DIY Battery Box

My Humminbird has a low voltage warning set at 9V, then, shortly thereafter the unit turns off.  If I recall correctly, the charts I've seen on voltage versus charge capacity indicate an 80% charge when the cell voltage first hits 3.2V (12.6V for our blue bricks).  This is generally when the charger indicates a full charge, so unless you go beyond the charger "full-charge" indication you should be good for storage.  I've been going 30 minutes past the "full-charge" indication and the charging current drops substantially from 10% to less than 5% over that time.  Perhaps I'll stop doing that.

sorry if these questions were answered already...

Can either the male or female connections be used for charging?

Also, what is the danger of having the li-ion's battery switch "on" all the time?

what I'm getting at is...it would be nice to create a little waterproof unit that doesn't need to be opened (often).  I'm thinking a small pelican case containing a blue brick, fuse and a waterproof connector leading to the outside of the case.  So, the case remains closed and you interact with the battery (draw from it or charge it) only thru the single waterproof connector.  I am new to electrical stuff.  As you can tell.

I believe you must charge it through the charging connector. 

Typical indicator LEDs consume about 20mA of power.  In 50 hours such an LED will consume 1 Ah - that's every 2 days.  If you have a 9aH blue brick in a week you will have drained about half the charge. 

Mini LEDs can have power draws as low as about 2mA.  This would lower your power drain by a factor of 10. 

I turn mine on and off. 

Just to be clear, the charging connector is the FEMALE connector on the battery itself, yes?  I've been trying to charge my battery with the "smart charger" and all I get is red.  The first time it was charging for a week, then zee told me the battery switch has to be on for it to charge.  So now it's on and has been charging for three full days and it's still red.  Am I somehow using the wrong connector?  the smart charger connector is male....


smart charger connector (male at the bottom), connecting to the female connector on the battery.  Correct for charging?


what I assume is the "on" position.  Tried charging in the other position for a week and never got green.

WTF is up?

The light on the battery is still red, or the light on the charger is still red?  The charger light should change, the battery will always be red light.

On my charger there's 2 lights.  One that's green when the battery is plugged in and turned on.  The other is red.  Does the red one eventually turn green when the battery is charged?

Somebody correct me if I am wrong, but li-ion batteries should be charged in an open area right? My battery experience comes from RC cars and we have "charging" bags you put batteries in to charge them in incase something happens to them. I've been told to never charge my batteries in the car or an otherwise "closed" enviroment.

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I had similar charging questions when I received mine. Responses I received from the  people that sold the battery on ebay:

This product is a green light, the charge must be 12 hours at the first time ,followed by charging at any time, switch to control charging time can be opened or can not open, off when the lights are not bright, open red ,fully charged when the green .please try it again

If still not work ,please check if the charger is not work or the battery does not charge storage , if the charger is not work ,you can buy it in the local ,if not cost too mouch ,we can cover the fee .
please don't warry ,We will take the responsibility if you still can't make it work

Please keep "on" when you charge for it,
the charger has two ligths , when the battery charge enough , only red light .
we wonder whether the battery has a problem? or the charger.

I gave up and used my 800mA charger, then later bought the 1.5A charger that demonick referenced earlier.

hahahaha...those instructions are hilarious.  OK, I finally figured it out.  I was thinking the light on the battery itself would change to green but that's not the case.  I didn't notice this before, but there is a light on the smart charger itself that goes from red to green (note this is not the stock charger).

Someone should do a definitive "blue brick" setup guide.  The info in this thread is AWESOME but there's alot of tech-speak that is pretty incomprehensible to a knucklehead like me!
I'd buy that person a box of donuts or something.

It really boils down to two simple things:

Switch battery to "on" to charge
Light on the charger will turn GREEN when it's done

*Don't make weird modifications - lithium batteries can kill you.

well, got it all together.  Along with a new finder.  Interested to see how this system does on a fishing day.  Wee bit of a hackjob, but that's my trademark. 

"There's no waterproofing task that half a tube of marine goop can't solve"

I think it achieves the overall goal of reducing weight and simplifying the electronics BS. 

I did a test and found that the blue brick powers my humminbird 587ci HD for 10 hours before dropping below 9V.  Could do probably do longer if I dimmed the screen.

The old 12v SLA generally lasted about 7-8 hours with the screen dimmed.

UPDATE: with the smart charger, it charges full overnight (about 9 hours)

Sweet dude. Is that a rubber grommet in there? If so where did you find it? Might copy this, looks easier than using the mast mount.

Yeah. The guy at the hardware store found it pawing thru some random drawers. I showed him some of the pics posted in the "waterproofing FF cables" thread.

You're going to like that 597 Rory. The lings have no where to run, nowhere to hide. Nice install.