Suggestions invited on what to do with Makita 18 Volt battery holder?

[John the kiwi]

I bought said item thinking i could use it to replace the NiMH battery on the lawn mower that simply starts the motor - or it used to anyway!
The NIMH was charged by a wall charger NOT by the electrics on the mower, so I figured i could get a Makita battery holder, fix and connect it to the lawnmower and just plug in a battery to start the mower when needed. I have a number of Makita tools and batteries so there is always a charged battery available.

In theory there is no difference between theory and practice but in practice there is! And so it proved!

The makita battery started to spin the motor momentarily then blew the 30 amp fuse.
My reading is that 30 amps is the upper sensible limit for a 4 Ah Makita battery.
I suppose i could get another and put them in parallel, but that is starting to be a non elegant solution. I have a plan b for the mower.

My question now is what could i usefully do with the Makita battery holder? Something boat related would be favourite, but 18 volts presumably limits options in a world of 12 volts or 24 volts?
Ideas solicited.

 

[Refueler]

Why are you using such holder which is designed to Failsafe protect the battery.

I suggest you construct own connection to battery direct to mower so no longer using such holder.

But its possible that the Makita battery is just not suitable and you may be pulling more amps than the battery itself can live with. Starters tend to have very high initial demand and then reasonably high to continue. That initial could exceed what battery can do.

What to do with holder on the boat ?? You could always get a DC to DC converter for just a couple of quid of eBay and create a 12v power supply ......

 

[Boater Sam]

If the motor turns over slower than intended, the current will be higher due to there being less back EMF.
Hence the fuse blows.
I suspect that the original NiMH battery limited the available current due to its internal resistance and the better Makita battery does not.

 

[GHA]

My question now is what could i usefully do with the Makita battery holder?

You could add something like this >

And have yourself quite a sophisticated roving power supply, I've similar & use it a lot, useful setting a current limit low so you can test stuff without blowing it up