Batteries - lithium ion vs closed cell

So I'm debating on what kind of battery to use for my fish finder.  I've seen a few posts about using lithium ion batteries, and to weigh the pros and cons of each before choosing.

I've searched and truthfully I can't really find any cons to using a lithium ion.  They seem to be affordable, last longer, faster charging, smaller size and lighter, etc.  They seem to beat out the old school batteries in every aspect nowadays.  Does anyone have any experience with them on their fish finders?  Are there any real cons to going with one vs a closed cell lead acid battery? 

Tradeoff is usually cost & generally higher cost for quality charger to yield those results out of a Lion battery. 

A lot of the ones I see on ebay and whatnot seem to come with chargers and are less than $100 for the battery plus charger.  Are the chargers they come with not sufficient?  Considering I spent $400 on a fish finder, I won't exactly skimp on a good power set up to go with it. lol 

  Been using Li for several years...   they keep getting better and cheaper.   

 Make sure you get large enough Ah. to handle your FF.

Plan for 1amp draw & 75-80% use ability of the battery capacity.  This should leave a little fuel in the tank for those emergencies or longer days.

What would you say the minimum mah rating would be to power the unit for let's say, a 2 or 3 day trip? 

This one is 20000mah with charger for 45 and free shipping.  Seems pretty reasonable to me? 

http://www.ebay.com/itm/DC-12V-20000mAh-Super-Rechargeable-Portable-Lithium-ion-Battery-Pack-NEW-/171867425580?hash=item280418cb2c:g:ctEAAOSwMmBVqfKE

See my earlier post.  Figure 1amp/hour & 75-80% useabble battery.  That will give you an idea of the # of hours ... Approx.

I use LiPo's.  I own a 7 inch Dragonfly CHIRP 7.  I've been using 10000mAh 4 cell  LiPo (lithium polymer) batteries for about 6 months.  Its been working great after every single trip. 
Pros:
They are light weight and widely used by Radio Control enthusiasts.
Manufacturer publishes full specs of the batteries. (Minimum Capacity, Configuration, Constant Discharge etc)
After a day of fishing I can tell (through my Professional Balance Charger/Discharger or battery tester) how much charge is left in my battery pack, down to the voltage readings of each (4) cell.
Dragonfly 7 power consumption is 8 W at full brightness.  Battery capacity rating is 10ah / .67 results to 14.9 hours battery life .
Battery Life = Battery Capacity in Milli amps per hour / Load Current in Mill amps
Lithium Ion or Polymer has a higher usable capacity of 85%+ in my experience.
Cons:
It takes special knowledge to set up LiPos for a FF.  Fortunately I have a good buddy who helped me out. 

I had a chance to use mine for the first time two weeks ago with a Garmin 53DV fish finder / GPS combo. After 3.5 hours on the water, it was still 4/5 full. Nice and light, and also has USB ports to charge your cell phone or other devices. They are simple to wire, lightweight and work very well.

I went with this one - Anker Astro Pro which is 20,000mAh: http://www.amazon.com/Anker-20000mAh-Multi-Voltage-Portable-Notebooks/dp/B00B45EOYS/ref=sr_1_2?ie=UTF8&qid=1446693499&sr=8-2&keywords=astro+pro

I started with this Anker Astro Pro2, however, the amperage output was too low and my Garmin would shut off during bootup so I returned it to get the original above: http://www.amazon.com/Anker-20000mAh-Aluminum-Multi-Voltage-Technology/dp/B005NGLTZQ/ref=sr_1_1?ie=UTF8&qid=1446693499&sr=8-1&keywords=astro+pro

Greg

FishingAddict, I'm good at electronics, but not when it comes to wiring and whatnot.  What kind of special stuff is needed to hook up a lithium ion battery?

I use this type of battery:

http://www.amazon.com/gp/product/B0056BXE6A/ref=pd_lpo_sbs_dp_ss_2/191-6685255-3139640?pf_rd_m=ATVPDKIKX0DER&pf_rd_s=lpo-top-stripe-1&pf_rd_r=0RWWMZ1AY2J0B1JZMXHS&pf_rd_t=201&pf_rd_p=1944687582&pf_rd_i=B0056BWK8I

They're pricey, but supposed to last forever and it's worked great so me far. Having said that, the ebay lithium ion battery mentioned above would be hard to beat---provided it doesn't overheat and melt your kayak...

http://www.engadget.com/2015/04/30/lithium-ion-battery-failure/

Following this. I am looking at some lighter battery solution that wont break the bank....

What would you say the minimum mah rating would be to power the unit for let's say, a 2 or 3 day trip? 

This one is 20000mah with charger for 45 and free shipping.  Seems pretty reasonable to me? 

http://www.ebay.com/itm/DC-12V-20000mAh-Super-Rechargeable-Portable-Lithium-ion-Battery-Pack-NEW-/171867425580?hash=item280418cb2c:g:ctEAAOSwMmBVqfKE

I would think twice about buying overseas and low price points. You have no visibility with their quality control, buy something that shows its a proven product.  Check out HobbyKing where their buyers rate the goods they purchased.   Another nice thing about LiPos is if you need more power (livewell pump, deck lights) you can buy another battery pack and connect them together.
When I get a chance I will write a report on my LiPo battery.  To date approximately 18 trips, ranging from 4 to 8 hours.

Here you go Quinn..

battery - I got all mine on Ebay but Amazon might be better if you're the nervous type about purchasing oversea stuff, not me.
http://www.amazon.com/Sangdo-Portable-6800mAh-Rechargeable-Battery/dp/B016U2B3R0/ref=sr_1_3?s=electronics&ie=UTF8&qid=1446741251&sr=1-3&keywords=12v+Portable+9800mah+Li-ion

waterproof plugs
http://www.amazon.com/Bluecell-Waterproof-Electrical-Connector-Marine/dp/B00ROSXT0E/ref=pd_sim_sbs_422_3?ie=UTF8&dpID=51wuEvczgEL&dpSrc=sims&preST=_AC_UL160_SR160%2C160_&refRID=11EVEQ6CDJ9STZA8YRF6

waterproof case - Drill two small holes for wires and goop.
http://www.amazon.com/CASE-1040-MICROCASE-YELLOW-CLEAR/dp/B00152PF4I/ref=sr_1_6?ie=UTF8&qid=1446741852&sr=8-6&keywords=pelican+1040

Did it, love it, won't ever go back. I own two setups. I can go all day with my Elite 7Chirp on #8 screen power.

Mike

Here you go Quinn..

battery - I got all mine on Ebay but Amazon might be better if you're the nervous type about purchasing oversea stuff, not me.
http://www.amazon.com/Sangdo-Portable-6800mAh-Rechargeable-Battery/dp/B016U2B3R0/ref=sr_1_3?s=electronics&ie=UTF8&qid=1446741251&sr=1-3&keywords=12v+Portable+9800mah+Li-ion

waterproof plugs
http://www.amazon.com/Bluecell-Waterproof-Electrical-Connector-Marine/dp/B00ROSXT0E/ref=pd_sim_sbs_422_3?ie=UTF8&dpID=51wuEvczgEL&dpSrc=sims&preST=_AC_UL160_SR160%2C160_&refRID=11EVEQ6CDJ9STZA8YRF6

waterproof case - Drill two small holes for wires and goop.
http://www.amazon.com/CASE-1040-MICROCASE-YELLOW-CLEAR/dp/B00152PF4I/ref=sr_1_6?ie=UTF8&qid=1446741852&sr=8-6&keywords=pelican+1040

Did it, love it, won't ever go back. I own two setups. I can go all day with my Elite 7Chirp on #8 screen power.

Mike

what do you use to charge them?