AGM Battery Charging and keeping the battery charged from AC continuously

[booster]

Looks like you are correct, I must have been remembering Marko changing his. The newer 2100 series does look to have the settable programs, but it still doesn't appear to have the temp compensation it really needs.

[markopolo]

Originally Posted by eric1514

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.

On the sealed units like the 9100 and 9200 series it was likely an undocumented option on the board because those units were not intended to be opened by anyone other than a trained tech.

Here's a photo of a 9280 board that was shared on RV.net by DryCamper11 that shows the H4 jumper position: ->

h ttp://i1054.photobucket.com/albums/s485/DryCamper11/_Bottom_Labels.jpg

He also shared a top view ->

 h ttp://i1054.photobucket.com/albums/s485/DryCamper11/_Top_labels.jpg

and you can just see the white plastic base and two pins of the unused jumper in the upper left area where the fan, heatsink and large coil meet.

I think the 9100 board had it also if I remember correctly. I took one apart once and think I would have remembered if it didn't have the jumper position.

It was a documented feature on the various power center units like the 4045 as they were open and accessible. If you Google Progressive Dynamics "h4" you get a few pdf links.

It's possible it is still on the circuit boards but no longer mentioned because Gel batteries don't seem to be a common choice and some folks might think Gel is AGM - it is not.

However, if the jumper option is in a sealed case then it is of no use to most people anyway.

[g1g]

Originally Posted by Travelknowing

Hi everyone,

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.

When he told me this, I was rather disappointed - I'd had sailboat for 30 years and always plugged into shore power at the marina to keep the batteries in top shape.

Rebecca

All I did was connect a Batteryminder to mine. It has been on for the past 7-8 years. I just realized that my battery is over 10 years old. Anyway the batteryminder is connected to both vehicle and house batteries keeping both charged and ready to go. All i have to do is fill my water tanks and food then we're off.

[Travelknowing]

Originally Posted by g1g

All I did was connect a Batteryminder to mine. It has been on for the past 7-8 years. I just realized that my battery is over 10 years old. Anyway the batteryminder is connected to both vehicle and house batteries keeping both charged and ready to go. All i have to do is fill my water tanks and food then we're off.

10 years for the battery! That's awesome! You must have it in a garage to be able to open the hood for the battery minder connections.

[g1g]

I have kept it in the garage for the last 8 years give or take. I don't need to open the hood to connect it. I have a jumper wire directly on the batteries to a 12v connecter hanging outside. Then all I have to do is connect the batteryminder to the jumper connectors.

[rockymtnb]

One potential safety drawback to leaving the RV charging from the power converter or inverter/charger is the possibility of an overheated battery fire.

A couple of users on the Sportsmobile forum have experienced this when batteries developed internal plate shorting that led to slow but runaway battery overheating, eventually leading to engine compartment fires or damage.

The situations were apparently caused by internal battery short circuiting that was sufficient to pull high amperage from the converter/charger but still had enough internal resistance to avoid tripping the charger's circuit breaker. Interestingly both times it was the vehicle battery, being charged via the transfer relay, that suffered internal shorting and overheating.

Based on those incidents, and because our van is stored inside our garage where fire would be catastrophic, I switched to a temperature compensated trickle charger for long-term battery maintenance. Now if such an internal short occurs presumably the battery would fail but the 3 amp maximum charger current shouldn't be enough to fatally overheat the battery.

Note this should NOT be an issue with lower current solar or trickle charging, it's only a danger when using the full strength converter/inverter-charger for long term charging.

[Travelknowing]

Originally Posted by rockymtnb

One potential safety drawback to leaving the RV charging from the power converter or inverter/charger is the possibility of an overheated battery fire.

A couple of users on the Sportsmobile forum have experienced this when batteries developed internal plate shorting that led to slow but runaway battery overheating, eventually leading to engine compartment fires or damage.

The situations were apparently caused by internal battery short circuiting that was sufficient to pull high amperage from the converter/charger, but still had enough internal resistance to avoid tripping the charger's circuit breaker. Interestingly both times it was the vehicle battery, being charged via the transfer relay, that suffered internal shorting and overheating.

Based on those incidents, and because our van is stored inside our garage where fire would be catastrophic, I switched to a temperature compensated trickle charger for long-term battery maintenance. Now if such an internal short occurs presumably the battery would fail but the 3 amp maximum charger current shouldn't be enough to fatally overheat the battery.

Note this should NOT be an issue with lower current solar or trickle charging, it's only a danger when using the full strength converter/inverter-charger for long term charging.

That's more than a little alarming! I think I'll leave the van unplugged (it has 100W solar) unless I have the refrigerator on.

[booster]

I think that the likelyhood of such a fire is really very low if you have good equipment and good batteries. It used to be fairly common, in the days of fixed output chargers and water consuming wet cells, to dry out a battery and short it. I can't say I have heard of it happening in decades for anyone I know. It would be very interesting to know what the the circumstances were of the fires mentioned.

That said, even with today's available chargers and batteries, you could still generate such scenario. If you have a charger that floats at 13.7v and wet cells, not a good idea. If you have a non temperature compensated charger, not a good idea if you see temps much off of the 77* baseline, especially if hotter. If your batteries are not holding charge well anymore, or using way more float current, they should never be left unattended.

Solar can also cause a big problem, especially if you are plugged into shore power also when the van is in the sun. Many of the solar controllers will run a full charge cycle every day regardless of if you are on shore charge or have full batteries. Definitely a hazard.

We leave ours plugged in, inside the garage, most of the time. I do cycle the batteries down a maybe 20% every month or so. We have 440ah of AGM and all our chargers are temp compensated and do amp based charge control, but I still look at the monitor whenever I happen to be in the garage to see if the charge amps have gone up, as it is just common sense.

Personally, I would worry as much, or more, about the multitude of small charging going on around the house, much of it on lithium batteries and with aftermarket chargers. Cordless phone, cell phone, wireless headphones, cordless tools, gps units, you name it. Even the trickle charger can catch fire, but it would be at the wall plug and not the batteries, most likely. I had a Battery Tender melt a couple of years ago, and all it was doing was keeping a 10ah AGM topped off as it had periodically for many years. The battery was fine, but the Tender failed internally, it appears, and shorted enough to melt the guts until the GFCI tripped on the outlet.

[rockymtnb]

Originally Posted by booster

...If you have a non temperature compensated charger, not a good idea if you see temps much off of the 77* baseline, especially if hotter. If your batteries are not holding charge well anymore, or using way more float current, they should never be left unattended....

These were Sportsmobile vans so presumably they had the standard Tripp-Lite or Magmum Inverter/Charger units with 3-stage 100 amp temperature compensated charging. It's worth noting that the charging units presumably didn't do anything 'wrong'. They were presented with a high current resistive load and they supplied it, not having any way of knowing it was overheating a failing battery.

Your point about monitoring battery charge amperage to spot an unexpectedly high load during storage is well taken. Perhaps a remote monitoring smartphone app would be helpful for those who can't provide continuous monitoring in person.

Originally Posted by booster

I had a Battery Tender melt a couple of years ago, and all it was doing was keeping a 10ah AGM topped off as it had periodically for many years. The battery was fine, but the Tender failed internally, it appears, and shorted enough to melt the guts until the GFCI tripped on the outlet.

Your Battery Tender failure seems to well illustrate the problem. Although charger and battery internal shorting are relatively uncommon overall, your experience and that of the Sportsmobile owners show they do sometimes occur, with potentially dangerous results.

[Roadtrek Adventuous RS1]

Batteries love to be charged...we have a solar panel on ours and it's always topped off...and when it's plugged in the controller reduces the flow to the batteries of they are full....plug in and enjoy......

YES...we leave the refrigerator running 24/7..... discovered that if you don't then it's more likely to get moldy...

[Travelknowing]

Originally Posted by Roadtrek Adventuous RS1

Batteries love to be charged...we have a solar panel on ours and it's always topped off...and when it's plugged in the controller reduces the flow to the batteries of they are full....plug in and enjoy......

YES...we leave the refrigerator running 24/7..... discovered that if you don't then it's more likely to get moldy...

Sounds good to me!