Charging rate elec question

path1 wrote:
Thinking about upgrading elec system because I keep having little problems with connections and cables etc. If I upgrade I'm going to put in a "smart charger". Talking with a guy at battery shop and got me confused and here is question:

A good "charge rate" is 10 - 20 percent of Amp hour rating of battery?

He went on to say, don't go over 25 percent as it actually bad for the battery. I'm pretty sure I heard him right. Any truth to this?
Reason I ask is: won't a "smart chargers" know how much to charge for the battery(s)that I have?
(OK you can tell by question elec is not one of my finer points).

the charger does not know if its connected to a 12amphr motorcycle battery or 8 big deep cycle batteries for 1000amp hrs

all the smart charger know is how much resistance is in the circuit aka how many AMPS the batteries are taking, it doesn't know if they can only accept 5amps or 200 amps

it can only check the battery voltage against how many amps the batteries are taking
it will stop periodically to do battery voltage checks

I am hybrid. House used to hide out on hot afternoons in a small room with window AC, huge patio with aluminum roof to hear the afternoon thundershower roar, but the convenience of sealy posterpedic at night, five inches of memory foam, UPS lighting. But I still have to drive to watch the playoffs in Ingles. Watching American football announced in Mexican Spanish must be akin to watching a Liverpool Rugby game announced in Hindi.

"He goes forward the end tight. The defensor from the middle catches him almost"

"GOOOOOOOOOOOAAAAAAAAAAAAAALLLLLLLLL !!!!!!!!!!" (the same for Futbol or Football)"

MEXICOWANDERER wrote:

Sunsets, cocktail hour, the NFL playoffs, working in my garden, now THAT'S sacred.

Hear! Hear! MEX, I don't even charge while camping! I do that at home. Don't have time foe that!

PS - I know you full time. Much different than us weekenders.

I starts my generator

I twists the timer dial on my charger

I goes and sits in my chair

While others run around solving "Automatic charging" nightmares and running to the battery store, I sit in my chair and watch them burn gas and their vacation.

Rather than sit in my lazy boy on a Saturday morning, I may once in awhile go check the specific gravity. Takes a half hour. Of course I may miss the cartoon hour on TV but that's life.

Sunsets, cocktail hour, the NFL playoffs, working in my garden, now THAT'S sacred.

Hi,

Powermax boondocker may be just the ticket you need.

PowerMax

With two batteries probably the 60 amp unit would be good.

Thanks to all that responded. I was concerned about getting the wrong thing specifically getting to big of a system and causing other problems as this is a tiny Class C(Majestic). Wiring has been worked on(spliced, bad connections etc) so was going to clean up and put in converter charger that would re-charge faster. Only has one battery right now (group 27)and that does us usually one night in winter. Don't like running genny at 3/4 of gallon per hour. Going to add one more battery and something that charges faster. Currently have Parallax model 7345 and label also states "Average charge rate 5 Amp" so want to double battery power and reduce charge time. Should pay for itself pretty quick not to mention getting rid of "spaghetti" mess of wires.
Thanks again

Here is what happens at various charging rates with smart chargers (in this case Vector -now B&D-portables)

You see that you get to a lower SOC sooner with a higher rate, but then as amps taper, they are still higher than if you had started with a lower rate.

Eventually, you get to the same point (SOC at that voltage) the lower rate charger starts to taper, so after that it is the same. (as controlled by the battery itself with its "natural acceptance rate")

You can see how the time saved at the higher rates by going higher is a diminishing return. You can decide whether the cost of going to an 80amper over a 60amper is worth that many minutes of reduced gen time to do a 50-90.

Note it is all proportional, so you can ratio it out for other than 220AH. eg, doubling the capacity with the same amps, doubles the time. Doubling the amps with the same capacity does not halve the time.

Some want to get back to RVing/camping ASAP at the expense of battery life. Batteries are expendables. Watching sunsets trumps any time spent on battery maintenance in comparison. Charging should be automatic and not intrusive.

Others choose battery life over RVing/camping. Batteries will last longer if they are removed from the system and charged at the lowest allowable current. So what if this detracts from RVing/camping? Some say charge at the 20HR rate which means a 100AH will be charged at 5A until ~115% of the used amps are restored. How long will that take, who cares? Fun is making batteries last a long time.

Each one believes the other is looney-tunes. :)

HTH;
John

OK I'll break it down. With a series pair of 6 volt batteries 14.8 divided by 2 is 7.4 No?

When using the 14.8 formula do not exceed 7.4 volts across each golf car battery or L-16.

5% to 10% for maximum life is fine if you are always plugged in with lots of time. If charging from a generator 20% to 30% is more realistic.

How many batteries (capacity) do you plan to have?
How big is the generator?