18v powertool battery to start quad

Hiya all

Looking for some input on an Idea I have been mulling over.
I have a yamaha kodiak 450 that I use for hunting infrequently, because it doesn't get used much the battery always goes flat between uses.
It is an auto so no crash starting, it has a pull start but it's a pain to use, very high compression.
I have been jump starting it off a makita 18v battery and a couple of bits of wire, which works although it's a pain to lift up the seat, sketchy holding wires etc. The other thing I think that's going on is some kind of voltage leak as when I use it at night the lights start to get dim and flicker.

So I had been thinking of making a more permanent set up using the battery connection of an old powertool to hold the battery, run a couple of decent wires off it to the battery leads on the quad, and mount it all securely where the battery normally goes, the idea being that I have lots of makita batteries so can just swap them out as needed and carry a spare one under the seat too.

Just thinking about the electrical side of it, wonder whether I need to put in a resistor or some other way of stepping down the voltage from 18v-12v or just not worry about it.
Also if I need to put in a diode so the bike isn't trying to charge the battery as I know the makita batteries have all sorts of clever electronics in there. (Possiblity that the generator on the bike isn't working anyway)

The whole plan here is to have a bike that I don't need to keep buying new batteries for as they seem to drain beyond recharge levels, and use batteries that I already have so I can just plug them in and away I go.

I've seen there are a few electronic geniuses on here so hopefully you can throw in your 2c.

Cheers

Why not just put a battery maintainer on it?
If you have power where the bike is just put it on a battery maintainer plugged into an outlet.
If you don't have power buy a solar battery maintainer.
Then it'll keep your battery healthy.

Had thought about it, no power where it's stored, didn't know you could get solar ones

Just fix it properly instead of re engineer the bike around a fuked battery and or charging system...

Have a mate who uses his dewalt battery to jump start his dmax ute.

I'd suggest fix the issue.
Maybe a isolator switch, for when not in use.

Or -
Just found this amazing item on AliExpress. Check it out!
NZ$28.61 50%OFF | DC 18V to 12V Step Down Converter Adapter for Makita Li-ion Battery 10A 120W DIY Adapter Automatic Buck Boost Voltage Regulator
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just get a small solar panel and a controller
try sunnytech.co.nz

Just get yourself a lithium ion jumpstart pack, they are the same size as an external hard drive. I carry one on the boat and it's saved my arse on 1 occasion so far

Repco do a set of connectors like the Anderson type, with these you can run a set of leads directly off the battery and have a decently rated easy to connect plug tucked away somewhere on the quad so you can simply plug a solar trickle charger in or if you have to connect a jump pack without have to fart about getting the seat off and into the battery.

As far as the pull start, there is usually some sort of emergency decompression lever setup on the motors around the head area, have you looked for that to see if it's present?

Agree with whoever said that you need to fix the cause of this issue though - it could be simply you have a rooted battery with a cell bridged or reversed inside it so that it's internal resistance is super high or it's self discharging in a matter of days. If this is the problem it could result in damage to other electrical bits that result in the machine stopping on you no spark no go walk home. Not ideal... If it's a charging fault and not the battery could have the same effect. Other potential issues are the starting circuit or ignition full of crud which is allowing electrons to run away - it's amazing how quickly one of those little batteries can go flat.

I went through a TRX300 a couple of years ago, got it cheap off someone on here (can't recall who and lost the PM's but thanks). Very handy little lifestyle block yard tractor... Welded up the chassis, replaced the front diff which meant I had to replace the front swingarms due to seized bolts, and then had to sort the electrics out which basically meant stripping everything electrical and removing the cowshit and mud and then replacing the battery and aux starting solenoid - after all of that it's a reliable good running easy starting machine and I can leave it parked up for a few months with the key off with no issues. You can do it haha.

my wifes quad has a $10 solar panel from bunnings mounted we are on the 3rd battery in 13yrs the first was original 2004 and lasted 10yrs we only buy the lead acid yuasa bats now that you fill up and charge the rest are crap . Im on my 4th yammy and I swear I dont even touch the starter most of the time they just start if I hover my finger over the button . All my toys and chargers have mini 50amp anderson plugs on short leads made out of old jumper leads I get boxes of 10 plugs from ali for about $20 , cheaper than buying here .

If the generator on the bike isn't working, it wouldn't run for long without a charged battery, if you get more that 5 mins from the bike after a jump start, the generator should be working. Speaking as someone who was an electrician in a previous life, I can say that there are all sorts of ways and means for doing what you are trying to do.
But the two most pragmatic things that have already been suggested are:

1 Small solar panel and regulator.
2 Emergency jump starter pack.

Not a silly idea to go with both. for the emergency jump starter, you could wire a cigarette lighter socket plug onto your bike, this would make it easy to plug in for jump starting. These starter packs can also run a spotlight quite well so it isn't like a PLB that is useless until it is useful.

I wouldn't persist with jump starting from an 18V Makita battery. In due course it may ruin your bike electrics and or the battery.