I've used my Dewalt 14.4 volt cordless drill's battery, oh, 83,423 times in the last 8 years,
Most times were regular drilling and screwing.
BUT
32 times were for running a night light on my mountain bike
AND
21 of them were on fishing trips running a FF strapped on a float tube. Which ran an easy 7 + hrs.

14 volts worked just fine, I wouldn't suggest 18 volts tho...

What a great multi use investment.

Anyone else do this?
Do lithiums last very long?
Mine are the old school NiCad's
I have two from the .

I think most FFs are set to run on 12VDC. I would be careful running it on a different voltage. 14V is probably fine but I would think going to 18V could cause some problems. Increasing the voltage is not going to make the FF run longer. You need more amp hours in your battery to make it run longer.

I'm not an electrician but that is just my understanding.

I mentioned the 14.4 volt cause I've done it and I think its hard to get 12 volt cordless drills any more... at least in the better brands of tools. Most are 18 + volts.

Anyway, its a good way to have an excellent kit, a good battery and matched charger, (and a drill)

I bought one of these and stole the battery from it! Its lithium and lasts for ever and weighs almost nothing!

http://www.harborfreight.com/12-volt-cordless-38-pro-lithium-ion-drilldriver-69360.html

Most charging system charge 1-2 volt above battery voltage so 14 is fine. I use a 12v Makita battery for a couple years but corrosion did it in. I had extra so no big deal but at $70 a battery I wouldn't buy it for that purpose.

Lithium is great but if you use it too long and drain it too much it will be damaged. Most litium devices have a shut off to avoid damaging the battery by drawing too low.

The extra batteries are cheap! 19.99!!! and lithium last a long time most fish finders dont draw that many amps! and way better than those heavy lead acids!
http://www.harborfreight.com/12-volt-lithium-ion-replacement-battery-68059.html

This may be stupid but how do you hook the wire leads to it? How about a picture.

Understood. I like the idea I just would caution others about using an 18V battery on a 12V fish finder. I think you will do damage to the equipment. For example, don't take a tv in America that is set up for 120v to London and plug it in because they use 220v. You'll screw up the TV. The voltage has nothing to do with how long the battery will last. I could be wrong here. Can someone clarify?

The Humminbird spec is 10-20vdc.

I stand corrected.

For batteries like the Dewalt, simple female blade connectors are all u need


I had some makita batteries that had only simple but recessed flat pads for contacts, those required some sort of cannibalizing of an old tool or.... some small wads of wire and duct tape !