DIYbanter - View Single Post

mike[_22_]

On 4/13/2018 9:46 PM, wrote:
On Fri, 13 Apr 2018 19:27:00 -0700, mike wrote:

On 4/13/2018 4:59 PM, wrote:
On Fri, 13 Apr 2018 15:42:38 -0700, mike wrote:

I considered a cordless tool battery.
I have a 24V lithium drill battery with 6 18650 cells rated for 30A peak.
If I use 3 cells or parallel up 3x2=6 cells, I loose all the advantages
of protection and a working charger. And I'm thinking that 3-cells
may not be enough and 4 cells
in series might be a better option.

I'm seeking suggestions.
Maybe a pointer to a good value on a jump starter that may not
be crap.

* Batteries Plus is a ripoff place. DO NOT do business with them.

Walmart, Menards, and other places sell 12v garden tractor batteries for
around $20 (plus core). By one, and live with it till it dies. I've had
them last 5 or 6 years.

This thing is a 5AH battery with low volume/turnover.
They're not typically on the shelf. Even the local lawnmower place
had to order one and charge me for shipping.
Depending on where you buy it, it may have been in the distribution
chain for most of those 5 years.
It's also not as cheap as a 7AH alarm battery.

OR

Hire some kid to mow your lawn and pay them $20 every week,

OR

Go to a nursing home, where you dont have to mow, but you will pay $2000
every week for your care.

That's insightful. My trigger point for moving to an apartment is
when I can no longer take care of the yard. I plan to pull the plug
before I get to a nursing home.

OR

Screw around with all those laptop batteries, which may cause a fire and
burn down your house, costing you $200,000 (or more).

It's really more about the hobby than the $$.

Looking at these figures, I'd say the $20 battery is your best bet.

If it's a hobby, then do it right. Get a REAL mower battery, as I
suggested. Then modify that mower so you can mount the battery, and
connect that. I kind of know what sort of battery is in the mower and
they were never really useful. They are too small and too costly to
replace. It was a poor design right from the factory. Your job is to
IMPROVE their poor design.

Isn't that what I'm trying to do?
Put in a lithium that will still be charged when I need it and maybe
have other applications.

I'm not entirely stupid.
I have motorcycles and batteries and computers and batteries
and power tools and batteries.
An an engineering degree.
Fire insurance.
I've got a battery tab welder.
A balance charger.
I've built computer controlled battery analyzers.
The hardest part of the whole project is the overdischarge
protection. 46A is a lot for the disconnect switch.
Available/affordable packaged cell monitors draw a lot of current doing
nothing.
It's conceptually trivial up until you have to start packaging it up
into a usable box.

My question was not about any of that.
The question was about a pointer to a specific cost effective
lithium jump starter (see the subject line). All the rest was
just context to stimulate...

If the actual mower batteries are too large
to fit anywhere, motor cycle batteries are a bit smaller, or find a Gel
Cell on ebay and use that. The Gel Cells are typically 12V, but some are
also 6V. They are used in road barracades with flashing yellow lights,
and other things. They are just a small scale lead-acid battery like a
car battery, but the acid is a gel, not a liquid.

If you have a farm supply store nearby, these Gel Cells are also sold
for Solar-Charged Electric Livestock Fencers.