Charge rate, is faster better?

Re: Charge rate, is faster better?

When battery is discharged to 50%, you are okay at 25% C charge rate. Charging is very efficient when battery is less then 85% SOC.

Current should drop quickly once absorb voltage is achieved.

If you have batteries in more then one series string just make sure parallel groups don't end up greater then 25%. It is common to have some unbalance in parallel strings.

When running from generator you want to load generator to at least 50-70% capacity to get best fuel efficiency.

Re: Charge rate, is faster better?

the 13% upper limit was really a factor set by trojan and some generic batteries. many quality batteries out there can take 20% or even as much as 30%, but don't assume yours can if you don't know. even at the 13% level it is a bit more maintenance involved over time, but nearly all batteries should be fine at the 13% rate. this will stir the electrolyte better than say 5% or 6%. 90a is over a 20% charge rate and may do harm unless the manufacturer gives the ok. the 13% rate for 440ah is 57.2a. 10% is a good level to be at for a lead acid battery as it is a good compromise to gassing, stirring electrolytes when applicable, speed of charge, and probably a few more points that i'm not thinking of right now, but the world isn't ideal and circumstances can differ to move off of that ideal at times.

Re: Charge rate, is faster better?

For example, when the charge controller hits "Float"--You could automatically (or manually) turn on a water pump and fill your cistern/irrigate your land.

How would you automatically go about doing this? For example I would like to turn on an AC water feature pump to use excess power while the sun is shining and then turn it off at perhaps a 15 or 20 percent draw down of the battery.

I was going to use a timer and an estimated pump run time.

Thanks

Zeuspaul

Re: Charge rate, is faster better?

BB. wrote: »

Also, more than ~13% of solar panel charge rate is Expensive for panels and charge controllers. And does not do much for you unless you (batteries will not take all of the available energy once they are 80-90% charged) have something that can take much of the power during the day...

For example, when the charge controller hits "Float"--You could automatically (or manually) turn on a water pump and fill your cistern/irrigate your land.

-Bill

Bill,
And I am with you on expensive except when offgrid and you get into non ideal solar weather. The cost then becomes running a genertor as oposed to having enough solar for most conditions in a location that supports it. Either way you are going to pay, so one might as well decide if it is BP solar or BP petroleum/gas/?

To the OP, Keep in mind that batteries, most all of them, like to be charged/discharged slowly for longest life. The manufacturer really has a conflict of interest when they publish high charge rates. They really want you to exceed the warranty and then start getting ready to buy again. The 10 percent max charge for a liquid Surrette or Trojan/similar is a time tested number that goes back decades. If you look at old recomendations from either of those companies you will see that they are really not your new best friends.

You easily can get 10 to 15 years or need new batteries in less than 5. Other factors like depth of discharge, maintenance all are part of it. You also may find that as you grow into your system, it may not be such a bad thing to replace them at 5 years with the idea that things may be unplannable now.
Buenas Suerte!

Re: Charge rate, is faster better?

Dave Sparks wrote: »

Bill,
The 10 percent max charge for a liquid Surrette or Trojan/similar is a time tested number that goes back decades.
Buenas Suerte!

You you believe 10% C recharge rate is max. then you must also believe 10% C discharge rate is max.

Re: Charge rate, is faster better?

The 10% charge rule really has little to do with what I believe. It is based on what I was told by Mr. Surrette in 1978. I am too old to try anything new with charging a battery that I live off of.

Hey Marc! winter is coming! We had the nastiest lightning storm Sunday night.
I was worried about the ultimate discharge rate!

Re: Charge rate, is faster better?

Cariboocoot wrote: »

We've already had the first snow fall - two days before Autumn began!

And I should have mentioned that the "4%" rate is actually during the day, when the panels are producing so it isn't really a discharge. Also, at night with just the inverter & 'frige running it's more like <1% average.

We on the other hand are having the same fall that was spring. Temps 20c, with over night lows about +4. We should be maybe +4 during the day and -4 at night! Beautiful fall days though, I'm sure we will pay the price.

Tony