Lead Acid puzzle

Of course there are. On that page:

1. no V_out data, no temp comp, 110v only
2. adpow: too high V_out for flooded cells
3. 8
4. noco: no 24v AGM mode, no temp comp
5. topac: no V_out data, no temp comp
6. V_out too high & not temp comp
7. noco: 9
8. beeleb: no V_out data, claims unsuited to

Not sure what you mean by "no V_out data"

Beeleb says it is suited for 2 to 200AH.

no data on voltage output. Most chargers go too high for SLA. The present charger is causing problems by outputting 2x 13.7v, eveything I've seen on Amazon is worse.

I suspect I'd need to either build one. I don't really want to spend the time though. Or use a bench supply, varying V_out manually between winter & summer.

They probably all are, despite the claims. But not SLA.

NT

Float, or end of charge trickle is critical, as is the voltage. Normally, ups batteries are float charged at a low current continuously, but one manufacturer has patented the idea of disconnecting the float charge until the voltage reaches some lower level, then topping up, rather than a continuous float charge current. Apparently, it does improve cell lifetimes, but no direct experience here.

Not too much trouble to build a charger using such ideas, perhaps with a micro to manage it all, so long as it's not commercial...

Chris

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How could that idea be patented? Seems obvious that many battery charging systems cut the power when they reach a preset voltage, then energize again when the voltage falls to a certain point. All I can see them patenting is the particular electronic process, but automobiles have been using this since alternators and generators first came out to charge the battery. I am sure the process predates that application too.

John (I have never applied for a patent, and am unlikely ever to want to! )

Chargers for ups systems don't cut the power, but keep a small current float, ma, to make up for losses, whereas the idea is to switch off the charge completely until the voltage has dropped to a defined lower level, then re charge to the original end of charge level. Apparently, this does improve cell life and helps to equalise the individual cell voltages, a serious problem as battery stacks age. No reference, sorry, but it may have been APC...

Chris

ALL those chargers provided "data" on output - what DON'T they provide?

We were doing the Re-Float thing you just described in your last post at OutBack Power Systems in our inverter/charger almost 20 years ago.

Yes, it supposedly does increase battery life if you don't need to Float all the time. It will draw as much current as necessary to hold the battery and loads, if any, at that voltage.

I wonder how long ago this patent was ? I haven't heard of it being patented. But since patents are only good for 20 years now in the US, the prior art would be real close in this case.

boB

I read the whole ad of every single one on the page. Lots don't give V_out data. Those that do all output unsuitable voltage. They're designed for flooded cells or only very occasional charge of SLAs.

The list above answered that.

NT

As I said forgot the source, so could have orgiginated much earlier.

Cell balance is a serious issue, in that even with cells from the same batch, the internal resistance varies with age and with that, the float voltage, Some cells get undercharged and others over, which causes gassing and premature failure. One way around that is to fit each substring, say 12v, with a clamp that bypasses charge current when the terminal voltage exceeds optimum float value. Float current is typically 10's of mA, so not much dissipation in the shunt.

Telcos probably know more about this than most, with their 50v systems and BT in the uk at least are big users of gel cel batteries. Some of their stacks have a separate charger module for each 6 or 12v battery...

Chris

Beeleb does, for one, but you said it doesn't.

I think it may be the same here. I also seem to remember Nickel Iron batteries were used because of their very long life however they needed to have their electrolyte changed out every so often.

Not sure about Gels but I seem t remember them as well were used.

In either case, long easy life in Float for CO batteries.

Now, AGMs are newer. AGMs plump when you cook 'em !

Batrery balancing is a good thing even for lead acid if you can get it, especially on a 2V cell basis but 6V at a whack is OK too.

boB

I see you're right, it says

" 3 Knobs means different charging voltage : Low Medium, High For axample, Charging 12V Battery, "Low" knob voltage between 13.8V to 14.2V, "Medium" voltage between 14.2V to 14.8V , "High"knob voltage above 15V , "

But 13.8 - 14.2v is too high for AGM. The present 13.7v charger is overcooking them. I wonder if the beeleb is moddable. But still no temp comp :/ $255 inc delivery is a bit steep too, and no clue if it'll run on 240v either. Too many issues.

NT