Low battery alarm feature

[southtexasbassin]

I just bought and installed a new Humminbird 587ci fishfinder/gps.  The unit has a low battery alarm feature.  What would be a good voltage for me to put on this option?  I am not sure what voltage I need to be able to start my outboard before my battery is completely dead.

[Way2slow]

I would set it at 12.3 VDC.  That's low enough to scare the crap out of you when you start cranking the motor, especiallly if it's a DFI motor.   A good battery will still crank a motor at that level and even a little lower.  A bad battery will not, it will not deliver the cranking amps needed.  When you try to crank the motor, the voltage will drop way down on a bad battery or bad battery cable connection.

[southtexasbassin]

When it gets to this point, do you just start the outboard and let it run for a bit while the battery charges? If so, how much time do you let it run for? Would you recommend replacing the cranking battery with a deepcycle/cranking battery? From my understanding the cranking battery will not last as long as a deepcycle. As far as usage goes.  I run everything of the cranking battery except the trolling motor. I have this concern because today I was at the lake and noticed on my graph that the volts were at 11.9 after 2 hours of fishing. I recently added a new graph about 3 days ago and I was wondering if this was causing my battery to drain faster. I have an interstate brand cranking battery.

[Wayne P.]

The best choice in recent years is a dual purpose battery of the largest size you have room for. The minimum size one should have is the MCA it takes for the outboard. Once you add electronics, livewell pumps, lights, etc. you need extra capacity for deep cycle uses. Newer sonar/GPS units use more amps than in the past. Most fishermen do not run the outboard long enough to fully charge the battery between starts. When you add the other accessories that may run all day, a lot of reserve is needed to assure you have enough power to start the outboard for the last run to the ramp. Cold weather will make that even more evident.

[Way2slow]

If your cranking battery was at 11.9 volts after two hours, you have a "PROBLEM". There is not enough electronics in any bass boat to kill a battery that quick. 11.9 volts is a fully discharged battery and it would take a 30 - 50 amp draw to fully discharge a good battery in two hours.

First, if the battery is not fairly new, I would go ahead and get a good group 27, 30, or 31 Dual Purpose.

Second, make sure all the battery connections a clean and corrosion free. Clean everything good with a small wire brush, using a baking soda and water solution.

Third, run the motor on a water hose at approx 1,500 - 2,000 rpm and see what the voltage is showing on your new LCD. It should be approx 14.2 volts but no lower than 13.8 VDC. If you're not getting that, double check it with a good DVM across the two battery terminals. If it's still low, you have probably fried the Regulator/Rectifier.

Also, as mentioned, most people do not run the motor enough to keep the battery charged during a days fishing.  Most of the time, at the end of the day your cranking battery will only be at 80% or even lower and it should be charged after every trip.   If you have an onboard, it should be taking care of that so you might want to check the voltage across the battery with the charger on to make sure the charger is putting out at least 14.6 VDC.

[southtexasbassin]

What brand of batteries do you all recommend?  Size and any other specs that would help?  i want to be able to fish 10 hours with out any problems.

[Way2slow]

I use Deka batteries for two reasons. They are one of the best you can buy and I get them wholesale. There are higher capacity TM batteries than Deka's deep cycle, their group 31 is only 105Ah while some other brand's 30/31's will be 120 - 130Ah, but their quality is not better. Deka just does not pack the case so full of plates so there is more room for expansion during aging and lessen's the chance of plates shorting out after it starts to swell some. However, if max capacity is what you need, Trojan SCS225 is the TM battery to go with.

I think you will find any of the top name brands will give you good service. There are only four battery companies left in the US. Johnson Battery is by far the biggest and they make a lot of different brand names, some cheap, some OK, some Very Good.

What you don't want are those sold buy a local battery dealer that has their own house lable or some other unknown label. Most of those are cheap very cheap imports they label and sell at a slightly discounted price from the major brands. Pure Junk.

For a cranking battery, I use a group 27, never had a problem with electronics lasting all day and still plenty of voltage at the end of the day. Get the highest capacity battery in what ever brand you get. Ask them if that's the highest capacity that company makes in that size. Most of the time, they quote a cheaper battery because most people shopping for one don't understand batteries and only go by price, thinking that's the only difference between a $75 and $105 battery. Plus, sometimes they don't have them and just make out like it is and just say that's the highest they have, like it's the highest made.

Unless you have a very good microprocessor Controlled "Smart or Intilli charger" stay away from dual purpose AGM's. While they are the best cranking battery you can get (massive amounts of CCA's), they cost about twice as much and require a very good charger that's AGM compatable. You pay a lot for the extra life an AGM gives but you standard charger will not give you that extra life you pay for.

One more thing, buy your batteries from a high volume dealer, not you're local marina or such.  They battery may have been sitting on the shelf for months, and never give you full capacity.