Walmart Marine-Maxx Batteries

[DaveB]

Are you running a frig.? Your chart shows deep discharge, What type batteries and what kind for house?
That chart is way off base in what I use. My twin 29 group WM house batteries run my 63 quart edgestar for 3 days before it gets down to 50% battery.
That's without using my solar panels and engine in SW Florida.
Your Charge rate at AC should be around 13.6-13.8 volts.
What kind of charger are you using? Chargers must be built in with auto shutoff, you will sulfate or burn out batteries on any type car charger.
You stated one of batteries, is that one house battery that's connected to another? If so you have to disconnect other battery for testing.
Take your batteries to Batteries Plus, or Auto Zone ETC. and do a load test.
Sometimes they can put a heavy load to desulfate the battery, this usually requires 4 hrs. Ask them.
Dave

Boblee,

My problem is the possible discrepancy between the quoted Ah's and the amount I seem to be able to extract from these batteries. To make this better understandable here is the charge/discharge data for one of the batteries:

You may note, that the battery is fully charged after a >24hr charge and the charger supplying 13.3V float voltage.
The first partial discharge after drawing <C/25 for 6hr's should result in a remaining capacity of >75% at voltage under this load of about 12.5V (see discharge graph above). In reality, the ending voltage was only 12.06V, representing a remaining charge of about 27%. The no-load voltage then recovered to 12.31V by the next morning. When I started a second like discharge-cycle in the afternoon, the no-load voltage had slightly dropped to 12.3V and under <C/25 to 12.17V when the discharge started and dropped to 12.05V within the next 15 min. At the end of this discharge-cycle the voltage was 11.78V, representing a remaining charge of about 18%. It seems, I used about 46% of the batteries capacity, but I depleted >80% according to the discharge voltages.

Obelix

[seahouse]

Hey Obelix- I was wondering the same thing as Dave - what were you using to apply the discharge load?

And how did you measure it?

The amp draw of a load can vary with the applied voltage, which is changing in this example as the battery discharges. A regular (as opposed to LED , which almost is the opposite) flashlight bulb, for example, draws WAY more current when the battery voltage drops, although it would be natural, though quite incorrect, to expect it to remain constant.

This greatly accelerates the discharge of flashlight batteries toward the end of the cycle when their voltage drops, and the bulb dims. This is one possible explanation for the shortfall you are seeing.

[raycarlson]

You are correct, my answer will not help you determine your batt capacity or AH discharge rate. Your main question in your post implied your main concern was getting Walmart( likeum or not the greatest retailer on earth) to accept your battery's for warranty exchange. They don't care that your discharge rate doesn't match the decal on your battery, that's just an approximatation not worth the money it took to print it as far as warranty goes. All they will be concerned with is will it take a full charge, and supply a specific load for a given time. There are way to many variables in an electrical boat system, no one chart could supply you with the data you seek. You just have to learn how your system works and its recharge and discharge times for your boats system, those same batteries would perform different in my boat due to wire size, length of run,# of circuts, alternator charge amps, battery charger rates and a hundered other different variables.

[Obelix]

This is to clarify some questions.
I realized that there no convenient way to monitor events inside the boat; I moved therefore the batteries and the charger from the boat to the bench. Here I have controlled conditions and can meter voltages, temperatures and discharge-current on an ongoing basis using separate V- and A-meters.
Wire length was short and wire-size was over-dimensioned for the expected currents (<5A).
The charger-type is mentioned in the top-line of the chart, it is a 2 bank charger and recommended up to two group 31 batteries.
The discharge load was a incandescent bulb and you can see the starting- and ending-current on the chart. Since the discharge over this voltage range (Δ<5%) should be close enough to linear, I applied the average current at about 4.3A (equals about 52W at 12V) in my calculations.
The battery temperature during charge and discharge was monitored using an infrared thermometer, that showed another peculiarity on only one of the batteries. When scanning along the side of the battery, I found the area of one cell regularly about 1.5⁰F – 2.5⁰F warmer then all other cell areas. All no-load "Voltage to Load" tables show values for 68⁰F to be an indicator for the remaining charge; I applied the temperature factor in my table to normalize the voltages.
Unfortunately these are sealed batteries and opening them to measure acid-density would void the warranty.
The batteries were yesterday again fully charged and will be load tested by a battery outfit, after the recommended 24hr settling period.
My main goal starting this was firstly to understand what capacity I have available when far from shore-power and only secondly to get proof if the batteries are significantly underperforming compared to their specs. I'm fully aware that getting an exchange without failing an official load-test will not happen, but at least I will know what I'm dealing with.

Obelix

[DaveB]

Obbelix,
You didn't give type of batteries, only they were closed cell and that could be AGM, Gell or car batteries.
Charging on Gel or AGM batteries require a auto charger that limits the voltage as they require less charging voltage than a wet cell deep cycle.
Give us a clue here in what type batteries and charger.
You mentioned you have a 2 bank charger, one bank goes to your twin house 31 group and other goes to your starter battery.
Next time I replace the house batteries will be twin Trojan 6 volt Golf Cart Batteries. Used them before and get 5 years out of them at same cost as the Group 29 Walmart Marine Batteries.(much thicker plates and you can bring them down to 25% without damage were the WM you can only bring down to 50% without damage)
When hooking up to twin House Batteries makes no difference if in Series or Parall.
If one battery shorts a cell it will bring down the other either way.
Dave

This is to clarify some questions.
I realized that there no convenient way to monitor events inside the boat; I moved therefore the batteries and the charger from the boat to the bench. Here I have controlled conditions and can meter voltages, temperatures and discharge-current on an ongoing basis using separate V- and A-meters.
Wire length was short and wire-size was over-dimensioned for the expected currents (<5A).
The charger-type is mentioned in the top-line of the chart, it is a 2 bank charger and recommended up to two group 31 batteries.
The discharge load was a incandescent bulb and you can see the starting- and ending-current on the chart. Since the discharge over this voltage range (Δ<5%) should be close enough to linear, I applied the average current at about 4.3A (equals about 52W at 12V) in my calculations.
The battery temperature during charge and discharge was monitored using an infrared thermometer, that showed another peculiarity on only one of the batteries. When scanning along the side of the battery, I found the area of one cell regularly about 1.5⁰F – 2.5⁰F warmer then all other cell areas. All no-load "Voltage to Load" tables show values for 68⁰F to be an indicator for the remaining charge; I applied the temperature factor in my table to normalize the voltages.
Unfortunately these are sealed batteries and opening them to measure acid-density would void the warranty.
The batteries were yesterday again fully charged and will be load tested by a battery outfit, after the recommended 24hr settling period.
My main goal starting this was firstly to understand what capacity I have available when far from shore-power and only secondly to get proof if the batteries are significantly underperforming compared to their specs. I'm fully aware that getting an exchange without failing an official load-test will not happen, but at least I will know what I'm dealing with.

Obelix

[Obelix]

Dave,
All marine "MAXX" -series Walmart batteries are sealed, wet lead/acid batteries carrying the EverStart brand; these are made by Johnson Controls.
I don't have any group 31 house batteries, I just mentioned that my "ProSport 20" dual bank marine charger is recommended for 2 batteries in sizes up to group 31.
No batteries are in the boat at this time, since both are sitting on my workbench at home.

Obelix

[DaveB]

Looks like Walmart changed there open deep Cycle marine batteries to closed cell from what you are saying. Tried to call at 9pm tonight but no answer.
Will find the answer in the morning, thanks for heads up.
Dave

Dave,
All marine "MAXX" -series Walmart batteries are sealed, wet lead/acid batteries carrying the EverStart brand; these are made by Johnson Controls.
I don't have any group 31 house batteries, I just mentioned that my "ProSport 20" dual bank marine charger is recommended for 2 batteries in sizes up to group 31.
No batteries are in the boat at this time, since both are sitting on my workbench at home.

Obelix

[Boblee]

Welcome to the world of batteries bloke, I did pick up on one thing you mentioned and that is that one cell on one battery is hotter this could/most likely means that cell is breaking down and that will drag both batteries down when hooked together but personally the batteries seem IMHO to be working ok by your charts, if one cell is breaking down it will show if left for 24 hr's.
I just tested a little car start battery that was charged a week ago and it is still reading 12.91v and it is an old battery but that could just mean my multimeter reads high? but one of the 100 ah dual purpose ones I mentioned above and was charged two days ago is reading 12.93v and both readings seem to me to be spot on.
If you want to test for the factory AH you need to use the same test as the factory specs, it should be written on the battery or on their website but whatever, saying that the battery is eg 60ah you are not going to get 60ah out of it except under test conditions, for that you need to use exactly the same parameters.
You should only be interested in what the battery can do under your conditions and requirements and adjust accordingly but what one brand/type of battery does will not mean another type will do it especially if conditions are changed.
Eg Dave said his batteries run the fridge for three days easy but that can be so variable eg stocked with frozen food and pre run before going on battery or hot meat put in it fresh on board also ambient temp etc etc etc, you using a set load is good but you should have left it on till it reached your min voltage and tested either full load or no load and if no load allow a rest between testing and removal from load.
BTW just because a battery is deep cycle it does not mean it can be run below 11.2 v without damage it just means it can handle it better or with not as much damage.
Here is a link to someone doing a test IMHO he is wrong because he is a using the battery direct off float with no delay he gets the benefit of the overvoltage and he is using 2.3 amps load which I think will be much smaller than standard testing so he will get a bigger AH rate than normal but if that is what load he runs at in his situation it will be how long he can run his battery at that resistive load and the test for what he is doing is great but not suitable for me to find how long my battery will last in my situation or more importantly how long it will take to recharge.
http://www.youtube.com/watch?v=hrq67tYV1Pw
http://www.youtube.com/watch?v=2yo7K6iKDRg
Note he took 36 ah out but had to put 44ah in to get back to float charge which seems fairly low to me but it is what it is for that battery and that charger in that time.
Still too hot to go out so did a google got this giving a rough idea how the factory ratings are performed and all good but irrelevent for testing for practical purposes on a particular situation but could be good if you can find the factory specs for your batteries to find out if crook. http://www.cdtechno.com/pdf/ref/41_7135_0412.pdf
If you had this battery it would be easy to test ah against factory by reading the specs but note the huge rating difference as amps are changed. http://www.ebay.com.au/itm/130AH-AMP-HO ... 3138wt_922

[seahouse]

Good demo in the link. Batteries are a notoriously inefficient way to store electrical energy- it has been a major ball and chain in the advancement of a lot of technologies. They've been pouring tons of money into the problem for a long time now, with no light visible at the end of the tunnel.

Putting 44Ah in to get 36Ah out seems not out of line to me. The charging is around 90% efficient when the battery is lower in charge, but to get the last top up of the battery the efficiency drops to around 50%. This is exactly what has been frequently reported in these forums, the last little bit of charge takes a long time. That inefficiency is the result of the production of heat.

It is still important to battery life that the charge cycle be brought to completion, though. Chronic undercharging is just as fatal to the health of a battery as overcharging.

I'm also thinking again that an incandescent light bulb does not provide a uniform linear discharge, it's resistance varies with the filament temperature, especially now that I see that he used a CFL and an LED for the discharge load in the video.

[Obelix]

Boblee,
This cell-temperature issue on 1 battery is not the only anomaly, the other battery seems not to settle after removing the charger and is staying at above 13V for now more then 48hrs. The battery with the 1 odd cell is settling to an expected 12.9V.
Your posted clip looked like the high-tech version of what I had set up, dual DVM and constant load (I wish I had the logging capability). I noticed the float-voltage in his demo was 13.9V while all sources I could find stated the ideal float voltage to be 13.3 V - 13.4V, higher float voltages would cause long-term damage to the battery.
Seahouse,
It is irrelevant, for what he does in the video, if the load is linear or not. He is measuring and logging Watt (Amps*Voltage) in 60 sec intervals, any change in load and battery voltage will be captured. Furthermore, once lit, the internal resistance changes in an incandescent bulb are far smaller then the current-change caused by the change of battery voltage during discharge.

Obelix

[raycarlson]

I think either you have the only walmart that sells agm marine maxx batteries or your misunderstanding what you have. I have two marine maxx #29 and looked at walmart last night, they do not sell agm sealed batteries that the auto dept manager has ever heard of. Look at the top of your battery, if it has two 4 inch long square caps on top it is not a sealed battery and you can easily pop the tops off and check your water. Maybe post a picture of your battery so we can help you understand what you have.Only Li-, gel and agm are sealed with no access to cells.all others inspite of maintaince free advertising are Not sealed.

[Obelix]

Raycarlson,

All marine "MAXX" -series Walmart batteries are sealed, wet lead/acid batteries

Reading helps

Obelix

[Dimitri-2000X-Tampa]

Are all Walmart marine batteries called "MAXX" now or do they differentiate between two different kinds of marine batteries? I haven't bought Walmart marine batteries in 5-6 years but I just recall them being called "marine".

[Obelix]

No, they sell two kind of marine batteries. The regular Evercharge and the MAXX-Evercharge series. The main difference for the customer is that the regular marine Evercharge carry a 1 year warranty and the marine MAXX carry a 2 year warranty. The MAXX are slightly more expensive then the regular ones.

Obelix

[Andre Emmenegger]

I had a Walmart starter battery. I turned the key to start the motor, and the top blew off of the battery. When I looked into the compartment, you could see the individual cells. An internet search said that the probable cause was a short igniting the gases inside the battery. I returned the battery to Walmart and got another one, after some pushback.