Quick Battery Question

Rngr275
Rngr275 Solar Expert Posts: 127 ✭✭
in Solar Beginners Corner #1
While we are waiting for our PV system to get installed we will be living in out Off Grid no power house for about a month. On a very good reccomendation froma member here I have purchased a Shurflo 12Vdc pump which will pull water from my cistern and pump up an 85gal pressure tank (which I will use for the whoule house eventually). The pressurized water will feed an Ecco LP tankless water heater so that we can take showers. My question is 2 fold: I saw SAM's had both 12 and 6V golf cart batteries. The 12v was ~$180 (I think) @115Ahr, I don't know the cost of the 6V but they were either 215 or 230Ahr. Which would you suggest to use for my set up? The second thing is: I will be charging the battery(s) with my generator as needed (hopefully not to often since the pump doesn't draw to much power) and I don't want to trash them (or said another way I want to charge the correctly). Do you have any suggestions for a good charger and can I use it no matter which batteries I go with. One 12V or 2 6V. I have this charger just not sure it will work; http://www.walmart.com/ip/Schumacher-SpeedCharge-15-Amp-Marine-Battery-Charger/13005745
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  • Blackcherry04
    Blackcherry04 Solar Expert Posts: 2,490 ✭✭✭
    #2
    Re: Quick Battery Question

    I have looked at the 12v battery they carry, For $160 the GC-2 batteries end up being a better deal if you need the AMP's and they'll last longer because you'll pull them lower. Your charger will work ok.

    The microprocessor of the Schumacher SSC-1500A Ship 'n Shore SpeedCharge Charger monitors the attached battery's voltage level from the moment it is connected, using this ever-changing data to improve the charging system's multi-stage charging cycle. Multi-stage charging allows a battery charger to automatically cycle between a variety of charging phases including desulfation, bulk charging, absorption, monitoring, float mode and a minimal drip charge maintain mode when a connected battery again falls below a certain set level. The microprocessor collected data allows the SSC-1500A to more accurately measure the charging needs of a connected battery, resulting in quicker charge times and a lessened chance of damage due to overcharging.
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #3
    Re: Quick Battery Question

    Without knowing the actual price of the 6 Volt batteries it's hard to say. If they're less than $90 each, then you'd be buying more capacity for the same or less money. That's what matters.

    As for the charger, any charger will work to one degree or another. Most of them do not have the Bulk/Absorb/Float (& Equalize) profile the deep cycles need. The one you link to appears to adjust for battery type, but only in so much as adjusting maximum current and peak Voltage level. As far as I can tell it brings the battery up to "full charge Voltage" and holds it there. This is probably 13.8 Volts, as that is standard for most automotive type batteries. It may be more complex than that, but it doesn't really say so.

    The Iota chargers are closer to correct for charging deep cycles. Of course they're more money. But if this is a long-term investment it works out to a better value as any charger use will be in the right profile for the batteries, making them last longer.
    Iota 15 Amp: http://www.solar-electric.com/ioen12vo15am.html $129
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  • squarebob
    squarebob Registered Users Posts: 25 ✭✭✭
    #4
    Re: Quick Battery Question

    Our host also offers the Power Max brand of chargers in various amps. I would think a 45 or 55 amp charger would be a good match for Golf Cart Batteries. No EQ charge with these units.

    225 amp/hr batteries charged at 25% = 56 AMPS

    http://www.solar-electric.com/pomax12vo45a.html

    http://www.solar-electric.com/pomax12vo55a.html

    Bob
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  • Vic
    Vic Solar Expert Posts: 3,208 ✭✭✭✭
    #5
    Re: Quick Battery Question

    My $0.03,

    The fewer cells per battery the better, in general. In this exact case, it may not make too much difference. Many here use 6V Golf Cart (GC-2) battteries with very good results.

    You might decide in the intirim to power a TV set etc, so a little reserve battery and charger capacity is often good.

    The FloJet pumps are often used in RVs, and can deliver a reasonable volume of water at 15-ish PSI. It could take a long time to charge that pressure tank, at least initially. If your flows are modest, you might not need the pressure tank. Altho, some Tankless WHs do need appreciable water flow.

    Done guessing, Vic
    Off Grid - Two systems -- 4 SW+ 5548 Inverters, Surrette 4KS25 1280 AH X2@48V, 11.1 KW STC PV, 4X MidNite Classic 150 w/ WBjrs, Beta KID on S-530s, MX-60s, MN Bkrs/Boxes.  25 KVA Polyphase Kubota diesel,  Honda Eu6500isa,  Eu3000is-es, Eu2000,  Eu1000 gensets.  Thanks Wind-Sun for this great Forum.
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  • Rngr275
    Rngr275 Solar Expert Posts: 127 ✭✭
    #6
    Re: Quick Battery Question

    Appreciate everyone's help.
    Stopped by Sam's

    6v batteries are $78 and $88 depending on which Ahr one you buy
    12v battery is $184

    Think I'll give the 6v a roll for the extra Ahr.. as Vic said might need a TV :)

    I figure the pump will take som time initially to fill the tank, but I was hoping to keep the run times of the pump after that to a minimum by using the volume of water stored in the PT. Kind of a balance... use more power to run a bigger pump but with less run time or less power pump run longer because of low flow. The Shurflo is 3.5gal /min @0psi and ~2 gal/min @30psi and drwing~ 5amps... if I read thjis right: http://www.shurflo.com/files/RV-Product-Data-Sheets/Classic-Series-Pumps/Premium%20Plus%20Pump%20-%20pds-2088-453-144_444_.pdf
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