Continuous charging with Tripplite Inverter/Charger

[PeteM]

Is there a consensus on whether it's ok to leave the Sportsmobile plugged into 120v during winter months and charging continuously from the Tripplite 2kW inverter/charger?

Tripplite specs indicate that Stage 3 float charging will drop to 13.5 volts at 77 deg F (25 C), and my SMB supplied plug-in voltmeter stabilizes around 13.6 after absorption charging finishes during the summer. That seems about right. During winter garage storage the float voltage rises to 14.1 when the temperature drops to around 50 degrees, presumably due to the Tripplite's temperature compensation circuitry.

Do others leave their van plugged in and charging during the winter? Any problems, or better alternatives for optimal battery life?

Thanks

[Scalf77]

I have had my Van/Tripp-lite plugged in for 10 years while parked at home. I have not had any issues.

Greg

[daveb]

I keep plugged in all the time but I don't leave the charger on for more than a day anymore. I almost burned my van to the ground doing that. Fortunately my inverter has a low amp maintenance mode that can't over charge the batteries. It doesn't take long to top off the batteries. Smart chargers aren't really smart. Maybe your charger can be set to supply a constant low amp charge?

[86Scotty]

Originally Posted by Scalf77

I have had my Van/Tripp-lite plugged in for 10 years while parked at home. I have not had any issues.

Greg

Me too. Not for 10 years but for a few and no problems. I leave it on charge as well, but DaveB is scaring me.

[daveb]

Just monitor the charge If a battery goes bad, a smart charger turns into a dumb charger. When one of my starting batteries went bad, I came outside and noticed the old rotten egg smell and a battery so hot I couldn't touch the battery box. The battery was ready to explode and made a mess of the box and frame. I had left the charge on for about 3 or 4 days and I didn't know when the starting battery failed.

Earlier that week I had noticed the amperage had gone from the normal tapering down to an amp or so to a constant 6 or 7 amps... a big red flag. Before I turned off the charger (when I smelled the battery) it was way over 40 amps pumping in way more than what was needed. At least it didn't destroy my house battery. This happened twice to me but I had learned a lesson and now know the warning signs.

I have my shore power charger on right now and I'll check it before I crash out. But I will never just leave it on for days at a time anymore.

[PeteM]

Wow, that's scary to have two catastrophic starter battery failures! I assume the battery internal short circuit occurred gradually enough that the charger just kept ramping up current which kept voltage above the short circuit protection level? (I think battery protection cut-out is around 8 volts on the TrippLite).

I do use the low current charge setting on my TrippLite but that still provides up to 25 amps. I suspect that's still enough current to cause overheating on an internally shorted battery as you've described.

How about switching to a low current battery charger such as the 1.25 amp Battery Tender units? That should be low enough that even a shorted battery wouldn't overheat. Anyone use that approach for continuous storage charging?

[daveb]

That is probably what I'd do for long term storage. You still have the chance of undercharging a paralleled battery if one fails and pulls the other down due to a cell short. It just comes down to monitoring the charge. Pulling the batteries would be a lot of work for me. I have two lifeline batteries and I would not be too happy if I killed those and had to purchase new ones. Might make sense to have a way to separate the big expensive batteries if you have more than one. If you only have a single starting battery and a single house battery the separator should do its job with a lower amp charge.
My inverter does have a maintenance only charge and that works great for me.

[Scalf77]

One way of minimizing potential problems is to first disable the separator. This way you are only charging or maintaining one battery bank at a time. If the van sets long enough, you can always turn it back on for a day to get van batteries topped off and then turn it off. A primary reason for losing one of the starters is that generally we have a AGM for house and common wet cell for a starter, while the constant maintenance charge may be fine it will reduce the water level, which usually ends up with a shorted cell. A battery with a shorted cell will put the charger back in bulk charge and result in the overheated boiling battery. Another way of minimizing this is to change your starters to AGM batteries also.

Another possible issue with leaving the charger on all the time is any possible current draws could kick it back into the absorption phase. Tripplite does not provide any data on how they handle this or if they even do. In most cases I have a continuous 1 amp current draw from the various sensors and I also have Single Board Computer running at all times. I leave my refrigerator so I will get that current draw cycling on and off. One of the reasons for the SBC is to monitor the voltage and current from my house. I use to check it all the time, I even have weeks of continuous data logs looking for anomalies and never really found any.

greg

[86Scotty]

I don't want to hijack this thread but have a related question. I'm in the process of buying two group 31 AGM's because my wet cell house batteries are toast. I added a Tripplite inverter/charger to my 95 SMB which has the older blue (big heat sync) separator under the hood. My van has never charged the van battery (I only have one) when plugged in, only the house batteries. If my blue separator is working properly, should it charge the van battery as well as the house, or is my situation normal for the older SMB separator? Thanks and I'll be happy to separate this question if it drags us too far off topic. If need be I can get a model number or pic of my separator but SMB buried it pretty deep under the hood.

[Scalf77]

Scotty,
You would be correct the unit you have is commonalty refereed to as a isolator, it uses Diodes to prevent current flow in one direction. It will not let your inverter/charger charge the starting batteries.

-greg