[Public-List] Batteries, solar panel.

Sat Aug 4 08:07:20 PDT 2018

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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