I will be leaving my 2013 GEM with Gel batteries in a garage in AZ for 6 months through the 100+ degree summer. Should I keep it plugged in and charging or unplug and turn off main disconnect switch?
Looking for comments. Thx.
I would use a timer on whatever outlet the cord plugs into, set for 1-2 hours a day or once a week for a few hours [depending on how fancy your times is]
I am in the camp that thinks there is too much that tends to go wrong with “leaving it plugged in”. Leaving the Main Switch ON (so your charger can see your battery) also feeds your DC Converter. If anything happens to your charge path, the converter will drain your pack to Zero.
Charge it up, run it through a couple charge cycles, then unplug and switch off your battery. If you have anything else hooked up to your batteries outside the normal car wiring, then make sure it is all disconnected.
Here is the technical answer. I lean towards AR’s simplicity answer, less things that can go wrong, the better. But in your case is a bit extreme. Lead batteries self discharge , This discharge rate is very dependent on temperature. the colder they are the less they discharge, warmer will discharge faster. If you charge a battery and put it in the snow, it will lose very little charge over 6 months. The chemical reaction is slower in cold temperatures, That same battery in hot climates will have a faster chemical reaction and discharge considerably faster. A 6 month period in can lose half of its charge. The problem is when the battery gets around 12.4v the cells start to sulphate. So to prevent this the battery must stay close to full charged. The other issue is charge voltage in hot climates. Every battery manufacturer has a temperature compensation chart for their batteries . Basically when they are cold, charge them higher. When hot charge them lower. East Penn states a gel battery should be charged to 14.2v at 45 degrees, but only 13.3v at 100 degrees. Fortunately the Deltaq charger is very intelligent and does this temperature compensation.(most chargers cant).
I believe the best storage in hot temperatures would be to use a timer to turn on once a week to keep them topped off(the charger will compensate for the heat). The ideal way to store them would be to put them in the refrigerator.
For those in cold climates, fully charge, turn off main switch and forget about them.
Hmmm… I guess 6 mos is a long time for a battery.
I still don’t like the DC Converter still being active. In the 2013 cars, the DC converter is part of the charger(so unhooking it is not an option).
Some people install small individual float chargers direct on the batteries. Con- This is an added expense.
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Get someone to drop by weekly and unplug, plug in charger. My 2000, 825, will shut itself off and drain the batteries if left unattended.
ya, there needs to be a way to bypass the rest of the system and get the battery charger connected directly to the batteries on the other side of the master disconnect. So the only thing connected to the batteries is the charger and the timer method of 2-3 hours once a week would do the trick.
You know the system quite well, any thoughts on an easy way to disconnect the positive leg of the charger and jump it over to the positive terminal of the battery pack or the master disconnect?
If the batteries are fully charged and then the reconnection is done, there shouldn’t be but a few amps going through the jumper wire so it doesn’t have to be much smaller gauge than maybe a #10.
that would be a good way to do it for someone who is ok with a little work. Charger only does 10a so 14ga or bigger would be fine. Jump from the back of psdm where red charger wire connects to terminal where positive battery cable comes from the rear. turn off switch and try plugging it in. I would still use a timer on charger to come on once a week. @inwo may have another suggestion.
Or just by a lithium pack and dont worry about any of this 
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Not if it’s a dci charger.
Sure, Jumping the B+ charge wire to the battery side of the MBD switch allows the DQ to still see the pack while the rest of the car remains off.
It gets complicated with the Gen3 cars (like @Ciolek '13 car) due to it having the DC Converter integrated inside the DQ Charger. It sources/backfeeds through the charging wires and quite difficult to get in and disconnect for a long term storage solution.
As an exercise, I’ll go measure stray consumption when chargers and converters are left connected. There sure is quite a spark from inrush to the caps when the MBD switch is flipped to ON. I can see why they fail.
Thanks to all for replying so quickly. I wound up buying a multi-day/multi-hour charger on Amazon: the “Charge-o-matic” (sounds like something from Ronco!)
Next day delivery.
I will try a 7 day interval at 3 hours each cycle.
I will post again in October to let you know how it works out.
When the gel batteries need to be replaced, I will be moving to lithium!
Well in that case, I recommend putting your batteries in the oven at 350 degrees for 2 hours.
It will feel almost like that in the Arizona summer!!!
Does anyone know what the steady state max current on that thing is? Can’t believe it’s not front and center and because of that I wonder how poor it really is. I see on the back it says 15(3)A but what does that mean? Is it 15.3A, is it 15A peak/3A continuous and without knowing I would not trust it.
$0.02
We leave ours plugged in to a smart plug that we can monitor… That way if something happens we gat a notification and can send someone to go check on it. we have it turn on every 4 days or so to keep the batteries topped off when we are gone… that way it’s technically “unplugged” most of the time. We’ve had the same set of 6 Polaris (Dekka) AGM’s in our cart do 8+ years now and they somehow are still going (Although suffering some major range loss at this point.) I feel like keeping them at 80%+ charge is critical to longevity.
How old are the Gel batteries? If older, replace them and convert to Lithium Ion (LFP). They are much more heat tolerant.
I have been working with Lithium Ion (LFP) systems for over 16 years. I guess I am biased…
Major range loss, major range loss. Hi 
Yeah, I know… Still waiting for these old dirty bustards to die for real so I can convince the wife to go lithium. Right now I still get drop my kids off at school, get my Panera soda, to work, and pick up kids on a charge, (~6-7mi) So, according to her, its fine. First part of the day I’m going 33-35 (Reprogramed T2) but those afternoon runs i’m hoping for 25 
Eyeing the Mighty Mite or a custom SDI94 or DIY CATL 93 NMC pack for the front when the time comes.
That’s this best thing to do! Need to put the charger on a timer since the charger is not a trickle charger that monitors the batteries