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Old 08-26-2018, 05:50 PM   #1
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Default Inverter left on - it's all DEAD!

I have a 2015 RoadTrek with a new inverter and 4 new AGM batteries, installed Spring 2018. Everything was working great, but then I mistakenly left the Inverter turned on. It was on for a couple of weeks and drained everything to the point where neither shore power, or the on-board Mercedes engine generator, will charge the batteries. Any suggestions would be appreciated. The display on the inverter won't even light up! Thanks.
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Old 08-26-2018, 05:58 PM   #2
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You likely don't have enough voltage to in the batteries to get the charging sources to activate.


Get a hold of an old school battery charger, not smart charger, and do the initial charging with that, or run a jumper from the van starting battery to the coach batteries to get the shore charger or engine generator to initiate.


Be prepared for the AGM batteries to be damaged, especially if they have been dead for an extended time. Likely not trashed completely, but also not likely to be like new anymore.
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Old 08-26-2018, 07:57 PM   #3
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Originally Posted by Lakesidemn View Post
I have a 2015 RoadTrek with a new inverter and 4 new AGM batteries, installed Spring 2018. Everything was working great, but then I mistakenly left the Inverter turned on. It was on for a couple of weeks and drained everything to the point where neither shore power, or the on-board Mercedes engine generator, will charge the batteries. Any suggestions would be appreciated. The display on the inverter won't even light up! Thanks.
Hello and welcome to the forum!

There are 3 subjects involved in your question: inverters, battery chargers and battery condition.

Inverter:
Clearly, the idling load on your inverter discharged your batteries but before you go and burn down the RT factory, understand that all inverters, even the best of them, have significant idling loads in the whereabouts of a couple of amps. However, the Roadtrek inverter consumes even more than that at idle - somewhere around 5 amps, so it can discharge batteries in fairly short order. What's less appreciated is that even when inverters are shut off, as long as their input leads are still physically connected, they can still consume trace (milliamps) amounts of power. Both Xantrex Prosines and even Magnum units are examples of this. So, the best move when leaving the coach unattended is to hit the battery disconnect switch prior to leaving.

Battery Charger:
"Smart" charging technology can drive you nuts. Because of the low terminal voltage of the fully discharged battery, in their infinite wisdom, the alternator or the shoreside converter/charger concludes that there isn't any battery there at all and refuses to cooperate. This is even the case with typical current production external chargers which when hooked up to a dead battery will report that the battery is unusable and will refuse to come to the rescue. After dealing with that frustration for years, I threw mine in the trash and bought a "smart" battery charger that would report the same symptom, but had an override button that would at least attempt charging regardless of the battery condition.

AGM battery:
Considering that your discharge period is in the whereabouts of 5 - 6 months, the prognosis is a little dubious. When lead sulfate produced during discharge becomes crystallized on the plates, it's reluctant to return to a pure lead state and even if the battery will recharge, it's capacity is typically diminished well below its design capacity. Some batteries like the Concord Lifelines will bounce back better than others.

Since the batteries were so recently purchased, aren't they still under full replacement warranty? If so, consider skipping any recharging effort and see if they qualify for replacement under that warranty.
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Old 08-26-2018, 08:27 PM   #4
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i have actually read an old post about this situation. the poster was able to connect jumper cables to the posts on the inverter/charger. the batteries eventually charged enough to allow normal charging.

Since i did not do it myself i don't know exactly where to hook the cables on the inverter/charger but you could inquire.
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Old 08-26-2018, 08:43 PM   #5
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i have actually read an old post about this situation. the poster was able to connect jumper cables to the posts on the inverter/charger. the batteries eventually charged enough to allow normal charging.

Since i did not do it myself i don't know exactly where to hook the cables on the inverter/charger but you could inquire.
You're spot on. Paralleling the fully discharged battery with a well charged battery will bring the terminal voltage of the dead soldier up sufficiently to have it recognized by the alternator or converter/charger.
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Old 08-26-2018, 08:43 PM   #6
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Originally Posted by gerrym51 View Post
i have actually read an old post about this situation. the poster was able to connect jumper cables to the posts on the inverter/charger. the batteries eventually charged enough to allow normal charging.

Since i did not do it myself i don't know exactly where to hook the cables on the inverter/charger but you could inquire.

Yep, that is one of the options I mentioned. You can hook up to the inverter plus and minus or the existing batteries, but you will get good sized spark both places as the vehicle or jumping battery tries to charge the dead ones.
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Old 08-26-2018, 09:06 PM   #7
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Since i did not do it myself i don't know exactly where to hook the cables on the inverter/charger but you could inquire.
Today, I looked up how to revive a Ryobi battery for power tools and I found some good videos on YouTube...maybe there are some for this case.

I'm having trouble not letting my power tools lithium batteries run below the recharging point which is only a $35 mistake if reviving doesn't work...stories of invertors draining battery banks or forgetting one time to turn something off costing $$$ to fix keeps me on the fence .
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Old 08-26-2018, 09:19 PM   #8
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Today, I looked up how to revive a Ryobi battery for power tools and I found some good videos on YouTube...maybe there are some for this case.

I'm having trouble not letting my power tools lithium batteries run below the recharging point which is only a $35 mistake if reviving doesn't work...stories of invertors draining battery banks or forgetting one time to turn something off costing $$$ to fix keeps me on the fence .

I would think your power tools would have a low voltage shutoff that would reactivate the battery when it sees the charger. That is what my Bosch ones do, although I still try not to ever cycle them off the bottom.


The RV is really no different than your car, which will also go totally dead if you let it sit too long, as it also has a power drain.



One issue that there can be is that some RVs don't have a complete battery disconnect switch, so you can shut off the 12v power switch but things like the shore charger and solar controller could still be connected to the battery and using small amounts of power. If you have one of those types of RV, it is a good idea to put in a full shutoff manual switch, to totally isolate the batteries from all loads.
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Old 08-27-2018, 11:45 AM   #9
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Power tool batteries can not be compared with AGM or any other lead acid battery. If your AGM battery is that dead for that long they can be dangerous to use. Replace them.
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Old 08-27-2018, 05:55 PM   #10
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Careful charging dead AGM's.

I had a "Redtop" battery go dead due to mice chewing off insulation and causing a short. It was only a few months old so I took it into Advance Auto for replacement. They had to put it on the charger first to prove it was dead. I went back an hour later and the place stunk of battery acid. They had blown up my battery trying to get it to take a charge. I am guessing they put more charge to it than you will but still something to be aware of.
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