Killer Amps

you guys might be right
and he might NOT permanently damage the battery, if he does this only once or twice

What are you trying to accomplish? Might be easier to simply add a 2nd battery.

A problem with maintaining a 100w load is if it is a DC load, such as a big light, it will go dim as the battery voltage falls during that hour.

If the load is from an inverter, the inverter will attempt to maintain the 100w by raising its amp draw from the battery as the battery voltage falls. The increasing amp draw could skew the results.

valhalla360 wrote:
What are you trying to accomplish? Might be easier to simply add a 2nd battery.

Run a 100 watt heater off an inverter. my inverter has a low voltage shut off, so I might give it a try. Only out $70 if it won't then I can get the 100 ah battery that I really need.

If the inverter is a small one like 300w, it will have OEM skinny wires to the battery and could hit its low voltage right away.

TomG2 wrote:


Run a 100 watt heater off an inverter. my inverter has a low voltage shut off, so I might give it a try. Only out $70 if it won't I can get the 100 ah battery that I really need.

One thing to keep in mind is that the battery at 32F only has about 85% of the capacity it has at 77F and it gets worse as it gets colder.

at this battery size I ahve to ask if it's a AGM or liquid. (LIquid would be like a garden tractor battery or motor cycle, though if I had a cycle that is one place I'd use AGM)

I woudl say try it. draw your 10 amps for an hour (10 amp horus) let it sit for like 20 mintues and measure voltage.. If it's too low add more battery

if it's still at say 70% recharge

NOTE: for batteries other than DEEP CYCLE 70% is too low. DEEP CYCLE (Golf car mostly) can go to 50%, but Starting batteries and MARINE/Deep cycle should never drop below 75-85% depending on the battery so you are likely doing damage .

You can also google the Effect (purket? Someone mentioned it above) and find some calculators that may help you find your discharge level.

Marshall stack or Orange are killer amps. Sorry, couldn't resist.

TomG2 wrote:

valhalla360 wrote:
What are you trying to accomplish? Might be easier to simply add a 2nd battery.

Run a 100 watt heater off an inverter. my inverter has a low voltage shut off, so I might give it a try. Only out $70 if it won't then I can get the 100 ah battery that I really need.

100w heater? That puts out slightly more heat than if you stick your hand in front of the side vents of your laptop...actually about double that but the point being, it won't heat much of anything.

Batteries really aren't good for heating.

How much heat do I need to make a camper shell a little warmer on a sixty degree morning? Not much. I am not trying to heat a house. I am more concerned with the effect on the battery than on whether it will warm me up or not.