Was watching the GT3 kids talk about lightweight batteries, and it feels like this tech has come into its own in the last couple of years, and is refined rather than cutting edge.

Anyway, the GT3 crowd seems pretty jazzed about these:
https://shop.antigravitybatteries.com/produ...tomotive/rs-30/

Steep, but then again, a set of tires can cost this much (or a lot more) and these batteries look to be cheap on a per-pound-saved basis...and the remove weight high up in the car. Having converted to a six, that's appealing. Also like the on-off feature as well as the built in jump start.

Thoughts? Alternatives? What are you using? How are they holding up, and what are the downsides?

$700.00 That is not a low cost unit

Do they have those at kmart

Last time I brought this up I got some flack. But there's no question where things are going. Just be careful, because technologies change rapidly. Heck, most people won't know if LiPoly or Lithium Ion is the newer tech. And something better is around the corner.

Things are evolving. In lighting, the incandescent is dead. Compact fluorescent bulbs have come and gone. Even some LEDs are dead because of recent improvements.

People are resistant to change until the market proves to them there is something better.

Are you running a lot of electronics? If not you might look into a UPS battery. They're Gell cell, very small and light. IIRC, they were about 3x8x6h. I used to run them in my plane. They ran anywhere from $45-$60 in 2000.

I had an odyssey PC680 (17lbs) in my SC. There is always a slow drain in that car in about a year of draining it dead over and over again, it wouldn't come back to life. Other than that it would start the car just fine when there wasn't that slow draw when the car sat.

So I searched out batteries for golf carts and bought 2. One for the 914 and one for the 911. So far so good.

Mighty Mite ML-35, which is 28amp/hr and 23lbs which is about the same as the PC925 and about $60.00. Its a bit smaller than stock and will fit on its side just about perfectly in the stock battery tray, or fits just fine in the standard upright config (although this particular one, the poles are reversed). You just need to make a mounting plate.

Here's a pic, I was contemplating moving the battery and not putting in the stock tray on my rust repairs - I will be putting the stock tray back in and keeping it there though.

Ironically, it is the smaller scale model aircraft battery technology that really pushed things forward.
Elon isn't using old school battery technology in full sized cars or trucks, especially going forward because the newer tech is more efficient, especially at the the coveted power to weight ratio. Battery technology is growing exponentially and for the better.

Ok, I need to go fire up a gas engine now...

I just picked up a Lithium motorcycle battery to replace my failed Optima. Optima is about 55lbs, the motorcycle battery is maybe 2.

300 CCA is plenty to start my modern low compression engine and the alternator will take care of the rest of the electrical components.

Started it a couple times so far with no issues. Thing is TINY. Best thing is it has an on board tester to see if the battery is charged.


I figured it was worth the try.

https://www.amazon.com/YTZ10S-Lithium-Seale...&ref=plSrch

Looks like I need a new battery, that little sucker could mount at the bottom of the hell hole off the firewall

The battery in my jump box starts cars just fine and it's half the size on a normal car battery. It's also the one that's doubled up for lawnmowers. 18-19ah + sealed

Funny to hear you got flack last time around. People think nothing of fiberglass GT bumpers and lids that cost far more than even a $700 battery if you do them right—particularly if a body shop gets involved. It's all high fives and handshakes for those mods, which alter originality and require other kinds of commitments. A battery bolts in, and this is no small weight savings in a 914...and it's high in the car even if the original idea was to offset the driver's weight.

This is a discussion worth having.

Interesting, Andyrew...tell us more. Anyone else? Fwiw, my ideal scenario is a significant weight loss with no downside in functionality. Like the idea of an on-off switch on the battery and built-in jumpstarter, but would be very happy to find a cheaper alternative without those features. If we can determine the "go-to" Li-Ion battery in 2018, that wouldn't be a bummer. Wonder if it's safer than my Optima with re: to rust as well? Turning the battery off when the car is in storage/not in use definitely has to be safer....

Some more info on the subject - https://www.roadandtrack.com/new-cars/video...st-for-hybrids/

This option appears to be very cost competitive with a standard battery with a huge weight savings! If it works well it sure seems like a good option with many benefits.

Jeff B

I have a 25# Miata AGM battery in the street car. $99 shipped.

Race car uses a 13# Deka ETX-15 AGM battery. ~$75 shipped.

$700 for a battery...? That's Porsche GT3 "look at my battery!" money, not Porsche 914 money. But to each his own...

I have used the PC680 extensively in my airplane - Cranks a 9:1 compression 360 cubic inch four no problem. Really good service, made in USA and 16 pounds. Got one going in the race car too. $109 at Amazon

The YTZ looks very interesting at 2.1 pounds!!

I have a PC680 in my 3.0 /6, 10.1CR twin plug conversion.
It wouldn't crank a brand new engine, but now the engine is broken in no problem.
I made a mount so it lies on its side in the battery tray.
Not bad for a lawn tractor, motorcycle sized battery.

Same here re. the Odyssey PC680. They are fantastic; I disconnect the battery when not using the car, and it can sit a month and fire right up.

https://www.youtube.com/watch?v=DMVT3nj6C4M


Took a quick video. Note car will not start due to undiagnosed wiring issue (Crank position sensor has to be right on the money to start, so I think thats the issue but cant tell and Ive replaced it 5 times). But you can see it turns over great. Also the onboard tester as I mentioned

Battery is only 2lbs.

Would I use this on a daily driver? No, Would I use this on a weekender hooked up to a tender or a race car? Hell yes.



Side note: I havent driven this on the street, Just swapped the battery in last weekend for the build day so I could drive it up and down the trailer.

3.75 lbs. starts a 3.6 - $150

Here's a very long thread about lightweight battery's and how Jack got to his. I think he's been using it now for 3-4 years.

Wrong thread - Here's the correct one - http://forums.pelicanparts.com/porsche-911...ht-battery.html

Somewhat amazingly, a 914-6 is 996/997/991 GT3 money these days depending on condition/etc....while a really nice six conversion is 996 Turbo/997 money. Crazy times.

Fwiw, the "hey look at" factor is of zero interest to me. The weight savings are VERY interesting to me...though I agree $700 is hardly a "let me pick up the phone and order one of those right now" price point. Odyssey PC680, at 15.4 pounds for $110~, is looking pretty interesting for a street car. Wondering what else is out there. Maybe something in the middle ground.

Whatever the case, this is a very interesting weight loss option to me. Andyrew has me wondering about his setup for my weekender/occasional use car (as it would essentially negate somewhere between one third and getting towards half of the weight gain with the 911 engine, but I wonder if it's too extreme a solution as well as how it will deal with headlights, heated seats, audio system, etc...and any possible detriment to the charging system or ignition system. Have to admit, these are areas I don't know much about or understand. But I dig the idea of taking advantage of what's going on with batteries right now...

Are people stil using the drycell batteies?

I think that us what Harry (cali914) is running in his Acura/Honda V6 conversion.

It has to 1/3 the size of a normal battery.

Now we are talking...

Should've thought to search out Jack over on the bird board re: batteries. Of course he's been down this road. 3.75 pounds, and usable in a real car? Yum.

I used a very small dry cell battery for a few years in my 914. It only had one problem. If I didn't put it on the battery maintainer, it would discharge. Not sure how much you use your car Pete but mine can sit for a week or two and longer in the winter.

And small

I followed Jacks thread with interest,got me thinking so I bought a very small GSM battery $55 mates rates,nearly 3 years of abuse and still going,weighs 9 pound and has been very good,very low discharge rate when not in use is handy also.
I really don't understand why folks run full size batteries ,see little point in lugging all that weigh around.
Down side for me is the little 6mm bolts threads on the posts they are fiddly to work with,it also appears mine is hard to charge if it gets really flat,my smart charger says its fully charged when its not,I use an old school charger and that works ...I don't know why ???

That's where that $700 battery's on-off switch had a lot of appeal to me, but...I suspect that isn't hard to replicate. Used to use one of those terminals with the spin-off peg to kill the battery, though it got loose and caused a lack of contact. Bothered me enough that I didn't use one again. May be worth revisiting...

Race car uses a 13# Deka ETX-15 AGM battery. ~$75 shipped.

Us the same battery not an issue ever, we will see with the Subaru EG, but on the -4 it was perfect.

Easy mount lower firewall as low as you can go on the passenger side. No heater so none of that stuff.

I always think of Beavis and Butthead saying "Fire, Fire, ha ha Fire'" when thinking of Lithium Ion batteries...

laptops, cellphones, wireless earbuds, ect

From Samsung?

Time for a bump. I am about ready to install a new battery tray and keep going back and forth whether or not I should do a stock tray, or do a super small battery and make a small battery tray in the hell hole next to the firewall.

Only time smaller is better........ I have one, no problems. Reference to a earlier post concerning fires. I agree Lithium does not react well with water, but these are encased in plastic so no worries.

I've had my $75 sub 2lb lithium on the bench for the past month and a half testing my electrical components (Im cleaning up wiring) while doing stuff and its still showing full battery life.

Still VERY happy with it..

So my concern is reserve capacity. I know that the small lithium batteries will start the car, but what if you are having trouble getting the car running and have to do a whole bunch of cranking?

Thanks Andyrew. I was hoping you would share how that little battery was working for you

Same thing I did when I drove my 914 in high school - push and pop clutch.

Quick note, looks like they raised the price of my battery to 107.

I have longevity concerns with my battery (And all lithiums) just judging from what I know about lithium batteries in my phones.

I was figuring this would be a yearly battery replace (Like my phone batteries). But at that price its a little less forgiving.. Time will tell.

I've been using Lithium batteries on my bikes since 2013. And ever since then I've been trying to find a replacement for car batteries. The weight, the size, the shelf life, all of it lend perfectly to a sports car, especially a second car. Plus add in the ability to mount in any orientation, hide in small spaces, etc...

I'm gonna have to go read more of Jack's battery thread on the bird board, because he's inside of my price window. My threshold is $300, especially considering that's about what my last Mercedes battery cost.

Can you wire two bike batteries together. Still cheap but more power and reserves. Maybe

Many OEM manufacturers do this. I see no issue with it, and most Lithiums are just smaller cells put together. Probably a good idea for a street car.

If you got a couple of small 300cca batterys at less than 2lbs each thats still only 4lbs in battery, plus another lb for a holder and wire to link them..

You could wire a couple up like they do for boats and rvs where the engine battery is isolated from the cabin batteries. They do that so even though you run down the battery using the lights the motor will still charge. They both charge off of the alternator. That way you would always have one in reserve, like if you forget to turn something off, or run through the first one cranking.

Reading through Jack's thread on the bird board, he has had great success with his battery, although he does live in one of the warmer climates.

I think I'd be willing to try one on my 914 or just about any toy car, but I don't think I'd do it on the Mercedes. I did just replace the battery on it, and searched for something in the Lithium family that might be suitable. Living in Indiana, -10F is always a possibility, so I don't think we're close on a daily driver.

Jack posted a quote from a guy who had been using his LifePo4 in colder areas on ways to have better success in cold weather, but I think it's still a stretch for a daily driver in colder climates.

One last thing I found interesting, the use of those micro jumpstart devices with warnings that they are for Lead Acid batteries only. I have 2 of these, and they work great! The one I have is no larger than one of those phone recharging batteries. I wonder why the incompatibility?

Anyone have any ideas or thoughts on that?

Oh, and Amazon lists Jack's battery as being In Stock on 9/20 if you want to order one.

I am not too awful far from you, and have cold weather to contend with as well. On the other hand, I have to assume that the play cars will be garage-bound about six months out of every year. Would you want to start your car at ten below? On the minus twenty days, my cars will get down to close to zero in the shop. So weathering storage conditions is what I would worry about.

I don't see storage conditions being an issue. I had my KTM 990 in my buddy's garage in LA. I went 16 months without it being started, turned on, etc...but it started right up on an early version Lithium Ion battery.

As long as you don't have anything sucking on the battery when its stored, I consider storage a non-issue.

And yes, the toys will be parked during our coldest days.
(But I long for the day I can put one in my daily driver) ;-)

Click to view attachment

OK....I'll bite.
I did make the big leap of faith and purchased one of these.
Still getting the car finished, so no idea how she works.

Lightweight (about 11 lbs), fits in our battery tray (with a small mod to the battery base bracket they use), and some neat features, like the automatic turn-off so the battery doesn't drain too low to start the car.

Lithium ion are not the same as the cell phone batteries that catch fire...a whole different animal.
So no worries there.

If your car has a lot of amp usage like a gi-normous stereo or hydraulics, this is not your battery.
But for small electrical usage cars like most 914's are, they're perfect.

Sometimes it's better to go with a proven solution.