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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

#201

Post by userbinator »

Kluny wrote: post #145
conjecTech wrote: post #129

Earlier quoted context omitted.

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.

Good to know, thanks, I wasn't aware of that. I'm guessing the guys that I know who do this have either accounted for that or don't care.

The grandparent poster could be talking about magneto or traditional points-based ignitions, which are still common in certain classes of racing cars.

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

#202

Post by msandford »

jaytaylor wrote: post #193
msandford wrote: post #66

Earlier quoted context omitted.

It's definitely driver error and not the car's fault. I try not to rev too hard and slip too long, and it occasionally results in a stall. I'm spoiled from having driven a number of very powerful manuals. Big engines mean a lot of rotating mass which means that no revving is needed, just pop the clutch and go. That extra rotating mass also means that the ECU has more time to notice the drop in RPM and give it a littl…

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 twice as fast.

When the clutch engagement time is say 1 second and your engine is idling at 900 rpm you're only doing 1.5 rev/sec. In a four stroke, four cylinder engine that means you're getting on average 1.5 combustion events per second. In the 1 second engagement, you get 1 or 2 combustion events. In the 8 cylinder you get at least 2 and probably 3.

I thought about doing the math for how much energy is in a cylinder firing versus stored in the rotational inertia of the moving parts, but honestly I don't know that I really care. I know anecdotally that big engines make it easier to get cars moving for some reason, and that smaller engines make it a little more difficult. I just speculated as to why I thought that might be.

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

#203

Post by Rebelgecko »

thrownaway2424 wrote: post #106
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,…

You're right about the life. Who here has replaced a car battery after 3 years? My '89 Miata had the OEM battery (an AGM lead-acid battery), 25 years later.

If you live somewhere hot, it can be rare to get even 5 years out of a battery (although if you buy ones with a 3 year warranty you may only be paying for a battery every 5 years or so)

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

#204

Post by ars »

CamperBob2 wrote: post #81
heywire wrote: post #76

Earlier quoted context omitted.

>Nobody with a modern car or SUV is going to get three hours' runtime for their accessory equipment. Really? I've left the satellite radio playing for hours in my 2011 Hyundai Sonata at moderate volume with no hint of problem starting my car afterwards. It has the premium sound system (including subwoofer) and navigation.

There are always going to be anecdotes to the contrary, but the trend is pretty clearly in the opposite direction. Usually what happens in my case is I forget to turn the headlights from 'Auto' to 'Off.' But even with the lights and fans off I don't tend to see more than 20-30 minutes of operation at most. The car's version of HAL 9000 tries to be conservative and shut things down as soon as the battery voltage goes…

Headlight != radio.

The headlights can be easily 150watt. I doubt the radio uses more than 15.

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

#205

Post by NeutronBoy »

atourgates wrote: post #167
baudehlo wrote: post #150

Earlier quoted context omitted.

When I bought my Civic Type-R it didn't even have an option for air conditioning due to the weight it added. For some types of car every pound (though they are called grams in the real world) counts. I suspect this will be popular in the lightweight performance car world.

For sure losing 30+lbs is a big deal in the high-performance automotive world, and Ohm's price premium is nothing compared to, say, replacing structural elements with carbon fiber etc. But I don't think your average mass-market consumer is going to care much about 30lbs, or notice a difference in performance or handling if they did.

> But I don't think your average mass-market consumer is going to care much about 30lbs, or notice a difference in performance or handling if they did.

In reality, if you looked through the car of a random sample of the population, you'd probably find about 30lbs of crap in their car that they could remove (sporting equipment, rubbish, bags, etc).

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

#206

Post by WalterBright »

icanhackit wrote: post #198
MBlume wrote: post #173

Earlier quoted context omitted.

I leave my lights on and kill my battery once every few months, so this is easily worth it for me, but I'm probably an outlier[0]. [0] https://en.wikipedia.org/wiki/Attention_deficit_hyperactivit...

> I leave my lights on and kill my battery once every few months, so this is easily worth it for me I compulsively check to make sure my lights are turned off yet my battery still dies at least once a year because I don't regularly use my car, costing around $200 in on-site service and replacement per go. The smart shut-off feature is worth it to me - even if it's just to save time waiting around for someone to perfo…

One of the best tools I ever bought was a 6 amp battery charger. Plug it in, and in 20-30 minutes the battery has enough charge to start the engine, then you're good to go.

This has saved me many, many hundreds of dollars, being late for work, etc.

I also have a battery maintainer that keeps a battery sitting around charged up.

The last thing is a battery shut-off switch that sits on the battery terminal. If you're going to leave the car a while, shut it off. It prevents the trickle going to keep the radio alive from killing the battery (which takes a week or two).

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

#207

Post by ars »

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 don't understand how you can charge $200 for this (plus shipping??). A battery at Costco costs $83 for 4.5 years full warranty.

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

#208

Post by WalterBright »

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,…

> For some (BMW) it can even mean a trip to the dealership for a special new battery ritual.

Really? That would kill any interest I'd have in a BMW. Heck, whenever I work on my car, the first thing I do is disconnect the battery.

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

#209

Post by zevyoura »

WalterBright wrote: post #208
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,…

> For some (BMW) it can even mean a trip to the dealership for a special new battery ritual. Really? That would kill any interest I'd have in a BMW. Heck, whenever I work on my car, the first thing I do is disconnect the battery.

Few owners of modern luxury cars do their own maintenance.

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

#210

Post by WalterBright »

thrownaway2424 wrote: post #106
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,…

You're right about the life. Who here has replaced a car battery after 3 years? My '89 Miata had the OEM battery (an AGM lead-acid battery), 25 years later.

A lead acid battery will last a long time if it is never deep-cycled (i.e. run down). Always keep it topped up with charge.
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