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Battery Selection

1K views 9 replies 7 participants last post by  haffiman37 
#1 ·
Yet another post on my fiancee's boat as we try and complete her... On my Catalina, since I run an outboard my only need for electricity is for accessories. It was my understanding that for this purpose, "Deep Cycle" batteries would be best. I haven't had any issue with my battery to date, but it does take a long time to charge.

As we are now at the point where the Harpy na Mara is ready to accept her battery, I want to be certain I am buying the correct type. I was just going to pick up another Deep Cycle battery, but I think I recall reading in a related discussion recently that maybe the Deep Cycle battery would be overkill.

The accessories we will be running are:
- bow lights
- mast light
- stern light
- VHF (or should I just get a handheld and charge it?)
- GPS/fish-finder/depth-sounder
- cabin light (LED cluster)

Your input would be appreciated. Oh - as the Harpy is not a lifelong investment, we want the minimum requirement to do the job right. I.e. cheaper is better but I don't want to cut corners on the next owner.
 
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#3 ·
Hmm... Are the lights incandescent or LED? A deep cycle battery would probably be the proper choice, but unless you charge the battery back up properly, it will die rather quickly. Do you have an electrical budget, which gives you the number of amps x the number of hours or Amp-Hours you would need for the time between recharging the batteries.

For instance, say you don't want to use the outboard to charge the batteries, but you want to spend a weekend out on the water. That's two nights with an anchor light, and two evenings of cabin light, three partial days of VHF and GPS use.

By figuring out the number of hours you use each piece of equipment between recharging, you'll get a rough idea of how much battery bank you need. Normally, the battery bank should be roughly 2-4 times the average amp-hour usage between recharging periods. Discharging deep cycle batteries more than 50% of their capacity on a regular basis is a good way to kill them early.
 
#4 ·
SD - So does the quality of the charger play a role in this? Do deep cycle batteries require a specific type of charger?

We're buying the GPS this weekend and replacing the remainder of the incandescents with LEDs as well, so we'll be able to work out the electrical budget after that. Thanks for the "2-4 times" tip, though... My "safety" margin was going to be a little slimmer than that.

At the risk of inviting spam, are there any brands in particular that you recommend? A shop that I've bought some supplies at recently sells "Spinach" brand. Are they reputable?
 
#6 · (Edited)
Hyperion...you need a small 3 stage charger (bulk, acceptance, float) to properly charge a deep cycle battery to maintain its health and avoid premature death. As a guideline...the rated amps of the charger should be abou 25% or less of the battery capacity in amp hours of your battery bank. So...200 amp battery bank...50 amp charger or smaller. This is for WET cell batteries. You may be much more aggressive in charging AGM type batteries.
 
#7 ·
Handheld, if range is not a big issue, is more convienent, for a VHF. If your anchor light is an incandescent, it will eat up amps, as will the running lights.

You don't mention how you currently charge the battery, so knowing that would help in further info.

Currently at 35 32 11 N 76 37 20 W
 
#8 · (Edited)
Even if you have a handheld, you will probably want a way to recharge it on-board, otherwise you could end up with no way to call for help. As for the charger, Cam's got you covered there. BTW, AFAIK, there aren't any LED cluster replacement bulbs that are USCG approved for nav lights... so I hope you're replacing the fixtures. If you are just replacing the bulbs in the fixtures, chances are very good that the lights won't be bright enough or have a wide enough angle of visibility to be legal.
 
#10 ·
There is one unavoidable rule: You do not get more out of the battery than what You manage to put in!
If Your only charger is the outboard:Does it have a regulator or just a rectifier?
Anyway You probably get only one option: 'Cheapest' possible lead/acid.
AGM and similar needs more voltage and amps to get properly charged than what You will ever get out of that outboard even at 7000rpm! No 'supercharger' may change that fact: You do not get more out than what You put in!
 
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