Seeking info on a giant battery charger - Page 1
Forum section: electronics / projects

author: TerraHertz
author_rank: Super Contributor
timestamp: October 15, 2019, 01:35:11 pm
content: I'm looking for information on this:L M Ericsson Pty Ltd. Melbourne AustraliaBattery charger Type BMTP 244001 Mfg: 1985Input 200-260V 50Hz2400 VA Max (output up to around 40V 50A max)The chassis wiring is mostly dead simple; what I'm after is an operating manual for the unit and most of all a schematic for the control board.Can anyone suggest a source?Perhaps not many of these were made. And being Australia possibly all documentation may be lost.

author: edpalmer42
author_rank: Super Contributor
timestamp: October 16, 2019, 04:40:15 am
content: I don't have any specific info on that unit, but I doubt that it would go to 40V. It appears to be a 24V charger for lead-acid wet cell batteries that would be used in a rather small telco office. I wouldn't even call it a charger. It's actually intended as the primary 24V power source for the equipment. The batteries are across the output and are float charged while the equipment is operating. I'm not sure what Float 2 is for, but boost would be for occasional battery maintenance to ensure that they were fully charged and to remove any sulfate that might be accumulating. Units like this usually need some fairly significant batteries to meet their specified noise levels.Ed

author: TerraHertz
author_rank: Super Contributor
timestamp: October 17, 2019, 09:38:47 am
content: Maybe. I can't find my notes/photos of the battery string it was originally connected to.The circuit is a bit surprising - huge transformer, with thyristor switching of the output rather than the input, then very beefy inductive chokes.Since I guess I'll be tracing the circuit, I'll know soon enough. Also, will power it up soon.You're right about the 'primary power'. But it was on telecoms stuff with a significant string of batteries.I'm hoping to use it on a string of 15 single cell lead-acids. So in the 33V to 36V range. We shall see.Oh, and I have two of them. Did have four, but dismantled two. They are very bulky and heavy.

author: BradC
author_rank: Super Contributor
timestamp: October 17, 2019, 09:46:06 am
content: Quote from: TerraHertz on October 17, 2019, 09:38:47 amThe voltages stamped into the spec plate would be a bit of a giveaway.

author: beanflying
author_rank: Super Contributor
timestamp: October 17, 2019, 09:50:16 am
content: Being 40V high current most likely it came out of a phone exchange and charged a bank of 2V cells. The 40V is not longer the normal but it used to be fairly sure we now run 50VSo trawl Post Master General, PMG and not Telecom as your date is pre that I think.

author: TerraHertz
author_rank: Super Contributor
timestamp: October 17, 2019, 10:56:05 pm
content: Quote from: BradC on October 17, 2019, 09:46:06 amBut they are adjustable via trimmers on the control board. The plate just shows what this particular unit is adjusted to.The question is, what's the adjustable range, and is all of it within spec for total power?Without the manual/schematic that's not obvious.I do have an electronic load that can handle this. EL750BR, 0-60V, 0-200A. Still to set it up, and waste some electrons.Here's the battery string. All single cells, 300 AH each.Hah. I ran 20A charging current into this for 6 hours (with a big HP bench supply), and the cell voltages increased about 0.1V.They are a bit old, but still seem good. Presently wondering about how I'd arrange for a capacity measurement discharge-charge cycle. Also, automated cell leveling.

author: tautech
author_rank: Super Contributor
timestamp: October 17, 2019, 11:47:31 pm
content: Quote from: TerraHertz on October 17, 2019, 09:38:47 amToo many IMHO. I'd think you'd find it's for a nominal 24V 12 cell string.Typically Big FLA's are charged with 2.33V ea so you do the maths and see where the float voltages fit in.One will be for maintenance charging and the boost for a gassing/equalising charge.These big batteries can soak some charge and as they rise in voltage the current falls right away until you engage some maintenance charge.Currently (excuse pun) working on some 1100AH cells and you might want to consider getting some phosphoric acid for your old cells and give them some love like outlined here:https://www.instructables.com/id/Lead-Acid-Battery-Care-and-How-to-Restore-Them/

author: vk6zgo
author_rank: Super Contributor
timestamp: October 18, 2019, 04:13:23 am
content: Quote from: TerraHertz on October 15, 2019, 01:35:11 pmI would say it was from a PMG's Dept/Telecom Aust installation.Exchanges normally had a bank of cells making up a 48v battery, whereas Broadcast & some Radio Comm sites had a 24v battery in a similar format.This 24v battery supply was used for Diesel start, & for various devices which required a continuous supply.Ericsson was a major supplier to the above organisation, & I've definitely seen these chargers around the State.From memory, the city Broadcast sites had similar chargers, but made by STC.I doubt if it is possible to discern through external appearance, between the 48v & 24v Ericsson chargers.

author: TerraHertz
author_rank: Super Contributor
timestamp: October 19, 2019, 09:32:03 am
content: Quote from: vk6zgo on October 18, 2019, 04:13:23 amOh I know where they were from, I retrieved them myself. A very soon to be demolished installation.It was coms-related. And I think I do have pics of the installation, just haven't found them yet. Was years ago.Also sadly it seemed that all service docs had been removed/destroyed already.Quote from: tautech on October 17, 2019, 11:47:31 pmI have doubts about the worth of that article. Zero mention of sulfation as a factor in Lead-acid battery demise (and the major cause of plate swelling.) Also his talk of adding phosphoric acid... hmm, if that was such a great idea for battery improvement, why isn't it done by battery manufacturers as standard?Also his spelling and grammar sucks, which isn't inspiring either.That he specifies phosphoric acid additions in ml, rather than moles for some other concentration-adaptive units, suggests he's a bit naive.Plus, if he's such an expert on lead acid cells, how does he not mention other common types of cell-death, such as plate disintegration, fracturing of cell interconnects, etc? Seehttp://everist.org/NobLog/20180430_lead_acid_ruin.htmHas anyone else actually tried the phosphoric acid treatment, and what were the effects?I'm NOT going to do something like that to 15 seemingly good 300AH cells, just on advice of one dodgy article.It's something to research some more.

author: MagicSmoker
author_rank: Super Contributor
timestamp: October 19, 2019, 12:55:06 pm
content: Quote from: TerraHertz on October 19, 2019, 09:32:03 amThat article makes no sense... and it even fails the sort of basic chemistry someone who isn't a chemist remembers from decades ago: the strong acid liberates the weak acid from its salt. In this case, the instructable author claims that lead phosphate is somehow forming in the presence of the much stronger sulfuric acid, but sulfuric acid would immediately convert any phosphate salt it found into phosphoric acid and a sulfate. Which seems like exactly the wrong outcome, but again, where would the lead phosphate come from in the first place?As is usually the case with any claim of being able to revive dead/abused lead-acid batteries, this one is wrong.

author: edpalmer42
author_rank: Super Contributor
timestamp: October 19, 2019, 04:49:40 pm
content: These batteries are sealed AGM batteries. Trying to add anything to them would be difficult at best. But, before adding anything, remember that they are telco-grade batteries with a 20 year design life. They've spent their entire life in a temperature-controlled environment with precisely monitored and temperature-compensated charge voltages and have rarely, if ever, seen any significant discharge. They've lived a perfect life and, depending on their age, they could all be in excellent condition just as they are.

author: tautech
author_rank: Super Contributor
timestamp: October 19, 2019, 08:05:45 pm
content: Quote from: TerraHertz on October 19, 2019, 09:32:03 amIt is and has been for some 100 years.A little Googling of 'phosphoric acid lead battery' reveals this.However the process is only really useful for FLA cells.This 1977 paper is worth a study:http://jes.ecsdl.org/content/124/10/1478.full.pdf

author: TerraHertz
author_rank: Super Contributor
timestamp: October 20, 2019, 01:41:34 am
content: Quote from: tautech on October 19, 2019, 08:05:45 pmThat makes much more sense. From the abstract:QuoteSo, it somewhat inhibits the formation of lead sulfate. Nothing like what the first article claimed.Thanks for that link.However, as edpalmer42 pointed out, these are moist glass mat batteries, so 'adding something' is not feasible.Edit: Unrelated - OUCH! Remember that 'advertising photo-fails' thread, with the lady holding a soldering iron (not turned on) by the hot end?Well I just did pretty much that, except hot. Stripping some axial-lead components off an old terminal strip board, needing lots of awkward fiddling with the iron and needle nosed pliers to unwind the lead ends wrapped around posts. Fumbled the iron; it ended up with the hot end between fingers as my grab reflex acted. Very briefly. Butter fingers, ending up with buttered fingers (it helps with burns.)

author: edpalmer42
author_rank: Super Contributor
timestamp: October 20, 2019, 03:38:21 am
content: Quote from: TerraHertz on October 20, 2019, 01:41:34 amThankfully, it's been many years since I had such an accident. When I did, I made an interesting discovery. Pinching an ice cube between my poor burned fingers helped numb them and so reduced the pain. However, I didn't expect that pinching the ice cube until I melted through it took away the pain permanently. I was quite amazed. Maybe the cold killed the damaged nerve cells. Everything healed up without further discomfort or other issues.