Battery test?

Discussion in 'Wiring' started by adrianpglover, Jan 9, 2018.

  1. adrianpglover

    adrianpglover Active Member

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    My 2015 Somerset E3 has a Interstate Battery SRM-27, which was installed by the dealer in early October of 2014. When we camped in my BIL's backyard just after Christmas, the roof lift wouldn't work from the battery alone - sound of the motor turning until it came under the load of the roof and then it stopped due to the current limiter in the controller. After plugging into shore power (15 A circuit using an adapter) the roof lifted up fine. It also came down just fine. The temperature that day was in the high 30s or low 40s. I have not had a chance to try it out since.

    Being that I live in Southeast Texas, I'm used to batteries only lasting around 3 years or so in vehicles. The camper is stored in a garage and I do regularly check the water level, adding distilled water as needed. We camp with shore power everywhere we go, so the battery typically doesn't get much heavy use or deep discharges. When we're not camping I plug the camper into the household power and the camper has a good multistage charger/maintainer builtin to the converter/fuse box. I'm not certain that the battery is going bad yet or that I don't have some other issue going on.

    The camper manual does state that the roof should be able to be lifted by the battery alone, at least once up and down. It also states that the converter alone isn't enough power to supply the roof motor and a minimum of a group 27 is needed to supply lift the roof. I can go into detail as to why the design is as such, but for now I'll leave it out. (Being an Electrical Engineer I went through the design in as much detail as I could after purchasing the camper out of curiosity.)

    My question to the knowledgeable multitudes gathered here is what is a good way for me to go about testing the battery? Would just taking the battery to an auto parts store and have them test it with a battery tester be enough? I'm not certain if the battery tester at auto parts stores is more testing for voltage drops at cranking amps levels vs the voltage drops at lower, more sustained currents.
     
  2. f5moab

    f5moab Retired from the Federal Government

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    Check the electrolyte levels and if ok, see if the local auto parts can test the battery with a load. Some do, some don't.
     
  3. tenttrailer

    tenttrailer Art & Joyce - Columbus, O

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    After checking the water and full charging for one day. If it is a group-24, or 27, 29, 31? I would take it to the auto parts store and have them do a test. If the battery is bad low voltage, bad cell, etc, its time for a new battery. But if it has low CCA or CA it might still be usable for you??

    On the group batteries they have several different specifications on the top. The auto parts store is going to check the CCA and/or the CA compared to those numbers. I would use whatever there results are compared to the listing on the battery. Figure out the percentage from the reading and the number on the battery. Use that percentage multiplied my the by the RC value on the battery to come up with your current battery RC value. You then have to determine if you can live with that value?
     
  4. adrianpglover

    adrianpglover Active Member

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    @tenttrailer - That's an interesting approach. I'll have to take that into consideration. Of course once you've mentioned that I started thinking of the equipment that I use at work and how I could perform my own test on the battery. The battery is a group 27. The specs on the manufacturer's website state CCA 600, CA 750, and RC @25A is 160. I have the appropriate equipment at work to set up an automated test to measure RC and it wouldn't take too long to do it, I just hate the idea of dragging that battery from the parking garage up the elevator and into my lab.

    I should check for a shorted cell, but so far the few lights that I have run on the battery alone (the incandescent porch light and LED light just inside the door) have worked fine without any dimming, so I wasn't suspecting a bad cell just yet. That doesn't preclude the possibility of a weak cell though.

    I likely won't have time to do anything tonight about the battery, but I might be able to check it with a meter and maybe unmount it on Thursday night. If I do so I'll have to put some serious thought into if I want to test it at work or not.
     
  5. rabird

    rabird Howdy!

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    how long does it take to disconnect the battery, wait overnight and probe with a volt meter?

    hydrometer or lead test, the load test is free at autoparts stores. They may even need to charge it first and then test, drop it off and let em do their thing.

    Is your fancy on board charger/maintainer really adequate? Can you set it somehow to charge at a voltage that will bubble the battery and mix the fluid?
     
  6. tenttrailer

    tenttrailer Art & Joyce - Columbus, O

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    I would not bring it into work. Throughout the years I have had to many pairs of pants that developed hole after having a battery rub against them. I'm sure your are wearing nice pants to work??

    I have been testing my batteries for year using that approach. For years using an auto parts store. The last 6+ years I have use a tester that attaches to my auto scanner which has both the US and European automotive testing standard. It use to be you need a large carbon pile resistor. The new method seems to be measuring the voltage and measuring the internal resistance. I'm sure there is more to it with the micro processor.

    Poorly maintained batteries many time have good voltages when charged, but the amp storage capability is greatly diminished. If it holds a good voltage after charged the cells are not shorted.
     
    Last edited: Jan 10, 2018
  7. joet

    joet Active Member

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    On a battery that is not worked, the plates will sulfate, this will reduce amp capacity. Voltages will still remain high. Just setting on a maintainer is not working the battery.
    A deep cycle battery needs a periodic equalization charge, which the convertors cannot provide
    There are a few chargers that have a desulfurization cycle. These chargers pulse volts at a high frequency to break to the sulfur deposits.
     
  8. Wrenchgear

    Wrenchgear Near Elmira, Southern Ontario

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    You probably know this already, but for others who are reading this trying to gain batt knowledge, remember that just putting a volt meter on there may not tell you much at all. You could see around 12 volts on the meter, but until you try to pull amps out of it, you still don't really know whats going on in there. If you see 10 volts on the meter (after charging), obviously there is a bad cell and the batt is toast.
    You could see 12v on the meter, but there could be a crack internally at the bottom of a post, or at a cell connector. Voltage will trickle across the crack and show 12 volts on the meter, but as soon as you try to draw amps across the crack, nothing will flow. I still believe in putting a carbon pile, or some other big load on the batt to test it properly. IMO.
    As a side note, I have that same batt in my Pup. It was first used on my boat for the small electric fishing motor (trolling motor) to pull my boat into the weeds. My batt is still very strong after all these years, knock on wood. Its a 2005, 12 summer now. I think those are very quality batts.
     
    Last edited: Jan 10, 2018
  9. adrianpglover

    adrianpglover Active Member

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    Thanks everyone for the input. It is true that I have never exercised the battery, so I wouldn't be surprised if I had built up a sulfur layer on the lead plates.

    It turned out last night that one of my family members were under the weather so we didn't go to the event that would've taken up all of my time. I plugged in the camper and let the battery charge up for about 10 hours overnight, then unplugged the camper and disconnected the battery this morning. I normally plug in the camper as soon as we get home and don't unplug it until we hitch up. This time around we had to drop the camper off and turn around for another trip too quickly for me to be able to do all of my normal tasks after getting home from a camping trip. The camper was unplugged from either a TV or shore power for some 11 days or so. Prior to plugging in the camper the battery read as 9.5 V. After charging, but before relaxation it was 12.9 V, so no shorted cell but definitely something going on. I wouldn't expect 11 days to be enough time for the camper's static power draw to drain down a group 27 battery.

    Depending on how my work goes today, I may try setting up a test on the battery for lunchtime. If not then I'll get to work a bit earlier tomorrow and do something with it then.


    To answer a few questions posed above -

    @rabird - I looked up the converter again yesterday, a WFCO WF-8735-P, and found that it is not a battery maintainer, but just a three stage battery charger (bulk, absorption, and float). The difference is that a battery maintainer will, at the completion of a charge cycle, turn off the float charge and wait for the voltage to drop to some threshold, and then turn back on the float charge. The WFCO documentation doesn't state whether it ever turns off the float charge portion. After having the battery charging for about an hour last night I went back out to check the electrolyte levels. The plates weren't exposed but the cells weren't to the full mark. I did hear bubbles and saw a few of them pop up while I had the vent caps off, so yes, the charger can stir the electrolyte.

    @tenttrailer - I did drag it into work today. Threw my hand truck in the back seat of my car and used that to carry the boat anchor in. My "nice" pants that I wear to work are blue jeans. Gotta love the "dress code" requirements of IBM development teams these days. They haven't required suits and ties for a very long time now. As for your new battery tester - It is very likely that it reads an initial voltage, then uses a bunch of high power FETs and some small, but high power resistors to momentarily load down the battery, and take some more voltage measurements. It also would likely do many pulses of this in quick succession, while keeping the power dissipated in the module low to keep the temperatures down. If this is how it works it is a fairly fancy battery tester. What brand/model is your auto scanner and battery tester? I'd like to read up on it some more.

    @joet - I'll have to read up on how to perform an equalization charge myself. Since I have the battery sitting in my lab I have quite a bit of programmable equipment at my disposal that I might be able to use to perform such a task. Obviously I would need to get a device to do this more often at home in the long run, but for now I just want to see if I can make it a few more months with this battery or revive this battery for now.

    @Wrenchgear - Its good to hear that this battery can last so long. I have known that it is a reputable brand for some years now, but I haven't had many long life experiences with lead acid batteries in the past.
     
  10. rabird

    rabird Howdy!

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    Seems your voltage was so low the WFCO actually went into bulk 14.6v mode, it only does this with an abused battery that has very low voltage and only for 4hrs, then it drops to 13.6v which is not enough to FULLY charge a battery. If that is the charge profile you like then stick with the wfco! normal usage and it will start at 13.6 and never go to bulk. I don't believe you have ruled out a shorted cell yet, remeasure voltage.

    Your load test (trying to raise the roof) has already shown the "well maintained" (your suggestion) battery is no longer up to the task and/or has been mistreated and needs help to recover or easier to replace.

    hydrometer does not lie!
     
  11. 1380ken

    1380ken Well-Known Member

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    They should not make a camper where the converter can not lift the roof alone. I would replace the converter or add a power supply just for the lift.
     
  12. adrianpglover

    adrianpglover Active Member

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    The battery has been unplugged from any source or load for 4 hours now and it reads as 12.72 V.

    @rabird - I do not currently have a hydrometer but will pick one up to check the cells individually.

    I never stated that the battery was "well maintained". I also haven't stated that I have a wonderful or praiseworthy converter. Instead I made comments that it isn't just a power inverter without any battery charging profile in it.

    I'm here genuinely looking for assistance and advice, not to argue with anyone on one device or method over another. If you have something constructive to add to the conversation without turning this into an argument, then please do. If you have objections with being calm in a conversation on a forum, then I would ask you to please find another thread to post on.
     
  13. 1380ken

    1380ken Well-Known Member

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    The best advice that you received so far is to buy a new battery. Trying to perform an equalization charge at IBM using automated lab equipment is probably not the best use of your time. You would be surprised how people will gossip if they see you doing strange home projects at work. I have seen people struggle to get a couple of more years out of their battery and in my opinion it is not worth the effort.
     
  14. rabird

    rabird Howdy!

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    Wfco is not a typical 3 stage charger. It does not like to go into bulk or stay there till the battery is full. Battery makers suggest charging your batter to 14.8v and keeping it there as the current tapers as the battery gets FULL. This is considered bulk and absorption, when current has tapered to 1% of battery capacity then change the set pt from 14.8v to 13.8v, 13.3v (all over the map), temperature compensation is recommended for all 3 stages. Furthermore, an occasion top charge or equalization is suggested, this is an intentional overcharge to 15+v, 15.5v-16.2 is often suggested.

    Your equipment does not follow this suggest charge profile. Solar gets very close!
    here is the theory of operation from WFCO
    http://wfcoelectronics.com/wp-content/uploads/2016/03/WFCO-Theory-of-Operation-v2.pdf
    here is a well know battery makers advice.
    http://www.trojanbattery.com/tech-support/battery-maintenance/

    My suggestion is you keep doing what you do and keep it plugged in and replace batteries as often as needed than to baby a battery unless you are interested in taking good care, they are expendable. A good charger may be hard to find and expensive.

    Take care if you decide to dip batteries, rinse the hydrometer when done, the sulfuric acid can be strong, as high as 1.300 but 1.265 or higher is generally considered full.

    Johnson Controls makes the srm-27, and the enrgizer group 27. They don't provide much info to the public. Besides trojan, rolls is a good source of support
    http://support.rollsbattery.com/support/solutions/articles/430-corrective-equalization-instructions

    If your fridge is on 12v operation that could be an issue, take care and audios.
     
  15. tenttrailer

    tenttrailer Art & Joyce - Columbus, O

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    Just about any of the lower end RV power centers (converters) are good for charging the battery before an trip or when you are on a trip. But they will over charge and slowly destroy a battery on continuous storage charging. There seems to be two schools of thoughts on storage. Either a good tender, or storage with recharging before the battery drops down to 70% SOC. Depending temp that is around 12.2. I use 12.4V to be on the safe side. Most of the time I recharge at around 12.6.

    I have done it both ways. For many campers, I have gotten 6+ years with the max 8+ years from my batteries. Currently I follow the charge before drops to 12.4V. The down side is you must remember and you need to do a 24 hour charge before trips.
     
  16. adrianpglover

    adrianpglover Active Member

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    I ended up just taking the battery home without doing anything to it at work. In the end I just didn't feel like trying to find a "good" profile to recover what I thought was a possible dead battery, especially after reading the last three posts here. I was not aware that a modern low RV power center, even a low end one, would cook a battery.

    On my way home yesterday I stopped by a NTB to have them test the battery. The printout stated that it was charged to 12.68 V and that out of the 600 CCA it only measured as 448 CCA, so yeah...very weak/dead. I'll plan on replacing it once money is available to be budgeted for it. We're not going anywhere at the moment so I'm in no hurry.

    As for future plans, do any of you have a good suggestion on a battery maintainer? Even if it is more expensive, if it makes the battery last 6 years over 3, then I could at least recover the cost of one battery during that time. I have a cheap HF one, but I don't trust it enough to leave it plugged in for long periods.
     
  17. tdiller

    tdiller Active Member

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    take it to any of the auto parts stores and have them test it. Or go to harbor freight and buy a battery testing device.
     
  18. roybraddy

    roybraddy Well-Known Member

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    For whatever it is worth I have never had and good experience using the WFCO WF-8900 series units that were suppose to be the SMART MODE Chargers. I suspect the WF-8700 series unit do the same thing... My WF-8945 unit would never put out anything but 13.6VDC. This will charge your batteries but will take forever to do it.

    You need to have 14.4VDC giving you around 17-20AMPS DC current for each battery in your bank if you want to recharge it to at least its 90% charge state in a short three hour charge time. It takes over 12 hours to get my battery to its 100% charge state starting out with the 14.4VDC charge mode.

    I replaced my WF-8945 unit with a PD9260C and it does all of the smart mode different DC voltages when charging.

    When camping OFF-GRID which is what we do most of the time I will run my battery bank to its 12.0VDC reading which is approximately the 50% charge state and then hookup my PD9260C Converter/charger to my 2KW Honda Generator and run it (when allowed) for three hours to get my battery bank back up to its 90% charge state.

    Been doing this 50% to 90% charge states since 2009 on my battery bank of three each 12V Interstate 85AH Batteries and they have lasted until the 2016 season where they would not hold a charge any more. I was doing 12-14 of these 50% to 90% charge states before I had to do a full 100% charge state which of course took over 12 hours to do. I usually did this at home between camping trips.

    I am now in the process of replacing my batteries and hopefully will be back into camping again this upcoming season.

    [​IMG]

    Roy Ken
    [​IMG]
     
  19. rabird

    rabird Howdy!

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    is it a ole manual charger like
    https://www.harborfreight.com/10250-amp-12v-manual-charger-with-engine-start-60653.html

    Hook it up to ye ole battery overnight and then measure the voltage while still hooked up in the morning. It may be perfect for doing a top charge (15v) several times a year, correct, not for long periods. It may be perfect for giving your new battery a full charge before use. You will need to make it smart by disconnecting it when the battery is charged. I use the term overnight but you could check voltage ever hr or two.

    WFCO is designed to go to float after 44 hrs at 13.6v and no big loads detected, 13.2v is low especially for the cold and may be perfect at summer temps.
     
    Last edited: Jan 12, 2018
  20. 1380ken

    1380ken Well-Known Member

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    Not to change the subject but I am sill caught up on the fact that shore power alone can't lift the roof. It is hard to believe. Totally unacceptable design.
     

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