Design/Build Power Box...to Power Fish Finder

Hi guys,  It's winter time, no salmon chasing. I have sometimes away from work here goes the project.
I am designing and building a power bank(I like to call it power box) for a couple closed friends as well as for myself.
It will be using Lithium batteries.
I'd like to see what you guys Needs and Wants in a power box. These are two different things. Give me ideas.

Example: How long would you it to power your FF on the water. Lowrance Elite-5 HDI use 12v 450mAH at Brightness 5. It uses 12v 900mAH at Brightness 10.


At a recent meet up with one of the guy, he loaned me his power bank(Recently release, well known kayak manufacture). It claimed to have 15Ah using only 6 high-capacity cells.
I have worked, tested power bank before. I just could not believe this spec to be true at all due to the size of the power bank.
Sorry, I don't includes the pictures so that I don't meant to bash them. If you know what I am talking about you must have followed the threads or have owned or intending to buy one.

So I gut open this power bank, and here is what I found.
It powers by 6 x 2500mAh Li-ion batteries in parallel. 2500mAh is not high-capacity cell 
They are wired in parallel so 6 x 2500mAh = 15,000 mAH at 3.7V nominal voltage.
Then it uses a boost circuit to bump 3.7v to 12V. This circuit design is not the greatest it can only runs at 1A before it overload and shut off.

15Ah x 3.7V = 55.5W (Convert to Watt)
55.5w/12V = 4.625Ah ( Find out the Ah at 12V)
Technically it is a 4.625Ah Power bank. It is only 1/3 of their paper claim. It will run the Elite-5 HDI for ~10 hours at Brightness 5, and 5 hours at Brightness 10.

Hi guys,  It's winter time, no salmon chasing. I have sometimes away from work here goes the project.
I am designing and building a power bank(I like to call it power box) for a couple closed friends as well as for myself.
It will be using Lithium batteries.
I'd like to see what you guys Needs and Wants in a power box. These are two different things. Give me ideas.

Example: How long would you it to power your FF on the water. Lowrance Elite-5 HDI use 12v 450mAH at Brightness 5. It uses 12v 900mAH at Brightness 10.


At a recent meet up with one of the guy, he loaned me his power bank(Recently release, well known kayak manufacture). It claimed to have 15Ah using only 6 high-capacity cells.
I have worked, tested power bank before. I just could not believe this spec to be true at all due to the size of the power bank.
Sorry, I don't includes the pictures so that I don't meant to bash them. If you know what I am talking about you must have followed the threads or have owned or intending to buy one.

So I gut open this power bank, and here is what I found.
It powers by 6 x 2500mAh Li-ion batteries in parallel. 2500mAh is not high-capacity cell 
They are wired in parallel so 6 x 2500mAh = 15,000 mAH at 3.7V nominal voltage.
Then it uses a boost circuit to bump 3.7v to 12V. This circuit design is not the greatest it can only runs at 1A before it overload and shut off.

15Ah x 3.7V = 55.5W (Convert to Watt)
55.5w/12V = 4.625Ah ( Find out the Ah at 12V)
Technically it is a 4.625Ah Power bank. It is only 1/3 of their paper claim. It will run the Elite-5 HDI for ~10 hours at Brightness 5, and 5 hours at Brightness 10.

Chet buddy, its super cool that you are using your Super Focus on this project (it gives those poor salmon some time to bounce back after you thrashed them (yea Keith, I'm talkin' to you too, along with that other thrasher Andrew)) [emoji23][emoji23]

About Chet's Super Cool Power Bank, I suggest that although you have that HDI handy now, that model and all related have been discontinued, and replaced with the new Carbon models, which use the awesome side-scan transducers. I haven't seen the specs for the sidescan, but it's a good bet that these new units will need more juice than that Elite-5 you are modeling. More juice because they are scanning the area that the HDI's & Hook series scan PLUS side scanning, which all adds up a much larger area & more signal. It's only a matter of time before we all have to upgrade to these new Bad Boys, so you may as well design for that.


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Technically it is a 4.625Ah Power bank. It is only 1/3 of their paper claim.

Thanks for the info. That's a pretty lame excuse for a battery.

Hey Scurvy, hope all is well with you. You know where to find me on the salmon opener.
I'll keep that in mind about those power hungry model. This is a beast FF, it will need a beast power box to go with it.

- HDS Carbon 7 Price at $1,249. 1.5-2.3A @13V.
That is a power hungry unit. I think this will fit in the boat especially at that price.
- HDS-7 Gen3 7 Price at $649. 1.3A @13V.
This one might work.
-Elite Ti, Hook2, Hook run at 0.45-1A @12V.
All these definitely work within a small power box.

Technically it is a 4.625Ah Power bank. It is only 1/3 of their paper claim.

Thanks for the info. That's a pretty lame excuse for a battery.

I have read mixed reviews. Some said it lasts all day. Some said it only last several hours, some said it won't even power their unit.
This will clear some doubt if they know what their unit power usage at. Plug the number and see how long it will run.

Update on this project.

I did some test on current usage on all brightness level as follow:
Why this is important? The more current it draws the faster it runs out of power.
Level 0 - 0.28 A
Level 1 - 0.30 A
Level 2 - 0.34 A
Level 3 - 0.36 A
Level 4 - 0.37 A
Level 5 - 0.39 A
Level 6 - 0.42 A
Level 7 - 0.46 A
Level 8 - 0.51 A
Level 9 - 0.60 A
Level 10- 0.90 A

Something to pay attention to: the current usage jumps from Level 8-9-10 exponentially.
You would get a lot of run time if you stay at Level 8 and below.

Great info, and I don't even have a Lowrance FF.