I have some land along with the many things used for upkeep - tractors, mowers, ATV, log splitter, boats, etc, etc. And keeping all those batteries charged and in good condition can be a chore when some are stored far away from a power supply.

What I'm wanting to do is put together a lithium 3S or 4S battery pack (depending on chemistry) with a BMS to protect it and maybe even a large capacitor like used in car audio(?), that I can take to whatever I'm using that day and clamp it on and be able to start it 15-20 times - maybe twice that for good measure. Most of the machinery has a battery rated around 300 CCA. I imagine my current boat with a 115 hp outboard requires the most amps but will have to look into it's specs for a number.

Is this something that is feasible? I'm great with mechanical things and ok with basic electrical but get uncomfortable with stuff like this without getting advise. I don't mind if it's 20 or even 30 lbs and the size of a large truck battery, but it would be great to only have 1 battery to worry about for the things that may only get used a few times a year.

Any and all thoughts would be appreciated! I have done some research but would like to get some input first.

Thanks!

 

If building a battery lithium iron phosphate seem to be safer and i like the headway 38120hp 200amp discharge 3.2v 8ah so a 4s 3p 13.3v at 600amp. i have a 4s 4p 13.3v 800amp and have used it a lot have not found a car it want start just can't leave it on the car for more then a few min or it will over heat your alt and over charge the battery a 4s bms is best.

 

The best solution is to put a small Solar-Charger on all of your Batteries.

The second-best solution, is a Golf-Cart,
either a Battery-Powered Golf-Cart,
or if Gas-Powered,
one with a large Automotive-style-Alternator and Battery installed.

Letting your Batteries routinely go dead will seriously shorten their Life Expectancy.
I'll bet that You replace Batteries on a regular basis.
.
.
.

 

Hi Buddy, that's the type of info I'm looking for. Using your example, would that 4S3P have a 24 AH capacity?

I just read about a prismatic cell and how they have more internal surface area and might be better for short, high drain applications? Will research more.

Could a capacitor be a good idea if there is no other battery that is being "jumped" that has some capacity left? If the battery pack is starting engines alone it seems like a cap could help get things turning so it's not all on the battery?

I have more questions but out right now so will start with this.

Thanks!

 

Lithium-Based-Batteries are very "high-maintenance" items,
and will NOT tolerate even the slightest misuse or neglect.
Not recommended on a Farm for any application.
( but they're great for Race-Cars, much lighter weight )

For a Capacitor to be useful in this scenario,
it would have to be twice the size of the usual Car-Battery,
and cost a least 5-times as much as a Car-Battery.
The only advantage is that it would be around 1/3rd of the weight.

Use an "Optima" Spiral-Wound-Gel-Cell-Battery,
they are worth their ~$250.oo price-tag.
( they still need to be kept fully Charged, just like any other "Lead-Acid" Battery ).
( they'll last well over ~5-years when kept on a maintenance Charger )
Optima-Batteries have the lowest "Internal-Resistance" of any readily available Lead-Acid-Battery,
and, they are completely sealed, and can even be mounted upside-down with no issues.

If You have to "Jump-Start" any other Lead-Acid-Battery,
that dead Battery is already internally damaged to some degree.
If it happens twice, start saving-up to replace it.
If it happens ~4-times, the Battery is completely ruined.
The trick is, KEEP THEM CHARGED at all times.
13.6-Volts minimum Charge.
.
.
.

 

Crack yes that would be a 24 ah 307.2wh at 600amp continuous discharge. Prismatic cells are great I have sum for my solar the ones I use are 25 amp hour in 4S 2p configuration for Max discharge of 100 amps the problem with Prismatic cells are that thay don't have a very high discharge rate so you would need 100 ah Prismatic cells to do a 300 amp discharge. The Headway 38120hp were originally designed for starting diesel engines in cold climate from everything I've read on the internet and they're actually Surplus batteries I use mine in my solar setup too but I also use them for starting cars I do bypass the BMS because I just can't afford 900 amp BMS the one I use is 100 amp and it's great for charging an equalizing the cells.