Replace batteries

Batteries, Generators, Solar, Wind and Electronics
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mjwalek
Posts: 29
Joined: Mon Jul 16, 2012 2:43 pm
Location: Jamestown, RI

Replace batteries

Post by mjwalek »

Seems like it’s time to replace my batteries. With all the newer technologies now available, I’m wondering if anyone has some good advice on suitable replacements. Does one buy a cranking battery and a deep cycle or can a deep cycle fill both roles? Any thoughts on the new lithium batteries?
"Take Five"
1993 Freedom 35 hull #1
Jamestown, RI

Pearce
Posts: 65
Joined: Sat Feb 22, 2020 10:28 am

Re: Replace batteries

Post by Pearce »

Think the answer is it all depends on your situation.

The simple answer to your first question is yes. Traditionally one has a separate starting battery v house bank. Generally starting batteries are built for a quick burst of high energy while house batteries are a slower, steadier draw. So the plates are different.

Although it does depend on the application and system design. Smaller boats can get away with one small battery bank. The more energy usage and bigger the engine then more power required.

Your second question is in regards to lead acid, absorbed glass mat (AGM) v lithium batteries.
Generally the newer tech costs more but has more features. AGM and lithium are maintenance free and have different charge and discharge characteristics. They will also require revisiting charging settings.

Was just reading an article from Practical Boat Owner on battery types.

https://www.pbo.co.uk/projectboat/best- ... ries-73177

Simple question but complex answers.

Jeff Cote also has a terrific site with lots of videos and articles on all manner of marine electronic design issues.

https://www.pysystems.ca/
Pat
Schoodic - F36
Beverly MA

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newt2u
Posts: 236
Joined: Wed Sep 11, 2019 11:24 am
Location: UK

Re: Replace batteries

Post by newt2u »

I use Lithium (LifePo4) batteries on my F21 (no starting battery as I use an outboard and arm power). Advantages are weight, long life, battery management, so no overcharge, over discharge, whatever your equipment is doing. I use 2 * 50Ahr in parallel for house/electronics and in series for my auxiliary power, a small electric motor. According to my data sheets you can parallel up to 4 batteries with no need for additional electronics. Charging characteristics are similar to lead acid, indeed my solar charger tells me the same, for 12V nominal lifePo4 it says set to lead acid settings. The disadvantage of course is the cost, although this is coming down. However, this should be considered against lifetime, which is generally longer than lead/acid and the fact that for 100Ahrs of battery you get 100Ahrs, whereas for lead acid it is not good for the battery to discharge more than 50%. So twice the capacity for twice the cost.
Rockin - F21 twin drop keels - located Whitehaven, Cumbria, UK

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