Announcement

Collapse
No announcement yet.

Battle of the Blue Top marine agm hybrids!

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • Battle of the Blue Top marine agm hybrids!

    Finally got around to measuring the internal resistance of both 6 month old contestants with my Junsi 306B charger that can do IR:

    Optima D31M Blue Top (light case) 75ah (classic pure-lead)
    3.4 mOhm

    Exide Edge FP-AGM24DP 75ah (dual purpose, GRAPHITE additive. Also seen rebadged as a Rural King model)
    3.7 mOhm

    Measurements were made on the screw-thread terminals of each, which might account for being slightly higher than published for Optima. I can't find the Exide spec, so I measured it myself.

    There are still differences of course, but I'll need another lifetime to find out and test it all.

    The low internal resistance of the Exide pleases me, as that just enhances solar charging. Looks like graphite was a good idea.

  • #2
    Got tired of pampering the Optima with dinky chargers.

    Did a total discharge at 25A down to 10.5v when the inverter kicked off. Convenient. After a minimum 1-hour rest period, I hit it it back up with 40A charger and a nice long float afterwards. Woke it up with no major heating occuring. Back in the old EV days, guys would do this like 3 times to get them commissioned, or after a very lengthy storage. Whaddya know - it still works. Not for daily cycling!! AND only done after ensuring that it got decent charge in the first place!

    That first charge is so important - or at least several rounds of normal cycling to make sure the cells are balanced internally. If you start out with an unknown, and one or more cells are badly balanced internally, then this drop-dead test could harm those severely undercharged cells. ALWAYS get an Optima on a charger upon receipt. Don't do the parking-lot swapout with a lot of short runs to Starbucks! Buy some insurance with a bench charger at least once in it's lifetime - preferably at day one.

    Tip: the Optimate 6 charger with the oscillating absorb and charge verification makes quick work of this...

    I haven't done the same to the Exide Edge yet. However, it appears the graphite and the lower internal resistance has boosted the max charge current to about .5C up to 14.1v according to their specs. Of course the Optima laughs at .5C, but in reality, when am I ever going to go .5C with solar anyway - although I suppose with a genny ....

    I'll keep ya' posted!

    Comment


    • #3
      I was dubious about the whole requiring deep discharges on new batteries to get them "settled" until i did one accidently on my 2 month old 800ah bank. It has 4 strings of 12 volts batteries in series and one string always gave/took more current in a cycle, it was only 10-20 percent more current but definitely not good.. stupid parallel batteries...

      Accidently took it down to around 60 percent DoD over the weekend, and the next day they got a good and deep charge, and now all strings are equal. I did actually do an equalising charge and discharge the day i got them set up but obviously not enough.

      Comment

      Working...
      X