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question about livescope power use

Posted: Wed Jul 03, 2019 8:50 am
by hlindsay
I recently installed a Garmin Livescope but have not had much chance to use it. When I have used it it is great. My question is about how much power it uses. I will be going to Sekiu this month for 3 days. I have a 20ft Hewes Sea runner with a 150 and 9.9 kicker. I have two scotty electric downriggers. In the past I have fished for 5 days using the down riggers and depth sounder, I did not have any problems running the battery down.
I have read that the livescope uses a lot of power. Should running the kicker a lot of the time keep the batteries up (I have 3)or do I maybe need a small generator to charge on the water or back at the dock. There is not shore power.

I plan/hope to use the livescope to see fish depth when trolling and also to look for schools of rock fish when drifting jigging in area 4.

Thanks for any help

Re: question about livescope power use

Posted: Thu Jul 04, 2019 12:45 am
by Sideburns
Looks like the livescope uses 21 watts typically and 58 max. If you have 3 batteries, I'll assume one is main and the other 2 are auxiliary?

So, a couple of fairly healthy marine batteries are likely around 200 amp hours together. (only use 80% before recharging/ 160 ah usable)
a couple scotty downriggers run for an hour each per day at 10 amps would be 20 amp hours of power
the livescope will likely use 2 amps average, so 8 hours of use would be 16 amp hours ....or....
if the livescope used its max 58 watts (5 amps) all the time... for 8 hours would be 40 amp hours (doubtful from what the garmin site says)

So you could use 30-60 amp hours per day. Likely 40ish. Sounds like 3-4 days of power till recharging time if my guesses are correct.
If you run a stereo on the same batts, add about 40 amp hours and plan on recharging somehow after 2 days

Double check exactly what you have for battery capacity and I can help recalculate if you like

Re: question about livescope power use

Posted: Thu Jul 04, 2019 12:58 am
by Sideburns
A small kicker at low speed will not do much charging btw, only a few amps. The main motor, if its wired to charge all three batteries, might give priority to the main starting battery, then charge the aux batts, depends on how it's wired. The main motor at high speed will likely charge at anywhere from 15-100 amps (depending on engine), so possibly recharging 10-80 ah (reduced for efficiency losses) of power back into the batteries if run for an hour a day.

Check out your charging specifications for your motors and we'll get that range narrowed down. Your main motor might completely recharge your electrical system daily....

Re: question about livescope power use

Posted: Thu Jul 04, 2019 4:18 am
by hewesfisher
Most small kickers in the 8 - 9.9 range produce 6amps @ WOT (what my 8hp electric start kicker produces). At trolling speeds you might get 1 to maybe 2 amps.

Too many variables without knowing what engines, batteries, or an onboard charger (if you have one) to answer the questions. If you've got an onboard charger, I'd plug it into a generator at the end of each fishing day to ensure you leave the dock knowing each battery is fully charged.

Re: question about livescope power use

Posted: Thu Jul 04, 2019 12:12 pm
by hlindsay
Thanks for the help. I was afraid of the to many variables not enough information.

My boat is setup with bank one a single marine starting battery, bank two is two deep cycles that are size 27 with 116AH @ 100Hr/105AH @ 20Hr/85AH @ 5Hr.
I tried to do some research and just couldn’t get my head around it. Sideburns I’m glad you found the info on the livescope I wasn’t seeing or I just wasn’t getting it.

i have a Yamaha 9.9 electric start, but it doest sound like it will give me much when trolling. My Battery switch is set so I can start with bank one and switch to bank two for trolling running the depth sounder GPS and down riggers from that.
I think what may work for me is keep #1 in reserve and if I start getting down fire up the 150HP and do some cruising with the switch in the both location to recharge everything.

If I already had the generator I would go with that in the evening but i don’t think I can justify that $ right now. My wife wasn't ok with it when I started talking about that. The switch to Garmin and a livescope was pushing it.
I do have a 3 bank 20amp onboard charger.

Re: question about livescope power use

Posted: Sat Jul 06, 2019 6:38 am
by hewesfisher
I'd preserve your main as it is what will get you home. The current model F150 Yamaha alternator produces 50amps, but don't know how much of that is dedicated to engine.

Thought you had a small generator since you mentioned one. Might check into renting one, it could be an economical solution. [wink]

Re: question about livescope power use

Posted: Sun Jul 07, 2019 7:12 am
by rseas
You have the same motor set up as I do, a 150 main and a 9.9 electric start kicker. I have never had to "top the batteries off". We have been on extended trips of a week or more and have not had to resort to an axillary charger.

My boat has a full Lowrance system including; HDS 9" Gen 3, autopilot, radar, GPS, side scan and down scan. The electronics all route through a Lowrance SonarHub which has a large draw but I'm not sure what the numbers actually are. I also have a VHF, running lights and 4 downriggers to consider.

I make sure the battery switch is off at night and I do have the voltage overlay on for my frequently used FF screens. While trolling on the kicker; as a precaution, if I do see that the voltage is dropping I will start the main and just let it idle in nuetral while trolling on the kicker and the voltage pops right back up to 13.4 V plus. Another thought when trolling the salt your running 2.4-3 5 MPH so your kicker rpms will be up in the higher charging range.

Hope that this helps and good luck.

Re: question about livescope power use

Posted: Mon Jul 08, 2019 1:31 am
by Sideburns
I'll bet my first guesses are pretty close. (as far as power draw, available run time etc) If you do have the 50 amp charging system, I would think that at high speed when all batteries are switched together that the aux batteries could be recharging at a good 30 amps. Run that main motor at speed for an average of an hour a day, and the batteries will likely be very close to topped off, If not, your daily losses will still be minimal and the "party" could last for weeks anyways.......

Re: question about livescope power use

Posted: Tue Jul 09, 2019 6:36 pm
by Larry3215
Keep in mind that the big motor wont put out the full 50 amps unless your running at full throttle. Your going to need to run it well above idle to get decent output from the alternator. Thats going to use a fair amount of gas, be noisy for any neighbors, etc.

Also, how far down the batteries get drained will depend on how long and at what power level your running your trolling motor. Most of them draw in the 50 amp range at full throttle, so it wont take long at that rate to run those batteries down. We have a 24 volt Ulterra, and two 100ah batteries just for it alone. Usually we can easily run all day with plenty of reserve, but last fall on Couer d'alene, it was windy as heck and we ran the batteries down so far that motor had a huge drop in power in about 6 hours. The batteries are less than a year old.

Re: question about livescope power use

Posted: Tue Jul 09, 2019 7:16 pm
by hlindsay
I was hoping to possibly get a generator but that was a no go. It sounds like I would be ok, I would be running on the big motor some, there is the run up current to troll with it on the kicker and run back up. Then there is the 30 min run into area 4 for bottom fish.
Larry as far as trolling motor I only use electric in fresh water.
But it looks like all this help you guys have given me will have to wait awhile. It looks like my grandson is going to arrive early and with a new born grandson in NICU I don't think will be going fishing, at least not for a long trip.

thanks again for all the help

Re: question about livescope power use

Posted: Tue Jul 09, 2019 8:48 pm
by Larry3215
Oh no! I hope everything works out and all are well.