Battery Tender touch switch problems...? - Page 1
Forum section: electronics / repair

author: Willys
author_rank: Newbie
timestamp: March 25, 2023, 04:55:18 pm
content: Hello folks, my first post, thanks for any and all help.I bought a Battery tender that maintains 3 types of batteries with 2amp and 8amp capabilities. I purchased it for my lithium battery in my van. The problem I am having is with one of the touch switches. It doesn't work all the time. I have opened up the glued together housing carefully and have exposed the board and two touch switches. I do not understand how these switches operate or know when you touch the what seems to me a thick hard plastic case? The case doesn't flex to allow pressure to operate the switch. Then I thought maybe the switch uses your skin to make a connection but how through such a thick case? The switches are round with what looks like a 555 timer chip on them . It also has 4 contact spots, one is 5V, second is Grd, third is SW1 and finally the last is SW. There are only 3 wires running to the switch Black , white and orange.The unit works when the switch works but if the switch is acting up then the unit will not switch to the lithium battery option.Can someone suggest how this operates so I have some sort of idea on how i can solve this issue? Or ask me to supply more information, basically so i know what to give you in regards to what labels etc you may need to know what switch these are.I know this is not the best way to describe things, but i have no other knowledge on how to explain to you what I am dealing with?Again thanks for any help you can offer.

author: floobydust
author_rank: Super Contributor
timestamp: March 26, 2023, 04:00:13 am
content: Welcome to the forumsCan you give a model number and pictures, any markings in the chip? It sounds like a touch (capacitive or maybe magnetic) switch system they are using.It is sensing either of those properties I think, through the plastic housing.

author: Willys
author_rank: Newbie
timestamp: March 26, 2023, 01:52:44 pm
content: Thank you for your response....the unit part number is p/n 022-0337-dl-wh

author: Willys
author_rank: Newbie
timestamp: March 26, 2023, 02:53:01 pm
content: Hopefully these help also..??It is very hard to get a good clear pic as the camera always wants to focus just beyond or too close, augh...!!!...lolSorry.

author: floobydust
author_rank: Super Contributor
timestamp: March 26, 2023, 07:46:45 pm
content: That little circuit board PSL1 40x02 is very likely a capacitive touch sensor and a custom part to the Battery Tender.The chip used on the other side could be replaced, it might be a TTP223.The way these work, is on power up they calibrate themselves thinking no finger is nearby.So if you power up the charger with your finger or hand close to the buttons, it will learn wrong and then never recognize a finger near it.Check the board for dirt and flux or anything conductive, crappy glue included. That white glue is notorious for turning conductive with age, I would pick it off the switch board. I think the touch pad is the copper on the back side.Something else that can affect the touch switches is electrical noise.These chargers do wear out their electrolytic capacitors, which makes more noise and causes erratic operation.If you can get your camera to focus on the object and not the background, pictures of the main board can show fractured soldering joints (also a common problem) or bulged top prego capacitors.There is a chance the switches work fine but there is too much noise for them.

author: Kim Christensen
author_rank: Super Contributor
timestamp: March 26, 2023, 08:13:45 pm
content: Quote from: Willys on March 26, 2023, 01:52:44 pmWhat's the part # on the little round PCB? Too blurry to see for me. Looks like there are a ton of similar PCBs like that available online for under a dollar each...

author: Willys
author_rank: Newbie
timestamp: March 27, 2023, 01:14:03 pm
content: I can't seem to get a clear pic of the board...? So here's the next best thing....hope this is enough.....maybe I also need a better phone...lol.

author: Willys
author_rank: Newbie
timestamp: March 27, 2023, 01:21:18 pm
content: The unit is basically brand new, too much trouble and red tape to return it....so I will either use it as it is or do my best to solve the issue. It was like this from the second I unboxed it. Return shipping and such ...etc etc. Cross border shopping also and them using a warehouse to ship from ...etc etc....The switch that chooses what style of battery which is giving me the trouble wasn't tight to the case, would that make this happen? It wasn't flopping around just not rock solid in it's holder. It looks like both of the two switches are identical.There is a 6 pin chip along with 4 other items I can see on this tiny board, possibly diodes and resistors. I need better eyes, mine are getting lazy! lol.Thanks again everyone for all your help.

author: Kim Christensen
author_rank: Super Contributor
timestamp: March 27, 2023, 03:23:51 pm
content: Quote from: Willys on March 27, 2023, 01:21:18 pmIt's possible if the switch was far enough away from the case. They are proximity switches, so if your finger doesn't get close enough to it, then operation would be sporadic.Since both switches are identical and plug in, what happens if you swap them around?

author: BILLPOD
author_rank: Frequent Contributor
timestamp: March 27, 2023, 08:03:44 pm
content: I think those type of 'trickle chargers' are meant for lead-acid batteries,as Lithium batteries don't like that type of charge, but I may be wrong.Worth checking with manufacturer.

author: Willys
author_rank: Newbie
timestamp: March 27, 2023, 09:00:34 pm
content: I think those type of 'trickle chargers' are meant for lead-acid batteries,as Lithium batteries don't like that type of charge, but I may be wrong.Worth checking with manufacturer.You are correct but this charger is capable of switching from lead acid to gel to lithium. That is the switch that switches it from each type that is the trouble. I want lithium as my van house battery is a 200 amp hour battery.As for the distance away from the case it was just lose or cocked a bit to one side , maybe a 32" difference...? How does a proximity switch work? What does it work off of...It's a black case so no light so to speak goes through the case. Also the case doesn't distort when you touch the switch area..? I doubt heat from your fingers make it work..? Electrical ..?Thanks again for all your help and guidance.

author: Kim Christensen
author_rank: Super Contributor
timestamp: March 28, 2023, 12:45:00 am
content: Quote from: Willys on March 27, 2023, 09:00:34 pm32 inches? I'm sure you meant something else... 32 degrees? That would do it too...These type measure the capacitance change as a conductive object comes near it (Your finger is conductive enough). The closer the object comes, to greater the capacitance change. Below a certain threshold, the switch ignores any changes. So it'll work through a plastic case just fine, but not through a metal one.

author: Willys
author_rank: Newbie
timestamp: March 28, 2023, 01:30:09 pm
content: 32"...lol...sorry meant to say 1/32 of an inch, I'm old school and use non metric measurements so to speak...lol.I will reassemble the unit and try it again on my battery. Hopefully I have jolted it back to life...?IF not....this switch...is it replaceable or is this switch made specifically for the battery tender unit? Seems to me that any switch that operates on this theory should work if it has 3 wires running to it...maybe..As always, thanks for all the help and guidance.

author: floobydust
author_rank: Super Contributor
timestamp: March 28, 2023, 08:12:23 pm
content: The switch board is specifically made for Battery Tender. If you know someone into electronics, they could try scrape off the white glue or replace the chip.The switch activates by looking for anything conductive (metal, wet object, a person's finger etc.) close to its backside, within say a few 8th's. So it's important the switch board is not flopping around loose or near any other wires. Check the lead dress when it's being put together. The back of it (flat side) is the sensing side I think.

author: Kim Christensen
author_rank: Super Contributor
timestamp: March 28, 2023, 08:15:13 pm
content: 1/32 of an inch shouldn't make much difference. If it was me, I'd try testing it while it's opened up. Put some masking tape of the front of the switch and see how well it works when your finger comes close to the "switch"QuoteYou could check with a voltmeter (When it's running) what the voltage on the SW wire does when the switch is activated. (Measuring between the SW and GRD wires)Then you could figure out a replacement one.

author: Willys
author_rank: Newbie
timestamp: March 29, 2023, 12:29:42 am
content: Thanks again I will try what you suggest and let you know how it goes. But, I have a few projects that have been put in front of me, yep, I'm married...lol. I'll keep you up to date asap. Again thanks. Just wanted to say so people don't think I'm ignoring someone.