I am considering replacing four GC2 batteries with two 100 Ah LiFePo batteries with 100 Amp BMS each. My concern is whether they will be able to operate the microwave for light duty use (5-6 minutes) without voltage sag causing problems. The draw for the microwave is about 125 to 130 amps, depending on how much solar is coming in. The wiring is appropriately sized for the loads.I currently have four GC2s for this reason, not because I really need that much storage capacity. The LAs have served well; they are going into their 12th season and still have very good hydrometer readings. However, I know their time left is limited.Does anyone have experience operating the microwave with 200 Ah of lithium?

12thgenusa,So long as the Li are wired in a balanced manner, there should be no issue.I'd wait until the existing bank dies. Prices continue to drop.

Based upon the topic title I was going to say "Don't use lithium batteries in a microwave!" :)

You should be able to use a microwave for short periods of time as well as a coffee maker if you choose. It sounds like you already have some solar to replenish your bank so as long as it's somewhat sunny your good to go.You didn't state it but Im sure you know you need an Inverter for the 120vac devices correct?We have a bit more capacity at 560ahrs and I installed a 3kw Inverter for our AC loads when we need them.Got 510w of solar on the roof as well so that pretty much tops us off when we do use the Inverter.Good luck.

I’ll make my question a bit clearer.When I designed and installed my system 12 years ago, lithium was still a dream for RVs. The battery discussions revolved around whether it was best to use a 12-volt battery or multiples of them, 6-volt batteries in series, or break the bank and go with AGM.At the time, most agreed that a pair of GC2s in series were marginal to operate a microwave. That convinced me to go with four GC2s (440 Ah). My specific question is, are the characteristics of lithium batteries sufficiently different from FLAs that 200 Amp hours of lithium batteries with at least a 200 amp BMS will operate the microwave without voltage sag causing inverter under-volt alarm or shutdown?Should be, is not a helpful answer.

12thgenusa wrote:Does anyone have experience operating the microwave with 200 Ah of lithium?YEP.I had two Battleborns in my Nash 17k for about a year and a half. The Microwave worked fine on them along with the Victron Multiplus 2000 inverter. I think I installed them in early 2019.In 2020 I sold that rig, and then bought a different truck camper and moved the whole works into my AF992 truck camper in late 2020.Microwave still runs perfect with the same inverter and batteries.I've had two other RVs with 200 amp hours of batteries and a 2000 watt inverter to run the microwave. They've all performed flawlessly.

Lithium batteries and microwave use | Good Sam Community

pianotuna
Nomad III
Mar 12, 2023
12thgenusa,

So long as the Li are wired in a balanced manner, there should be no issue.

I'd wait until the existing bank dies. Prices continue to drop.
LouLawrence
Explorer
Mar 12, 2023
Based upon the topic title I was going to say "Don't use lithium batteries in a microwave!" :)
greenno
Explorer
Mar 12, 2023
You should be able to use a microwave for short periods of time as well as a coffee maker if you choose.
It sounds like you already have some solar to replenish your bank so as long as it's somewhat sunny your good to go.

You didn't state it but Im sure you know you need an Inverter for the 120vac devices correct?

We have a bit more capacity at 560ahrs and I installed a 3kw Inverter for our AC loads when we need them.
Got 510w of solar on the roof as well so that pretty much tops us off when we do use the Inverter.
Good luck.
12thgenusa
Explorer
Mar 12, 2023
I’ll make my question a bit clearer.

When I designed and installed my system 12 years ago, lithium was still a dream for RVs. The battery discussions revolved around whether it was best to use a 12-volt battery or multiples of them, 6-volt batteries in series, or break the bank and go with AGM.

At the time, most agreed that a pair of GC2s in series were marginal to operate a microwave. That convinced me to go with four GC2s (440 Ah).

My specific question is, are the characteristics of lithium batteries sufficiently different from FLAs that 200 Amp hours of lithium batteries with at least a 200 amp BMS will operate the microwave without voltage sag causing inverter under-volt alarm or shutdown?

Should be, is not a helpful answer.
deltabravo
Nomad
Mar 12, 2023
12thgenusa wrote:
Does anyone have experience operating the microwave with 200 Ah of lithium?

YEP.

I had two Battleborns in my Nash 17k for about a year and a half. The Microwave worked fine on them along with the Victron Multiplus 2000 inverter. I think I installed them in early 2019.
In 2020 I sold that rig, and then bought a different truck camper and moved the whole works into my AF992 truck camper in late 2020.

Microwave still runs perfect with the same inverter and batteries.

I've had two other RVs with 200 amp hours of batteries and a 2000 watt inverter to run the microwave. They've all performed flawlessly.
deltabravo
Nomad
Mar 12, 2023
12thgenusa wrote:
At the time, most agreed that a pair of GC2s in series were marginal to operate a microwave.

My First RV had a pair of Interstate GC2 golf cart batteries and a 2000 watt inverter. I owned that rig for 7 camping seasons. Microwave always ran fine on that system.
12thgenusa
Explorer
Mar 12, 2023
deltabravo wrote:

YEP.

Thanks
wa8yxm
Explorer III
Mar 12, 2023
Some numbers to consider.. MY JEEP
I have about 10 feet of #10 (10ga) ZIP cord between the battery (73AH Lead Acid) and the Rig Runner 5-40 (This is a power distribution box. 5 pair or anderson Power poles and fuses. the biggest one is fused at 40 amp. all pairs are rated 40 but may be fused smaller.

From there I use the stock factory 12 volt cable terminated in 40a amp andersons to my Kenwood TS-2000.. at 100 watts transmit power (About 20 amp draw) The radio shuts down due to low voltage.

Option 2 is a 12 AH LiFePO4 that's right 12 AH... I have a very short (like 6" or less) of 12 Ga wire and a pair or 40 Amp Andersons (We hams tend to use a lot of Andersons. I've a 40-12 Rig Runner behind me as I type. about half populate)

Full 100 Watts. NO voltage sag Im drawing nearly twice as many amps as the amp hour rating.

Your microwave may draw around 100 amps (100-120) or 1/2 the battery bank amp hour rating... I suspect it will work.. likel for around 1.5 Hours on a full charge.
time2roll
Nomad
Mar 12, 2023
My 4x GC2 needed to provide 165 amps to run the MW. My lithium needs to provide about 145 due to the higher resting and loaded voltage. That pair of lithium will serve you well.
3_tons
Explorer III
Mar 12, 2023
You didn’t mention the size of your MW, but if it ran good using GC’s, you’ll have no problem with two LFP’s… Microwaves are a reactive (capacitive) load, and LFP’s are well suited for such loads because of very little voltage sag…Also, it’s not uncommon for a 100a/h LFP to be capable of discharging at up to 200amps for short periods of time (with time increasing at lower discharge amps…), meaning the amp hour rating (capacity) is not always indicative of its typically greater (amperage) discharge ability…

3 tons