High load appliances and lithium batteries…

[ZionAcrossAmerica]

hey everyone, first post here.

i purchased a new 2022 roadtrek zion with the 600Ah option two months ago. i’m sure those of you who also own Roadtrek’s and are extremely detail oriented like myself are sorely disappointed by the lack of specifics in the manual…

that being said, i’m trying to determine if it is harmful to lithium battery life in any way to run higher load appliances like the microwave in our zion strictly via battery power with no supplementation from the under hood generator.

we have already done this multiple times with no apparent issues. from what i believe is a nearly full charge of 13.4v the microwave when in use will drop our charge to between 12.9v-13.1v.

again this is with the chassis off, battery power alone.

any knowledge you can share will be much appreciated.

[MsNomer]

Good Heavens! That's what they are made for. Go for it.

[booster]

It the lower voltage with the microwave on or off? When high loads are running, you will see a drop in voltage and it will usually come back up after you shut the load off and they sit a bit.


I don't know if Roadtrek is still using the 200ah modules of lithium batteries that you leave off until needed, usually one at a time, but if they are using just one will drop the voltage more than if two or are three are on.


Microwave runs are generally relatively low total power use. We find our typical average run uses between 3-8ah of capacity. Most of our runs are in the 5 range with a Dometic 700 watt microwave.


With 600ah of capacity you should not have to skimp on high power use unless you don't drive it for days at a time.

[ZionAcrossAmerica]

Originally Posted by booster

It the lower voltage with the microwave on or off? When high loads are running, you will see a drop in voltage and it will usually come back up after you shut the load off and they sit a bit.


I don't know if Roadtrek is still using the 200ah modules of lithium batteries that you leave off until needed, usually one at a time, but if they are using just one will drop the voltage more than if two or are three are on.


Microwave runs are generally relatively low total power use. We find our typical average run uses between 3-8ah of capacity. Most of our runs are in the 5 range with a Dometic 700 watt microwave.


With 600ah of capacity you should not have to skimp on high power use unless you don't drive it for days at a time.

thanks so much for the response. i should have specified, the voltage drop only occurs when the microwave is in use, after it finishes the voltage recovers. i’m not sure what the battery layout is either, roadtrek doesn’t specify anywhere and i haven’t asked their service department yet.

i understand the total Ah usage should be small compared to our total capacity, but as an amateur regarding battery and electrical setups i’m unsure if those high loads (even if temporary) are damaging or harmful to the system in any way?

i saw charts saying you should avoid discharging lithiums to 12.8v and below. curious whether the temporary drop would fall into this category, or if they mean allowing the state of charge to be reduced to those levels.

[booster]

Originally Posted by ZionAcrossAmerica

thanks so much for the response. i should have specified, the voltage drop only occurs when the microwave is in use, after it finishes the voltage recovers. i’m not sure what the battery layout is either, roadtrek doesn’t specify anywhere and i haven’t asked their service department yet.

i understand the total Ah usage should be small compared to our total capacity, but as an amateur regarding battery and electrical setups i’m unsure if those high loads (even if temporary) are damaging or harmful to the system in any way?

i saw charts saying you should avoid discharging lithiums to 12.8v and below. curious whether the temporary drop would fall into this category, or if they mean allowing the state of charge to be reduced to those levels.

Hi loads shouldn't hurt them at all.


The not below 12.8v is normally for no loads, but it is always best to try to get some charge into the batteries if they are getting close. Lithiums, by many recommendations like to be in the midrange of the state of charge if possible, for the longest life.

[ZionAcrossAmerica]

Originally Posted by booster

Hi loads shouldn't hurt them at all.


The not below 12.8v is normally for no loads, but it is always best to try to get some charge into the batteries if they are getting close. Lithiums, by many recommendations like to be in the midrange of the state of charge if possible, for the longest life.

got it, thank you so much for the info. time to get microwaving!

[W9TR]

Most LiFePO4 batteries have a maximum discharge rate of 1C. So a 200AH battery would like to see a discharge rate of less than 200A.

A 1000 W microwave will draw 1200 Watts. Throw in an inverter efficiency of 90% and you are at 1300 watts. That’s 100A @ 13 volts, so even with a 200 AH battery you are good to go, no problem.