reading voltage with a multimeter?

[yolofitz]

After reading the posts and the link to 12 volt side of life, I would like to offer my experience with my AGM battery. It is very contrary to the author’s view of AGM.
I have owned my 2002 17’ Casita SD since 2004. Removing the battery from the very small cubby hole is no easy task, then carry to the garage for charging, water, cleaning etc and then replacing it. 5.5 yrs ago I camped next to fellow Casita owner who had an AGM and explained the pros/cons. He gave me his small voltage reader which I plug into the volt outlet in the back corner of Casita. In a few days, it’ll be exactly 6 years since I purchased and installed my AGM.
In those six years I’ve never removed the battery. I charge it using my heavy duty extension cord via my converter/charger. It is a Progressive Dynamics converter and 4 stage charger. Two days ago I disconnected the shore line and today the charge is reading 13.0 volts. The battery is a Lifeline Marine AGM. I paid $331.70 including shipping. When it’s useful life is extinguished, I’ll buy another AGM.

[gordon2]

Originally Posted by yolofitz

After reading the posts and the link to 12 volt side of life, I would like to offer my experience with my AGM battery. It is very contrary to the author’s view of AGM....

In those six years I’ve never removed the battery.

I charge it using my .... Progressive Dynamics converter and 4 stage charger. T...

I’m glad to hear of your satisfaction with an AGM battery because after much consideration, I also made the switch to AGM only last week.

My primary reason was the corrosion associated with non-sealed lead-acid batteries. For maximum safety, I use a master fuse that mounts directly on the battery post. But if one is a using non-sealed lead-acid battery, then because the fuse holder is on top of the battery, and inside the box, it requires cleaning and refreshing the metal surfaces every year or two. And even if you use a fuse holder outside the battery box, maintenance and cleaning of the connections is needed on a regular basis. Also, after less than three years on a new camper, I found a good deal of rusting and corrosion on the parts of frame cross-members that the battery is mounted on, perhaps because of acid spilling out on rough roads. I expect that with the AGM battery it will likely be about five years before I even need to open the battery box. Which is good, because I put a cable and lock around my Vmax since it cost me $270 (with first time order discount).

But there is the issue of the slightly different charging parameters that are required to get the best use out of an AGM vs wet cell lead-acid battery. And in this area, I have done a lot of research, not that it was really authoritive. Much of what I read is not consistent, but my general conclusions are this:

1. Most AGM battery manufactures tell you to not use equalization. But at the same time, even AGM’s can suffer sulfurization. My concern was with my Progressive Dynamics 9100 with charge wizard, that uses an equalization mode every 21 hours for a period of 15 minutes. This cannot be disabled while the “Charge Wizard” is used. The potential problem with AGMs is with overcharging so that electrolyte is lost, which in an AGM cannot be replaced. But one author said that the “Charge Wizard” function was not a true equalization and indeed, I see that the with the “Charge Wizard,” the equalization voltage is 14.4 which is the same as the minimum charging voltage recommended by the manufacturer of my AGM battery. Still, I plan to not leave the converter with Charge Wizard on all the time so that I mostly avoid the questionable equalization every 21 hours.

2. By and large, the charging algorithms used by most quality multi-stage chargers will work OK for AGM as well as traditional wet cell batteries. You can squeeze a little better performance out of an AGM battery by using a charger that is engineered for the task, but the increase in performance is not that much and most chargers are not sophisticated enough to exploit the difference. For example, after even more research, I choose the CTEK 7002 charger for use for both my wet cell and new AGM batteries. But the settings on the charger to use with AGM batteries is either the one that for regular wet cell batteries, or the one called “snowflake” which is for either AGMs, or for wet cell batteries in cold conditions. I also use a Progressive Dynamics 9100 with charge wizard and a Bogart Engineering SC-2030 solar charger. The latter is the only one that truly has the ability to be programmed according the best options for the AGM battery, but it only works when I am using the solar panels.

3. Lastly, I went with the largest capacity battery I could fit on the trailer’s tongue without making major modifications (i.e. pair of six volt golf cart batteries). It’s 20 hour rating is 125 AH. The manufacturer (Vmax) specifies a minimum charging current of eight amps (consistent with the general advice of a charger capable of 5 to 20% of the battery's 20 hour rate). But out of three charging sources that I have, only the PD 9100 in boost mode can do more than 6-7 amps. Ideally I would use the higher amperage charger for the bulk stage and then use any of my three chargers to finish the charging (giving a preference to the solar charger programmed for an AGM battery). In practice I doubt that will happen so I don’t know what effect that will have on battery performance.

[tmaken2157]

Hi,


I'm a bit surprised no one commented on you running your frig on the 12 volt, I forget what the small frigs pull for amps but the mid size ones we had in our 17 ft casita will eat available power from a battery pretty quick. And if you run it too low too much you risk killing it prematurely. I know you have a charging line running fro the Truck but that goes through your charge converter which may not be up to the task of providing adequate voltage to the battery.


I'm no expert but I owned a scamp 13 and they put decent charge converters in and with a charge wizard you could just plug your rig into a small generator or shore power and it took good care of your battery. Our next camper was the casita LD17 and it had a substandard charge controller. I would bring a smary charger with me and run that using either of the two options mentioned about. Until I changed out the charge controller with an iota, then I just had to leave it plugged in and it was fine. Lastly when I added a solar system I also installed a Victron meter which combined with a shunt you know exactly how much goes in and how much goes out and what the state of battery charge is. You don't need a solar system to install a meter and the shunt gets installed in line with the group.


Happy Camping

[John in Santa Cruz]

the best multistage smart chargers are CTEK but they are fairly expensive. I've been making due with a Diehard (probably made by Schumacher).

[gordon2]

Originally Posted by John in Santa Cruz

the best multistage smart chargers are CTEK but they are fairly expensive. I've been making due with a Diehard (probably made by Schumacher).

Glad to hear it since I got my CTEK 7002 today. But boy does it run hot. - too hot to hold. I'm thinking of mounting it on a heat sink of some sort, and/or run a fan over it.

[John in Santa Cruz]

Originally Posted by gordon2

Glad to hear it since I got my CTEK 7002 today. But boy does it run hot. - too hot to hold. I'm thinking of mounting it on a heat sink of some sort, and/or run a fan over it.

how large of a battery were you charging, and how discharged was it when you connected it?

i would expect that the charger should be fine if its in the open air and out of the sun even if it gets fairly warm. the power brick that charges my Mavic drone gets really hot if the battery back is run down when I start the charge, and will fault if its in the sun on a 100F day (as I found out last weekend... in fact, I had to put the drone battery in my RV fridge for 30 mins before I could even start the charge cycle, then ensure it was all in the shade).

[gordon2]

Originally Posted by John in Santa Cruz

how large of a battery were you charging, and how discharged was it when you connected it?

i would expect that the charger should be fine if its in the open air and out of the sun even if it gets fairly warm. the power brick that charges my Mavic drone gets really hot if the battery back is run down when I start the charge, and will fault if its in the sun on a 100F day (as I found out last weekend... in fact, I had to put the drone battery in my RV fridge for 30 mins before I could even start the charge cycle, then ensure it was all in the shade).

Air temp 77, everything is out of the sun. Grp 27, 90-100 AH. About 60-70 % discharged. It was drawing 110 watts (120 VAC), and now its down to 88 watts input and a little cooler. Its still in bulk phase. I will be using it later for a 125 AH AGM. Its reported to be good for charging up to 150 AH batteries so if it burns up I have a good warranty claim.

[semievolved]

This is a good discussion and i agree with the recommendations to get a good charge controller and make sure to keep water over the plates. Although i've never had an AGM they also seem to be a good investment for lack of maintenance and safety and they are less probe to sulfaltion between full charges. It's nice they can be included inside a living space without having to worry about offgassing. But, at risk of hijacking this thread, when I need to replace my current pair of 6V, 230 Ah flooded batteries, I am very tempted to go to lithium batteries. Looking at their overall life cycle and the fact that you can effectively use close to 90% of their capacity rather than the ~40% of lead acid, they are quite cost competitive with lead acid. And, they don't require maintenance (after an initial balancing typically). They don't offgas and they are smaller and lighter than lead acid. Many modern solar charge controllers (my trailer has a 170W panel) can be programmed for lithium batteries as well. What am I missing here? The issue with fires is really not a problem on quality LiFePO4 batteries with a good controller.

[beardrum]

So, is the Progressive Dynamics 9100 series of charge controllers considered to be good ones, or not so much?

[gordon2]

Originally Posted by beardrum

So, is the Progressive Dynamics 9100 series of charge controllers considered to be good ones, or not so much?

I hesitate to call it a charge controller since that term often refers to the electronics used with solar panels. It does not control solar charging. I prefer the term (RV) converter.

IMHO (and IMHO only) the 9100 is acceptable (for wet or AGM) but only as long as you have the add on "Charge Wizard." Or you could use the PD 9200 which has the "Charge Wizard" circuit built in (and an optional pendent). The only concern I have using it with an AGM battery is the frequent "equalization", so I think it should not be left on 24/7 when using an AGM battery. Just charge it then disconnect the battery. Thats one (minor) reason I have a battery disconnect switch - When on shore power, I can use the 9100 converter with Charge Wizard to the charge the battery then switch the battery out of circuit and continue to use the converter to power things in the camper.

BTW, and again IMHO, if it does not have the charge wizard then you should not leave it on 24/7 for either type of battery.

[John in Santa Cruz]

Originally Posted by beardrum

So, is the Progressive Dynamics 9100 series of charge controllers considered to be good ones, or not so much?

whats the application?

I used their PD4645 as a replacement for my parallax, it was a drop in fit to the existing power center chassis.

if I was doing an install in a camper that didn't have any electrics to speak of, I'd look at either hte 4000 or 4100 panels, which include AC distribution and breakers, DC distribution with fuses, AND the ac to dc charger/converter...

[gordon2]

Originally Posted by John in Santa Cruz

whats the application?

Good question

Originally Posted by John in Santa Cruz

if I was doing an install in a camper that didn't have any electrics to speak of, I'd look at either hte 4000 or 4100 panels, which include AC distribution and breakers, DC distribution with fuses, AND the ac to dc charger/converter...

I concur that a (breaker / fuse) panel is important. I'm happy with my separate panel with the 9100 converter but one way or another, a panel should be used.

[Nick J]

I prefer Iota Engineering to Progressive Dynamics. My PD runs some halogen lamps at home, I trust the Iota in the Scamp.

[beardrum]

Originally Posted by John in Santa Cruz

whats the application?

The PD9100 is in my 2014 Deluxe 16' Scamp.

Sorry, I was reading the discussion here and on the The 12volt Side of Life (Part 1) and see that a 3 stage converter was recommended, and couldn't find mention of three stages in the PD manual I have. The Charge Wizard (which I DO NOT have installed) literature talks about a "Boost" mode, a "Storage" mode and a "Normal" mode, which I presume are equivalent to the Bulk, Absorption, and Float modes?

I'm interested because I just had to buy a new battery (in the middle of a trip) after my 48 month old battery that came with the trailer wouldn't hold sufficient charge to make it thru the night, especially with the furnace, lights, and water pump occasionally running. I suppose the symptoms were classic: charged at 13.2 volts all day while driving, it read 12.5 (or so) after resting when we parked, then with the night's use, it steadily dropped to 11.whatever. I had to go out and connect to the car and run the engine for a while to make it thru the night. The water level was good and connections were good, and while on shore power, it charged at 13.7, just as it always had.

So I suspect that over the four years of keeping the trailer plugged in whenever it wasn't in use, I managed to wear the battery out. So I'm interested in not doing that again.

I think I'll spring for the Charge Wizard.

Thanks

cg

[gordon2]

Four years is not bad for a battery. With better care you could go a few years longer before it would need to be replaced and I think the charge wizard might help with that, esp if you stay plugged into shore power for extended periods. 11 volts is way too low if that reading is taken with the battery at rest and not under load, as you read about in the 12 volt side of life. Even under load it sounds low, so its possible that you were discharging the battery too deeply (to get max life out of it), but it is often hard to judge the level of discharge. You can use a battery monitor with shunt to measure the current, or you can calculate a fair estimate if you know the power draw of everything you use and how long it runs. The objective is to stay above 50% discharge since the depth and frequency of discharge is a primary factor affecting battery lifespan. For many of the stock batteries that come with Scamps I would think that is around 40-50 AH).

You could even fine tune things even more with a temperature compensated charger, but the bottom line I think is that if you got four years out of the battery with a single stage charger / converter, then adding the charge wizard to make it a multi-stage charger will the be single best thing you can do.

[Joe MacDonald]

I have had an AGM spiral grid battery in my camper for almost 10 years, I use a PD9245 converter, and have never had a problem, it usually sits plugged in and turned on, even when I am not using it

Joe