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  • Dual Battery Woes

    I've got two batteries in my car, connected together with a Hellroaring battery isolator. One battery is a standard car battery. The other, isolated battery is an Optima Yellowtop. While the car is running, the alternator both batteries and all the loads are all tied together. When the car is off, the isolator seperates the deep cycle battery and carputer from the car's starting batter.

    My carputer is in standby mode most of the time, except while driving, and perhaps 20 minutes each day when it's running off of the isolated battery.

    My problem: After about 4-5 months of operation, the Yellowtop has a dramatically reduced capacity, and drops below 11 volts after just a short time (20 minutes) of use with the car off.

    Any ideas on my problem? I've actually had this problem occur twice now. The first time I thought it was just a bad battery.
    VIA EPIA M10000 | 7" Lilliput Touch VGA | PW70 | 256 Meg RAM | 20 Gig 2.5" drive
    Dual Battery with Optima Yellowtop | Hellroaring Battery Isolater
    ICOM 2720A| Delorme Earthmate GPS | Tiny Track APRS
    Survives Crank

  • #2
    hmmm.... I'd love to hear thoughts on this too... i'm prettymuch doing the same exact thing as you, although my second battery is a used Optima truck battery. (found the hellroaring units to be a tad pricy, going to make my own).... anyway, if theres gonna be problems, I'd be interested in hearing too this one too =)
    2000 Jeep Cherokee
    -CarPC: [_____]50% complete
    -planning done, still need a few parts
    -In-dash motorized VGA is finally out, need $$$
    -Need to replace factory HU

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    • #3
      I found this in the FAQ on the Optima web-site. I certainly don't have independant charging circuits, HOWEVER, I believe that the Hellroaring isolator does not result in much of a voltage drop. Could my problem be related to lack of independant charging ciruits?

      Q: Can I use an isolator with an OPTIMA?
      Yes, most any type of battery separator or solenoid can be used with an OPTIMA. The important thing to remember is that the charging voltage must be within the limits suggested by OPTIMA Batteries. If you are using an OPTIMA and a conventional battery, your system must charge each battery independently. Remember, some isolators cause a voltage drop, make sure your charging voltage AT THE BATTERY is sufficient. Continued undercharging of a battery will lead to premature failure and a drop in capacity.
      VIA EPIA M10000 | 7" Lilliput Touch VGA | PW70 | 256 Meg RAM | 20 Gig 2.5" drive
      Dual Battery with Optima Yellowtop | Hellroaring Battery Isolater
      ICOM 2720A| Delorme Earthmate GPS | Tiny Track APRS
      Survives Crank

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      • #4
        nice find.... gotta make sure i check that in my circuit....

        do you have a multimeter handy that you can check that with?
        2000 Jeep Cherokee
        -CarPC: [_____]50% complete
        -planning done, still need a few parts
        -In-dash motorized VGA is finally out, need $$$
        -Need to replace factory HU

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        • #5
          Multi-meter? yes. I've actually got a digital volt meter hardwired to the aux battery. It looks perfectly 'normal'. I'm more concerned about the 'independant charging circuit' comment.
          VIA EPIA M10000 | 7" Lilliput Touch VGA | PW70 | 256 Meg RAM | 20 Gig 2.5" drive
          Dual Battery with Optima Yellowtop | Hellroaring Battery Isolater
          ICOM 2720A| Delorme Earthmate GPS | Tiny Track APRS
          Survives Crank

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          • #6
            The Optima Yellow top battery is a Deep Cycle battery. These batteries are designed to be charged then discharged. These batteries use a thinker plate and thinner Active Paste layer than your standard automotive Optima. Each time you charge the battery, you consume some of the paste.

            Now, in a situation like a camper or other system where the battery is fully charged than used as a power reservoir, you consume a small amount of this paste during your charge cycle and a little during your discharge. Usually this is done "not so often" so this paste lasts a decent amount of time.

            In a car, your battery is in charge mode whenever your car is running. I know there are regulators and what not, but trust me, your car is constantly charging your batteries. During this charge cycle, you are consuming this paste layer. And since this paste layer is much thinner (with thicker plates) than the standard automotive Optima, you have a much shorter life cycle with your battery.

            Sure, the capacity is attractive, but you will suffer with a shorter life. I have always ran standard automotive optimas and never had a problem. If you do want some extra capacity, use the Blue Top Optima. It is designed better for continous charging.
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            • #7
              maybe

              maybe it is that the batteries (since they are different types) have different internal resistances, so they don't charge equally. Hence the need to charge each battery independently.

              ---- just my $0.02

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              • #8
                this issue has been asked in one of my car audio magazines and what OpenMind said is almost exactly like what they said. their suggestion was to use a normal car battery and mount, vent it correctly. I think stinger makes a series of sealed batteries that are not deep cycle batteries.

                Optima batteries are usually used in race vehicles w/out an alternator, the battery will last long enough to run a race. In the car world, they are used to power systems during shows and while the vehicle is off.

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                • #9
                  Thanks, Openminds, for the post. That explains why both times the battery has died shortly after a really long trip. I've just returned and gotten my third, new, optima yellowtop. Perhaps I'll return it in exchange for a bluetop.
                  VIA EPIA M10000 | 7" Lilliput Touch VGA | PW70 | 256 Meg RAM | 20 Gig 2.5" drive
                  Dual Battery with Optima Yellowtop | Hellroaring Battery Isolater
                  ICOM 2720A| Delorme Earthmate GPS | Tiny Track APRS
                  Survives Crank

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                  • #10
                    I've used an Optima Yellow Top as my car's starter battery for over a year now. (90A max alternator output).

                    No failure and voltages are correct.

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                    • #11
                      I just bought an optima yellow top and am looking at running into the same problems as you guys are.

                      One of my good friends that have experience with Optimas says it either hit or miss. Meaning that some are really good and work fine as the car battery and others fail.

                      I don't have mine hooked up yet to anything yet but one thing that would be interesting to find out is if there are any circuits that can detect when the battery is almost drained and then start charging it.
                      -Jesus- King of Kings Lord of Lords

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                      • #12
                        One thing I was thinking is you may want to make sure your alternator is putting out the correct voltage. It may be wearing down, from charging two batteries. I'm really just throwing darts here though. Good luck.
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                        • #13
                          My alternator apears to be OK, generating ~14.2-14.4V while the car is running. I've had no problems with the other (starter) battery, although it's been drained completely 2 or 3 times, and doesn't seem to charge beyond 12.4 volts or so.

                          I just purchased a 1.5amp trickle charger, and intend to plug it in 'occassionally' under the assumption that the battery isn't being fully charged during my 30 minute (1 way) commute. Perhaps I am putting too much demand on the alternator? I'm also considering replace the main (starter) battery in case it's part of the problem (could be close to failing, and sucking too much current, and diverting charging current from the yellowtop?)

                          Regarding Openmind's post, I received a note from the fine folks at Hellroaring. He said they've been running a Yellowtop connected to the alternator via a solid state isolator, and it hasn't suffered any ill-effects after several years of continuous charging. Sure, the battery may not be 'designed' for continuous charging, but his opinion is that the negative affects of this may be negligible.

                          I guess I'll find out soon enough!
                          VIA EPIA M10000 | 7" Lilliput Touch VGA | PW70 | 256 Meg RAM | 20 Gig 2.5" drive
                          Dual Battery with Optima Yellowtop | Hellroaring Battery Isolater
                          ICOM 2720A| Delorme Earthmate GPS | Tiny Track APRS
                          Survives Crank

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                          • #14
                            i'm also aware of a lot of people who use yellows as their primary battery (this is done a lot in 4x4s) ... you certainly can expect it to have a shorter life ... but when i say shorter i mean a few years ... 5 months is crazy.

                            the only concern i would have with your setup is alternator output. but you said you get 14v ... is that at the alt or at the yellow?

                            if you were straining your alt, you'd see a voltage drop more than likely.

                            Also, hav you considered using hibernate instead of standby? I'm wondering if having the PC in standby so often is causing the yellow to drain more than usual. having a yellow in the cycle of discharging a good bit and then recharging on a regular basis would cause it to fail much more prematurely i think.

                            when used as a the primary battery, it isn't drained much during cranking ... and most people don't run accessories for long periods of time very often. i would think this is why yellows in these situations will last for a few years.
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                            • #15
                              Standard rule of thumb is that your alternator should be able to provide at least 25% in amps vs. the battery's Ah rating. (e.g. 55Ah battery, you should at least be able to provide about 15A of charging at the proper voltage). Remember that the alternator's efficiency is usually 60-80% of rated after the engine/alternator has warmed up and decreases in efficiency as the alternator warms up and becomes hotter.

                              Like I said in a previous post, I have a Yellow Top (D34) as my starter battery for a little over a year. It's been through a little over 30,000 miles and is still operating like as it's brand new. It powers my Xtant A4004 amp among other things while the engine is off.

                              But 5 months, there's definitely something wrong. Has anyone contacted Optima to see what their stance is of what might be the root cause? But definitely not charging a battery to its rated voltage (i.e. failing alternator) will definitely cause the life of a deep-cycle battery to decrease considerably. No matter if it's lead-acid, AGM, spiral-cell, etc.

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