Smaller battery closer to the starter = weight savings?

[96vtec]

I tried doing a search and couldn't find much regarding this subject so please bear with me if this has been answered previously.

After having replaced the battery in my portable jump starter, and later making a motorcycle battery work in my Miata, I began to wonder if anyone has come up with this idea.

So we all know that smaller batteries put out much less cranking amperage and we also know that longer and thinner gauge wiring will decrease cranking amperage. So in that sense, if you were to solder a 2 gauge welder's cable to a smaller motorcycle battery's terminals, you would have the best connection possible. Now if you were to limit each cable to maybe one foot from the battery to the starter, you would have maximum potential cranking amperage (without having the battery bolted on the starter).

Just curious as to whether or not anyone had tried such a mod. I understand that the car would most likely go dead if the radio or lights were left on for a small duration of time but you could always carry a small jump starter in the trunk with you.

[NoD~]

I have used the Wal-Mart lawn and garden batteries several times now. One in my neon and one in my caravan. Both saved ~20lbs and NEVER failed me, so long as they were started regularly. My minivan doesn't see a start but every few months and is usually drained by then. However, when I had one in my Neon, winter through summer, NEVER failed cranking over.

[Frank Lee]

...but you could always carry a small jump starter in the trunk with you.

Then the point would be what?

[AntiochOG]

For most people a Miata battery would be a good weight savings. If you want to go even lighter you can try these: Braille Battery USA &nbsp&nbsp&nbsp&nbsp Lighter • Stronger • Faster - I'm guessing the weight reduction wouldn't pay for itself in improved MPG though.

[HydroJim]

id say battery mods are only worth it when you actually need a battery. and I'm not sure putting it closer to the starter changes much.

a few guys with geo's use this setup:



4S3P A123 Motorcycle Battery Quick Connector 13 2V6 9AH | eBay

Light W8 Battery

saves a lot of weight, better handling, and cleaner engine bay. Pretty good setup

[Ryland]

I agree with frank, if the idea is to save weight then carrying around a 2nd 30 pound battery/jumpstarter doesn't make any sense at all!
A motorcycle battery might work ok in warm weather when the battery is new but it will have limited amp output, that is where the cold cranking amp rating on a battery is useful, deep cycle golf cart batteries for example can put out sustained amps but they are limited to about 600 peek amps, put an amp meter on them and short them out with a solid copper bar and at 600 amps the voltage will start dropping down to near -0-
In the summer the amp draw of a starter is a lot lower then it even is at 40F, get down to -0- and the amp draw goes up even more and at that point a motorcycle battery will not work even if it is brand new.

If you over charge/undercharge lithium batteries you will destroy them, I don't know of any lithium batteries (without a battery management system) that you can over charge or drain way down, so altho you can put huge loads on them they are still sensitive.

Capacitors might be the solution, there are people who have replaced their lead acid battery all together with a big capacitor and have it last a few days before it goes dead, add a solar panel and it will stay charged outside forever, or pair it up with a small motorcycle battery and it will stay charged for months, then add the solar panel and you can park it in the garage too!

[Honda100]

I had a Nissan 240sx with a a 54 lb battery and then went 180 CA little tiny pack that I made myself. Weighed 14 lbs I think. However though, the CR on my car was 13.1:1 and the battery quite often did not have the power needed to turn the motor over, so I often had to bump the starter a few times until fuel made it into the cyilnders, which would lube them enough to get the car to start easier. However, that battery was for a track car, so I'd assume a regular car would be fine.

Also on a stupid note, for my Super Cub, I soldered a pack of NiMh double A batts (10 total) to make a 12v pack and it works just fine. I saved a massive 3 lbs of weight!

[NoD~]

WOW those are spendy little batteries (but definitely tiny!)

The batteries I'm talking about were like $30 from wal-mart a pop... lol.
EverStart U1P-7 Lawn & Garden Battery: Automotive : Walmart.com

I'd be using one now if my current DD didn't have a scrap full size battery already in it... whenever it goes out, I'm sure I'll pull out the 'ol 1/2 sized battery tray and mount a new L&G battery to it.

[96vtec]

Originally Posted by Frank Lee

Then the point would be what?

Originally Posted by Ryland

I agree with frank, if the idea is to save weight then carrying around a 2nd 30 pound battery/jumpstarter doesn't make any sense at all!
A motorcycle battery might work ok in warm weather when the battery is new but it will have limited amp output, that is where the cold cranking amp rating on a battery is useful, deep cycle golf cart batteries for example can put out sustained amps but they are limited to about 600 peek amps, put an amp meter on them and short them out with a solid copper bar and at 600 amps the voltage will start dropping down to near -0-
In the summer the amp draw of a starter is a lot lower then it even is at 40F, get down to -0- and the amp draw goes up even more and at that point a motorcycle battery will not work even if it is brand new.

If you over charge/undercharge lithium batteries you will destroy them, I don't know of any lithium batteries (without a battery management system) that you can over charge or drain way down, so altho you can put huge loads on them they are still sensitive.

Capacitors might be the solution, there are people who have replaced their lead acid battery all together with a big capacitor and have it last a few days before it goes dead, add a solar panel and it will stay charged outside forever, or pair it up with a small motorcycle battery and it will stay charged for months, then add the solar panel and you can park it in the garage too!

Actually, a second battery is very light. Motorcycle batteries are about 20lbs max and the more common ones weight around 10lbs. Now the small jump starter I refer to weighs about 8 lbs (personally weighed it myself) and has enough juice to jump start my 95 240sx when that battery dropped down to 8.5v)
Clore JNC300XL 'Jump-N-Carry' 900 Peak Amp Ultraportable 12-Volt Jump Starter with Light : Amazon.com : Automotive
So we're still looking at under 20lbs for the setup with the flexibility of carrying a small jump starter with you for the times you know you might be playing your radio for too long or maybe when you leave those parking lights on for too long.

You could always switch your hazards lamps to leds as well. You would need to sit around for hours on end for a 14ah battery to lose most of it's cranking amperage. With the 7ah battery found in my jump starter, which provides 115cca, it'll most likely make up for the difference.

For most, that lawn mower battery from Walmart will work just fine but a main reason why it may not have enough juice is because it's located too far from the starter. No one seems to have addressed the thicker wiring that'll be required to use these smaller weaker batteries successfully.

Again, as far as load testing the motorcycle battery goes, the Miata car battery I referred to earlier was tested at 420 Cranking Amperage while my 30ah motorcycle battery puts out 620 Cranking Amperage. Not too sure how accurate O'reilley's load testers are but they agreed to pull out another Miata battery to test and that had the exact same rating. Those Miata batteries are rated at 320CCA 400CA while my battery was rated at 385CCA ?CA...
References:
Super Start® Platinum MIATA - Battery | O'Reilly Auto Parts
Yuasa YUAM6230X YIX30L-BS Battery : Amazon.com : Automotive

AGM batteries are much more sensitive to over-charging and over-discharging than conventional batteries but that should be accounted for during the engineering process in motorcycle batteries.

Also as a side note, the Yuasa battery will be many times more reliable than the cheaper Walmart battery because they're owned under the parent company, "Enersys" (Same company that manufacturers Odyssey batteries)

"Unspillable. This means even if these batteries get tipped on the side or turned upside down the electrolyte is not going to spill out of an AGM battery. That makes this battery good for the environment and safer to handle.
An AGM battery never needs watering. It is considered to be maintenance free. This makes these batteries ideal to use in situations where getting hold of water to water a battery may be an issue.
AGM batteries don't give off any gas when being charged so there is less worry about having the right ventilation when charging an AGM battery.
AGM batteries can withstand very low temperatures without freezing or cracking.
AGM Batteries are highly vibration resistant due to their sandwich construction, making them the ideal battery to use in circumstances where vibration could otherwise be an issue."
What is an AGM Battery | Advantages of an AGM Battery | AGM Battery Charging

[Frank Lee]

The average car battery is 39 lbs. so you are looking at less than 20 lbs. savings. If losing 20 lbs. or less is satisfactory, take the stereo equipment out; that won't cost you anything either.