AGM Battery Charging and keeping the battery charged from AC continuously

[skagitstan]

Originally Posted by BillsPaseo

We have solar, but living in the PNW where the days get really short in the winter, and the sun is obscured by clouds for months at a time, solar isn't going to keep the battery topped off.

I also live in the PNW. We find our solar is entirely adequate for keeping the house AND car AGM batteries topped off.
True, they won't keep up with actual camping use current draw, but simply parked, they do just fine.

We mainly store Annie under shelter, so the solar doesn't work for that. But, if I have her pulled out, it does the job.

[GeorgeRa]

I have Morningstar MPPT 45 solar charge controller with maximum self-consumption of 2.7W which would equal to about 450 Ah losses during 3 months of storage in the garage. After my trip my 230Ah batteries where note completely dead so either the self-consumption was lower or ambient light was generating charging current but apparently not enough. The garage is painted white and the doors have one row of windows.

I simply forgot to flip the CB to off between the charger and batteries, now I have a check list.

[BillsPaseo]

We're another couple of hundred miles north (just a little bit north of the northern tip of Maine) and on top of that have heavy cloud cover most of the winter and early spring.

Edit: this was a quoting fail... It was supposed to be a reply to the above comment about Pennsylvania weather vs. PNW weather.

[BillsPaseo]

Originally Posted by skagitstan

I also live in the PNW. We find our solar is entirely adequate for keeping the house AND car AGM batteries topped off.
True, they won't keep up with actual camping use current draw, but simply parked, they do just fine.

We mainly store Annie under shelter, so the solar doesn't work for that. But, if I have her pulled out, they do the job.

Good to know! How many watts of solar do you have? We currently only have 100W, but plan to add more.

[skagitstan]

Originally Posted by BillsPaseo

Good to know! How many watts of solar do you have? We currently only have 100W, but plan to add more.

We have a fairly large system...560W. 400AH AGM.

We went large because we do live in the northwet.

We mainly remote boondock, and try to minimize driving or engine idling time. The system is almost able to keep up with our operating spring->fall operating needs, and certainly extends our stay time by at least a day even in the winter (if we are not deep in a forest).
It easily keeps things topped off when we are at home.

[BillsPaseo]

Originally Posted by skagitstan

We have a fairly large system...560W. 400AH AGM.

We went large because we do live in the northwet.

We mainly remote boondock, and try to minimize driving or engine idling time. The system is almost able to keep up with our operating spring->fall operating needs, and certainly extends our stay time by at least a day even in the winter (if we are not deep in a forest).
It easily keeps things topped off when we are at home.

Thanks! I don't have room on my roof to get to 560W, but hopefully I can squeeze around 300 in there. Might have to remove the TV antenna and move the radio antenna to get there... Don't care about the TV anyway.

[skagitstan]

Originally Posted by BillsPaseo

Thanks! I don't have room on my roof to get to 560W, but hopefully I can squeeze around 300 in there. Might have to remove the TV antenna and move the radio antenna to get there... Don't care about the TV anyway.

I am doing a bit of trim work carpentry in Annie today, so I pulled her out in front of the shop so I can use the brad gun.

Just for giggles, I took a quick look at how the solar is doing.

It's a rainy very overcast day. I took a look at the solar controller (Blue Sea MPPT), right after the start and move. Input is 17V at 4.4A. Output is 13V at 5.5A. House and car batteries are connected via ACR. Car electronics are still active, which accounts for about 5 of those amps. House battery is drawing < .5A. A few house LEDs account for the rest.

We were in float before the move. I'd guess we'll be back there in under an hour.
It's clear that keeping the batteries topped off by solar on a rainy day is not a problem.

[skagitstan]

It's been under 1/2 hour, and the MPPT says we are back at float.

[Mfturner]

Hi Booster, I have a Go Solar controller on my van with FLA batteries, but have only had the van a few months without a proper battery monitor. With that said, if parked in my driveway on a sunny day and the electronics are disconnected, it will sit at 13.7 when the sun is out (14.4 if I catch it early). If I connect the rest of the van's electronics without being plugged in, the various loads pull the voltage down a bit as I use things, I only have a single 95w panel. Once the sun is down, if nothing is connected the battery voltage will float down a bit until the next morning, and a few tenths of a volt lower if the electronics are connected but everything turned off. I am more of a "good enough" person than a perfectionist. So my plan is:

1. to not worry about chronic overcharging when I'm camping, maybe 20-50 days a year at this point,
2. to leave the electronics connected to add some parasitic load when In my driveway loading or unloading for a couple of days (only plug in in the driveway when the 3 way refrigerator is actively running, then on 120vac), maybe another 10-20 days a year
3. Store for the remaining 300-ish days a year under cover, so solar isn't an issue, plugged in and trickle charging the starter battery with everything otherwise turned off if over 2 weeks, simply disconnected if 2 weeks or less.

As I approach retirement and hopefully improve the camping to storage ratio, I may get more serious about what happens while camping.

[Saldar]

Originally Posted by booster

I just took a quick look at one of the Go Power solar controllers....

If plugged in, I would pull the fuse on the solar if it is outside in the sun.

It also will float at 13.7v, which IMO is to high for long term storage, so another reason to not have the solar on in storage if you can get plugged into shore power.

I don't know how the Zamp controller manages the daily bulk to absorb transition or how long it runs. Might it help to change from AGM charging mode to a chemistry with lower absorb voltage when I don't need solar? (LTO mode is 14.0V) According to the manual all modes float at 13.6V, however.

According to the install diagram the fuse is between the panel and the controller. Is this fuse in the right position to pull to turn it off as you recommend?

The 30A model manual at this link "covers" the unit on my Travato.

[booster]

Originally Posted by Mfturner

Hi Booster, I have a Go Solar controller on my van with FLA batteries, but have only had the van a few months without a proper battery monitor. With that said, if parked in my driveway on a sunny day and the electronics are disconnected, it will sit at 13.7 when the sun is out (14.4 if I catch it early). If I connect the rest of the van's electronics without being plugged in, the various loads pull the voltage down a bit as I use things, I only have a single 95w panel. Once the sun is down, if nothing is connected the battery voltage will float down a bit until the next morning, and a few tenths of a volt lower if the electronics are connected but everything turned off. I am more of a "good enough" person than a perfectionist. So my plan is:

1. to not worry about chronic overcharging when I'm camping, maybe 20-50 days a year at this point,
2. to leave the electronics connected to add some parasitic load when In my driveway loading or unloading for a couple of days (only plug in in the driveway when the 3 way refrigerator is actively running, then on 120vac), maybe another 10-20 days a year
3. Store for the remaining 300-ish days a year under cover, so solar isn't an issue, plugged in and trickle charging the starter battery with everything otherwise turned off if over 2 weeks, simply disconnected if 2 weeks or less.

As I approach retirement and hopefully improve the camping to storage ratio, I may get more serious about what happens while camping.

That sounds like a good plan. Of particular interest would be how long it stays in the 14.4v, once it gets there, when recharging. That might help answer the confusing statement i the manual. Of course, it is always hard to catch the point that it gets to 14.4v and when when it goes down again, as they always happen when you aren't looking.

[booster]

Originally Posted by Saldar

I don't know how the Zamp controller manages the daily bulk to absorb transition or how long it runs. Might it help to change from AGM charging mode to a chemistry with lower absorb voltage when I don't need solar? (LTO mode is 14.0V) According to the manual all modes float at 13.6V, however.

According to the install diagram the fuse is between the panel and the controller. Is this fuse in the right position to pull to turn it off as you recommend?

The 30A model manual at this link "covers" the unit on my Travato.

Looking at the pic in the manual, they show three 40 amp fuses if you have two batteries hooked up. If you are just charging one battery you would lose one fuse. For storage, and to be the safest (from voltage spikes, not death) on restart after storage, I think I would remove all three (or two). Removing the fuses from the batteries to the controller will get rid of the power drain, and removing the fuse from the panels will eliminate spikes. You would remove the panel fuse first, and reinstall it last, to prevent spikes. If you don't pull the fuse for the panels, either cover them, or make sure you are inside or in the dark so there is not solar output.

The manual, to my surprise, actually does say how the unit handles the absorption time and float transition.



So, once the unit gets through bulk stage, so it can maintain absorption voltage by supplying enough current to give the batteries all they want, plus you loads, the two different methods could happen if conditions are met.

The current dropping to .5 amps to go to float is very much lower than we would usually see in this kind of controller. The transition to float for Lifeline AGMs is .5%C or .5 amps per 100ah, so if the battery was bigger than 100ah, or old, you would never get there to trigger the transition. Add to that the fact that the unit doesn't measure battery charging amps, just total which includes loads, and it will never be triggered because most vans use .4-.6 amps just to run things without anything really turned on. The .5 amp thing would only be good for a battery of 100ah or smaller with the rest of the coach disconnected so no loads, so might be useful in storage with the right battery size. If the .5 amp was settable, it could be tailored to your setup, which would be much better. The manufacturer probably wouldn't tell you how, but it may be internally settable with a pot or maybe resistor change.

The second method to go to float is the more common fixed timer, that in this case is set at 4 hours, which is also pretty typical. My guess would be that the timer would control the system 98% of the time as the amp setting is so low. 4 hours is the manufacturer's best guess of how long it will take to get and unknown battery, or unknown SOC, to reasonably charged, without over charging. It is timer controls that can do the overcharge in storage issues as they normally run every day. 4 hours of absorption on already full batteries, every day all winter, is not a good thing. When camping, it won't likely be overcharging very often unless you are on shore power, and then it would overcharge unless the voltages worked out that the shore charger handled all the load so the solar cut to float on amps. With no other charging, unless the solar is a quite big system, 4 hours will likely not get the batteries completely full very often, but if the sizing of solar and batteries to use per day is good it could be quite close.

The whole "charging to full without overcharging" has been discussed here many times, and in most lead/acid applications is likely the weakest link in optimizing battery life and capacity. It can be done, but the charging equipment to do it tends to be quite expensive, and there aren't a lot of choices.

[Saldar]

Originally Posted by booster

The manual, to my surprise, actually does say how the unit handles the absorption time and float transition.

Thanks Booster. You not only are a good writer, but also a better reader than I am.

The van has a ladder near the panels so your idea of covering the panels might be the easiest and most KISS way to stop excessive solar charging in the Travato, especially since we added a second 100W panel.

[Travelknowing]

Hi everyone, I posted the question on the Coachmen website - here's the response!
_____________________

Hello,

Thank you for contacting Coachmen. It is ok to leave your Galleria plugged in. You have a three stage converter charging system and works as you described. If you have further questions feel free to shoot me a mail.

Thanks,
Greg



---------------------------------------------------------------
This email was sent in response to the message you sent us on Saturday, April 7, 2018. Your original message for reference:

I just purchased a 2018 Galleria 24T and would like to leave it plugged in to shore power all the time and keep the refrigerator on. The battery is a 330 AMP AGM Battery REV-8D-330, R4000 series. I have no idea what the battery charging system is.

Q: Is it OK to leave the RV plugged in to shore power all the time?
Q. What IS the battery charging system, is it a 3-stage that goes into trickle charge mode when the batteries are fully charged?

[fratermus]

Originally Posted by Travelknowing

I'd really like advice on if I can keep my new Class B constantly plugged into shore power. I like the idea of being ready to go at a moment, but the tech guy at our dealer said that wasn't a good idea for the batteries.

AGM batteries were literally designed for long-term Floating (the electrolyte doesn't stratify when quiescent).

The battery manufacturer will have a recommended Vfloat setpoint; I'd set my charger/converter/controller/whatever to that voltage and sleep the sleep of angels.

[markopolo]

If leaving the batteries on a charger then ideally the charger will have a temperature compensation feature. That feature has become one of my must haves for any future purchase. Not all of my current equipment has it.

I did have one wet cell battery boil over a little bit while being maintained at 13.2V with an automatic periodic boost to 14.4V. It may have occurred after driving in summer then plugging in or while in storage during hot summer temperatures. I didn't see the actual event occur.

Whilst AGM's would be unlikely to lose electrolyte like the wet cell did I'm sure the same set of circumstances that caused the wet cell boil over would be somewhat stressful to the AGM's. My assumption is that it could lead to premature drying out.

The PD charger used has the Wet/AGM 14.4v / 13.6v / 13.2v charging profile. It also has a Gel profile at 14v / 13.2v / 12.8v. During very hot temperatures or after driving during hotter temperatures and then plugging in I'll try to remember to switch it to Gel mode as a manual temperature compensation workaround.

[eric1514]

Originally Posted by markopolo

...
The PD charger used has the Wet/AGM 14.4v / 13.6v / 13.2v charging profile. It also has a Gel profile at 14v / 13.2v / 12.8v. During very hot temperatures or after driving during hotter temperatures and then plugging in I'll try to remember to switch it to Gel mode as a manual temperature compensation workaround.

I've never owned a PD charger with that capability or I maybe I haven't found the switch yet.

[booster]

Originally Posted by eric1514

I've never owned a PD charger with that capability or I maybe I haven't found the switch yet.

I think most of the PD chargers have that capability, and also have the very ability to manually change the charging stage, overriding the internal timers, to address over or undercharging manually based on battery monitor readings.

The huge thing missing from PD chargers is temperature compensation, so the mentioned change in profile to manually address hot temps is definitely a good idea.

[markopolo]

Mine is the PD4045 - AKA the Mighty Mini. There's a jumper on the board that lets you choose Wet/AGM or Gel modes. It is normally used once during installation of the unit. I installed a small switch to be able to toggle between modes easily.

PD4045 voltage control switch closeup.JPG

I forget to use it though - so automatic temperature compensation is way better than my manual control workaround.

[eric1514]

Originally Posted by booster

I think most of the PD chargers have that capability, and also have the very ability to manually change the charging stage, overriding the internal timers, to address over or undercharging manually based on battery monitor readings.

The huge thing missing from PD chargers is temperature compensation, so the mentioned change in profile to manually address hot temps is definitely a good idea.

Actually, none of the 9100 or 9200 series chargers, their most popular, have this feature which is too bad. Interestingly, the brochure and manual for the 4000 series panel/charger that Marko has makes no mention of this feature either. Perhaps it's been discontinued.