[Public-List] Batteries, solar panel.

Sat Aug 4 12:14:38 PDT 2018

I agree with Michael that you can over analyze everything. Unfortunately, I have an analytical mind so it is a battle!. 
I am trying to keep the system as simple as possible though and trying to learn more about the whole process. Greg’s explanations have been very helpful. This brings me to another question. If you added a second house battery, where would you locate it in a liner boat and would it be in parallel to the present house battery which is already in parallel to the starting battery?

> On Aug 4, 2018, at 1:16 PM, Greg Hounsell via Public-List <public-list at lists.alberg30.org> wrote:
> 
> 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
>>>>> 
>>>>> 
>>>> 
>>> _______________________________________________
>>> These businesses support your Association:
>>> http://www.alberg30.org/store/A30supporters.html
>>> Please support them.
>>> _______________________________________________
>>> Public-List mailing list
>>> Public-List at lists.alberg30.org
>>> http://lists.alberg30.org/listinfo.cgi/public-list-alberg30.org
>> 
>> _______________________________________________
>> These businesses support your Association:
>> http://www.alberg30.org/store/A30supporters.html
>> Please support them.
>> _______________________________________________
>> Public-List mailing list
>> Public-List at lists.alberg30.org
>> http://lists.alberg30.org/listinfo.cgi/public-list-alberg30.org
>> 
> _______________________________________________
> These businesses support your Association:
> http://www.alberg30.org/store/A30supporters.html
> Please support them.
> _______________________________________________
> Public-List mailing list
> Public-List at lists.alberg30.org
> http://lists.alberg30.org/listinfo.cgi/public-list-alberg30.org