Originally Posted By: badtlc
Originally Posted By: andyd
Isn't that what the higher end battery minders do? JHZR2, I'll accept that AC ripple isn't good for batteries. However, the phone company uses huge banks of wet cells to create "talk battery" -48 DC The cells last 30 yrs or more. Commercial AC power is rectified to keep them charged. Batteries are the ultimate noise filter.
30 years is really pushing it. To get that life from ventilated lead acid batteries, the climate control has to be perfect and the batteries have be used almost never and even then the original batteries probably needed to be DRASTICALLY oversized to account for the loss of life over that time.
+1.
Maybe some really noisy 6-pulse rectifier is used, but I sort of wonder if even there they did a bit better topology. Look at this:
And absolutely, if the system is way oversized, then the AC ripple for finite charge current is really low compared to the overall capacity.
That's not really the case here, unless were talking about a really small charger like 500-1000mA charger on a 100Ah battery.
Batteries used in float service do spec a max AC ripple for a reason... which doesn't really play into the life cycle of car starter batteries...
And the best mono bloc VRLAs are warrantied to 15-20 years now. Perhaps there are some longer, but I suspect that they are just a more expensive variant to amortize the warranty.