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Another battery question; cranking/trolling switch

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Another battery question; cranking/trolling switch

Old 10-07-2017, 08:45 AM
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Default Another battery question; cranking/trolling switch

Facts: bay boat, 1 outboard, 36v trolling motor, 2 stereo amps, blue sea selector switch, 1 cranking battery, 3 trolling motor batteries. The switch is a blue sea 6011, dual circuit, which indicates two positions, "on" and "combine batteries"

Based on the info I've gathered, I've decided to run my stereo amps (and everything else) off of my cranking battery. (I'm open to arguments, but I really don't care to add another battery, and I suppose that would be ideal for the stereo amps.)

Based on that, If possible, I'd like to wire my trolling batteries to my switch so that just in case I run crank battery down, I can use the trolling batteries to start my outboard. Is this a good idea? If so, How would I wire that?
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Old 10-07-2017, 10:30 AM
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Sounds like a mostly bad idea depending on how you use the boat. If you troll with the stereo going and main engine off then probably a pretty bad setup. If you only run the stereo when the main engine is running at mid/high rpms then probably OK. If you run the stereo with the main engine idling it is probably a bad idea again.
I can't really see any ideal setup for that battery configuration. Yes you could pick up one of the 12v cells in the trolling battery to use as an 'emergency parallel via a switch but will it have any charge left if you troll and use the stereo at the same time? Note that there are a few complications about which battery you use as 2 of them are 'floating above earth'. I would probably just buy a set of jumper leads so I could jump off any of the 3 trolling cells and maybe a 2nd set so I could parallel 2 of the cells if they are getting low. Note though that if there is a common earth between the trolling battery and the start battery you will need to start undoing the battery cables before doing too much paralleling.
A better idea is probably to get a 30A 36v - 12v DC/DC converter ($50 on ebay) and run your stereos off the trolling motor batteries. I would still keep the jumper leads and battery connection spanner onboard in case the start battery failed though.
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Old 10-07-2017, 10:56 AM
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I'm just watching and not much help but interested in solutions from the forum. I am thinking you'd have to combine the trolling batteries and cranking grounds to use the selector switch and that doesn't sound like a good idea. I always keep a set of jumper cables onboard even with my one battery setup. I'd start simple this way for a backup.
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Old 10-07-2017, 11:21 AM
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Cranking batteries are really not designed for long term draw. Running a stereo "and everything else" on them for hours at a time will seriously shorten their lifespan. Thats what deep discharge batteries are for.

You should treat your starting battery as a "safety device". (not to be messed with). Conversely, you can use your trolling batteries as the house bank. If you find they do not meet all your needs, you need bigger or more batteries.

Slight digression: No judgement here, but I've never understood the idea of having a stereo cranking when fishing. That would defeat the purpose of going out for me. Different strokes I guess...

Last edited by bobeast; 10-07-2017 at 11:29 AM.
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Old 10-07-2017, 11:48 AM
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Originally Posted by bobeast View Post
Cranking batteries are really not designed for long term draw. Running a stereo "and everything else" on them for hours at a time will seriously shorten their lifespan. Thats what deep discharge batteries are for.

You should treat your starting battery as a "safety device". (not to be messed with). Conversely, you can use your trolling batteries as the house bank. If you find they do not meet all your needs, you need bigger or more batteries.

Slight digression: No judgement here, but I've never understood the idea of having a stereo cranking when fishing. That would defeat the purpose of going out for me. Different strokes I guess...
X2 best idea with existing equipment.

You don’t mention current draw of 2 stereo amps and house loads but an alternative would be to add a combination deep cycle starting battery with selector switch which you could draw down with house loads while keeping the 2nd starting battery in reserve to start your engine. Downside is extra weight less space (gotta put it somewhere) and more cost and complexity.
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Old 10-07-2017, 11:49 AM
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Originally Posted by Dacman View Post
I'm just watching and not much help but interested in solutions from the forum. I am thinking you'd have to combine the trolling batteries and cranking grounds to use the selector switch and that doesn't sound like a good idea. I always keep a set of jumper cables onboard even with my one battery setup. I'd start simple this way for a backup.
You might be here to observe but you have the right answer. Best solution is a set of jumper cables sealed away in a bag. It can be set up to just pull 12 volts off of one batt but its just problematic and adding a battery would be more elegant and easier.

Jumper cables or a portable jump pack is the best answer. Especially considering you'll possibly never use it.
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Old 10-07-2017, 12:07 PM
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Quote.
Slight digression: No judgement here, but I've never understood the idea of having a stereo cranking when fishing. That would defeat the purpose of going out for me. Different strokes I guess... Unquote

When I was in my twenties I had amps in the truck and stereos in the boats. I think it's an age thing.
Now closing in on fifty and teen daughters, I rarely ever turn the stereo on in the truck and removed the one from the boat. Different strokes is fine.
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Old 10-07-2017, 12:38 PM
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Originally Posted by bobeast View Post
Slight digression: No judgement here, but I've never understood the idea of having a stereo cranking when fishing. That would defeat the purpose of going out for me. Different strokes I guess...
I'll go back and try to interpret everyone's help, but I should've added, that Most of the time, I only use the stereo when running, but occasionally while sitting.

I do agree, when I'm chasing trout, the tunes can wait.
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Old 10-07-2017, 12:41 PM
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I only have a 24 volt trolling motor but I have 3 deep cycle/starting class 31 batteries. My battery selector switch is wired so one of the trolling batteries can be a backup to the starting battery in position 2. This setup allows me to only need 3 batteries vs 4 and after 3 years I am completely sure it was the right decision. I never pull my trolling batteries down below 1/2. I suppose there could be a circumstance where I might need the backup to start the engine but the odds are low that my main battery plus my trolling battery would both be so low as to not start the engine. I fish in Charlotte Harbor and have a Bay boat. If I was doing heavy duty off shore fishing and drawing my main battery low during the day I would rethink my setup but for inshore fishing I believe this setup is great.

I would never run any other electronics off the trolling batteries because then you are pulling one of your trolling batteries down below the other plus your can get electronic interference using trolling batteries with instruments like depth/GPS equipment. I was told not to do this by Hummingbird factory tech.
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Old 10-07-2017, 01:07 PM
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Thanks again for the feedback.

I can believe that I just need to leave the two battery systems separate, and just jump one from the other if ever needed.

I also "believe" that it is most common on bay boats to run the house electronics off of the cranking battery. We're talking a gps/fishfinder and a vhf radio as "electronics."

So, this leads me to ask, which battery system should I run my stereo and 2 amps off of?

Amp info: JLMX280/4 (35 amp fuse if that helps), and JL M400/4 (40 amp fuse).
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Old 10-07-2017, 01:12 PM
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Originally Posted by Dacman View Post
Quote.
Slight digression: No judgement here, but I've never understood the idea of having a stereo cranking when fishing. That would defeat the purpose of going out for me. Different strokes I guess... Unquote

When I was in my twenties I had amps in the truck and stereos in the boats. I think it's an age thing.
Now closing in on fifty and teen daughters, I rarely ever turn the stereo on in the truck and removed the one from the boat. Different strokes is fine.
Good point! Guess I'm showin' my age.
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Old 10-07-2017, 01:13 PM
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Another thought would be to just bring along a Noco, or Weego, or similar jump pack battery booster. Most should have enough juice to crank and start any outboard that's otherwise healthy and simply has a flat, but not shorted starter battery.
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Old 10-07-2017, 01:16 PM
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Originally Posted by Brokenline View Post
I'll go back and try to interpret everyone's help, but I should've added, that Most of the time, I only use the stereo when running, but occasionally while sitting.

I do agree, when I'm chasing trout, the tunes can wait.
I suppose as long as you are only cranking the stereo when the engine is running, it would be fine to have it connected to the starting battery circuit. In that case you are mostly drawing off the alternator. You just don't want to do that while you are trolling and the engine is off.
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Old 10-07-2017, 01:21 PM
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Originally Posted by jerryclaybrook View Post
I would never run any other electronics off the trolling batteries because then you are pulling one of your trolling batteries down below the other plus your can get electronic interference using trolling batteries with instruments like depth/GPS equipment. I was told not to do this by Hummingbird factory tech.
Thanks for all the feedback Jerry. Seems like everyone likes to advise NOT to use one battery system or the other, huh? Poor little stereo, no one wants to share!


To the other "old" guys... I'm 53, and like tunes when I want them, which is often not often, but... I ended up with a boat with 8 speakers, so... might as well use them on those days when the fishing needs a little spice. Now my 16 y.o. daughter and I don't always agree on the genre'...
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Old 10-07-2017, 01:33 PM
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Originally Posted by Brokenline View Post
Thanks again for the feedback.

I can believe that I just need to leave the two battery systems separate, and just jump one from the other if ever needed.

I also "believe" that it is most common on bay boats to run the house electronics off of the cranking battery. We're talking a gps/fishfinder and a vhf radio as "electronics."

So, this leads me to ask, which battery system should I run my stereo and 2 amps off of?

Amp info: JLMX280/4 (35 amp fuse if that helps), and JL M400/4 (40 amp fuse).
Run the stereo and amps off the cranking battery, looks like you have a 70 amp alternator circuit and mostly crank the tunes with the engine running at speed. If cranking sound out at the sandbar , just start it up and let let it idle every once in awhile. 4 stroke shouldn't have a problem idling for periods. Another house battery would be the best bet I think but your setup is fine if you pay attention to the battery level.
I forgot I was just watching. Disregard .
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Old 10-07-2017, 01:47 PM
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Thank you Dacman
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Old 10-07-2017, 05:52 PM
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Originally Posted by Brokenline View Post
I'll go back and try to interpret everyone's help, but I should've added, that Most of the time, I only use the stereo when running, but occasionally while sitting.

I do agree, when I'm chasing trout, the tunes can wait.
If you only use house load while running then starting battery is fine.
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Old 10-07-2017, 10:52 PM
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2 x $50 30A 36v - 12v DC - DC converters and a little bit of wiring and you have the best possible setup with the stereo (and maybe some other items like fishfinder etc) running off your trolling battery as if it was a proper house battery. If you want to do a bit more you can even get a 12v - 36v converter to help charge your trolling battery off your main engine whilst you are powering things off it. Unit is around $160 but you do need to do a bit more work to set that up properly.
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