Naughty Battery Chargers.

SquirrellCook

Full Member
Inspired by another post, I thought I would have a look at loading from a switched off battery charger.
We have a very small gel lead acid battery used for a door sounder that requires regular charging. Say once a month or so.
If we leave the battery charger connected it only lasts a few days. So out of curiosity I thought I'd measure the current being consumed.
Shockingly about 200mA ! This is an old Ring 16amp Smart Charger.
So where can I lay my hands on another charger. The next one was a Victron blue smart 12 15. around 60uA's much better, not to bothered about leaving one of those connected.
Then my thoughts came to the wired in Battery charger in Murky. Unfortunately I don't have access to it at the moment, but I'm worried that the charger consumption will be worse. Each engine start battery has a charger wired to it along with the leisure batteries.
So I wonder how bad other wired in charging systems are ??
 

SquirrellCook

Full Member
The supply does not make any difference. Though the ones I'm most concerned about are the ones wired into "Murky"
Murky's battery chargers are set up so that they can use any mains supply available and be swapped around in the event of a failure.
Being "wired in" even when switched of from the mains I was concerned as to the loading they places on the batteries.
 

wildebus

Full Member
The supply does not make any difference. Though the ones I'm most concerned about are the ones wired into "Murky"
Murky's battery chargers are set up so that they can use any mains supply available and be swapped around in the event of a failure.
Being "wired in" even when switched of from the mains I was concerned as to the loading they places on the batteries.
I wonder if you could fit something like a TEC3M (cheap VSR used for caravan towing electrics), routed in-between the charger and the battery? these are uni-directional from memory and would only turn on when the battery chargers were active. Should be a very low loading with a simple relay and save some power?

I just fitted a new "SOC Meter" (it isn't really I think as just relies on Voltages :( ) to my portable battery box... It does have a very nice little mA as part of the display though - I'll plug in the Victron AC Charger I have and see what loading that seems to show when off if you like? (however I have a PWM Solar Controller connected and that is showing no draw at all despite there being a display shown so can't vouch for how accurate it is!)
 

SquirrellCook

Full Member
Found an older simple transformer rectifier battery charger this morning and that draws 600mA from a charged battery when connected to the battery but not plugged in. :(
 

Nabsim

Full Member
hmmmm, never even considered the mains chargers may be drawing power from battery bank, wonder if Schaudt are on top of this as I fitted and extra charger to allow for increased bank
 

Lord Lucan

Full Member
W0W..... This has probably answered why my car battery was loosing charge during the day. I had an Aldi charger connected at night, but unplugged during the day. Clips were always connected to the battery.
 

trevskoda

Full Member
You can leave a smart charger on 24/7,do not do this with old coil/rectifier type as it will damage the battery.
 

wildebus

Full Member
You can leave a smart charger on 24/7,do not do this with old coil/rectifier type as it will damage the battery.
The same is true of many (most? Nearly all?) of the systems that many factory-made motorhomes come with, where their battery chargers just put out a set voltage. It is quite disappointing really that those systems have not been updated for so so many years and are still sold with those limitations (as apart from that they are generally very nice).
 

SquirrellCook

Full Member
Murky has 3 Accumate pro's in it. These were supposed to be smart chargers. They are small, handy cube sized and have a cooling fan. Now the down side. They are not switched mode. They have an internal fuse mounted in the transformer windings! Yes you have to unwind the transformer to replace the fuse! One charger now has a self resettable fuse, same pennies as the original. The moulded wiring has high resistance connections that need to be cut out and replaced. Possible don't charge the batteries well or overcharge them. No monitoring equipment fitted until this weekend. Also can not be permanently connected due to current drain whilst not switched on. Due to some rewiring required two will be switched out of circuit when not in use. The third one is for emergency use with the habitation batteries. Yes wired in too :(
 
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