Noob question on AMP hour draw when connecting batteries in parallel, twice available AMPs?

[sma92878]

Hello all,

I've been watching some videos online to try and educate myself on this, and I "assume" I know the answer, but we know what that means. My goal is to power a 1800 watt tea kettle. This is what I have:

2 x 100 amp hour 12 volt batteries
1 x 12 volt inverter

When I hook up my inverter to run off one battery the system cuts out because at 12 volts would need 150 AMPs

I "think" that if I connect my 2 batteries in parallel this should give me 200 AMPs and I should be able to run my kettle is that correct?

EDIT:

It just occurred to me that I may get more "AMP hours" but not actual AMPs off the battery, so I still may not be able to power my tea kettle.

Still confused...

Kind regards

 

[DerpsyDoodler]

Hello all,

I've been watching some videos online to try and educate myself on this, and I "assume" I know the answer, but we know what that means. My goal is to power a 1800 watt tea kettle. This is what I have:

2 x 100 amp hour 12 volt batteries
1 x 12 volt inverter

When I hook up my inverter to run off one battery the system cuts out because at 12 volts would need 150 AMPs

I "think" that if I connect my 2 batteries in parallel this should give me 200 AMPs and I should be able to run my kettle is that correct?

Kind regards

what are the specs of the inverter?

 

[Supervstech]

Hello all,

I've been watching some videos online to try and educate myself on this, and I "assume" I know the answer, but we know what that means. My goal is to power a 1800 watt tea kettle. This is what I have:

2 x 100 amp hour 12 volt batteries
1 x 12 volt inverter

When I hook up my inverter to run off one battery the system cuts out because at 12 volts would need 150 AMPs

I "think" that if I connect my 2 batteries in parallel this should give me 200 AMPs and I should be able to run my kettle is that correct?

Kind regards

Your logic is sound.
If the limit is the battery, 2 in parallel will double the available amps.

 

[rmaddy]

For an 1800W load through an inverter your batteries would need to supply roughly 160A.

If one of your batteries is only rated to supply, for example, 100A of max continuous discharge current then you are correct. One battery can't supply the needed 160A. Two batteries in parallel would be able to supply 200A if each can supply 100A.

Do note that the 100A max continuous discharge current is not in any way related to the battery's capacity of 100Ah. You could have a 200Ah battery that only supports 100A of max continuous discharge current.

You should have sufficient battery to support the max load of your inverter, not just a kettle. How many watts is your inverter? What size wire are you using to connect the inverter to the battery? What size fuse is near the battery? What kind of batteries do you have?

 

[Bobert]

If your inverter is large enough and the batteries have capacity to output 100 amps each continuously and your using the correct gauge wire it should work.

 

[sma92878]

For an 1800W load through an inverter your batteries would need to supply roughly 160A.

If one of your batteries is only rated to supply, for example, 100A of max continuous discharge current then you are correct. One battery can't supply the needed 160A. Two batteries in parallel would be able to supply 200A if each can supply 100A.

Do note that the 100A max continuous discharge current is not in any way related to the battery's capacity of 100Ah. You could have a 200Ah battery that only supports 100A of max continuous discharge current.

You should have sufficient battery to support the max load of your inverter, not just a kettle. How many watts is your inverter? What size wire are you using to connect the inverter to the battery? What size fuse is near the battery? What kind of batteries do you have?

I have 2 x Battle Born Batteries, but I only had 1 hooked up at the time. It stated under Discharging Specifications Max Discharge Current is 100A but for an 12 volt battery with 1800W load wouldn't that be 150A? That would be more than the battery discharge spec.

https://battlebornbatteries.com/wp-content/uploads/2019/01/BB10012-Data-Sheet-4-29-2022.pdf

with this inverter

Renogy 2000W Power Inverter 12VDC to 120VAC​

https://www.amazon.com/gp/product/B081CLPDT9/?th=1

 

[sma92878]

what are the specs of the inverter?

The inverter is:

Renogy 2000W Power Inverter 12VDC to 120VAC​

https://www.amazon.com/gp/product/B081CLPDT9/?th=1

 

[rmaddy]

I have 2 x Battle Born Batteries, but I only had 1 hooked up at the time. It stated under Discharging Specifications Max Discharge Current is 100A but for an 12 volt battery with 1800W load wouldn't that be 150A? That would be more than the battery discharge spec.

Correct. You must have two of those batteries in parallel to support between 100A and 200A.

A 12V 2000W inverter can pull up to 200A from your batteries. So your two batteries in parallel are sufficient to make full use of your inverter.

Just make sure you are using at least 2/0AWG wire between the batteries and to the inverter to be able to safely support your inverter. 4/0AWG would be even better since it won't get as hot if you max out the inverter. You also need a 250A Class T fuse near the battery. Since one battery alone can't support the full load it would also be a good idea to add a 125A fuse to each battery, in addition to the 250A main fuse.

 

[Steve_S]

With Batteries in Parallel, the load gets divided by the number of battery packs within the battery bank. * A Battery Bank is a set of complete battery assemblies put into one logical bank to act as one "unit". This division is NOT as clear as it may seem at first blush as it is proportional relative to the individual battery capacity & the BMS managing it. This applies to both Charging & Discharging.

With 2 or more 12V/100AH Batteries in Parallel which have equal capacity & BMS it is generally pretty even. But when you have say a 12V/100AH & a 12V/200AH battery in parallel the 200AH battery will take a higher charge (amps) and will be capable of delivering more. If you can observe the BMS's during operation, this become very obvious and this is perfectly fine. I am not sure IF Battleborn offers software monitoring OR if they have added a BlueTooth Interface for users yet (it was in discussion a while ago).

One thing unmentioned YET.
The unwritten rule of not exceeding 250A Draw from a battery bank does play into this.
12V@250A=3000W, 24V@250A=6000W *not corrected for inefficiencies and losses.
Depending on Inverter a 12V system pushing 3000W is "on the edge" and this is where costs etc start to play into it.

A Ponderance.
I run 24V. 5 Pack Bank 2x175AH + 3x280AH.
- 1200W Panasonic Inverter Microwave pulls 75A from 24V (150A if 12V),
- Coffee maker pulls 52A from 24V which would be 104A from 12V. (No warmer plate, thermal carafe)

Hope it helps, Good Luck.

 

[DerpsyDoodler]

I have 2 x Battle Born Batteries, but I only had 1 hooked up at the time. It stated under Discharging Specifications Max Discharge Current is 100A but for an 12 volt battery with 1800W load wouldn't that be 150A? That would be more than the battery discharge spec.

https://battlebornbatteries.com/wp-content/uploads/2019/01/BB10012-Data-Sheet-4-29-2022.pdf

with this inverter

Renogy 2000W Power Inverter 12VDC to 120VAC​

https://www.amazon.com/gp/product/B081CLPDT9/?th=1

You'll be pushing that little renogy close to its limit. It'll be interesting to see if it can handle that load.