“Dumb” charger question

[Cush]

In every sense of the phrase!

it’s a 2003 Sargent wet lead acid charger , 13.7 volts nominal. I don’t think it has a profile.
will it reduce its draw from the 240v source as the battery reaches full or will it keep pumping out and draw a constant watts / amps?

tia.

 

[tonyidle]

It'll take the battery to 13.7v then stop.

 

[Cush]

Thank you tonyidle . Super-fast helpful response

 

[Richard n Ann]

battery reaches full

It will never reach fully charged without going up to 14.4v or so.

I'd get rid of the 'charger' and replace with a 3 or more stage smart charger.

 

[Lenny HB]

Agree with what Richard said, all that charger will do is your batteries. That's why in caravans and older Motorhomes the batteries only lasted 2 years.

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[Cush]

It will never reach fully charged without going up to 14.4v or so.

so it won’t stop charging as suggested above?

I'd get rid of the 'charger' and replace

not an option at the minute unfortunately.

 

[Richard n Ann]

so it won’t stop charging as suggested above?

Yes the charge will fizzle out when the battery gets to 80% or something.
Actually the charger never does anything, it's just a 13.7v power supply. The internal resistance of the battery goes up as it charges so it just eventually stops taking current.

 

[Cush]

thanks for the sage advice. Just curious as to how the system functions.

does “eventually stops taking current.” also mean the power supply will draw less and less electricity from the ehu?

sorry. I’m dim!

 

[Pausim]

Just curious as to how the system functions.

Badly.

 

[LithiumConvert]

I would play safe and disconnect it when the battery has reached 13.7 volts.

and then buy a proper charger for next time.

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[TheCaller]

Most smart chargers fall back to somewhere in the 13.6 - 13.8v range when they reach the 'float' stage, having been up to 14.2 - 14.7v, depending on what sort of battery they were charging.

So a constant 13.7v won't harm the battery, but the fact that it has never gone any higher to fully charge it will do.

Those chargers were originally designed for caravans that spent 95% of their time on site with EHU & were fitted with small, cheap wet cell batteries. The battery was not much more than a buffer, but also provided a bit of short term power when the caravan wasn't plugged in.

They are not suited to motorhomes that spend any time off-grid, not are they suited to either Gel or AGM batteries.

They are not suited to Lithium batteries either, but funnily enough, they won't damage them as much as other battery types though, because Lithium batteries don't mind being undercharged.

 

[Pausim]

I seem to recall one of the battery companies having a spat with a supplier saying that these products should not be described as chargers but as power supplies. Battery destroyers might be more accurate.

 

[Cush]

will it reduce its draw from the 240v source as the battery reaches full or will it keep pumping out and draw a constant watts / amps?

Love the direction the advice is taking me for when it’s financially possible, and now appreciate the WLAs will never reach full (that happens with the solar charger when the panels can see the sky). And, to answer the original question, it’s a “yes”, that it will keep drawing from ehu as it never reaches full But it may reduce it when it gets towards 13.7.

 

[Cush]

these products should not be described as chargers but as power supplies.

They do in fact call it a PSU so no trading standards breach there . How things have moved on in the last 25 years!

 

[Barti Ddu]

If you've also got solar and a decent controller, that will take the battery up to 14.4v to give your battery a proper full charge, even this time of year (most days), over and above what the Sargent charger/ PSU will achieve.

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[Odd-no-more]

I keep my caravan at home switch off the on board charger and connect a smart charger to keep the battery in good condition. I do use the on board charger on site if on EHU.

 

[Cush]

If you've also got solar and a decent controller, that will take the battery up to 14.4v to give your battery a proper full charge, even this time of year (most days), over and above what the Sargent charger/ PSU will achieve.

Agreed. Unfortunately in this scenario she is stored indoors with no light otherwise it wouldn’t be a concern.

 

[Cush]

I keep my caravan at home switch off the on board charger and connect a smart charger to keep the battery in good condition. I do use the on board charger on site if on EHU.

Thanks for thinking about a solution too. Explored that option on other threads