What is the Current State of Lightweight Batteries?

Are lightweight batteries available that are reasonably priced, reliable, and decently powerful yet?  On my previous rally cars I've run bigass Optima or Odyssey batteries, but now that we have jump packs the size of a phone and I'm prepping something less likely to require many attempts to start, I'm wondering what other options are out there around 600cca that people have had good experiences with.  Looks like there are plenty of awesome options up around $1k, but I don't even want to spend half that so what should I be looking at?  "You can't afford lithium/other lightweight stuff" is an acceptable response if it's true.

I have a dead ryobi 40V tool battery that I'm starting to look at with the "if I take you apart and test each cell and remove the bad ones and then rearrage them to make a 12V do you think you would start my car" look. 

Busted ones sell on ebay for cheap. 

So I went round and round on this and finally decided that the 22lbs I could save wasn't going to noticeably increase my lap times, if at all, in the Datsun and I've just stuck with the old fashioned lead boat anchor. 

I still glance at them but for the price I can go by two regular batteries, for me that means 7-10 years.

I just went with the smallest conventional battery that would do the job.

My view on batteries is that they are one of the things you need to be 100% reliable at all times. If your car develops some other problem that makes it hard to start, it's your battery you will depend on. So I am very conservative in my battery selection and tend to use Odysseys. PC680 for the fours, PC925 for the V8s. They work very well for cars that don't see regular use as they will hold a charge almost forever if you disconnect them from any load. 

I'm using an 11lb Braille battery in my FR-S.  It's only 360CCA but it rarely even gets below freezing here so it hasn't been an issue.

I used whatever cheap lawnmower battery Walmart had for years in my 1998 Neon.  It was probably even lower CCA.

Robbie (Forum Supporter) said:

I have a dead ryobi 40V tool battery that I'm starting to look at with the "if I take you apart and test each cell and remove the bad ones and then rearrage them to make a 12V do you think you would start my car" look. 

Busted ones sell on ebay for cheap. 

Rearranging the cells from 40V to 12V will yield more amperage, but I don't think that any Ryobi pack will give you enough CCA to start your car.  And I wouldn't trust a standard alternator to charge a pack of lithium cells.

Motobatt MHTX30 should fit the bill at 10lb 

Pasco battery definitely sells them cheaper as well

I've been very happy with this $55 lawn tractor battery:

https://www.autozone.com/miscellaneous-non-automotive/lawn-garden-battery/duralast-gold-u1r-3-group-u1r-lawn-garden-battery/335291_0_0

Small and light (relatively speaking). I've got one in each racecar and they've been dead reliable so far. At 350cca, they're about half what you're looking for though. 

I use said lawn tractor battery in my F500 for the past 5 years.

I use a $75 Deka ETX12 in my Mazda2. Rated at 180CCA, and weighs about 12lb.

I put one in November 2017 which lasted exactly two years, and replaced it last year in November 2019. It gets daily driven with sometimes sitting for 2-3 days without use (take other cars to work, etc).

I'm not doing a 1hr commute every day like I was before, so with shorter trips I anticipate this one may go sooner than the first.

I used whatever cheap lawnmower battery Walmart had for years in my 1998 Neon.  It was probably even lower CCA.

I have one in my Toyota Echo right now. The cheapest model is rated at 230 CCA.  I also have one running my shop stereo (~500w 4 channel running 4 12s, 2 5s, 2 tweeters) that just sits on a trickle charger whenever i have the lights on in there. So it gets abused and occasionally drained to where the bass hits will drop it to ~8.5v and cause the amp to cut out. I have one of the ~$16 100a harbor freight battery load testers parked on it most of the time and every time i let it charge back up and run the load test on it it does its rating, so im pretty happy with its longevity under actual abuse and misuse. 

Ironically, i run full size car batteries in the lawnmowers, but that's just because riding mowers are giant piles of E36 M3 that are designed poorly and have crappy cranking systems that still suck even after i rebuild the starters and upgrade all the wiring to stupid-huge. 

Thanks guys- and I do appreciate the lower CCA recommendations, but this thing needs to start at -30F (because Sno*Drift and Tall Pines are both events I'd like to do eventually) reliably so I don't want to cut that particular corner.

That Motobatt looks to have the best claimed price/weight/performance so far, anybody actually using one?

At -30 F no lithium-chemistry battery works at all. An EV will be continuously heating the battery even at rest at that temperature.

In reply to chaparral :

Interesting.... so I guess the R5 and other expensive open class cars at those events are either heating their batteries or never allowing the car to get that cold. Good to know!

I have had great luck with the DEKA powersports batteries for the low buck non-brail option.

The 1lb lithium battery that I put in the Accord over a year ago is still going strong. It hates the cold, but I live in Texas, so that works. It pulled over 25lbs from as high and far forward as you can put weight in an already nose heavy FWD car. I think it was worth it. It also created space for the intake. I alwasy carry a jump pack in that car. The very few times it's been too cold to start on it's own, 30 seconds with the hood up gets it going. 

Just a note about the light batteries.

Lithium batteries are not a great idea for use in a car with an alternator charging them.

However, lifepo4 are perfect and very stable.  Most of them also have a built in reset if there is something going on with the charging system or battery.

They are typically around 200$ and work well.  Lots of people in champcar run them with no issues.

https://www.amazon.com/Battery-Tender-BTL20A360CW-Supersmart-Lithium/dp/B07JV8X181/ref=mp_s_a_1_19?dchild=1&keywords=lifepo4%2Bmotorsport%2Bbattery&qid=1605101210&sr=8-19&th=1&psc=1

In reply to ¯\_(ツ)_/¯ :

I have the motobatt mhtx20 in all the BG things, it's 100 lower cca then the MHTX30, and it's been working flawlessly. 

This topic is relevant to my interest as my Rollerskate needs a new battery and more importantly, a battery mount. Trying to decide between a PC680 and a PC925.

There are also a couple of other manufacturers that make AGM and Lithium batteries in the same form factors, with seems to make these form factors a good idea as it looks like I could at least reuse the mounts.

flatlander937 said:

I use a $75 Deka ETX12 in my Mazda2. Rated at 180CCA, and weighs about 12lb.

 

I put one in November 2017 which lasted exactly two years, and replaced it last year in November 2019. It gets daily driven with sometimes sitting for 2-3 days without use (take other cars to work, etc).

I'm not doing a 1hr commute every day like I was before, so with shorter trips I anticipate this one may go sooner than the first.

Driving the car every 2-3 days is pretty healthy for the battery as it doesn't really discharge. It's the long periods of rest that are a problem. I'd be a little peeved about only two years of life with that use.

I'm not a battery expert, at all...

...However, my understanding is other than starting in the cold, or say a giant engine, the number of amp hours (ah), or "reserve capacity" is important because it indicates how much energy the battery can store. If you need it to be reliable, this is a factor. So for example, the LiPo4 batter wvumtnbkr linked to has 480 CCA, but only 8 ah. The lawn tractor battery LanEvo linked to has 350cca and 38 ah of reserve capacity. Obviously people are getting away with only 8ah in some circumstances. Thoughts?

Snrub said:

I'm not a battery expert, at all...

...However, my understanding is other than starting in the cold, or say a giant engine, the number of amp hours (ah), or "reserve capacity" is important because it indicates how much energy the battery can store. If you need it to be reliable, this is a factor. So for example, the LiPo4 batter wvumtnbkr linked to has 480 CCA, but only 8 ah. The lawn tractor battery LanEvo linked to has 350cca and 38 ah of reserve capacity. Obviously people are getting away with only 8ah in some circumstances. Thoughts?

Reserve capacity is an interesting detail- lead-acids is when you drain them to less than 50% state-of-charge and leave them there (i.e. no charging) after about 2 hours, the acid begins to cannibalize the lead plates for electrons so it can be stable whereas Lithium Iron phosphates don't have that problem and can take deep cycling far better than most battery types. The other thing is, lead-acids aren't capable of discharging at higher voltages which correlates to speed, so a lithium battery cell for a starter could run that starter FAR faster than the 12v ever could.

So... it's a big game of math. How much efficiency are you gaining? Can you use the added voltages to turn the starter faster and somehow, start the car faster? There's good reasons we have kept lead-acids in all our cars and it's not just federal highway regulations; they're stout and some of the worst they can do is boil over.

wvumtnbkr said:

Just a note about the light batteries.

 

Lithium batteries are not a great idea for use in a car with an alternator charging them.

 

However, lifepo4 are perfect and very stable.  Most of them also have a built in reset if there is something going on with the charging system or battery.

 

They are typically around 200$ and work well.  Lots of people in champcar run them with no issues.

 

https://www.amazon.com/Battery-Tender-BTL20A360CW-Supersmart-Lithium/dp/B07JV8X181/ref=mp_s_a_1_19?dchild=1&keywords=lifepo4%2Bmotorsport%2Bbattery&qid=1605101210&sr=8-19&th=1&psc=1

I have this one. When not in use make sure you disconnect it. Otherwise you take the chance of draining it below the point where its stays "awake". I had mine go below that level and it will not accept a charge until you first "wake" it up. Pita. 
 

But light it is. 

In reply to Keith Tanner :

Meh. It's a 180CCA battery that saw lots of track time, one accidental discharge from a door left open(which probably caused some damage), and 50k miles in that time. I'm ok with that. Bonus was I used to get them for $60ish through work. I should also clarify that I replaced it while it was cranking slowly, and didn't completely fail on me. It was coming up on winter again and I didn't want to risk it.

flatlander937 said:

In reply to Keith Tanner :

Meh. It's a 180CCA battery that saw lots of track time, one accidental discharge from a door left open(which probably caused some damage), and 50k miles in that time. I'm ok with that. Bonus was I used to get them for $60ish through work. I should also clarify that I replaced it while it was cranking slowly, and didn't completely fail on me. It was coming up on winter again and I didn't want to risk it.

I've got Odyssey PC680s that are over a decade old by this point and they'll stand up to that sort of use no problem. 170 CCA, about $100, 15 lbs.