18AH, 48v, SLA, max charge rate?

[Kenny'sID]

I have 4 12V 18AH SLA's wired together for 48v and there are times when I need a faster charge. I'm using a 2.5A charger now and wanted to add another to that for 5A total charge rate. So I guess I'm asking 2 questions here...what's the max charge rate for this battery (in case I want to add even more), and is there any problem with running 2 or more separate chargers on it at a time? (since I already have them) thanks.

 

[LockH]

Hehe... Back in the daze (of rolling with SLAs), the "fastest recharge" I knew of was just to swap batteries.

Thing is, lead-acid (like most/all chemistries) HATE a "fast charge"? ie "slower" is "better". Used to be that yah never wanted to run a charge less that 50%... and to "charge early and charge often". Yer dealing with dendrites... nasty little growths watt form in lead anytime yer not charging or discharging. (ESB "Search found 61 matches: dendrite").

Used to use "dead" SLAs as door stops... but ran out of doors. Start saving yer pennies to buy lithium. :wink:

 

[flippy]

fast charging is limited at the start. check the battery specs, it should say what the initial current limit is. (yes, lead also requires CC/CV charging)

BUT, doing this with all the batteries in series will kill them REALLY fast. fast charging is already bad for lead but you also dont give the cells the time to naturally balance out. that will result in a major inbalance in a battery and it will take your whole set out in just months after a imbalance started.

 

[Kenny'sID]

Then the maximum charge rate is 2.5A?

I'm not needing to treat these with kid gloves, yet I don't wan to ruin them with a few charges, as I have nearly 1000 18650's for some good battery builds, I just haven't gotten around to building them. IOW, this is temporary.

 

[Kenny'sID]

BUT, doing this with all the batteries in series will kill them REALLY fast. fast charging is already bad for lead but you also dont give the cells the time to naturally balance out. that will result in a major inbalance in a battery and it will take your whole set out in just months after a imbalance started.

When you say "cells" are you referring to the 4 cells (separate batteries) it takes to make up this 48v or each individual cell in each 12v battery. If you are saying the 4 x 12v batteries need to be balanced, I can easily disconnect them and charge them separately every so often, so not a problem there.

I never could find any substantial info on the batteries themselves and FWIW, this battery is used once a month, if even that..

 

[Matador]

BUT, doing this with all the batteries in series will kill them REALLY fast. fast charging is already bad for lead but you also dont give the cells the time to naturally balance out. that will result in a major inbalance in a battery and it will take your whole set out in just months after a imbalance started.

When you say "cells" are you referring to the 4 cells (separate batteries) it takes to make up this 48v or each individual cell in each 12v battery. If you are saying the 4 x 12v batteries need to be balanced, I can easily disconnect them and charge them separately every so often, so not a problem there.

I never could find any substantial info on the batteries themselves and FWIW, this battery is used once a month, if even that..

I fairly knew and more interested in Lithium technology. But aren`t 12V lead acid batteries made of 6 cells in series ?
with a nominal voltage of 2.0V per cell ?
http://batteryuniversity.com/learn/article/confusion_with_voltages

Matador