Fishfinder problem

[JohnPK]

Recently when I have my 115 HP motor not running, ie. perch fishing, but have my fish finder running...when I start my motor my fish finder shuts off. Never had this problem before and it was suggested to me that when a battery gets low/old that the draw from it to start the motor will cut out my fish finder. It was suggested that I get a capacitor to put on my wiring to my fish finder (obviously a new battery would likely solve the problem as I haven't had this problem until recently) but battery seems fine, takes and holds a charge very well. Anyone have any information regarding these capacitors (type, how to install, if indeed they work?)
Any help is much appreciated..can either post here or private message....thanks
John

 

[scrimmy]

If you wire your fish finder directly to the battery your problem will be solved.

 

[Bogz]

I agree with Scrimmy......mine is directly wired.........it will show a low battery warning sometimes, but never shuts down.

 

[Bassassin]

Wire to the battery x3. I did have the same problem with a Garmin unit when other electronics such as the marine and entertainment radio were all on, that fix solved it. Also 5 series Hummingbird units have reported interference problems even when wired direct to battery. A fix was to upgrade to 1000 series wiring. If the direct to battery doesn't solve the problem I would insulate the power and transducer wiring.

 

[knot on call]

does your fish finder give you a voltage reading?
if so see what the voltage is prior to starting your engine. I just had the same problem, the fish finder would work while I was still fishing but would shut off when starting the engine and then I could turn it on again. my issue was the battery wasn't charging and voltage was down around 8 volts. needless to say I added a charging relay pre season and forgot to add the fuse so the relay wasn't working properly. I would have the battery checked I believe they check it under load, so you may show 12or14 volts dc when everything is off but when under load like starting the engine the voltage can drop.
just my thoughts, good luck.

 

[Fish Whisperer]

to load test your battery under load , put a volt meter on battery , disconnect ign system. Use starter to draw battery down. If voltage drops down alot and is slow to return to prestart voltage replace battery.

 

[JohnPK]

Thanks everyone for your input on the matter...I had never had this problem prior to this year. In thinking it over, it makes sense that my battery under load is dropping down to a point where the fish finder shuts off. Once engine is started I start up fish finder again and it is good. Will check battery under load to see what it drops off to....thanks again everyone.
John

 

[Stick]

Take your battery to any auto parts store. We load test them all the time!

 

[Rob V]

Had the same problem for about 3 seasons. my batter was holding a charge okay and starting my motor fine - but every time I tried starting with the fish finder on (lowrance) the fish finder would shut down. This spring my batter finally let me down. I got a new battery and my fish finder doesn't shut down any more. Obviously my old batter was either too small for the motor (optimax 115) or it was past its prime. Proctors recommended an East Penn/Deka 24M7 1000 CA, 875 CCA battery. They carry them as does car quest (they're an Deka battery but has Car Quest branding on them)

 

[Bassassin]

I was taking to a well versed marine mechanic today and he said another problem was running the power and transducer cables next to the main power cable that can cause interference.

 

[G.Mech]

Just to recap, John PK's fishfinder worked fine in the past. There are lots of great suggestions here and lots of guys speaking from experience. VHF radios, large power loads, interference from wiring and all kinds of things can cause problems with all these electronics as we all know but his worked fine with the installation as it was until recently so what has changed? It seems to me that the most likely culprit is the aging battery. I would get a new one which is rated for the MCA required by the motor. Lots of the new high-tech engines (such as the Optimax) need mimimum 1000 MCA which is pretty high and you can void your warranty with too small a cell. It needs to be a cranking battery and not a deep cycle. With a good battery and decent wiring, your rig should perform as it always did before.

 

[JohnPK]

Thanks G. Mech....Yes everything worked fine in the past...the boat is a 20 foot legend with a 115 hp Merc...I bought it new and can only assume the battery was the correct one for the boat. I haven't got around to taking the battery out yet but I figure it need replacing....will keep it around for other emergency uses at my shop. One last question...approx. how long would one expect a cranking battery to last in a boat? assuming it is taken out each year and stored properly...also...how long with just leaving it in the boat each year through winter with a trickle charge on it?
Will post results of new battery once I have had a chance to get out there.

 

[whitetailhunter]

I use Interstate Marine Pro-29 ELC Series dual purpose (deep-cycle/starting) batteries - 675 CCA, 845 MCA, 210 RC. They have more than ample power to run all my equipment, have served me well and are reasonably priced. I leave mine right in the boat through out the winter inside my garage on trickle charge and got 10 years out of my last set before they started failing. You can get them at the Interstate Battery Centre in London at 555 Wellington Rd. South. Hope this is a help.

 

[jtrain]

JohnPK, I had the exact same problem this year, I have a 166 princecraft pro with 75hp merc, the start of the season I had the same thing happening.. I talked to Roger from "Magnacharge" in London on Brydges st. The guy is a battery wiz to say the least, The battery I had was manufacturd in 2007 and it still started the motor fine, run the tilt/trim motor no problem but would shut the fish finder down on start up. Turns out the battery reserves where low which means I needed a new one, after replacing it everything works perfectly. I would recommend talking to him and you can ask him about any battery and he will tell you his honest opinion on any one of them. The only reason I got a new one is I would be so pissed off if I left it full well knowing there was a potential problem and was stranded out there with dead battery. I have towed my fair share for boats in and certanly hope it doesn't happen to me. Tight lines. Jamie.