# ? re battery charger/tender



## Ultrared (Jun 29, 2018)

i have a portable inverter set up w/ the battery connected to a battery charger / tender - 24/7.

if the power goes out then the inverter is charging the batter. should i unplug the charger / tender - so that when the power comes back on the battery won't be getting input from both the internal charger in addition to the external charger / tender? It could be as much as 20-30 minutes before I shut it down after the power comes on?

Not hard to do - unplugging the charger / tender when I start it up - just wondering..

Thanks,

Jim


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## wingless (Oct 29, 2019)

Ultrared said:


> if the power goes out then the inverter is charging the batter.


 Sorry but I don't understand.

The portable inverter has an integrated on-board charger.

Can the question possibly be that the the portable inverter is using battery power, through the integrated on-board charger to recharge that same battery?

Note that only one properly-operating battery charger is required. The integrated on-board charger is sufficient.

The system and the battery will tolerate both the integrated on-board charger and the eternal battery tender. The system will tolerate any power sequencing of one or both chargers.

It is unlikely that the system will charge any faster w/ both chargers because the discharged battery will quickly transition from the constant current mode (where multiple chargers could speed the recharge cycle) to long-duration constant voltage cycle, where one or more chargers will have zero effect.


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## Melson (Dec 8, 2019)

I believe the OP is asking if there is a conflict if the battery tender is powered on at the same time that the inverter is providing battery power.

In this situation typically there is no problem if both are providing charging current at the same time.


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## Dutchy491 (Sep 18, 2019)

See post #13. Storing battery over the winter?


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## OrlyP (Oct 19, 2021)

I feel that it's best practice to disconnect the battery charger before starting the generator. Whether or not relying on the safeties and protection circuits to work is debatable. However, a totally isolated system prevents any potential differences to exist between the external charger and the generator charging circuit.


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## iowagold (Jan 22, 2020)

we just use an inline auto reset breaker on the charger dc pos.
they have little 1 amp up to rated for the charger used,
we use a 2 amp on the units we use.


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