Battery capacity shrinking?

[steilkurve]

Hey all. Winter here and AS is in storage. Took my Interstate lead acid batteries out and have them hooked up to a NOCO Genius 3500. Checking with a meter periodically, noticing the voltage drop. One started at 12.81 and is now at 12.74. Brand new AS and batteries. Is this normal? Thanks in advance for the advice.

[Al and Missy]

The only way to get good information on your batteries is to charge them up, then remove the charger and let them rest. After an hour or so, measure the voltage. Then check the voltage over a period of several days with no charging to see how well they are maintaining a charge.

That charger has several modes and could easily cause a difference in voltage if you are reading the voltage with the charger connected. Battery voltage will be higher when charging, lower when discharging. All the tables for state of charge assume no charge or discharge for a period of time before measurement.

Al

[BayouBiker]

Lead acid batteries self discharge about 3-5% per month. If it has been two months, that's about right.

[r carl]

You must let a battery rest and stabilize at least 12 hrs after charging before checking voltage.

[steilkurve]

Originally Posted by r carl

You must let a battery rest and stabilize at least 12 hrs after charging before checking voltage.

Ah! Did not know. Very helpful. Many thanks.

Question. They are in my heated garage on my work table. It does get colder momentarily when I open the door a couple of times a day but other than that, it’s about 60 in there. Could that be a probleM long term?

[steilkurve]

Originally Posted by BayouBiker

Lead acid batteries self discharge about 3-5% per month. If it has been two months, that's about right.

It has been two months but the NOCO Genius keeps them topped up at 100%.

[steilkurve]

Originally Posted by steilkurve

Ah! Did not know. Very helpful. Many thanks.

Question. They are in my heated garage on my work table. It does get colder momentarily when I open the door a couple of times a day but other than that, it’s about 60 in there. Could that be a probleM long term?

Ok so I’ve let the batteries unplugged from the Genius for 12 hours. Measured voltage: 12.74 for one and 12.78 for the other.

Normal or cause for concern?

When I plugged them in to the Genius in early November, they were at around 12.8 each.

Any info appreciated.

[Al and Missy]

12.6 is indicative of full charge. If they stay up then I say they are good.

Al

[Mattirs]

A momentary blast of cold air is not going to affect the battery temperature, which is what is talked about when temperature is mentioned not the ambient air temperature though after a number of hours they can be the same.

Thanks
Matti

[BayouBiker]

Originally Posted by steilkurve

It has been two months but the NOCO Genius keeps them topped up at 100%.

From your descriptions, I still believe the batteries are fine. The Genius, in maintenance mode does not trickle charge it cycles on and off with various current and voltage settings that depend on the user selected mode. It cycles on when the resting voltage it detects drops a bit below 12.8 in NORM mode and some not-described lower voltage in COLD mode.

You didn't say but I assume your batteries are hooked up to the charger in parallel so the charger is likely sensing the 12.78 voltage which is good to go. The other battery is a bit lower possibly due to poorer connections but it is still in the ballpark.

Perhaps clean the connections, check the leads for higher resistance, drain the batteries a bit and let it charge back up then check the voltage again. I feel pretty good that the "slight issue" you see is something other than the batteries.

FYI, the resting voltage at 60F is 12.72 Volts for a fully charged battery

[steilkurve]

Originally Posted by BayouBiker

From your descriptions, I still believe the batteries are fine. The Genius, in maintenance mode does not trickle charge it cycles on and off with various current and voltage settings that depend on the user selected mode. It cycles on when the resting voltage it detects drops a bit below 12.8 in NORM mode and some not-described lower voltage in COLD mode.

You didn't say but I assume your batteries are hooked up to the charger in parallel so the charger is likely sensing the 12.78 voltage which is good to go. The other battery is a bit lower possibly due to poorer connections but it is still in the ballpark.

Perhaps clean the connections, check the leads for higher resistance, drain the batteries a bit and let it charge back up then check the voltage again. I feel pretty good that the "slight issue" you see is something other than the batteries.

FYI, the resting voltage at 60F is 12.72 Volts for a fully charged battery

Thanks for the thorough explanation. Very helpful. The batteries are not in parallel. I’ve got a Genius on each. Based on your info, I’m sure they are fine. It’s 60 in my garage and the reading is above 12.72.

I will try and clean the connectors as well as charge them up fully after being disconnected for a while.

Question, water levels seems full but how often should lead acid batteries be filled. Got the AS late August and used it every weekend for 2 months before storing.

Thanks again.

[BayouBiker]

Water loss is a factor of many things, but is strongly a function of charging cycle variables. The primary reactions in Lead Acid batteries produce no loss in water, but contaminates and degradation of the lead plates contribute to Hydrogen (and Oxygen) production accounting for water loss. Failure to routinely fully charge the battery is a primary cause of plate degradation, mostly due to acid stratification in the lower part of the cells. Severe discharging of a battery is even worse for plate degradation. Continuous overcharging the battery, however is generally the leading cause of hydrogen production and thus water loss. Use of a simple charger for prolonged periods should be avoided completely. Even trickle chargers should be discouraged.

Okay so you have good batteries and you avoid the mistakes leading to battery degradation and excessive H2 production. Check levels once a month, but really you should not have to add water very often at all, maybe once in 2 years.

AGM (Absorbent Glass Mat) Batteries dramatically reduce issues with plate degradation and contamination effects so they don't produce H2 unless you abuse them as described above. Charging them properly and regularly fully charging them is critical, other than that they don't consume water to any significant degree.

[steilkurve]

Originally Posted by BayouBiker

Water loss is a factor of many things, but is strongly a function of charging cycle variables. The primary reactions in Lead Acid batteries produce no loss in water, but contaminates and degradation of the lead plates contribute to Hydrogen (and Oxygen) production accounting for water loss. Failure to routinely fully charge the battery is a primary cause of plate degradation, mostly due to acid stratification in the lower part of the cells. Severe discharging of a battery is even worse for plate degradation. Continuous overcharging the battery, however is generally the leading cause of hydrogen production and thus water loss. Use of a simple charger for prolonged periods should be avoided completely. Even trickle chargers should be discouraged.

Okay so you have good batteries and you avoid the mistakes leading to battery degradation and excessive H2 production. Check levels once a month, but really you should not have to add water very often at all, maybe once in 2 years.

AGM (Absorbent Glass Mat) Batteries dramatically reduce issues with plate degradation and contamination effects so they don't produce H2 unless you abuse them as described above. Charging them properly and regularly fully charging them is critical, other than that they don't consume water to any significant degree.

Very helpful. Thanks again.

[thewarden]

I have the same batteries as you do circa 2015. I live in Northern AB where winter temps get to -30, -40. This is my routine. When I put the trailer away, usually the beginning of October, I fully charge and desulfate both batteries with my Genius charger. That will look after any sulfate built up on the plates and acid stratification. They usually end up at 12.75 or so. I disconnect both and there they sit for the next 6 months. In the Spring they are still reading 12.6 - 12.5.

When they are fully charged, lead cell batteries can take a lot of cold temps without hurting them. The key is to keep them charged up, never let them discharge below 50%, keep the water levels up and run a desulfate cycle every couple of months. No reason even these inexpensive wet cell batteries should not last 6-7+ years, even when left out in the cold. That has been my experience, FWIW.

[steilkurve]

Originally Posted by thewarden

I have the same batteries as you do circa 2015. I live in Northern AB where winter temps get to -30, -40. This is my routine. When I put the trailer away, usually the beginning of October, I fully charge and desulfate both batteries with my Genius charger. That will look after any sulfate built up on the plates and acid stratification. They usually end up at 12.75 or so. I disconnect both and there they sit for the next 6 months. In the Spring they are still reading 12.6 - 12.5.

When they are fully charged, lead cell batteries can take a lot of cold temps without hurting them. The key is to keep them charged up, never let them discharge below 50%, keep the water levels up and run a desulfate cycle every couple of months. No reason even these inexpensive wet cell batteries should not last 6-7+ years, even when left out in the cold. That has been my experience, FWIW.

Thanks. Appreciate the info. Curious, see your TV in your avatar photo. May I ask what kind of vehicle it is? Looks like an SUV (a Cayenne?) and you are towing a 27'?

[thewarden]

Yes, it is a Cayenne Turbo and I tow a 27 FB Serenity.

[steilkurve]

Originally Posted by thewarden

Yes, it is a Cayenne Turbo and I tow a 27 FB Serenity.

Very nice. Didn’t know the Cayenne could tow that heavy of a load. Now I say that but I tow with a Model X and regularly get a similar question. I should know better!