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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

#251

Post by digitalneal »

msandford wrote: post #202
jaytaylor wrote: post #193

Earlier quoted context omitted.

Just out of curiosity- Do you recall the approximate weight of flywheels in referenced "big powerful manuals"? IIRC the Subaru flywheels for the Impreza weigh in at about 20 lbs - and this is likely similar or identical to what is used in the Foresters.

No idea, but one of the cars that I learned to drive stick in was a friend's 2003 Mustang Cobra. All cast iron engine and something like 400WHP. I don't know that the weight of the flywheel was everything, the crankshaft weighs a lot and I think even the moving mass of the pistons and rods translates into rotational inertia. Finally having 8 cylinders versus 4 means that your engine response time is theoretically twi…

I'd gamble it has more to do with the fact you have to overcome the resistance of 2 extra axles and mechanical differentials of the AWD forester that is making it appear to be a bit more difficult than the lazy v8 2WD Cobra.

With that said, check out where the engagement of your clutch is. I've had people complain about grabby clutches(stalling) only to find out the engagement point is almost at the top of the throw (Former Subaru tech)

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

#252

Post by conjecTech »

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…

Thanks for the comment. It is something we need to look into a bit more. Generally we haven't seen the capacitors be the limiting factor in lifetime, but they might be in extremely hot situations. I'll do some more work on getting a definite answer here so we can be more careful/specific about our claims in the future.

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

#253

Post by CamperBob2 »

paulmd wrote: post #222
CamperBob2 wrote: post #58

Earlier quoted context omitted.

Some thoughts: The price point is impressive if you can sell at only ~$50 more than a standard lead-acid battery. If pressed to find a flaw, I think the biggest is one you've already identified: There’s one: you can’t run your lights and/or stereo as long with your engine turned off. Ohm’s battery reserve comes in at 10 amp hours; most lead-acid car batteries come in at about 45 amp hours. If you can run your stereo…

I can't emphasize how wrong you are about the whole "you can only get 15 minutes of radio off a car battery". Your battery is broken or you have a near-short somewhere. I sit in my cheap-ass Jeep for 45 minutes a week listening to the radio for 5 times a week and have for years. Replace it, if it doesn't work seek professional repair.

Amusingly, I also have a cheap-ass Jeep, and gee, you're right, it has no problem running the radio for at least an hour with the ignition off.

So if you think this is a sustainable, scalable state of affairs, at a time when automotive tech is undergoing its greatest disruption since the horse, we'll leave the discussion at that. I'll just say that I think this is a really bad time to aim their business plan at a fixed target, and one that I'm not sure they actually understand.

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

#254

Post by sliverstorm »

blueintegral wrote: post #2

Hey everyone! I'm Hunter, one of the cofounders of Ohm. Let me know if I can answer any questions.

I was writing a reply yesterday but didn't finish it-

I was going to say, for the first iteration of the product you could consider using classic lead-acid instead of LiPo. It's cheap, so it would help keep you price-competitive. It's absolutely proven as an automotive battery chemistry.

The difference vs. a classic battery would be, your smart circuitry to shut off the battery, and the cap stage would allow for a tiny battery even on big engines. Your LiPo model already sacrifices capacity, and the only other reason for a big battery is CCA, which the caps solve. Thus you could put an itty-bitty 10Ah lead-acid in an F-550. Bigger & heavier than a 10Ah LiPo? Sure, but still way smaller and lighter than modern F-550 batteries.

You could then move to LiPo for later versions as you get the truly novel parts of the product dialed in and costs starts to come down.

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

#255

Post by aidenn0 »

ansible wrote: post #238
aidenn0 wrote: post #132

Earlier quoted context omitted.

It will probably take a few years to get certified, but take a look at what goes for $600 as a flooded-cell battery in general aviation. The fact that you use LiFePO cells will probably help, as there is no way a LiPo would ever get approved.

Wasn't there a problem at Boeing recently where LiIon batteries overheated and caught fire?

Yes, those were lithium cobalt IIRC. LiFePO were new technology when the 787 was designed (it's a long product cycle) and the FAA required a metal shield around the LiIon batteries.

LiFePO is much less likely to enter thermal runaway, and much less explosive when it does. Overcharging them is about as bad as non lithium chemistries (it's even possible to start a fire by overcharging a lead-acid). Don't try this at home, but overcharging and shorting a LiFePO isn't nearly as catastrophic as doing so with a LiCoO or LiPo. With those chemistries you're basically relying on the battery firmware to keep the battery from exploding under those conditions.

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

#256

Post by CamperBob2 »

atourgates wrote: post #131
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,…

If you look at this purely from the standpoint of the benefit to a consumer, it doesn't seem like a great deal. You gain: * Auto-shutoff when your battery gets too low. * Possibly some increased lifespan * ~34lbs in weight reduction, which might deliver a small performance increase. You lose: * 78% of your battery capacity * $20-$150 on the purchase price of the battery Personally, I don't like the idea of paying mor…

If, however, Ohm came with a rock-solid 7-year replacement warranty, I might be able to get over that.

That's a good idea, and they could even make it a lifetime warranty (lifetime of the car, that is). "Ohm: The last battery your car will ever need" could make a nice tagline.

In the fine print, the implementation would be a replacement guarantee for as long as the customer owns their car. Since most people don't keep the same car for 7 years, it would be a safer bet than a fixed 7-year guarantee.

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

#257

Post by [deleted] »

IshKebab wrote: post #243
jboy55 wrote: post #178

Earlier quoted context omitted.

Why not add the smarts to a lead/acid battery? Probably only a few bucks worth of electronics.

You could probably even do it as an add-on to batteries, although now I'm wondering why it isn't built into the cars themselves. They could easily do it.

[deleted]

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

#258

Post by CamperBob2 »

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?

The capacitors are only there to crank the engine. Once there's enough capacity to do that, there's no upside to adding more caps.

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

#259

Post by mzs »

hunter2_ wrote: post #250
JosephRedfern wrote: post #244

Earlier quoted context omitted.

What if you're not replacing one?

Valid concern: it means every possible application of a car battery, if the $300 fee is to be avoided, must involve purchasing a product that already contains a battery. Bad news for DIY makers that need one: they'd need to find a containing product rather than purchasing a battery alone, which might make for a market where fake containing products (to be completely discarded aside from the battery) exist to fill the…

That's a good point. For me though I have had plenty of cars that only last a few months before I drag them to the junk yard. I've used lots of parts from them for cores to offset the cost of rebuilt parts I need to keep another of my cars going. I've also borrowed the car battery from a running car that I'm not using much for art and audio projects. Considering how much some of them had cost another $300 would not have mattered much.

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

#260

Post by paulmd »

CamperBob2 wrote: post #253
paulmd wrote: post #222

Earlier quoted context omitted.

I can't emphasize how wrong you are about the whole "you can only get 15 minutes of radio off a car battery". Your battery is broken or you have a near-short somewhere. I sit in my cheap-ass Jeep for 45 minutes a week listening to the radio for 5 times a week and have for years. Replace it, if it doesn't work seek professional repair.

Amusingly, I also have a cheap-ass Jeep, and gee, you're right, it has no problem running the radio for at least an hour with the ignition off. So if you think this is a sustainable, scalable state of affairs, at a time when automotive tech is undergoing its greatest disruption since the horse, we'll leave the discussion at that. I'll just say that I think this is a really bad time to aim their business plan at a fix…

I wasn't putting a dog in this race with that comment, just urging you to get that battery checked up on before it dumped you at the side of the road. Headlights pull some wattage, but a radio really shouldn't and there's no way 15 minutes should cause any concerning symptoms. Just trying to help :)

I'm not sure how I feel about it, personally. I share a lot of the concerns that have been raised here (battery cutout wiping my clock+radio, vibration, longevity, cranking+jumping ability, etc), and I'm always a bit wary of "One Weird Trick; Auto Companies Hate Him!" claims. I'm certainly not going to be the test dummy for that one, I got places to be that aren't the side of the road. Give me 5 years of early adopters and we'll see.

Neither here nor there, but I was one of the early adopters of electric motors in R/C airplanes. I was doing it since before brushless was a thing (about 15 years), my first plane used a brushed Graupner car motor and Sub-C car packs (boy howdy was that underpowered). I can tell you that batteries have a very finite lifetime, especially when you abuse them under high-current loads. I worry that a lot of hybrid/electric owners are in for some sticker shock when their packs wear out. That one unit is a pretty significant fraction of the total cost and it's a wear item. I know there's steps taken to lengthen the life of the pack, but you can't run them indefinitely.

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