Any reason not to use drill battery for plotter

Brinormeg · 19 June 2021, 21:54

I'm away to build a power bank box for my plotter and probably add a usb and inline fuse for the phone using a kit off ebay. Not an expert in electronics and battery chemistry but is my reasoning below correct? What do you guys think?

Lead acid 12v: I can get free batteries from fire systems, hoisting equipment 2.8Ah/12.0Ah and even if buying new they are cheap but also heavy and bulky and not a great power to weight ratio

Lithium : Smaller and lighter, better power/weight ratio but expensive and I can’t them for free

LI-ion drill battery 4.0Ah/6.0Ah: Smaller, lighter than lead acid. Already have a few of them! Is a Li-ion battery using the adapter below a better option to use, as I havent seen anyone use these in their DIY power box builds on here.

https://www.ebay.co.uk/itm/193848496...gAAOSwAAtgf-01

Looking at my 7” fishfinder/plotter specs: Max Power Consumption 1.25A@13vDC with backlight on full. Fuse 5amp. Supply Voltage 10.8-17VDC

Edit: just realised my dewalt stuff is 18volt

Oldman2 · 19 June 2021, 22:02

You can use a buck convertor to drop your 18v to 12volt

GuyC · 19 June 2021, 22:03

You could use one of these to step it down from 18v to 12v

https://www.visionmarine.co.uk/victr...41215200r.html

GuyC · 19 June 2021, 22:05

I suspect we are talking about the same thing but I was a bit slower on the keyboard

Oldman2 · 19 June 2021, 22:07

Quote:

Originally Posted by GuyC

I suspect we are talking about the same thing but I was a bit slower on the keyboard

And mine are a LOT cheaper at £4 or less

well Ebays, not mine

Brinormeg · 19 June 2021, 22:23

Quote:

Originally Posted by Oldman2

And mine are a LOT cheaper at £4 or less

well Ebays, not mine

You could have been Aberdonian in a previous life

Been following yours and the other folks mods with interest
We are known as being as tight as a ducks arXe

Just had quick look on ebay to see what a "buck convertor" was

Just need to find one 18v to 12v prewired then put fuse between that and output just in case it goes faulty. Dont want to be messing about soldering.

Would that be right?
https://www.ebay.co.uk/itm/254355427...IAAOSwuxpZbsI1

Oldman2 · 19 June 2021, 23:39

You need one that accepts 18v input so really variable in and you set the output to 12v.
You made the choice harder by saying no soldering, here is an example though that should work for you. https://www.ebay.co.uk/itm/383870254792 It needs to be 4 or 5 amp working max load even though you say 1.25A total load, you might plug something else in and China max load are always think of a number and halve it!

Oldman2 · 20 June 2021, 03:55

Ive had a think about this and spending money to get drill batteries to do a job you already have access to "free" 12 volt batteries for is pointless. A YUASA NP7-12FR 12V 7Ah battery will run your plotter all day long with no add on convertor/adaptors, weighs more than your drill battery but its not much more.
Just keep it simple (and cheap)

Brinormeg · 20 June 2021, 12:15

Quote:

Originally Posted by Oldman2

Ive had a think about this and spending money to get drill batteries to do a job you already have access to "free" 12 volt batteries for is pointless. A YUASA NP7-12FR 12V 7Ah battery will run your plotter all day long with no add on convertor/adaptors, weighs more than your drill battery but its not much more.
Just keep it simple (and cheap)

Yeah...the extra hassle and cost, and with more things to go wrong while bouncing about at sea...I will maybe park that idea for the time being.
Although it might be practical for others. If they have the drill batteries and the charger.

For now I think you are right, its best to just have a straight connection with an in-line fuse from battery to finder unit, and stick the battery in a old camera bag or food container as others have done here. Will just need to buy a 12v charger, which is always handy to have anyway and saves borrowing the neighbours

Might buy one of that pre-wired cig/usb/voltmeter/display switched control panels off ebay and have a play, if I want to go really fancy

While looking for water proof boxes I did come across these below and something similar might be useful protecting other electronics onboard or for the plotter in transit.

But to be honest I think a Suzuki 20Hp and the Volaire 390 are going more of a concern to move around than a slightly heavier battery

Heard from terry last week and hopefully be on its way very soon. Getting impatient as hell now!

https://www.ebay.co.uk/itm/284193230...53.m1438.l2649
https://www.ebay.co.uk/itm/402774696...53.m1438.l2649

Oldman2 · 20 June 2021, 12:29

If you are buying a battery charger, make it a bit more future proof by getting one thats LiFePO4 compatable for when you go for that super light small battery.
Something like this but thats just the first I saw so research for best price that suits your needs.

https://www.amazon.co.uk/HTRC-Compat.../dp/B08L3LN8ZR

Fenlander · 20 June 2021, 12:29

Yep best decision really... I had similar thoughts to Oldman re simplicity of a 7ah battery which is what we always used when we had a "plumbed in" plotter/sounder. Lasted easily a couple of days.... would have done a week of shorter days.

willk · 20 June 2021, 12:38

Not sure I'd want to take a £50 lithium drill battery to sea in a wet SIB. Lithium and salt water aren't the happiest of bedfellows.

Brinormeg · 20 June 2021, 12:49

Quote:

Originally Posted by willk

Not sure I'd want to take a £50 lithium drill battery to sea in a wet SIB. Lithium and salt water aren't the happiest of bedfellows.

Yeah another reason to drop the idea for now, although any battery would be best kept in watertight container I suppose.
And will look out for future proof charger as well, as price and technology changes