Size lithium battery to run fishfinders

[fishintroop]

I’m thinking of getting a dedicated lithium battery for running 3 fishfinders and a 360. Any recommendation on size lithium I would need? TIA

[John Jackson]

I use a 50 amp Relion for mine.

[brianf.]

John, I have the exact same question as the OP and I’m curious as to how you charge the battery? Installing lithium in my boat would require a dedicated charger that would handle lithium batts.

[John Jackson]

I have a small 6 amp charger for mine. It doesn't take up much space. I have it mounted to a vertical wall, not on the floor. I also installed connectors so I can use the same small charger as a trickle charger for the main battery. My 3 trollers have their own dedicated charger.

[InternationalMarine Brian]

I always suggest 100ah.

[joe@lithiumpros.com]

Lithiumpros M3110 110ah and you can use your current on board charger to charge this battery with no problems, you can also use it for starting

[Ben Danbleume]

I always suggest 100ah.

Do you read the questions or just make a standard recommendation?

[fishintroop]

50ah seems reasonable but 100ah seems overkill for just running 3 graphs basically. I was thinking even smaller would probably work. I’m just not sure how you would figure the size.

[bobcoy]

What units and what draw do they pull. Take the total of all 3 units. I will use a 10 amp draw for ease of calculation. To run for 5 hours you will draw 50 amp hours(+or- a small factor) With lead acid you would use a factor of 50% draw to keep a longer life on your battery. With lithium you would want to use an 80% number. So lithium requires less capacity to handle the job. If you fish longer than 5 hours the size would need to go up accordingly. You do want to use the actual draw from your units and whatever else you put on the batteries load and round up some. So your battery should be sized by your draw times an hour for amp hours used for lead acid your battery needs to be twice the draw in amp hours to keep at the 50% number. Lithium only needs to be 20% more. I would figure on 10 hour days but your fishing day might be different. Bob

[fishintroop]

What units and what draw do they pull. Take the total of all 3 units. I will use a 10 amp draw for ease of calculation. To run for 5 hours you will draw 50 amp hours(+or- a small factor) With lead acid you would use a factor of 50% draw to keep a longer life on your battery. With lithium you would want to use an 80% number. So lithium requires less capacity to handle the job. If you fish longer than 5 hours the size would need to go up accordingly. You do want to use the actual draw from your units and whatever else you put on the batteries load and round up some. So your battery should be sized by your draw times an hour for amp hours used for lead acid your battery needs to be twice the draw in amp hours to keep at the 50% number. Lithium only needs to be 20% more. I would figure on 10 hour days but your fishing day might be different. Bob

Thanks Bob. I’ll be running 2 Helix 9 SI and a Helix 7 with 360. I’ll look up the numbers and see what I come up with. I might Pm you for some assistance. My typical day is between 6 and 10 hours. Thanks again!

[Dirtyeggroll]

Thanks Bob. I’ll be running 2 Helix 9 SI and a Helix 7 with 360. I’ll look up the numbers and see what I come up with. I might Pm you for some assistance. My typical day is between 6 and 10 hours. Thanks again!

Do us a favor and post your numbers so we can use them for future reference.

[InternationalMarine Brian]

Do you read the questions or just make a standard recommendation?

Ive never had anyone come back and wish they had purchased a smaller battery.

[brianf.]

The specs show that the Helix 12 is drawing 1.75 amps and the 360 is drawing half an amp. Not sure if the draw Humminbird cites for the Helix is with the light on though. The literature I saw didn’t differentiate. My Onix unit draws 2.5 amps with the light on, according to the website, so the new Helix could be drawing a lot more when lit up brightly as it is most of the time during the day. Does anyone know? I’m going to be conservative and round-up for both the two Helix units and 360, then figure on 12 hour days, which I often do. I’m thinking a bigger battery - 100ah - is probably needed to insure power for all those accessories over such a long day. To go light on the battery and have all my electronics blink out on me before the fishing day is done would suck.

[fishintroop]

Do us a favor and post your numbers so we can use them for future reference.

Will do

[fishintroop]

Can anyone tell me how I get the actual draw numbers? I have the numbers Humminbird supplies with the literature from the Humminbird site, however my Helix 9 units are not listed because they are 1st or 2nd year they started the series. I can't remember which. If I use the numbers listed of current Helix 9 Chirp SI units it is 2.5 amps, 900ma for the Helix 7 Chirp DI GPS g2n, and 500ma for the 360. So for ease of computation lets say 7 amps. At 10 hours that would be 70 amps. 20% of 70 is 14ah I guess that is the right calculation?

[WSfishin]

Can anyone tell me how I get the actual draw numbers? I have the numbers Humminbird supplies with the literature from the Humminbird site, however my Helix 9 units are not listed because they are 1st or 2nd year they started the series. I can't remember which. If I use the numbers listed of current Helix 9 Chirp SI units it is 2.5 amps, 900ma for the Helix 7 Chirp DI GPS g2n, and 500ma for the 360. So for ease of computation lets say 7 amps. At 10 hours that would be 70 amps. 20% of 70 is 14ah I guess that is the right calculation?

Actual draw with an inline amp meter........I’m guessing you probably dont have. There are several factors involved beside just the Manufacturers (those are usually Maximum)rated amperage draw. Your unit settings,the wire size,wire length etc..... I believe your calculation is wrong because the 20% is only in reference to battery discharge. Meaning the “usable” amperage of a batteries rating. Example: 100AH battery times 50%(lead Acid) = 50 AH. Lithium 100AH x 80% = 80AH. Theses calculations only assume you don’t charge at all until the end of the day and of course are very crude and I wouldn’t rely on them for sizing a battery. My. Suggestion would be to get as big as possible. If you can afford lithium I highly recommend you go that route. I have a strong opinion on Lithium brand but will not post that opinion. (I’ve owned them all) If you want that please PM me.Lithiums quite frankly perform better than lead Acid IMO. Hope this Helps.

[Wayne P.]

A cheap meter that will do in-line amps is this one. I have checked several sonar units with it.

https://www.walmart.com/ip/Digital-M...llow/174621239

[fishintroop]

Thanks Wayne. I have a meter. I don’t know where to make the connections