well.

I think someone already sells a device to work like that for commercial tractors, and I was wondering when someone more interested in starting a company than I am would realize you could have a tiny battery plus EDLCs for a car.

Re: Ohm (YC S15) is a smarter, lighter car battery that works with your existing car

#123

Post by bri3d »

aidenn0 wrote: post #116
bri3d wrote: post #112

Earlier quoted context omitted.

Sportbike owners are already buying cheap LiFePO4 batteries sans capacitors in droves, so there'd have to be some kind of strong differentiation for Ohm.

Do LiFePO4 provide enough cranking amps for a sportbike?

Yes, absolutely. There are hundreds of LiFePO4 sportbike, ATV, and race car batteries on the market already (for example, http://www.batterystuff.com/powersports-batteries/LFX14L2-BS... ).

I've also used one to run my Elise (2ZZ 1.8L 4-cylinder) for a few years now without issue.

The three major issues I've heard about are are longevity, price, and reserve capacity. Cold weather is a bit of an issue, but strangely it's actually made better by more load as the battery's internal resistance eventually heats it up to the point that it works fine.

I really don't get this product yet. Unless the supercapacitor provides an incredible enhancement in longevity (maybe it does, but my understanding and experience is that temperature and poor manufacturing are the main enemies to these batteries, not instantaneous load), I'm not sold on buying one instead of one of the inexpensive existing alternatives.

Re: Ohm (YC S15) is a smarter, lighter car battery that works with your existing car

#125

Post by Gravityloss »

sbierwagen wrote: post #70

Lithium-ion car batteries are already commercially available, though cripplingly expensive: http://www.jegs.com/p/Lithium-Pros/Lithium-Pros-12-Volt-Lith... The innovation here seems to be the capacitor bank, which lets you get away with a much smaller and cheaper lithium ion pack.

Trucks have recently started having capacitors for starting. http://www.greencarcongress.com/2015/03/20150325-maxwell.htm...

Re: Ohm (YC S15) is a smarter, lighter car battery that works with your existing car

#126

Post by blueintegral »

JshWright wrote: post #110
gcb0 wrote: post #107

if it is so smaller inside the big case, why not pack twice the caps and have double the running time/service life?

I suspect the limiting factor is cost.

Yeah, the supercaps are our most expensive BOM item.

Re: Ohm (YC S15) is a smarter, lighter car battery that works with your existing car

#127

Post by curiousjorge »

so another inaccurate and unscientific claims that investors love throwing their money at because it's a startup. Techcrunch is like the tabloids for questionable startups and it's really hurt the perceived quality. I've built a filter mechanism for TC since a few years ago when they just became a dvertising platform rather than a serious journalism

Re: Ohm (YC S15) is a smarter, lighter car battery that works with your existing car

#128

Post by gscott »

Recently my wife's car batter died, end of life. When a new battery was put in it the car ran poorly. Apparently when the battery dies something in the car resets and the car "figures" out the settings again and runs rough at idle. We called a repair shop and they said to just wait a few days and it will fix itself. Which was true, runs fine now. The moral of the story is that with a new car if the battery dies, weird things happen.

Re: Ohm (YC S15) is a smarter, lighter car battery that works with your existing car

#129

Post by conjecTech »

Kluny wrote: post #114
sandworm101 wrote: post #27

(1) Those nasty things inside car batteries are easily recycled and in fact are recycled more often than not (like 95%+) (2) Car batteries do not last only 3-4 years as per the OP. Car batteries can last decades. There are many variables, but the car in my battery is far older than 4 years. (lol) (3) Replacing an easily-recyclable product with a less-recyclable one is no step forwards. (4) XX addressed by OP comment,…

(7) This doesn't apply to all performance cars, but in track racing where you really need to save every possible ounce, it's common to take the battery out altogether after starting the car and run it off the alternator.

Co-founder here. Do the cars you're talking about use a distributor? The battery of a car works as a low pass filter for the alternator, and removing it entirely can cause huge spikes in the voltage it puts out. That can be destructive to just about any electronics it would be running. I've personally seen an accidental battery disconnect blow an ECU.

Re: Ohm (YC S15) is a smarter, lighter car battery that works with your existing car

#130

Post by [deleted] »

chillingeffect wrote: post #108
conjecTech wrote: post #39

Earlier quoted context omitted.

Hey, co-founder here. It's very forgiving to temperature. Supercapacitors don't store energy using a chemical reaction, which make them a lot less finicky. On the low side, our power architecture also allows us to boost the voltage slightly if we sense that its cold outside, so we can account for the increase in resistance. It's also still go superior lifetime at high temps as well.

fwiw, Wikipedia says "The lifetime of supercapacitors depends mainly on the capacitor temperature and the voltage applied." [ 1 ] This picture shows a 10x decrease in life when the temp varies from 25C to 65C: https://en.wikipedia.org/wiki/File:EDLC-Life_time_curves.png [ 1 ] https://en.wikipedia.org/wiki/Supercapacitor EDIT: I'm not trying to inject bad feelings here or contradict Ohm. I'm just clarifying the effect…

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