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reserve capacity in batteries

Discussion in 'Truck & Equipment Repair' started by murphy4trees, Feb 4, 2010.

  1. murphy4trees

    murphy4trees Member
    Messages: 62

    I AM sure this has been coverred before here, so I appreciate your support...

    Last couple times out the my battery has been dying early on after a couple of hours

    here's the story

    I plow with an 87 Dodge ram charger 318... great driveway machine

    I usually put a new battery in it every year, because it sits around all summer without getting driven much..
    So this year I went into Napa and instead of getting the regular battery that is called for in that truck, I asked for the "biggest" battery that could fit in it.. I AM concerned that they may have given me a battery with a lot of cranking amps, but a low reserve capacity. My plow guy tells me that you need reserve capacity, not necessarily cranking amps for plowing snow (gas not diesel).. the reserve capacity on this battery is 120.. whatever that means..

    We had a big storm on 12/20 and it plowed something like 30+ hours, no problem, then it was parked and the battery dies cause a light was left on. Could the battery have been damaged then?.. Since then, the last two storms have been real light, no drives just a couple hours of small parking lots... Both times the battery died after just a couple hours.. Lights got dim, and the plow motor sounded really windy, like it was drawing a lot of amps.. lights got dim and shortly thereafter truck died..

    The first time, I thought the pump may have been low on fluid, but it wasn't.. that is what it sounded like though.. then the alternator belts looked loose and whooped, so we replaced them and thought it would be fine. It did the same thing again this last storm, after just a couple hours, though I wasn't driving this time..

    Seems like the problem is only when the lights, wipers, and heat are running, though it may not be just that cause I haven't plowed during the day, since this problem started showing up. Last event, they put jumper cables on it and it started right up and ran fine, though the plowing was over...

    Big storm coming tomorrow and I need this truck right...

    It is definitely either the battery not able to recharge fast enough, though that seems unlikely, because it did plow 30 hours straight with that battery, or the charging system isn't working right, (maybe the brushed are worn), or the plow pump is drawing too many amps...

    I'll probably pull the alternator and have it bench tested.. though it might be better to just replace it Apparently the brushed could be starting to go.This truck has a 78 amp alternator and external voltage regulator.. Napa has a rebuild for $50.. volt regulator is $35.. I AM happy to spend the money on that.. I just need to know that that is the fix and the truck is right before tomorrow...

    How would I check the pump to see if it is drawing too much?

    any other suggestions are appreciated..

  2. murphy4trees

    murphy4trees Member
    Messages: 62

    I decided to put in a rebuilt alternator and new voltage regulator... Still want to check the plow pump to make sure its not drawing too much juice... One guy told me to make sure the battery is fully charged, then run the plow up and down and side to side with the engine not running and that should be enough to be able to tell by the sound of it, whether that could be the problem..

    any other suggestions...

    PS I AM looking for a myers undercarriage for a similar truck 90 Dodge Ram Charger 150.. Anyone gat an old one around, near philly?
  3. Brian Young

    Brian Young PlowSite Veteran
    Messages: 3,394

    I've said on here MANY times over....you need a high reserve capacity battery, NOT HIGH COLD CRANKS. There are a few things to consider, first, your battery. As you said you might not have got a high reserve capacity battery, second have the alt. checked. Most alternators in plow trucks are going to be putting out anywhere from 150-200 amps or so. Third, if you have an older plow, they seem to draw a lot more amps compared to a newer style. Example, my old 94 Ford had a high out put alternator, the same high reserve capacity battery my 06 does and a older Meyer's plow. Even with the alt being new and a new battery, it still drew a ton of amps when using the plow. My lights would dim very badly, voltmeter gauge on the truck would go down to the left side of the gauge. My 06 has a new style Fisher V blade and it barley dims the lights at all. Hope this helps. Good luck in your next storm, send some our way.
  4. plowzilla

    plowzilla Senior Member
    Messages: 290

    Murphy, You do some damage to a battery when it drains empty. It no longer holds it charge to full capacity. After a few batteries and massive reseach, one battery blows them all away. The sears diehard platinum. You could drain it 500 times before it loses its capacity to charge at full. Also, vibration ruins batteries. Not with the platinum, something about its internal cores are not affected by vibration. Reserve capacity is a measurement in minutes the battery should operate without a charge. Most auto batteries have very low reserve. The platinum has a very high reserve. And lastly, the warranty is the best in the business and sears is everywhere. I was considering the blue, red, yellow spiral bound batteries,( forgot the names but the a very popular) and they still did not compare.
    I run them in my 2 trucks. They have plows, strobe lights, salt spreaders, and extra reverse lights and not one problem compared to other batteries. One plow was an old cable style western that drew huge power.
    You may also want to consider (highly recommending) giving that alternator back and getting higher output. 120 or higher. If your altenator cannot keep up with plowing, how can it charge a battery at the same time?!! Good luck and God Bless
  5. Snowzilla

    Snowzilla Senior Member
    from Iowa
    Messages: 397

    I put the waterproof version Battery Tender/battery maintainer on my plow truck and leave it plugged in during periods of non use to keep the battery in top shape.
  6. Gumpy52

    Gumpy52 Member
    Messages: 70

    I would say get a higher output alternater,the bigger the better, almost all new truck come standard with 105 - 135 amp alternator. Your 78 amp alternator is barely keeping up this the truck when you are plowing. Plowing in a storm, you got the lights, wipers, heater, roof flasher going , that doesn't leave much for the truck keeping the battery charged up from the power drawn running a plow motor every couple of minutes.
  7. lilpusher

    lilpusher Senior Member
    from Indiana
    Messages: 140

    I was experiencing the same thing so I put a 163 amp alternator from napa on my 318 and made a world of difference. The stock sized alt is too small. I didn't have to replace the battery but had thought hard about it.
  8. basher

    basher PlowSite Fanatic
    from 19707
    Messages: 8,993

    When you replace your battery buy a dual post. Then you can hook your Truck 's draw and charge loads on one set of terminal and the plow supply to the others. This will make the battery a "buffer" against power or draw surges. also have them run an accessory wire from the battery to the alternator, the system will charge much better, fast then with the (inadequate) factory wire.

    What fluid are you running?