When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
New to electronics. Checking my newbie assumptions…
If my car is not running, and I power a small electric motor from the car battery with a 0.4 amp draw for six hours I will not do any damage to the battery and car will start just fine?
Going to Sevenstock and want to run my rotary engine model off the car battery rather than the Yeti portable battery I normally use. Motor will connect to the battery with alligator clips on positive and negative terminals. Show will be approx six hours long. Motor in model pulls 0.4 amps measured with a multimeter inline with the positive wire. Battery I assume as at least 40 watt hours so I will be using less than 5% of its capacity.
Looks just fine to me… but don’t want to learn something the hard way!
.4 Amps is a lot over six hours. That's almost 1/2 amp for six hours which is a lot for a battery at rest.
“Typically, the normal amount of parasitic draw is between 50 and 85 milliamps in newer cars and less than 50 milliamps for older cars.” A parasitic draw above this threshold is considered excessive. Over time, excessive drain can stress your battery, drawing it down quicker and shortening its life.
.4 Amps is a lot over six hours. That's almost 1/2 amp for six hours which is a lot for a battery at rest.
“Typically, the normal amount of parasitic draw is between 50 and 85 milliamps in newer cars and less than 50 milliamps for older cars.” A parasitic draw above this threshold is considered excessive. Over time, excessive drain can stress your battery, drawing it down quicker and shortening its life.
I am thinking this would be a rare event. Only when at events where the car is parked outside and the Yeti battery would be a thief magnet. Too darned heavy to cart into the motel.
Here is an option to hauling the Yeti around, and if running the "visual" aid affects you ability to start your car this should do the trick. And your battery can recharge on your drive home.
Little bit of thread necropsy here, but I was just shopping for a new battery for my FB ( FWIW I use a Group 24 size rather than the 35 as they seem to have higher CCA ratings and fit our trays just fine). Farm project liked the Walmart Everstart Maxx, incidentally.
To the point of this thread though, I think the relevant rating for @Slow_sevens 's question is the Reserve Capacity, which I just learned is the number of minutes you can draw a continuous 25A from a fully charged battery until it drops to 10.5 V at 80°F.
So if the battery's RC is, for example, 120 minutes, that equates to 50 AH capacity. For the little rotary model, 6 hours of run time at .4 A would be just 2.4 AH and seems like it would leave plenty of charge to start up after the show.
