[Public-List] Batteries, solar panel.

[Greg Hounsell]

Morning!

Are you using your two 80Ah batteries in parallel?

Just a couple thoughts... Just yell at me to sum up when bored 😁

A 60w panel, based on say 20V nominal will give you 3 amps in lab
conditions. Count on 50-80% efficiency depending upon time of day, angle of
panel, temperature, clouds etc etc.

Up here in the Great Lakes you can count on 3-4 peak sunlight hours for
maximum charging during the summer.  So with output of 1-2 amps and an mppt
controller you may boost that up another half amp for output into the
battery bank

This won't give you a complete recharge in one day of 25 amps (plus
whatever you are using while it is charging) to completely recharge the
bank, but it can help how many days you can stay out, or before you need to
use the engine.

Using 100W panel will potential give you 5-6amps (18V @ 100% efficiency)
and be able to give you a full recharge over the course of a sunny day with
no battery use during that time. In ideal weather you could get ~80% of
your used 25amps back during the peak sunlight time - after which a battery
typically slows down it's absorption rate anyways.

With the above sized panels mentioned you would only need a 10amp mppt
charge controller. The battery banks max recharge (if paralleled) is about
25% of it's ah rating - 40amps but for dollar you would need about 540W
solar working 100% efficiency.

Another thing to think about is adding another battery. This would be new
and would accept charging at different rates and efficiency than the older
other bank; having the banks wired up for "all" when charging I think adds
potential for lessening the life of both the newer battery and the older
bank.

On Sat, Aug 4, 2018, 1:29 AM Martin Privette via Public-List <
public-list at lists.alberg30.org> wrote:

> Hey Marcelo,
>
> I have 2 aux batteries and 1 starter batter in the base compartment, you
> can put another one there for sure( overlooking the plastic battery box ).
>
>  A 100w solar panel might be better if you haven't gotten one yet, with at
> least a 40w MTTP charger/controller.
> You can clamp the line to either bank and let it go( I let it charge all
> 3...Battery selector in " all " position )... The charger will regulate the
> output to about 13.7volts or so...no overcharge.
>
> The trick is setting the panel angle for optimum solar absorption.
>
> I saw a little rig that used the stern rails as a hinge for the solar panel
> .. plastic tie wraps., rubber bushings...a small block attacked to the
> backstay a couple of feet above the sailors head. The panel was reinforced
> at the top with 2" right angle aluminum.
>
> The angle is easily adjusted... under way, or stationary. This rig also
> incorporated a small clete below the block on the backstay as well, to tie
> off the bitter end.
> The solar panel is always off the stern... out of the way of navigation.
>
>
> I'd like to hear some input on this subject myself...
>
> Marty
>
> Reverie 21
>
> On Fri, Aug 3, 2018 at 11:53 PM, Marcelo D. Gentinetta via Public-List <
> public-list at lists.alberg30.org> wrote:
>
> > Good evening,
> >  I would like to know the group’s opinion on battery capacity and
> > recharging options for my Alberg 30. Some facts about my boat are:
> > 1. 80% daysailed. 20% 2-4 day long weekend cruises.
> > 2. Boat is at a marina.
> > 3. Worst case electricity consumption for an overnight cruise is at 25
> > amps/day. All LED cabin lights, LED tricolor/anchor light. No fridge.
> > Stereo/VHF. Low draw Hella fans (2). Occasional use of Raymarine tiller
> > pilot. Running lights on with engine. Cellphone/tablet recharge.
> > 4. Presently has two gp 27s dual use West marine flooded batteries in
> > under cabin sole. Each has 80ah capacity.
> > 5. Atomic 4 has 55 amp alternator with 2 blade prop.
> > 6. Guest smart charger on shore power keeps batteries up at marina.
> >
> > I am looking for more independence  from shore power to charge the
> > batteries. My total battery ampacity is limited. Where to locate another
> > house battery? My present idea is to add a 60W solar panel off the stern
> > pulpit with a charge controller to both batteries that should produce
> about
> > 20-25 amps on a good day.
> > Based on all this, I appreciate your input.
> >
> > Marcelo
> > “Alegría” #441
> >
> >
>