BATTERY CHARGING QUESTION

[frankS]

OK guys just a quick one.

To charge a 180 amp hour from flat to full charge. How long would it take at approx 15 amps charge going into the battery ?.

Just want to see IF my maths are correct.

Frank

[slothparade]

Your never run a batter completely flat, sorry just wanted to make sure. I'm pretty sure for lithium ion, the lowest it lets you go to is 15-20% of it's capacity and for lead acid I think it's like 30-40%. Someone probably knows the exact figures, I just know a rough estimate 

For your battery your probably looking at:  

0.3 x 180 = 54 that's your from 'flat' start point 

Then at a constant 15 Amps per hour would be 136/15 = 8.4 hours +- a bit due to battery health, resistance ect. These calculations are relying on ideal scenarios. 

[dunc333]

wow thanks sloth i luv learning things good answer

[Billmack]

Modern day batteries are best charged with a modern day charger… many on the market….it’s not just x amount of amps for x amount of time, it’s a combination of current and then a reducing voltage, the charger senses the batteries stage and condition and adjusts to suit. No human input needed. . We pay a lot for our batteries, a good charger is, to me an insurance policy, to prolonging battery life. 

[frankS]

17 hours ago, slothparade said:

Your never run a batter completely flat, sorry just wanted to make sure. I'm pretty sure for lithium ion, the lowest it lets you go to is 15-20% of it's capacity and for lead acid I think it's like 30-40%. Someone probably knows the exact figures, I just know a rough estimate 

For your battery your probably looking at:  

0.3 x 180 = 54 that's your from 'flat' start point 

Then at a constant 15 Amps per hour would be 136/15 = 8.4 hours +- a bit due to battery health, resistance ect. These calculations are relying on ideal scenarios. 

Thanks for the reply but I can't see where these figures come from. I can understand the 15 being 15 amps but where does the 0.3 come from ? and the 136 ? I unfortunately left school at 13 and maths was not among my best subject to start with.

Could you explain to me this formula.

Frank

[frankS]

15 hours ago, Billmack said:

Modern day batteries are best charged with a modern day charger… many on the market….it’s not just x amount of amps for x amount of time, it’s a combination of current and then a reducing voltage, the charger senses the batteries stage and condition and adjusts to suit. No human input needed. . We pay a lot for our batteries, a good charger is, to me an insurance policy, to prolonging battery life. 

Thanks for the reply. I do have a pretty good charger

My thoughts are to set this on about 2-3 which I guess is around 15 amps or so and run it for a few hours to boost some charge into the battery and then I do have another small CTec charger which I would use to trickle the final charge into the battery.

Just want to know IF my line of thinking would be the right way to go about doing it.

Frank

[noelm]

48 minutes ago, frankS said:

Thanks for the reply but I can't see where these figures come from. I can understand the 15 being 15 amps but where does the 0.3 come from ? and the 136 ? I unfortunately left school at 13 and maths was not among my best subject to start with.

Could you explain to me this formula.

Frank

Just guessing, the .3 comes from 30% charge left when flat. 54 comes from the battery being 180AH, divided by .3. 15 being the current (amps) from the charger. All those numbers are "rubbery" at best, batteries are very complicated, and way more complicated than most think, especially when modern day materials are used.

Edited December 11, 2022 by noelm

[slothparade]

2 hours ago, frankS said:

Thanks for the reply but I can't see where these figures come from. I can understand the 15 being 15 amps but where does the 0.3 come from ? and the 136 ? I unfortunately left school at 13 and maths was not among my best subject to start with.

Could you explain to me this formula.

Frank

Sorry for the confusion, been a while since I've don't any math. 

The 0.3 is 30% of 180 because lead acid stop releasing energy (running your electronics) at about 30% of total battery life. 30% of 180 is 54, so 180-54 is 136. 130 (remaining Amps in battery from 'flat' divided by 15 which is the rate at the battery charges. Hope this helps. Sorry again 

[slothparade]

5 hours ago, noelm said:

Just guessing, the .3 comes from 30% charge left when flat. 54 comes from the battery being 180AH, divided by .3. 15 being the current (amps) from the charger. All those numbers are "rubbery" at best, batteries are very complicated, and way more complicated than most think, especially when modern day materials are used.

Yeah, couldn't agree more. Tried to break it down to be pretty simple. There's to many variables to properly predict the time it will take for your battery to charge. Sorry I was meant to say that the numbers are basically theoretical and under controlled conditions, as there is way to many factors affecting everything. 

[big Neil]

4 hours ago, slothparade said:

Sorry for the confusion, been a while since I've don't any math. 

The 0.3 is 30% of 180 because lead acid stop releasing energy (running your electronics) at about 30% of total battery life. 30% of 180 is 54, so 180-54 is 136. 130 (remaining Amps in battery from 'flat' divided by 15 which is the rate at the battery charges. Hope this helps. Sorry again 

Sorry to muck up your very clear explanation but 30% of 180 is 54 and 180 - 54 is 126. Not trying to be a smart arse slothparade, it may be relevant to what Frank is trying to achieve.

bn

[dunc333]

so frank please tell us how long it took to charge cheers dunc333

[frankS]

Dunc. Havent done it yet, lazy arse.

My plan was to back boat up onto the front lawn run extension cord out to boat take charger to boat and charge battery, none of which got done, didn't fancy running electric cord out onto wet grass. was planning on going fishing tomorrow but now those plans have been cancelled. If my mate turns up at 4.30 in the morning he will be disappointed..

Been doing some work in the workshop and had a few set backs so fishing will have to take a back seat for a while.

Frank

 

Edited December 14, 2022 by frankS
typing correction

[Sharknado]

The only answer is charge whatever the particular battery type(lead acid, Gel, AGM, lithium etc) that it is with the right charger that suits the charge profile of that battery.

Then the charger will go through all its correct stages of charge like bulk charge, absorbent charge, float charge etc.

All battery types are different & you cant just charge them with the one charger unless it has the different profiles to select as options!

Edited December 12, 2022 by Sharknado

[slothparade]

15 hours ago, big Neil said:

Sorry to muck up your very clear explanation but 30% of 180 is 54 and 180 - 54 is 126. Not trying to be a smart arse slothparade, it may be relevant to what Frank is trying to achieve.

bn

thanks for picking that up, that would be on my end, been a while since ive done any math just want to forget about hsc lol. no hard feelings, appreciate you picking up on my error

[dunc333]

all good frank, when you do get round to it please time it cause my money is on the sloth cheers dunc333

[frankS]

14 minutes ago, dunc333 said:

all good frank, when you do get round to it please time it cause my money is on the sloth cheers dunc333

Going down to Bermi tomorrow so it will be a few days before I get around to charging it. Not taking the boat but might use the 13 footer that's down there to just fish the harbor and river for a few hours.

Frank