Battery Options (RC?)

So my ghetto rig ff setup corroded beyond repair so it's time to do it right.  I am thinking of building a battery box like Swafish details in his power supply article, but a visit to the RC car hobby shop and a conversation with a friend gives me ideas to try something new...

Option 1:  Use the scwafish method, 10 rechargeable AA's, but rather than pull them out to recharge individually, just seal up the whole deal in electrical tape and use an RC battery charger to charge the whole sealed battery unit, (inside a padded waterproof container, of course- detachable by 2-pin trailer connector).  I figure if you're dealing with 20 contact points each time you're just bound for problems eventually.

Option 2:  Instead of making my own rechargable battery pack, use an RC car battery pack.  They are relatively cheap, and basically the same thing, aren't they???

Thoughts, suggestions???
   

Eric it depends on what you want,major variables are weight vs cost.

 Look up  your Fishfinders "Current Draw", example Humminbird model 717= 250 mA.

Multiply the current draw by the hours of use you want,ie 10hours x 250mA=2500mA or 2.5Ah.

Or take a known battery size 3.4ah(3400mah)and divide by current draw 250mah=hours of use. ie 3400mA divided by 250mA =approx. 13.6 hours of use.

Examples of size-weight-cost

 The least expensive is a sealed lead-acid battery.             12volt- 3.4aH, 2.87lbs., $21

Next up the list would be a NIMH battery pack.                             12volt-3.8aH, 1lb.6oz., $39.95

Cutting edge but muy expensive LiFePo4 pack.                      12volt-3.0aH  .95lbs.,  $75.50

 The LiFePo4 is supposed to have a much longer lifespan.

EricB.... Excellent question.  I've been wondering the same thing.

Mark, THANKS for that great explanation.  Now, I think finally understand something about battery power.

I was considering the RC car battery packs because of the light weight.  I often portage my yak on my head, so every ounce counts, and I would like to avoid installing the battery pack on the beach. 

I had been using 2000ma AA's and they seem to last plenty long- several trips easily- and are light enough.  The weak point is so many contact points, (imo).

Thanks for the breakdown, Mark.

Update:

I am going to solder up ten 2000ma AA's and dip them in that plastic dip stuff made for coating tool handles, etc.  And that will go into a padded waterproof Loc n Loc container.  That should solve my corrosion issues.

My buddy gave me a RC battery charger that will charge any configuration, so I can plug the battery pac right into it instead of messing with charging 10 individual AA's.

Pics to follow.

Eric it depends on what you want,major variables are weight vs cost.

 Look up  your Fishfinders "Current Draw", example Humminbird model 717= 250 mA.

Multiply the current draw by the hours of use you want,ie 10hours x 250mA=2500mA or 2.5Ah.

Or take a known battery size 3.4ah(3400mah)and divide by current draw 250mah=hours of use. ie 3400mA divided by 250mA =approx. 13.6 hours of use.

Examples of size-weight-cost

 The least expensive is a sealed lead-acid battery.             12volt- 3.4aH, 2.87lbs., $21

Next up the list would be a NIMH battery pack.                             12volt-3.8aH, 1lb.6oz., $39.95

Cutting edge but muy expensive LiFePo4 pack.                      12volt-3.0aH  .95lbs.,  $75.50

 The LiFePo4 is supposed to have a much longer lifespan.

Mark, so then the water-bottle battery set up you described on my post is 4.2 ah, and is pretty juicy, right?

Eric it depends on what you want,major variables are weight vs cost.

 Look up  your Fishfinders "Current Draw", example Humminbird model 717= 250 mA.

Multiply the current draw by the hours of use you want,ie 10hours x 250mA=2500mA or 2.5Ah.

Or take a known battery size 3.4ah(3400mah)and divide by current draw 250mah=hours of use. ie 3400mA divided by 250mA =approx. 13.6 hours of use.

Examples of size-weight-cost

 The least expensive is a sealed lead-acid battery.             12volt- 3.4aH, 2.87lbs., $21

Next up the list would be a NIMH battery pack.                             12volt-3.8aH, 1lb.6oz., $39.95

Cutting edge but muy expensive LiFePo4 pack.                      12volt-3.0aH  .95lbs.,  $75.50

 The LiFePo4 is supposed to have a much longer lifespan.

Mark, so then the water-bottle battery set up you described on my post is 4.2 ah, and is pretty juicy, right?

Yeah Dave! Which FF are you using? Lets figure out the battery life...

Its an Eagle Fisheasy 245.  Real basic.  It can't draw too much.

Eagle 245s draw almost nothing...around 0.17A

This link posted by 2-skinny http://www.all-battery.com/index.asp?PageAction=VIEWPROD&ProdID=1590 in another thread looks terrific...newer version of the new school.  I am going to try on 3500mAh is plenty powerful for most apps.

Those appear to be out of stock.

Fisheasy 245 current draw is 170mAh to 240mAh with light on. So a 3.4Ah battery would be good for 14-20hrs. Thats the $20,3lb lead acid battery. The NiMh water bottle is 4.2Ah good for 17-24 hrs. Or heres a 3.4Ah NiMh battery pack and smart charger combo, but you would need a waterproof box and connector.
http://www.batteryspace.com/index.asp?PageAction=VIEWPROD&ProdID=2160

Eagle 245s draw almost nothing...around 0.17A

This link posted by 2-skinny http://www.all-battery.com/index.asp?PageAction=VIEWPROD&ProdID=1590 in another thread looks terrific...newer version of the new school.  I am going to try on 3500mAh is plenty powerful for most apps.

I wouldn't buy from all-battery.com, their batteries aren't very good quality.  They use these tenergy batteries that I feel like a sucker for buying.  Take a look at some of the reviews that aren't on their site:  http://www.productwiki.com/tenergy-aa-nimh-batteries/  They don't come anywhere close to their reported capacity...  I bought 26 of the 2600 MAH tenergys, and the ones that actually worked came in reported at 1.8 - 2.2 mah.  About 10 of them were doa, not charging when I got them.   I could go on, but will stop now...   

These http://www.thomas-distributing.com/maha_2700_rechargeable_batteries.php however last forever, and charge up to 2.85 - 3.5, but they do cost some $$$  You need a good charger to go with em, so picked up a couple of these as well:  http://www.thomas-distributing.com/la_crosse_bc-900_battery_charger.php 

I'm still leaning to the water bottle pack.  Having a bike water bottle rack installed under the main bulkhead sounds real convenient for sliding the battery pack in and out.  I've also been meaning to beef up my mountain bike lighting as well, as I just use a cat-eye light right now.  This will hit both objectives.  Sounds like I could go on 3-4 fishing sessions per charge. 

Thanks Mark, now can you give me advice on managing WAF after buying more toys?    I also want to get a 8 - 9' casting rod.

I'm still leaning to the water bottle pack.  Having a bike water bottle rack installed under the main bulkhead sounds real convenient for sliding the battery pack in and out.  I've also been meaning to beef up my mountain bike lighting as well, as I just use a cat-eye light right now.  This will hit both objectives.  Sounds like I could go on 3-4 fishing sessions per charge. 

Thanks Mark, now can you give me advice on managing WAF after buying more toys?    I also want to get a 8 - 9' casting rod.

I'm afraid you're on your own there buddy! I have a pretty cool wife, up to a point......

Update:

I made my own battery packs using 10 recharchable 2000ma AA's from Fry's, ($19 for ten).  After some trial and error, and on the water testing Sat I think I've got something that is an improvement over rechargeing individual AA's, is still lightweight, and best of all- cheap.

Pics to follow.