Battery idea! - Kayak Fishing Adventures on Big Water’s Edge

Zurc · 08-26-2010, 03:54 PM

Hey Everyone me again:

I was going thru all sorts of forums on this wonderful hobby and came across an article where someone used 8 AA battaries to power up there fishfinder. Now since I don't have a kayak yet i can't try this on my own but has anyone ever thought of using a pair of R/C battery packs to power up there fishfinder?

Now most of these packs are about $14.00 and are 7.2V, but I figure if you have a little electrical knowlage you can connect 2 of them in series and get 14.4V out of it and run a fishfinder for a few hours and reduce the weight in your yak considering they only weigh a few ounces.

Let me know what you guys think and if it's doable.

R/S
Hector

dsafety · 08-26-2010, 06:56 PM

Ignoring for the moment the weight factor, you can get a 7ah 12V battery online for less than $20 delivered. Yes they weigh a lot more than the little batteries but they last much longer.

Personally, I don't think about the weight that much. If you are worried about it, leave the beer at home. Most kayaks can easily handle a load of several hundred pounds.

If you get lucky and have to transport a bunch of 60 pound fish, you might have a problem but I doubt that going with a lighter battery would make much of a difference.

Bob

RedSledTeam · 08-26-2010, 08:03 PM

Zurc,
Cool idea, however you need to compare battery capacities for an accurate comparison. And when it comes to capacities, there is a matter of milliamp-hr versus amp-hr:

Milliamps Hour (mAh) is important because it's the easiest way to distinguish the strength or capacity of a battery. The higher the mAh, the longer the battery will last. Batteries with different mAh ratings are interchangeable. If your battery is rechargeable then the mAh rating is how long the battery will last per charge.

Milliamps Hour is 1/1000th of a Amp Hour, so a 1000mAh = 1.0Ah Think of your truck's gas tank. Voltage is how much gas is being used, and mAh is the size of the gas tank. The bigger the gas tank (mAh) rating the longer the device will run. If your battery is rechargeable, then think of the gas tank as refillable (rechargeable).

Connecting 2 - 7.4 batteries in a series (+ to - ) will give you about 14.8 volts, however capacity ratings on the side of your batteries are about 1200 mah or 1.2 ahs. Safety dude mentions a 7 ah battery, your system is about 2.4 ah, 34% of Safety dude's. So in this case, capacity size matters!!

Zurc · 08-26-2010, 08:29 PM

Quote:

Originally Posted by RedSledTeam

Zurc,
Cool idea, however you need to compare battery capacities for an accurate comparison. And when it comes to capacities, there is a matter of milliamp-hr versus amp-hr:

Milliamps Hour (mAh) is important because it's the easiest way to distinguish the strength or capacity of a battery. The higher the mAh, the longer the battery will last. Batteries with different mAh ratings are interchangeable. If your battery is rechargeable then the mAh rating is how long the battery will last per charge.

Milliamps Hour is 1/1000th of a Amp Hour, so a 1000mAh = 1.0Ah Think of your truck's gas tank. Voltage is how much gas is being used, and mAh is the size of the gas tank. The bigger the gas tank (mAh) rating the longer the device will run. If your battery is rechargeable, then think of the gas tank as refillable (rechargeable).

Connecting 2 - 7.4 batteries in a series (+ to - ) will give you about 14.8 volts, however capacity ratings on the side of your batteries are about 1200 mah or 1.2 ahs. Safety dude mentions a 7 ah battery, your system is about 2.4 ah, 34% of Safety dude's. So in this case, capacity size matters!!

I never even thought about that good catch! This idea came spur of the moment when I was looking at an R/C catalog. Hey It was an idea i figured I would throw it out there. Well till next time!

R/S
Hector

peguinpower · 08-27-2010, 09:56 AM

I bought a bunch of 8000 mah nimh d cells off eBay and made pack for my ff only because I already had charger. Worked good, for little while. a few months of use corroded them pretty bad despite my efforts to seal them. I wouldn't recommend it. Sla batteries and chargers set ups are sealed and way cheaper.

Fiskadoro · 08-27-2010, 10:15 AM

Quote:

Originally Posted by Zurc

Hey Everyone me again:I was going thru all sorts of forums on this wonderful hobby and came across an article where someone used 8 AA battaries to power up there fishfinder. Now since I don't have a kayak yet i can't try this on my own but has anyone ever thought of using a pair of R/C battery packs to power up there fishfinder?

I do it.

Been using a 12v 10ah RC/Scooter battery (they market them for different things) for about three years now. No issues, works fantastic!!

12v 10Ah (10,000mAh) NiMH built from 10 NiMH D cells

It's much smaller and lighter weight then even a seven amp hour battery

What most people do not realize is that a Lead acid battery drops voltage in a curve so when you run a finder on one it usually stops working when the battery is about 2/3 through it's discharge, because by then the voltage output is too low for the finder.

In contrast NiMH batteries hold their voltage flat until completely discharged, so you actually get more time as you can use the full capacity (ah) of the battery.

Like I said works for me wouldn't even consider using a lead acid (sla) for my finder at this point. I use a lead acid for my bait tank 6v 12 ah, but I have had to replace those twice since I switched to the NiMH for my finder.

It just lasts and lasts and lasts.....

Jim

peguinpower · 08-27-2010, 10:42 AM

You forgot to mention that that is a 50 dollar (min) pack, with 5 bucks of HD shrink wrap, another 5 for a tube of goop, and that you need a 100 dollar charger (10 cell chargers arent cheap)and a 12 v power supply

25 bucks for an sla, 5 bucks for a float charger from harbor freight, is reasonably cost effective.

Fiskadoro · 08-27-2010, 12:46 PM

Quote:

Originally Posted by peguinpower

You forgot to mention that that is a 50 dollar (min) pack, with 5 bucks of HD shrink wrap, another 5 for a tube of goop, and that you need a 100 dollar charger (10 cell chargers arent cheap)and a 12 v power supply...25 bucks for an sla, 5 bucks for a float charger from harbor freight, is reasonably cost effective.

Yeah it's not cheap. I got mine as a packaged deal with a multi voltage float charger set up specifically for it, and the package was $75.

The charger alone was around forty, and the batteries alone would of been over sixty.

My take is it's already outlived two SLAs so it's pretty much getting to the point it paid for itself, and the performance is superior. It's supposed to be good for a thousand charges we'll see how long it lasts.

Jim

dsafety · 08-27-2010, 01:02 PM

Quote:

Originally Posted by Jim Day

What most people do not realize is that a Lead acid battery drops voltage in a curve so when you run a finder on one it usually stops working when the battery is about 2/3 through it's discharge, because by then the voltage output is too low for the finder.

In contrast NiMH batteries hold their voltage flat until completely discharged, so you actually get more time as you can use the full capacity (ah) of the battery.

Like I said works for me wouldn't even consider using a lead acid (sla) for my finder at this point. I use a lead acid for my bait tank 6v 12 ah, but I have had to replace those twice since I switched to the NiMH for my finder.

It just lasts and lasts and lasts.....

Jim

This is great information Jim. I never thought of the discharge rate curve before.

You are absolutely right about the lead acid batteries voltage dropping to a point where the FF will not work. At this point there is still plenty of juice left to run a bait tank pump but not the electronics.

I can usually get about 8 hrs out of my 7ah battery before the screen goes dark. Leaving the unit off for a while will coax a bit more life out of the battery but not a lot.

Do you have a reasonably priced source for the scooter batteries that you use? What is the typical cost?

Bob

08-26-2010, 03:54 PM	#1
Zurc Junior Join Date: Aug 2010 Location: Tunis, Tunisia Posts: 26	Battery idea! Hey Everyone me again: I was going thru all sorts of forums on this wonderful hobby and came across an article where someone used 8 AA battaries to power up there fishfinder. Now since I don't have a kayak yet i can't try this on my own but has anyone ever thought of using a pair of R/C battery packs to power up there fishfinder? Now most of these packs are about $14.00 and are 7.2V, but I figure if you have a little electrical knowlage you can connect 2 of them in series and get 14.4V out of it and run a fishfinder for a few hours and reduce the weight in your yak considering they only weigh a few ounces. Let me know what you guys think and if it's doable. R/S Hector

08-26-2010, 08:03 PM	#3
RedSledTeam Daddeo Join Date: Jul 2010 Location: OC Posts: 660	capacity ratings Zurc, Cool idea, however you need to compare battery capacities for an accurate comparison. And when it comes to capacities, there is a matter of milliamp-hr versus amp-hr: Milliamps Hour (mAh) is important because it's the easiest way to distinguish the strength or capacity of a battery. The higher the mAh, the longer the battery will last. Batteries with different mAh ratings are interchangeable. If your battery is rechargeable then the mAh rating is how long the battery will last per charge. Milliamps Hour is 1/1000th of a Amp Hour, so a 1000mAh = 1.0Ah Think of your truck's gas tank. Voltage is how much gas is being used, and mAh is the size of the gas tank. The bigger the gas tank (mAh) rating the longer the device will run. If your battery is rechargeable, then think of the gas tank as refillable (rechargeable). Connecting 2 - 7.4 batteries in a series (+ to - ) will give you about 14.8 volts, however capacity ratings on the side of your batteries are about 1200 mah or 1.2 ahs. Safety dude mentions a 7 ah battery, your system is about 2.4 ah, 34% of Safety dude's. So in this case, capacity size matters!!

08-26-2010, 06:56 PM	#2
dsafety Olivenhain Bob Join Date: May 2008 Location: Olivenhain, CA Posts: 1,121	Ignoring for the moment the weight factor, you can get a 7ah 12V battery online for less than $20 delivered. Yes they weigh a lot more than the little batteries but they last much longer. Personally, I don't think about the weight that much. If you are worried about it, leave the beer at home. Most kayaks can easily handle a load of several hundred pounds. If you get lucky and have to transport a bunch of 60 pound fish, you might have a problem but I doubt that going with a lighter battery would make much of a difference. Bob

08-27-2010, 09:56 AM	#5
peguinpower bing! Join Date: Mar 2007 Location: socal Posts: 246	I bought a bunch of 8000 mah nimh d cells off eBay and made pack for my ff only because I already had charger. Worked good, for little while. a few months of use corroded them pretty bad despite my efforts to seal them. I wouldn't recommend it. Sla batteries and chargers set ups are sealed and way cheaper.

08-27-2010, 10:42 AM	#7
peguinpower bing! Join Date: Mar 2007 Location: socal Posts: 246	You forgot to mention that that is a 50 dollar (min) pack, with 5 bucks of HD shrink wrap, another 5 for a tube of goop, and that you need a 100 dollar charger (10 cell chargers arent cheap)and a 12 v power supply 25 bucks for an sla, 5 bucks for a float charger from harbor freight, is reasonably cost effective.