Lithium battery for kayak fish finder.

[king fisher]

I would like to upgrade to a lithium battery for my fish finder on my kayak.  I have a Garmin Echomap 64 CV, and would like to get 16 hours between charges.  What brand and model do members recommend?  I also will need recommendations for a charger.  Thanks.

[casts_by_fly]

Per garmin, typical power draw is 0.7 amps. Max is 1.25. Not sure what drives the difference in their numbers, but screen brightness is one for sure. If you run your screen bright then look to the top end.

 

1.25amp * 16 hours is 20 ah usable. With most lithiums, you get 90% of capacity so 22.5 Ah battery. 
 

0.7 amp * 16 hours is ~12 ah usable and 14 ah battery. 
 

the above lead you to either a 30 ah for the first or 15-20 ah for the second. It depends how critical 16 hours is and if you use it at full brightness all the time. If you want to be sure, a 30 ah battery will do it.  I run a 9” helix and mega live on a 30ah but not for 16 hours. It’s a single day for me. 
 

im running an amped outdoors battery and have been for 3 years now. It’s $200 right now. I don’t have experience with cheaper batteries but you can get more capacity for less $$ for sure. 

[Bankc]

Casts by Fly is right.  30 Ah is a good size.  That should give you more than you need.  

 

As for a charger, I'd get a Noco Genius.  Probably a Genius 5 for your needs.  That would fully recharge your battery within 6 hours.  They're durable, high quality, versatile, and relatively cheap chargers.  They have settings for lithium, lead acid, and AGM, so you can use them for other things as well.  I use mine to charge my wife's car battery once a month (if I remember), because she never drives.  And then use it to charge my lithium trolling motor battery and AGM battery for my fish finder on my kayak.  

[flyfisher]

22 hours ago, casts_by_fly said:

Per garmin, typical power draw is 0.7 amps. Max is 1.25. Not sure what drives the difference in their numbers, but screen brightness is one for sure. If you run your screen bright then look to the top end.

 

1.25amp * 16 hours is 20 ah usable. With most lithiums, you get 90% of capacity so 22.5 Ah battery. 
 

0.7 amp * 16 hours is ~12 ah usable and 14 ah battery. 
 

the above lead you to either a 30 ah for the first or 15-20 ah for the second. It depends how critical 16 hours is and if you use it at full brightness all the time. If you want to be sure, a 30 ah battery will do it.  I run a 9” helix and mega live on a 30ah but not for 16 hours. It’s a single day for me. 
 

im running an amped outdoors battery and have been for 3 years now. It’s $200 right now. I don’t have experience with cheaper batteries but you can get more capacity for less $$ for sure. 

Nice to see someone actually post the math to solve the problem rather than people saying get the 100ah because i ran mine for a whole day and have 90% left...waste of weight and money.

 

I personally run an Ionic lithium and have for 4 years now and it has been a great battery for my NK180s and I even run a 30ah for that.

[casts_by_fly]

Yeah, I forgot the charger question. Noco genius 5 is the answer for the size you want.