Lithium battery installed, monitors fluctuate

[Hughesfamily]

So we bought a Lithium 100ah 12.8 volt battery. Fairly robust trolling motor version. We are enjoying it; no doubt it lasts a long time. We bought a battery monitor to keep track of the voltage. Solar charger (MPPT) it’s monitor is never the same as the little attached battery monitor. I have a small inverter. Strictly to use with the drip coffee maker. Love the French press but........ battery monitors go crazy, inverter goes crazy. Voltage drops quite low, coffee finishes battery recovers but my gosh, it’s quite the show lol.

Sound normal? All tests show this battery can pull 500 amps and protect itself, I can barely make 5 cups of coffee! Lol

[senormechanico]

The coffee maker has a heating coil which is probably rated around 1000-1500 watts.
That will draw a ton of current at 12 volts powering the inverter.
What voltage drop you are seeing is not surprising to me.

[Hughesfamily]

I appreciate that but the battery is rated for a continuous 100 Amp discharge. I thought my simple 15 Amp draw for a short period would keep me happy on Saturday and Sunday mornings.

So basically an inverter that reads an input voltage of 10-15 volt DC MAX @ 1500 watts output actually means 10-15 seconds at 1500 watts :-)

Not a lot of AC power on our boats then?

So I need a DC coffee maker LOL ( not many options )
I'm living the same when in the RV too.

[yalla]

I'm not sure you're getting the math right... 1500 watts from a12 volt source equals 125 amps current.
you mentioned a battery that supports a 100 amp max current. so you are over that by quite a bit.

[yalla]

looks like you are also pushing the limits of your 1500 watt inverter.

[Hughesfamily]

I just want to brew 2 pots of coffee over 2 days.

I'm not doing the math right. I figured 1500 watts was 15 amps.

How do y'all survive without coffee out there! :-)

[yalla]

yeah the math is simple yet confusing. seems like you are calculating the ac current i.e. using a100 volt source - you are indeed getting about 15 amps from the inverter. but the inverter gets the 15a x 100v =1500 watts from a 12 volt source, thus pulling 1500w / 12v = 125 amps from your battery.

try to find a coffee pot that only needs 800-1000 watts. which of course will take longer... or break out the french press - though you still need to boil the water.

[yalla]

and no, you can't survive without coffee out there.

[OldManMirage]

Originally Posted by Hughesfamily

I j

How do y'all survive without coffee out there! :-)

i have a vintage little Revere pot that I put on the stove.

When it starts boiling I pour it into a coffee mug with Foldgers instant coffee.

I know, it's quite the sacrilege.

[Hughesfamily]

Thanks, learning everyday.

Perhaps designing a liner for the French press would be less arduous. :-)

[newhaul]

Originally Posted by Hughesfamily

I just want to brew 2 pots of coffee over 2 days.

I'm not doing the math right. I figured 1500 watts was 15 amps.

How do y'all survive without coffee out there! :-)

Get a small 6 cup cheap west bend rice cooker draws 300 watts and will boil the water for your French press in about 10 minutes runs great on a small inverter.
Then French press all the coffee you want or need

[newhaul]

Originally Posted by OldManMirage

i have a vintage little Revere pot that I put on the stove.

When it starts boiling I pour it into a coffee mug with Foldgers instant coffee.

I know, it's quite the sacrilege.

Buy a cheap French press you will be amazed at the improvement in your life over that barely coffee instant stuff

[Hughesfamily]

Ok, that’s an interesting idea. Appreciate it, thanks.

[CaptainRivet]

Instead of that expensive trolling battery you should have bought the 200AH normal lifepo4 battery as that can do 200A and would fully support the coffeemaker plus have more capacity.

What for do you need the high peak current of the trolling battery?
If via Amazon just exchange it to the 200Ah normal model. If ypu cannot exchange, get a 100Ah for 169Euro additional and parallel them. With 100AH you get nowhere even with lithium. Like this you can use your coffeemaker as well as your inverter properly.

Another opportunity for coffee is I have a nespresso pixie that needs around 75A and I use refillable capsules.
Add for the morning treat my coffee latte a nespresso milk foam maker, the professional version that lasts forever plus has a wide standing base thats not tripping over even in harsh conditions and need around 60A. For the tea or more person coffee I have a big French press plus a 700W 0.5l water kettle, again only 60A.
For storm conditions where I have no time I have capsules to hand to still get my coffee.

[CaptainRivet]

Originally Posted by yalla

yeah the math is simple yet confusing. seems like you are calculating the ac current i.e. using a100 volt source - you are indeed getting about 15 amps from the inverter. but the inverter gets the 15a x 100v =1500 watts from a 12 volt source, thus pulling 1500w / 12v = 125 amps from your battery.

try to find a coffee pot that only needs 800-1000 watts. which of course will take longer... or break out the french press - though you still need to boil the water.

Add to that 125A x 1.4= 175A is the real inverter load due to AC 50 or 60Hz for milliseconds and the 125A is the average current your battery monitor shows.
So if you wanna run inverters 200AH is minimum till 1500W, 300AH till 2500W and 400Ah for 3000W.