Help with lead acid battery ratings
- Thread starter mikefamig
- Start date
Desert_AIP
Senior Member
Go back to my original post, I fixed it.
I can't copy links here so I had to type it in manually.
I think you quoted the mistyped linked before I got it to work.
If that doesn't work, Go to Pacific Power Batteries and search the Deep Cycle FAQ it's FAQ article 4.
I can't copy links here so I had to type it in manually.
I think you quoted the mistyped linked before I got it to work.
If that doesn't work, Go to Pacific Power Batteries and search the Deep Cycle FAQ it's FAQ article 4.
Desert_AIP
Senior Member
AH is the most important factor for deep cycle batteries.
It's used almost exclusively when talking about off-grid and battery backup systems, solar, wind, battery banks, inverters, etc.
In charging, the size of the battery (or bank) determines the max rate to charge.
Older chargers used to be undersized to prevent battery damage, so the max limit was approximately C/10.
So a 100 AH battery should not be charged at a rate any greater than 10A. High rates of charge on a full or nearly full battery causes the electrolyte to boil and produces sulfation.
Smart chargers monitor voltage, current, and sometimes battery temperature, and have ideal charge curves in their memories, so they can prevent damage through monitoring and adjusting the charge profile better than the analog limited older charges that used voltage only. The smart chargers "Dump" charge into a discharged battery until the voltage rises to a certain point and then start throttling the current back. The smart chargers also charge the batteries "more fully", because they tailor the charge profile to the battery and switch to high voltage low current when the battery is almost full to prevent damage.
So the newer chargers are sized to C/5 maximum, with a recommendation to remain around the C/10 range for maximum battery life.
So at C5, a 100 AH battery could be charged with up to 20A without much damage.
The more deeply discharged batteries have a higher "acceptance rate" and can tolerate higher initial charging rates. Even up to 25% of their AH capacities. That is also affected by type of battery. AGM batteries have acceptance rates of nearly 100% of their capacities.
The C/10-C/12 limit also on the chargers themselves.
If they charge battery banks over their C/10 rates, they will be supplying their maximum current for longer than designed and the charger is subject to overheating and damage.
So the 20A charger above shouldn't be used on a bank larger than ~200 - 240AH.
It's used almost exclusively when talking about off-grid and battery backup systems, solar, wind, battery banks, inverters, etc.
In charging, the size of the battery (or bank) determines the max rate to charge.
Older chargers used to be undersized to prevent battery damage, so the max limit was approximately C/10.
So a 100 AH battery should not be charged at a rate any greater than 10A. High rates of charge on a full or nearly full battery causes the electrolyte to boil and produces sulfation.
Smart chargers monitor voltage, current, and sometimes battery temperature, and have ideal charge curves in their memories, so they can prevent damage through monitoring and adjusting the charge profile better than the analog limited older charges that used voltage only. The smart chargers "Dump" charge into a discharged battery until the voltage rises to a certain point and then start throttling the current back. The smart chargers also charge the batteries "more fully", because they tailor the charge profile to the battery and switch to high voltage low current when the battery is almost full to prevent damage.
So the newer chargers are sized to C/5 maximum, with a recommendation to remain around the C/10 range for maximum battery life.
So at C5, a 100 AH battery could be charged with up to 20A without much damage.
The more deeply discharged batteries have a higher "acceptance rate" and can tolerate higher initial charging rates. Even up to 25% of their AH capacities. That is also affected by type of battery. AGM batteries have acceptance rates of nearly 100% of their capacities.
The C/10-C/12 limit also on the chargers themselves.
If they charge battery banks over their C/10 rates, they will be supplying their maximum current for longer than designed and the charger is subject to overheating and damage.
So the 20A charger above shouldn't be used on a bank larger than ~200 - 240AH.
Desert_AIP said:
I understand charge rate and discharge rate and agree that C/10 is a good safe rate but my charger does not set charge rate automatically. It requires me to enter the maximum charge rate explicitly in amps rather than deriving it from the AH rating.
For this battery with RC=41 and a resting voltage around ~12.5v I will set the charger:
Bulk charge at a rate of 2 amps until voltage reaches 14.5 volts
Absorption down to float voltage = 13.25 volts (lowest setting allowed)
AH = 20
2 cars have batteries sort of hidden in the trunk with posts going to the front. They came with wiring kits (quick disconnects).
Pete
My father-in-law has a 2000 Mercedes that has the battery in the trunk. The battery went dead sitting and he couldn't open the trunk to charge it. Even the mechanical key would not open the trunk. It turned out that you have to peel back the floor carpet on the passenger side of the car and remove a metal plate from the floor board to get to cables that go to the battery and can be used fro charging or jump starting. It was easier than it sounds and only involved a few 10mm nuts but if it wasn't for youtube we may have never found it.
Nothing is ever simple.
Pete
My father-in-law has a 2000 Mercedes that has the battery in the trunk. The battery went dead sitting and he couldn't open the trunk to charge it. Even the mechanical key would not open the trunk. It turned out that you have to peel back the floor carpet on the passenger side of the car and remove a metal plate from the floor board to get to cables that go to the battery and can be used fro charging or jump starting. It was easier than it sounds and only involved a few 10mm nuts but if it wasn't for youtube we may have never found it.
Nothing is ever simple.
pete_c
Guru
What a PITA that is.
The 1998 E300TD (diesel) and E320 (gas) (with 60 k miles that is never driven) has the battery under the passenger seat in the rear. There are also posts in the front engine compartment that go straight to the battery. Thought that MB kept that the same over the years.
Dad totalled two new E series MB's in the 1990's.
Well one dad and mom were hit by a car going 70 or so while they were at a stoplight. Dad just go thrown out of the vehicle knocked out and broke his watch. Mom got her hand broken. Just saying here it is a solid well built vehicle.
Personally not impressed with putting a battery under the back seat or in the trunk next to the gas tank on the vehicles anyways. But diesel doesn't burn like gasoline.
The bimmers never changed from putting the battery in the trunk (new and old, automobile and SUV). You can crawl to the back of the SUV from inside to get to the battery as there is no key for the rear hatch. Old and new utilize very large batteries; actually never seen one this big on any of my other automobiles. Electronics is very modular as I can get to the bus from the engine compartment for diagnostics and reset stuff with a paperclip. The sedan seats have a ski compartment opening from the inside and the seat backs fold down but you can only do this from the trunk.
The 1998 E300TD (diesel) and E320 (gas) (with 60 k miles that is never driven) has the battery under the passenger seat in the rear. There are also posts in the front engine compartment that go straight to the battery. Thought that MB kept that the same over the years.
Dad totalled two new E series MB's in the 1990's.
Well one dad and mom were hit by a car going 70 or so while they were at a stoplight. Dad just go thrown out of the vehicle knocked out and broke his watch. Mom got her hand broken. Just saying here it is a solid well built vehicle.
Personally not impressed with putting a battery under the back seat or in the trunk next to the gas tank on the vehicles anyways. But diesel doesn't burn like gasoline.
The bimmers never changed from putting the battery in the trunk (new and old, automobile and SUV). You can crawl to the back of the SUV from inside to get to the battery as there is no key for the rear hatch. Old and new utilize very large batteries; actually never seen one this big on any of my other automobiles. Electronics is very modular as I can get to the bus from the engine compartment for diagnostics and reset stuff with a paperclip. The sedan seats have a ski compartment opening from the inside and the seat backs fold down but you can only do this from the trunk.
Desert_AIP said:
http://batteryuniversity.com/learn/article/charging_the_lead_acid_battery
Desert_AIP said:
I found this link that helped me (and maybe will help others) to better understand the difference between AH and RC specs.
http://batteryuniversity.com/learn/article/charging_the_lead_acid_battery
and it agrees with what you've said. The "AH = .4167 x RC" formula is correct if the battery has an RC rated at 25 amps draw at 80 deg F. That is true of my Interstate battery so your .4167 figure is correct and I'll set the charger to 17AH.
Now if only I could remember all this for the next time.
Mike.
Desert_AIP
Senior Member
Good link.
I'm working with a couple D8 batteries for a refrigerator UPS and portable power cart.
200AH
~165lbs each!
I'm working with a couple D8 batteries for a refrigerator UPS and portable power cart.
200AH
~165lbs each!
pete_c
Guru
Here a few years back inherited a large UPS doing a project of converting a building over to backup generator and UPS (well it was a room). Well it was my project any ways.
I figured to use it at home wiring it to the fuse panel. It had 6 batteries (new) and they were car small battery sized.
I asked a buddy and two neighbours to help move the UPS from work to home. I also borrowed one neighbours pick up truck.
It was a PITA to move. Rather than dismantle it and remove the batteries we moved it to the basement (4 of us as it was heavy).
Well it sat for a couple of years and I decided to not use it. I dismantled it piece by piece slowing getting rid of it.
The batteries were most difficult to get rid of.
The 80's W126 S Class one was a tank and very quick and very nicely built. (levels above the Eldo and Lincolns of the time).
Around the same time picked up a new Peugeot sedan Diesel TD from France.
It was a tank, sounded like a semitruck, ugly but it had titanium bumpers. Lasted for a very long time (> 200k miles with no real issues)
It did have a 2 foot deep ash tray. Never seen this before on any automobile.
This car was kind a lark purchase and I drove the car for a bit and liked it way better than the new Eldo at the time.
IE: the Eldo was moved to FL where it rusted to death in 2 years. It became a death trap and I wasn't a happy camper especially using the vehicle with my children.
The 90's E (E320) series MB's (W124 series) that dad had only had one battery.
The 1998 E300TD (W210) with one battery was a step down in construction cheapened up by the Chrylser purchase I suppose.
I figured to use it at home wiring it to the fuse panel. It had 6 batteries (new) and they were car small battery sized.
I asked a buddy and two neighbours to help move the UPS from work to home. I also borrowed one neighbours pick up truck.
It was a PITA to move. Rather than dismantle it and remove the batteries we moved it to the basement (4 of us as it was heavy).
Well it sat for a couple of years and I decided to not use it. I dismantled it piece by piece slowing getting rid of it.
The batteries were most difficult to get rid of.
The 80's W126 S Class one was a tank and very quick and very nicely built. (levels above the Eldo and Lincolns of the time).
Around the same time picked up a new Peugeot sedan Diesel TD from France.
It was a tank, sounded like a semitruck, ugly but it had titanium bumpers. Lasted for a very long time (> 200k miles with no real issues)
It did have a 2 foot deep ash tray. Never seen this before on any automobile.
This car was kind a lark purchase and I drove the car for a bit and liked it way better than the new Eldo at the time.
IE: the Eldo was moved to FL where it rusted to death in 2 years. It became a death trap and I wasn't a happy camper especially using the vehicle with my children.
The 90's E (E320) series MB's (W124 series) that dad had only had one battery.
The 1998 E300TD (W210) with one battery was a step down in construction cheapened up by the Chrylser purchase I suppose.