Helping a neighbor

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Cariboocoot
Cariboocoot Banned Posts: 17,615 ✭✭✭
My neighbor here needs new batteries. Ignoring my advice to buy two Trojan T-105's (which he insisted he need 4 of because he had 4 before) he got a great deal on two Surrette S-460's: slightly marred, $350 each.

The trouble is, he has one 80 Watt panel.

The best I can figure is, he'll get about 320 Watt/hours (no, he has no monitoring equipment and I don't know what his CC or Inverter are - I'm going to look) per day. But the charge rate will only be 6 Amps peak, no? That's not going to cut it for a 350 Amp/hr battery. It'd be a shame to see those Surrettes toasted before their time. But he says it worked with his old batteries, which total about 410 Amp/hrs.

Now, is it so hot here I can't think straight anymore, or is this not going to work?

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  • BB.
    BB. Super Moderators, Administrators Posts: 33,479 admin
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    Re: Helping a neighbor

    Surrette recommends 5 amps per 100 AH battery rating for equalization (this is for "Corrective Equalization" -- how to try and recover from deficit charging).

    Presumably, as long as their 80 watt panel is at least equal to the load removed from the battery bank every day (no deficit charging)--then they can equalize once or twice a month with the genset for a few hours.

    You can follow the link above and get more details about their recommendations for charging/maintaining the batteries.

    Or go here for there online battery information:

    http://www.surrette.com/content/troubleshooting-0
    Deficit Cycling

    Rolls batteries have been designed to provide many cycles and therefore long life. This long life, however, is dependent on the correct charging regime.

    To fully charge a lead acid battery, more ampere hours must be returned to it than have been drawn from it. This is not always possible in renewable energy applications because they rely on the Sun and Wind. In these instances the battery may not receive a full charge before it is discharged again. If this deficit is not corrected the battery will eventually sulphate and its capacity will deteriorate. To lessen these symptoms it is essential the battery is returned to a fully charged state at least once a month. The battery’s state of charge (SOC) can be checked using a combination of its voltage and specific gravity.
    If the batteries do not respond to normal charging, a course of equalization* will be required. This is in essence controlled overcharging in order to return the acid back into the electrolyte. Given that the acid is more dense than the water, no noticeable increase in the SG will be noted until the gassing voltage has been reached (2.4VPC) and the two start to diffuse.
    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
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    Re: Helping a neighbor

    6 amps at -40 maybe!

    Let's say 5 amps,

    5 amps* 4 hours= 20ah

    Into ~350 ah would be ~1.4% probably (maybe?) enough to cover self discharge.

    I sure would like to see at least 15-20 amps.

    What is he going to use the bank for and what are his other charging system(s)?

    I would buy him a Tri-metric for a neighbourly gift.

    T.
  • TnAndy
    TnAndy Solar Expert Posts: 249 ✭✭
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    Re: Helping a neighbor

    You're my kinda neighbor, T

    :D
  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
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    Re: Helping a neighbor

    from tony,
    "6 amps at -40 maybe!

    Let's say 5 amps,

    5 amps* 4 hours= 20ah

    Into ~350 ah would be ~1.4% probably (maybe?) enough to cover self discharge."

    that's not quite how the rate of charge percent is done. you are adding all of the hours at the rated charge current and then dividing into the battery ah and that's wrong. the rate going in, in amps, divided by the battery ah is the charge rate %. in this case 5a/350ah=1.4%. this could maintain the batteries until a proper charge can be delivered and that means no loads until then. for the record the t105s have an ah of 225ah and 5a into that is 2.2% and still falls too short.
  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
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    Re: Helping a neighbor

    Neil,

    I only used 20 ah as a daily harvest, to compare to loads. Since Marc gives no info as to the loads, I thought it illustrative. If the person in question is using say 20 ah of loads, he will fall behind from day one.

    The 5 amps is ~1.4% of battery capacity (if my math is correct)

    While estimating self discharge may be difficult, but giving a AH/day estimate is part of the whole calculation of draw VS recharge.

    If I have missed something, please let me know,

    T
  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
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    Re: Helping a neighbor

    So what you're all saying is: I'm right; there's really not enough panel there to do a proper job of charging.

    I'll see what the rest of the outfit is when I go over later this week.

    As for buying him a Tri-metric ... I haven't got mine yet. This year the resources are going to stop the cabin from falling down.

    I'll print out the more pertinent info and try to explain it to him. It's a hard go when people say "but it worked with my old batteries."
  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
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    Re: Helping a neighbor

    Cabins never stop falling down! We just keep running around them jambing stuff in them to offset gravity!

    T
  • BB.
    BB. Super Moderators, Administrators Posts: 33,479 admin
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    Re: Helping a neighbor

    Offset Gravity. See Santa Cruz Mystery Spot. Print Tickets. Make money. QED ;)

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
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    Re: Helping a neighbor

    One of mine, it was built as a trappers shack with unpeeled log framing, has so many bugs in it, the only thing holding it up is the ants doing aerobics! I swear, every time I sweep, I sweep up buckets of saw dust from the bugs!

    T.