Posted By: Tony from Oak Point
AA batteries for a bigger fish finder? - 09/25/16 08:30 PM
Curious if anyone has tried powering a big fish finder with just AA rechargeable batteries? The other day I tried out the "big" Hummingbird 798 SI finder with 16 AA batteries and it only lasted an hour or so. I'm going to go up to 20 AA batteries to bump up the voltage and then I hope to get 4 or 5 hours per charge.
My luck with cheap lead acid AGM "deer feeder" batteries is not too good as the last two that I've purchased have failed quickly with hardly any use. For the last year or so I've been using 16 NiMH AA batteries in two 8 battery holders wired in parallel with a Plano 3400 case. This has worked great giving me all day light weight power for a smaller Lowrance fish finder.
With my test the other day, the voltage started at 10+ volts. The power cut out soon after the 9 volt alarm was triggered so the batteries only used about 25% of their capacity before the voltage dropped too low. Since NiMH batteries operation at 1.2 volts instead of 1.5 volts compared to a regular AA battery this was part of the problem. To help bolster the power I'm now adding two, 2 battery holders so that each battery bank will have 10 batteries instead of 8. This will bump up the voltage from 10v to 12v per bank so I should be able to discharge the batteries much further before the fish finder cuts out. I will be interested to see if I can get the 4 or 5 hours per pack or if it will fall short? It will probably be a week or so before I can test out this setup. In the mean time I'm curious if anyone else has gone this route and if so how did it work? If it's not feasible I may go in another direction.
My luck with cheap lead acid AGM "deer feeder" batteries is not too good as the last two that I've purchased have failed quickly with hardly any use. For the last year or so I've been using 16 NiMH AA batteries in two 8 battery holders wired in parallel with a Plano 3400 case. This has worked great giving me all day light weight power for a smaller Lowrance fish finder.
With my test the other day, the voltage started at 10+ volts. The power cut out soon after the 9 volt alarm was triggered so the batteries only used about 25% of their capacity before the voltage dropped too low. Since NiMH batteries operation at 1.2 volts instead of 1.5 volts compared to a regular AA battery this was part of the problem. To help bolster the power I'm now adding two, 2 battery holders so that each battery bank will have 10 batteries instead of 8. This will bump up the voltage from 10v to 12v per bank so I should be able to discharge the batteries much further before the fish finder cuts out. I will be interested to see if I can get the 4 or 5 hours per pack or if it will fall short? It will probably be a week or so before I can test out this setup. In the mean time I'm curious if anyone else has gone this route and if so how did it work? If it's not feasible I may go in another direction.