Lead acid battery float chargers and schematics

kennybobby · 2019-10-11T02:26:21.000Z

with notes for setting the output voltage if you want to make it something different. This is to set the unloaded Vout. i need to play with it some to see how it does under load.

Q2 provides a short-circuit protection if you touch the output leads together.
R5, R5A may need to be increased to 1.2k each to limit LED current a bit.

picture of board, Centech 42292

wle · 2019-10-11T11:58:51.000Z

is it protected against reverse polarity connection?

kennybobby · 2019-10-12T19:59:22.000Z

Yes, the Q2 leg shunts the output for both short circuit and reverse polarity.

The L7805 regulator that i’m testing is only putting out 4.9 instead of 5V on its output, so the max Vout is reading 13.65 open circuit and seems to be charging my battery up toward that limit.

The 13.65 corresponds to an Id of 3mA from the regulator with the 4.9V. So some twiddling and adjustment of the r1 and r2 combination may be necessary for your particular L7805, but these values are a good to get started.

kennybobby · 2020-01-20T21:10:40.000Z

i have been testing several versions of automatic chargers and maintainers, and this one seems to be the best so far, it does not overcharge and boil out the acid. Here is a link to the manual, YUA1AMP-Manual-English

WHY IS THIS NEEDED?

Lead acid batteries must be kept at full charge all the time to achieve a long service life. Permanent damage can occur after only 3 days if stored at a low state of charge. The nissan leaf uses a DC/DC converter to provide 12V power and charge the aux battery, but it holds the voltage at only 13.1 VDC. As a result many leaf owners have suffered premature aux failure due to sulfation of the plates. One remedy is to regularly use a maintainer such as this to desulfate at 14.4 VDC, then pull back to a holding float value. Also motorcycles, lawn mowers, ATVs that are seldom or seasonally operated could extend battery life by using such a device.

i would like to read out the firmware of the STM8 microcontroller in order to understand details of how the system operates. Have any of yall done this before and could provide some advice?

AC Input section with EMI filter and HV rectifier

Primary Side Switching Regulator and RM08 Transformer

Secondary Side DC Output Control

Kevin_Z · 2020-01-20T21:06:37.000Z

kennybobby:

i have been testing several versions of automatic chargers and maintainers, and this one seems to be the best so far, it does not overcharge and boil out the acid. Here is a link to the manual, YUA1AMP-Manual-English

WHY IS THIS NEEDED?

Lead acid batteries must be kept at full charge all the time to achieve a long service life. Permanent damage can occur after only 3 days if stored at a low state of charge. The nissan leaf uses a DC/DC converter to provide 12V power and charge the aux battery, but it holds the voltage at only 13.1 VDC. As a result many leaf owners have suffered premature aux failure due to sulfation of the plates. One remedy is to regularly use a maintainer such as this to desulfate at 14.4 VDC, then pull back to a holding float value. Also motorcycles, lawn mowers, ATVs that are seldom or seasonally operated could extend battery life by using such a device.

i would like to read out the firmware of the STM8 microcontroller in order to understand details of how the system operates. Have any of yall done this before and could provide some advice?

AC Input section with EMI filter and HV rectifier

Primary Side Switching Regulator and RM08 Transformer

Secondary Side DC Output Control

Some information in this post is false or urban myths at best.
Have you tested the cetek chargers ?

kennybobby · 2020-01-20T17:20:05.000Z

No, but here is a teardown video—they seem to be a bit dodgy with a patched bodge board and cheesy assembly. Over-rated and over-priced in my opinion, not worth spending the money for a teardown.

“In this video, I reveal the sheer horror that resides inside one of these CTEK chargers, and I track down and remedy an issue that causes the charger to be unresponsive to the mode switch.”

” the only thing “smart” about it is the marketing.
All it does is output a set voltage (should be 14.4v) wait for the current to drop to near zero, it turns off the output and then waits for the battery to self discharge to 12.9v before simply turning on it’s output again. There’s nothing clever or “smart” going on, it’s just a standard battery charger.”

BTW, there is no need to quote an entire post just to ask a simple question that is unrelated to the post content. Please save some bandwidth for folks and edit your post.

kennybobby · 2020-01-20T17:19:05.000Z

Battery Tender Jr.: simple circuitry like the HF version in the OP, uses ATtiny13 micro, seems over-priced for what little it is in there and i won’t be buying one of these either.

video teardown

Photonica · 2020-01-20T17:31:25.000Z

I looked into reverse engineering an STM32 product, but abandoned the project. This was a good walk through of the process. I don’t know if it’s the best tool chain.

Kevin_Z · 2020-01-20T20:31:40.000Z

kennybobby:

No, but here is a teardown video—they seem to be a bit dodgy with a patched bodge board and cheesy assembly. Over-rated and over-priced in my opinion, not worth spending the money for a teardown.

https://youtu.be/14DhsJejnJs

“In this video, I reveal the sheer horror that resides inside one of these CTEK chargers, and I track down and remedy an issue that causes the charger to be unresponsive to the mode switch.”

” the only thing “smart” about it is the marketing.
All it does is output a set voltage (should be 14.4v) wait for the current to drop to near zero, it turns off the output and then waits for the battery to self discharge to 12.9v before simply turning on it’s output again. There’s nothing clever or “smart” going on, it’s just a standard battery charger.”

BTW, there is no need to quote an entire post just to ask a simple question that is unrelated to the post content. Please save some bandwidth for folks and edit your post.

Thanks but that video is next to useless ,the tester seems a bit of a drama queen trying to convince people he knows what he’s doing ,and what did he expect when testing something from a trash bin lol.
Also that is quite a basic model ,
Also this is just a quote copied & pasted from one of the comments,it’s all laughable really

” the only thing “smart” about it is the marketing.
All it does is output a set voltage (should be 14.4v) wait for the current to drop to near zero, it turns off the output and then waits for the battery to self discharge to 12.9v before simply turning on it’s output again. There’s nothing clever or “smart” going on, it’s just a standard battery charger.”

kennybobby · 2020-01-20T21:08:03.000Z

Sure i understand, but there is just not much information out there—that’s why i started this thread.

Please feel free to trace the circuits and post up the schematics, i would be happy to take a look at your detailed findings.

Kevin_Z · 2020-01-20T21:31:00.000Z

I have no detailed findings ,I’ve had two ctek chargers for about 5 years & they do what they’re suppose to , you seem to be dissing some of the best known brands & saying this that or the other about how you think they’re not up to the job , so then you’re cobling together your home made jobby & saying it works better , good luck to you if you think yours is better , maybe mass produce them & sell them as there seems to be a gap in the market for one that actually works .
PS , what you said in post #6 about saving bandwidth, you could have saved loads of bandwidth by just using the first word of your post which was the word “no”
To answer that question.

kennybobby · 2020-01-20T23:22:24.000Z

Please feel free to open up your CTEK units and post some photos to identify the ICs and other chips that they use in YOUR OWN THREAD, since you obviously haven’t been serious enough to actually read or understand anything about this topic, and have added nothing constructive to this investigation.

Kevin_Z · 2020-01-21T00:09:46.000Z

If they ever pack up or go wrong then I’ll take them apart but they’ve been a pleasure to use these past 5 years. They’ve charged & maintained six of my 12volt batteries ,all as good as the day I bought them ,they hold charge pretty well between 12.8 - 13.2volts for a few weeks after taken off the charger , I just don’t understand why you think most of the charger/maintainers out there don’t work , you might have been unlucky and got duds.
I’m a bit picky when it comes to electronic devices,
call me a nerd/geek if you like but I’ve monitored these devices whilst doing their thing & believe me if they didn’t do what they were suppose to then the first one would have been sent back but instead I was quite impressed and I bought a second one.
I’ve also bought & monitored some knockoffs from ALDI / LIDL , & they were sent back.

kennybobby · 2020-01-21T06:05:45.000Z

The yuasa board has a 4-pin header with connections to the STM8 micro, Vdd, Gnd, RST, SWI.

The SWI is the single wire interface described in the user manual for the debug module, so maybe that is a tool to examine the firmware.

kennybobby · 2020-01-23T13:23:33.000Z

Here is a picture of the board. i really like that the components have reference designators, some of the other devices have no RD or labels, which makes tracing the schematic a pain.

There are isolation slots cut in the board for the AC power, and a fairly large isolation gap in the copper traces underneath the transformer to separate the HV from the LV DC sides.

Top side

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