New Lead Acid Batteries; Charge & Monitor Upgrade?

[peteco]

I noticed a bulge and a small crack at the positive terminal on my 9-year old Deka GC15 lead acid batteries. The sidewalls were also bulged somewhat, which I had noticed starting a few years ago. These batteries have worked great despite probably undercharging from the Tripplite 750 inverter charger. Yet whenever I checked the specific gravity the cells would show full charge and very little variance between cells. I have always kept the water above the plates. I could boondock for 2-3 days with careful use of power. So I am not sure why the batteries bulged like they did. Perhaps long trips subjected the battery to high voltage (14+v alternator charging)???

I just replaced with 2 Duracell SLIGC115 lead acid batteries (same as the Deka GC25, great price from Batteries+ $117). I am wondering if I should upgrade my charging system from the Tripplite RV750ULHW and add a battery monitoring system. A variety of systems and charge settings have been mentioned over the years on the forum here. So what would be the latest recommendations for a system like mine?

[Julia]

NINE YEARS??? Wow! Sounds to me like you got a great run out of those batteries!

I'm in a similar situation. Just purchased a 1998 Roadtrek 190 Popular which unfortunately only accommodates a single group 24 house battery. The one currently in the box is dead. As a doornail dead. I was hoping to replace that with a group 24 deep cycle AGM battery so that I could add another under the bed as they are the only ones that don't need to be vented. I've been told that unless I upgrade my inverter charger (mine's a single stage - the original in the RT), I will destroy those very expensive batteries.

Sorry I'm not more helpful. If I were able to get 9 years out of my house battery/batteries and had been able to boondock for 2-3 days using them for the past nine years, I'd replace them with exactly the same batteries and keep my inverter charger just as it is for the $$ savings. Nine years is a darned good run.

Happy day to you.

J

[markopolo]

If upgrading a charger I'd look for one with temperature compensation and one that exits the absorption phase based on programmable current setting.

You're probably right about overcharging causing the bulge and subsequent crack. Chronic undercharging would cause a battery to lose capacity and a battery that has lost capacity would be more easily overcharged IMO. I've noticed that older batteries that have lost capacity get to the gassing / bubbling stage very quickly when a charge voltage is applied to them. The gassing / bubbling occurs almost immediately on old depleted batteries whereas it doesn't occur until much later in the charge cycle with newer batteries.

As noted, they lasted 9 years on the existing system and care so hard to find fault with that.

[booster]

Originally Posted by markopolo

If upgrading a charger I'd look for one with temperature compensation and one that exits the absorption phase based on programmable current setting.

You're probably right about overcharging causing the bulge and subsequent crack. Chronic undercharging would cause a battery to lose capacity and a battery that has lost capacity would be more easily overcharged IMO. I've noticed that older batteries that have lost capacity get to the gassing / bubbling stage very quickly when a charge voltage is applied to them. The gassing / bubbling occurs almost immediately on old depleted batteries whereas it doesn't occur until much later in the charge cycle with newer batteries.

As noted, they lasted 9 years on the existing system and care so hard to find fault with that.

I would agree, and add that although you likely were overcharging, maybe from the tripplite, maybe from alternator or solar, good quality wet cells handle overcharging pretty well as long as you do a good job of staying topped off on the water. The Tripplite, based on what I saw with ours, was much more likely to undercharge than over, except on very shallow discharges. Your use pattern may well just be in a way that has the Tripplite slightly undercharging and the driving slightly overcharging (mini equalize?) so the combination works really well together. A "better" system may actually not do as well for your use patterns.

It would be very interesting to see what a battery monitor would shoe about it all, as 9 years is really good battery life.

[peteco]

I would have kept using the batteries were it not for the small crack that developed near the positive post. Deka recommended replacing.

I have been using the Water Miser caps for a few years and they work great. I had some water at the base of a couple of the caps. I contacted the company and they thought it might be due to overcharging or some damage to the cap seal area. They suggested I check to make sure I am not overcharging.

I did have to add water about every month, especially during heavy use while camping: a lot of driving and some campground electric. The vehicle is driven about 3 times a week when I am not out camping.

I had never checked the Tripplite charger before so I will do that now.

[peteco]

The table shows the Tripplite charging test. This is the first time I have done this test. I used a clamp-on meter on the + battery cable to measure the amps. At a couple of the times (40 and 60 min) the voltage would cycle up and down slightly over about 10 seconds. Otherwise it was steady.

I am not sure what the charge profile should be but it doesn't look like this would cause an overcharge. If anything the peak voltage could be a little higher to push the batteries to 100% faster.

[rowiebowie]

Originally Posted by peteco

The table shows the Tripplite charging test. This is the first time I have done this test. I used a clamp-on meter on the + battery cable to measure the amps. At a couple of the times (40 and 60 min) the voltage would cycle up and down slightly over about 10 seconds. Otherwise it was steady.

I am not sure what the charge profile should be but it doesn't look like this would cause an overcharge. If anything the peak voltage could be a little higher to push the batteries to 100% faster.

Interesting chart, thanks. I have the Tripplite RV750U from '2012. Is that the model you have by any chance?

The chart looks like the charger is "battery friendly" and certainly not overcharging. My Tripplite model (above) has a dip switch (B4) that changes between low & high charge rates. Don't know if yours has that option or which setting it was on when you took the readings.

[booster]

Originally Posted by peteco

The table shows the Tripplite charging test. This is the first time I have done this test. I used a clamp-on meter on the + battery cable to measure the amps. At a couple of the times (40 and 60 min) the voltage would cycle up and down slightly over about 10 seconds. Otherwise it was steady.

I am not sure what the charge profile should be but it doesn't look like this would cause an overcharge. If anything the peak voltage could be a little higher to push the batteries to 100% faster.

That table looks a lot like what would be expected if the charger was put onto a nearly full, or one with some surface charge on it. It appeared to sample acceptance and decided the battery didn't need charging probably based on voltage. Under those conditions it would then go right to float of 13.5v, assuming it is set to the wet cell profile with the switches. On non full batteries our Tripplite would run for up to about 4 hours at rising voltage and then steady at over 14v, and then go to float.

[booster]

Originally Posted by rowiebowie

Interesting chart, thanks. I have the Tripplite RV750U from '2012. Is that the model you have by any chance?

The chart looks like the charger is "battery friendly" and certainly not overcharging. My Tripplite model (above) has a dip switch (B4) that changes between low & high charge rates. Don't know if yours has that option or which setting it was on when you took the readings.

If that battery needed charging, which it may not have (or at least not much charging), the 13.5v is way to low for wet cells and would never get them agitated and fully charged. 14.4v is kind of the norm now, with many even recommending 14.6/14.7v.

[peteco]

Originally Posted by rowiebowie

Interesting chart, thanks. I have the Tripplite RV750U from '2012. Is that the model you have by any chance?

The chart looks like the charger is "battery friendly" and certainly not overcharging. My Tripplite model (above) has a dip switch (B4) that changes between low & high charge rates. Don't know if yours has that option or which setting it was on when you took the readings.

Yes, Tripplite RV750ULHW.

B4 is set on high charge.

[peteco]

Originally Posted by booster

If that battery needed charging, which it may not have (or at least not much charging), the 13.5v is way to low for wet cells and would never get them agitated and fully charged. 14.4v is kind of the norm now, with many even recommending 14.6/14.7v.

Battery was probably full as I had it hooked up a few days prior for a full day.

I have wondered about criticality of the peak charge voltage to get to 100% charge. Even if the peak is a little low (14.4v) wouldn't a long time charge at float of 13.5v eventually get the batteries to 100%?

Sounds like I need a battery charge monitor; any recommendations for a simple system like mine?

[booster]

Originally Posted by peteco

Battery was probably full as I had it hooked up a few days prior for a full day.

I have wondered about criticality of the peak charge voltage to get to 100% charge. Even if the peak is a little low (14.4v) wouldn't a long time charge at float of 13.5v eventually get the batteries to 100%?

Sounds like I need a battery charge monitor; any recommendations for a simple system like mine?

The whole charge voltage thing has been changing the last few years, and higher voltages have been getting recommended more and more. Trojan and Lifeline were among the first to go higher, with Trojan going to 14.6v on the wet cells and Lifeline allowing equalizations. Lots of mfgs are now showing a preferred profile with a mini equalization at the end.


My opinion of it all is that the original change, now universal, from constant 13.9v to the three stage addressed gassing out and undercharging at 14.4v and that would likely be fine for repetitive use and a full charge to transition amps. I think what they are seeing is that batteries are, in general, winding up undercharged and the higher voltsges are to help recover some of the lost capacity from the under charging. The big deal is probably to get the batteries back to totally full as fast as possible while also trying to fix some of lost capacity.



Again a guess, but it would appear that the battery mfgrs are compensating for the current chargers in almost every case don't have the ability to determine how long to charge to fill any particular battery.


So I guess to answer if charge voltage is important, I would say definitely yes, but the actual best voltage could certainly vary per application.


I run our system at 14.3/14.4v absorption and 13.2v float, which are both on the lower en of the range. All our charging systems control by transition amps so I think we have very little chance of capacity loss from undercharging and thus none to try to recover so no need for the higher voltages that can cause other issues.

[peteco]

Originally Posted by booster

The whole charge voltage thing has been changing the last few years, and higher voltages have been getting recommended more and more. Trojan and Lifeline were among the first to go higher, with Trojan going to 14.6v on the wet cells and Lifeline allowing equalizations. Lots of mfgs are now showing a preferred profile with a mini equalization at the end.


My opinion of it all is that the original change, now universal, from constant 13.9v to the three stage addressed gassing out and undercharging at 14.4v and that would likely be fine for repetitive use and a full charge to transition amps. I think what they are seeing is that batteries are, in general, winding up undercharged and the higher voltsges are to help recover some of the lost capacity from the under charging. The big deal is probably to get the batteries back to totally full as fast as possible while also trying to fix some of lost capacity.



Again a guess, but it would appear that the battery mfgrs are compensating for the current chargers in almost every case don't have the ability to determine how long to charge to fill any particular battery.


So I guess to answer if charge voltage is important, I would say definitely yes, but the actual best voltage could certainly vary per application.


I run our system at 14.3/14.4v absorption and 13.2v float, which are both on the lower en of the range. All our charging systems control by transition amps so I think we have very little chance of capacity loss from undercharging and thus none to try to recover so no need for the higher voltages that can cause other issues.

I just noticed that HandyBob has raised concern with the push to higher charging voltage and has backed off a bit to 14.5/14.6v absorption recommendation.

https://handybobsolar.wordpress.com/...-voltage-down/

[booster]

For a monitor, the standard has been the Trimetric for years. I don't have any experience with most of the more recent brands, but I am sure others do here. Basic monitors like this are very good for basic systems.



One thing I like about the Trimetric is that it does NOT use Peukert. We have had a lot of discussion on whether or not Peukert applies or not, and I am a firm believer that it does not apply well to how most of us use our batteries, especially if you have varied loads. Short, large loads in particular can i dictate more battery capacity was used than actually was if Peukert is in use.

[peteco]

In looking for recent info on battery monitoring systems I came across this article.

https://www.rvwithtito.com/articles/...attery-monitor

I recall seeing discussion here on the Bogart and Victron units so perhaps I should search the BMS reviews here again.

As with most things, you can go to different levels of sophistication (and cost).
I came across this very inexpensive unit that has mostly positive reviews. This may be all I need for my (presently) simple system.

https://www.amazon.com/bayite-6-5-10...t_sims?ie=UTF8

[avanti]

Originally Posted by peteco

In looking for recent info on battery monitoring systems I came across this article.

https://www.rvwithtito.com/articles/...attery-monitor

I recall seeing discussion here on the Bogart and Victron units so perhaps I should search the BMS reviews here again.

As with most things, you can go to different levels of sophistication (and cost).
I came across this very inexpensive unit that has mostly positive reviews. This may be all I need for my (presently) simple system.

https://www.amazon.com/bayite-6-5-10...t_sims?ie=UTF8

There are many such inexpensive meters around. They are fine, except:
1) This one is not capable of measuring current in both directions. I.e., it can show you charge current or discharge current, but not both. You could use two, I suppose.
2) The shunt is limited to 100amps.
3) Most importantly: Such meters do NOT count amps in/out. They only show you instantaneous current. The fancy expensive ones attempt to keep track of the SOC by counting amps in and amps out.

[booster]

Originally Posted by avanti

There are many such inexpensive meters around. They are fine, except:
1) This one is not capable of measuring current in both directions. I.e., it can show you charge current or discharge current, but not both. You could use two, I suppose.
2) The shunt is limited to 100amps.
3) Most importantly: Such meters do NOT count amps in/out. They only show you instantaneous current. The fancy expensive ones attempt to keep track of the SOC by counting amps in and amps out.

Yep, agree on that. IMO amp hour counting to know how far you are discharged is very important in day to day use, and seeing the amps into the batteries the critical thing for current.

[peteco]

Originally Posted by booster

Yep, agree on that. IMO amp hour counting to know how far you are discharged is very important in day to day use, and seeing the amps into the batteries the critical thing for current.

Thanks Avanti and Booster: yes SOC is a critical reading.

[markopolo]

Originally Posted by peteco

Yes, Tripplite RV750ULHW.

B4 is set on high charge.

So, with B4 on High, transition to Float occurs when acceptance at 14.4V drops to 10 amps.

I'm curious to know what amp flow would trigger the transition to float with B4 set to Low. If it is a lower trigger point like 5A or 2A then that could be a useful trick to force the absorption phase to continue.

[peteco]

Originally Posted by booster

Yep, agree on that. IMO amp hour counting to know how far you are discharged is very important in day to day use, and seeing the amps into the batteries the critical thing for current.

Originally Posted by markopolo

So, with B4 on High, transition to Float occurs when acceptance at 14.4V drops to 10 amps.

I'm curious to know what amp flow would trigger the transition to float with B4 set to Low. If it is a lower trigger point like 5A or 2A then that could be a useful trick to force the absorption phase to continue.

I thought B4 controls the max charging current: 45 amps (high setting) or 11 amps (low setting).