Fixing a Battery Maintainer

[evilkitty]

My dad has a few of there not working and nags me to fix them now and then
I have this 1.5A battery maintainer
it says it is fully automatic with float mode monitoring
It looks like it uses the transformer to drop the AC voltage down
how should i begin testing this thing?

the big cap is a 330 uf 25v
the medium cap is a 16v 1000uf
the 2 small ones are 10uf 50v
Caps are G-luxon

[evilkitty]

Re: Fixing a Battery Maintainer

Ok so i decided to just start pulling caps out
both the big and medium caps are shot, both meters are with the margin of error for 0uf
I found these 2 caps:
https://www.mouser.com/ProductDetail/EKYA350ELL332MLN3S
https://www.mouser.com/ProductDetail/EKYB350ELL102MJ30S
How would i know if i need to find low esr?

the big cap looks to be there to smooth out the dc output
the small cap look to smooth the input dc, does this thing not use a bridge rectifier? i only see one diode per low voltage AC am i not seeing something?

given the caps are in the bad cap brand list, would these be good to replace the 10uf 50v caps:
https://www.mouser.com/ProductDetail...L1H100KDDANATD (I have these onhand)

[diif]

Re: Fixing a Battery Maintainer

Find the datasheet for the caps you want to replace. They will show the ripple and ESR.
I use Panasonic FR, FM and FC in that order after recommendations on here a few years ago.

[evilkitty]

Re: Fixing a Battery Maintainer

I can't find any, but i really suck at finding them

is this a series number?
large cap: 808P(M)
medium cap: 809Q(M)
small cap: 805X(M)

[redwire]

Re: Fixing a Battery Maintainer

It looks like a linear regulator, I don't see a SMPS anywhere.
Does it have a wall wart or transformer or something.
One resistor is brown and sorta burned.

[evilkitty]

Re: Fixing a Battery Maintainer

yes there is a transformer
you mean the odd looking diode between the 2 1% resistors near the cap in the corner?
it does not look burned to be, no trace of residue or anything
I managed to find a few FR caps
https://www.mouser.com/ProductDetail/EEU-FR1E332
https://www.mouser.com/ProductDetail/EEU-FR1E102B
https://www.mouser.com/ProductDetail/EEU-FR1H100B
is there any way these could be a bad decision as replacements? is low esr ever bad?

[Longbow]

Re: Fixing a Battery Maintainer

This is just a simple linear supply. They are usually set to deliver about 14v when connected to a battery. Output current automatically decreases as the battery charge gets up to normal. The connections on the wires easily break. Mine had a wall-wort transformer under-rated and it got hot - it might have to be replaced with a larger one. If you found some bad caps, replace them and you are done. Don't worry about low ESR caps - that does not apply to this simple device. This is not the unit you want to bring a battery up from 10v or lower, but they work fine for maintaining a charge while you replace the engine.

[evilkitty]

Re: Fixing a Battery Maintainer

Thanks, then i just get what ever quality brand has the longest life span
edit: about how much ripple current should i look for?

[sam_sam_sam]

Re: Fixing a Battery Maintainer

Thanks, then i just get what ever quality brand has the longest life span
edit: about how much ripple current should i look for?

The more ripple the better as long as you can fit in the space that you have
Because the more ripple they can handle the bigger the cap get

[redwire]

Re: Fixing a Battery Maintainer

This resistor I think looks burnt, but your pics are kinda fuzzy

[evilkitty]

Re: Fixing a Battery Maintainer

This resistor I think looks burnt, but your pics are kinda fuzzy

Good eye, missed that, i think it was probably overheated by the cap that failed next to it, definitely needs testing

[jazzie366]

Re: Fixing a Battery Maintainer

I can't find any, but i really suck at finding them

is this a series number?
large cap: 808P(M)
medium cap: 809Q(M)
small cap: 805X(M)

No, those are lot codes. G-Luxon brands their caps by putting a two letter combination before the temperature rating. Take the TW series for example, it will look like "TW 105C". You'll find something along those lines on there.
Also, those look to be standard caps, non low ESR, as it's a linear regulator and they can go both ways. Seeing as they are failed without bulging points more towards age killing them, instead of the load/ripple they had to withstand. You can get middle of the road caps (in terms of ESR) that would do the job just fine.

IMO if I were you I would use low ESR, but not extremely low ESR such as is used on motherboards.

My recommendation:
https://www.amazon.com/Illinois-Capa...+25v+capacitor

https://www.digikey.com/products/en?...CKE025M&v=1572

https://www.amazon.com/ECEA1HKA100-A...words=10uf+50v

I'd say use those unless there is high frequency filtering needed, which unless you have a scope we can't figure that out.

[budm]

Re: Fixing a Battery Maintainer

It is just linear power supply so FM/FR series will work.

[kc8adu]

Re: Fixing a Battery Maintainer

select 105c replacements by endurance.
low esr not needed but fine if they have best endurance.

[budm]

Re: Fixing a Battery Maintainer

I would go with FR which has more choices for life rating.

[kc8adu]

Re: Fixing a Battery Maintainer

and use the largest can that will fit.
i used fr in a product i manufacture.
the lifespan being the most needed parameter.
the devices power supply is live at all times.