Need help with boat solar & 4 banks

DavidR
DavidR Registered Users Posts: 7 ✭
in General Solar Power Topics #1
Hi guys, the name's David, a newbie to the wind & sun board. I want to add a solar 12V trickle charge system to maintain the 4 banks of batteries on my boat. I have 2 sets of 2x6V GEL batteries wired in series for the House ( A & B ), and 2 sets of Group 31 12V GEL for the engines ( A & B ). I could use your helpful advice on the following please:

How many watts do I need the solar system to produce to properly maintain these batteries while the boat sits for weeks/months at a time in storage?

Should this be just one panel OR 4 panels (1 for each group 31 battery and 1 each per pair 6V's) ? And these are GEL batteries... do I need charge controllers/regulator for each or is it doable w/o them?

And last, is there a good dependable brand(s) you recommend? Thanks in advance for your help!

David
· Share on Twitter

Comments

  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #2
    Re: Need help with boat solar & 4 banks

    Welcome to the forum David.

    There's a key piece of information missing: the Amp hour capacity of the batteries. Group size is only how big the case is.

    The good news is that maintaining a battery requires a lot less energy than recharging one.

    The bad news is that the two battery sets (house and engine) are probably so different in capacity that two different systems will be needed.

    And yes charge controllers are definitely necessary; GEL batteries are very sensitive to incorrect charging. Are you sure they aren't AGM's?
    · Share on Twitter
  • DavidR
    DavidR Registered Users Posts: 7 ✭
    #3
    Re: Need help with boat solar & 4 banks
    Cariboocoot wrote: »
    Welcome to the forum David.

    There's a key piece of information missing: the Amp hour capacity of the batteries. Group size is only how big the case is.

    The good news is that maintaining a battery requires a lot less energy than recharging one.

    The bad news is that the two battery sets (house and engine) are probably so different in capacity that two different systems will be needed.

    And yes charge controllers are definitely necessary; GEL batteries are very sensitive to incorrect charging. Are you sure they aren't AGM's?

    Thank you Cariboocoot. Yes, these are GEL, not AGM's. The 2 – GEL 31’s for the engines are West Marine SeaGel 12V Group 31 97.6 Ah, CCA 550, MCA 780.

    The 4 – GEL 6 volt batteries for house systems located are wired in-series (2 x 6v) for two 12 volt sets of house batteries. These batteries are West Marine SeaGel batteries 6 Volt; 180 Ah; 6v; 585 CCA; 850 MCA.

    1 system, 2 systems or 4 systems... whatever would be best within reason to maintain the batteries for best value is what I am seeking. I will purchase the components and then install it.
    · Share on Twitter
  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #4
    Re: Need help with boat solar & 4 banks
    DavidR wrote: »
    Thank you Cariboocoot. Yes, these are GEL, not AGM's. The 2 – GEL 31’s for the engines are West Marine SeaGel 12V Group 31 97.6 Ah, CCA 550, MCA 780.

    Good. You don't need much at all to keep them up. One or two Amps per battery would do it. That's about 70 Watts of panel for the two. If the batteries are or can be paralleled then one charge controller will do it. The controller needs to be one capable of the GEL batteries low Voltage requirements. The little SunGuard might be just right here: http://www.solar-electric.com/sg-4.html
    The 4 – GEL 6 volt batteries for house systems located are wired in-series (2 x 6v) for two 12 volt sets of house batteries. These batteries are West Marine SeaGel batteries 6 Volt; 180 Ah; 6v; 585 CCA; 850 MCA.

    Not unexpected that these would be larger. About 3.6 Amps each for maintenance. Again if they can be left in parallel then that's around 7 Amps or a 130 Watt panel on a 10 Amp SunSaver http://www.solar-electric.com/ss-10.html for example.

    If for some reason you can't parallel either set you'd have to go with individual panels & controllers each. But it looks to me like one set-up for the small batteries and another for the large ones would do it.
    · Share on Twitter
  • DavidR
    DavidR Registered Users Posts: 7 ✭
    #5
    Re: Need help with boat solar & 4 banks

    Thank you once more. I will look into what it will take to implement your recommendations.


    .
    · Share on Twitter
  • DavidR
    DavidR Registered Users Posts: 7 ✭
    #6
    Re: Need help with boat solar & 4 banks

    I cannot parallel the engine banks nor the house banks as I believe that would defeat the purpose of the battery switches. Here is a pic of the panel.

    Attachment not found.

    If I was to use one 70 watt panel for the 2 group 31 engine batteries, would I then use 2 charge controllers, one wired to each battery? Or would I need to have a panel with a control for each 12v battery? Would I still use an sg-4 controller, or is there anything smaller that would be appropriate?

    Pretty much the same question when it comes to each set of 6 volt batteries, except for the ss-10 controller (same or go to a smaller one x2) ?

    I appreciate your efforts to help me resolve this. Thanks.


    .
    · Share on Twitter
  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #7
    Re: Need help with boat solar & 4 banks

    Your battery switches are standard and include the 1+2 position, but I expect in that position everything is 'live' as it uses the switches for "off".

    It might be feasible to use similar switches, 'in reverse' so to speak, on the controller outputs so that the batteries would be paralleled for charging during non-use only. But there would be no 'interlock' to prevent them being paralleled by this switch when the main systems are active.

    How good is your memory? Would you be able to remember to turn off the the solar charging when you are going to use the boat?
    · Share on Twitter
  • DavidR
    DavidR Registered Users Posts: 7 ✭
    #8
    Re: Need help with boat solar & 4 banks

    My memory is OK, but launching and retrieving my 30'er does have it's own checklist I'd rather keep this simple and leave the chances for errors to a minimum.

    Even though it might cost 50% or so more, wouldn't it be best (least problematic) to set up each battery (or set of 2x6v) with it's own panel and charge controller? If so, then does your prior parts recommendations change (since you were basing the parts on sharing panels and paralleling the battery banks) ?

    Again, your help is most appreciated. Thanks.


    .
    · Share on Twitter
  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #9
    Re: Need help with boat solar & 4 banks

    Then you have to set up for one battery, one panel & controller. It's a bit wasteful considering how little power is actually needed.

    You'd end up with four of those little controllers plus one panel for each battery; 30 Watts each for the starting batteries and 65 Watts each for the house batteries.

    It gets pricey:

    4.5 Amp charge controller four @ $30 each = $120
    30 Watt panel two @ $125 each = $250
    65 Watt panel two @ $200 each = $400
    Total: $770

    Alternate plan would be to use two dual controllers like this http://www.solar-electric.com/modubachco251.html For $168 and one panel per battery bank: a 65 Watt for the starting batteries ($200) and a 130 Watt for the house batteries ($285). Total $653. Somewhat simpler installation too.
    · Share on Twitter
  • DavidR
    DavidR Registered Users Posts: 7 ✭
    #10
    Re: Need help with boat solar & 4 banks
    Cariboocoot wrote: »
    It gets pricey: Total: $770... Alternate plan would be $653.

    Ouch... that is pricey, particularly considering I paid about that amount for the 6 batteries brand new at wholesale. I guess I was thinking this could be done simple, and for way less bread. Any other options that would cost much less (ie: along the lines of Harbor Frieght Tools) perhaps, but marine quality application?

    Again, thank you.
    · Share on Twitter
  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #11
    Re: Need help with boat solar & 4 banks

    When you go cheap you introduce possible problems, especially with GEL batteries which aren't very forgiving. Otherwise tiny 'battery minder' panels that put out an Amp or so and are unregulated would be acceptable. It's that unregulated part that can be the problem. A flooded cell will have a lot more tolerance of having Voltage pushed up.

    When the boat is out of the water is there shore power available? If so some battery tender type chargers and a small timer might be a better option; set them to turn on once a month for a small charge and you should be good.

    Solar is expensive. On the small scale it's even more expensive per Watt than large scale. Look at that 30 Watt panel: $4.16 per Watt. A 'full size' 200+ Watt panel will be around $1 per Watt.
    · Share on Twitter
  • unseenone
    unseenone Solar Expert Posts: 61 ✭
    #12
    Re: Need help with boat solar & 4 banks

    When you factor in the price of the batteries, and the extended life you will get by doing it right, as well as reliability it's not so bad. I like the SunSaver duo option. What kind of boat is it? Do you have any pictures?
    · Share on Twitter
  • DavidR
    DavidR Registered Users Posts: 7 ✭
    #13
    Re: Need help with boat solar & 4 banks

    I keep the boat on it's trailer in local storage. There's no power there to plug in the charging system so I occasionally tow it home to charge it, and will perform some maintenance work on it when I bring it home. It's not that I'm going to be cheap, but I would need to see a better value for the money invested just to add solar trickle charging. Besides $$$ is tight and our government wants to take more every chance they get....... get my drift? Anyway, thanks again and best regards!


    .
    · Share on Twitter
  • TenMile
    TenMile Solar Expert Posts: 62 ✭✭
    #14
    Re: Need help with boat solar & 4 banks

    Hi David,

    I have a solar setup on my boat -- battery system is somewhat smaller in that I have 2 banks. One start battery (only one engine), and then a single house bank of 2 x Trojan 6V batteries.

    First, with your house batteries, I would consider combining them into a single large 12V system rather than 2 x house systems and then consider getting yourself a good battery monitor like a Trimetric or Xantrex that will provide you with the actual State of Charge info. I'd think you would get a longer life out of one large system as in general you'd use less capacity than 2 smaller systems.

    But, assuming you have a good reason for 2 house systems...

    For charging, I use a device from Blue Sea Systems called an Automatic Charge Relay (ACR) and would never own a boat without one. When the ACR measures a positive charge (e.g. from your alternator, solar or charger) it will combine multiple battery banks and charge them. Given you have twin engines and twin battery banks, you could install 2 ACR systems. Alternator 1 and Solar 1 and Charger Output 1 charging the Start batteries, Alternator 2 and Solar 2 charging the House systems.

    What I really like about the ACR is that you no longer have to guess on which battery system to charge, and guess whether your system is fully charged. System including the battery monitor can tell me the exact story. No more fiddling with the battery combiner switches ever...

    Note that the ACR has some intelligence in that it won't connect a good battery system to a bad one (e.g. if one system is discharged or shorted it won't combine). Google Blue Sea Systems ACR -- your case would be 2 engines, 4 battery banks.
    · Share on Twitter
  • unseenone
    unseenone Solar Expert Posts: 61 ✭
    #15
    Re: Need help with boat solar & 4 banks

    Great information, I'm currently figuring out upgrading my boat battery/charging schemes and adding solar.
    · Share on Twitter

Categories