[Public-List] Batteries, solar panel.

Sat Aug 4 11:16:02 PDT 2018

Afternoon!

In your case, and this is just my personal preferences, I would keep them
separate for solar charging. The start battery will get charged when the
engine is running ( as long as the alternator gets to sufficient rpm to
excite the system to put out charging current,).

50% is a good max level to aim for whether 40 or 50 amps.

 If you are wanting to top up the battery each day then you'll need a
system than can put ~30 amps total back into your battery over the course
of a nice clear sunny day. A 100W panel may get there (~ 20amps during the
3-4 peak sunlight hours and the rest off peak based on about 5-7amps from
the panel.

If you are looking to be able to put some back each day to lengthen the
number if days before you reach 50% depletion then you could go for a
smaller panel.

With either battery you mentioned, the generalized max charge they can
accept is 1/4c or ~20-26 amps. So if you are going for 100W panel or less
then a 10A charge controller is all you need. I would not go less than a
50W panel.

Cheers
Greg
#592 Impromptu

On Sat, Aug 4, 2018, 11:07 AM Marcelo D. Gentinetta via Public-List <
public-list at lists.alberg30.org> wrote:

> Yes, the 2 batteries are in parallel. Battery 1 is used for engine start
> only and #2 is used as house battery based on how the battery selector
> switch is positioned. I have a battery isolator between them. My
> understanding is that if the house battery is rated at 80ah, my “usable”
> portion of that is around 50% or 40ah so that the battery is not damaged by
> the deep discharge. So if the #1 battery is used solely for cranking,
> should it really be part of the solar panel or does the engine alternator
> take care of it? If I upgrade the house battery to say a gp 31 rated at
> 105ah, would this change my recharge requirements for better or worse? I
> would still be consuming the same number of daily amps.
> Marcelo
>
> > On Aug 4, 2018, at 7:29 AM, Greg Hounsell via Public-List <
> public-list at lists.alberg30.org> wrote:
> >
> > 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
> >>>
> >>>
> >>
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