RJH wrote:
On 8 May 2021 at 05:30:15 BST, "Paul" wrote:
RJH wrote:
Would it be OK to charge on of these:
https://www.walteronline.com/en/tool...mpressor-p3155
(jump starter/compressor/light/USB) by connecting the jump leads to a car
battery charger, rather than use the supplied AC adapter?
Charger = 15V @ 500mA for K640046
https://www.walteronline.com/en/acce...arger-p3956016
Product pictures. Vorne and Hinten.
Switch for jump-starter leads.
That's actually the compressor switch. The jump leads are permanently live.
Switch for compressor is not shown in detail. Noise warning sticker. 10
minute run limit.
https://www.walteronline.com/Produkt...nks
Note mains connector.
https://www.walteronline.com/Produkt...eraet@ 2x.png
It was from Aldi so came with a UK plug/PSU. That's actually why I'm asking,
in part. The insulation/wire going i to the PSU has broken down a little.
Considering the battery could be a sealed lead acid with
limited regeneration rate, and the battery is 12V @ 17.2Ah,
that's probably a good rate. That's like a third of an
automotive battery. It could be a sealed battery, not
intended to leak hydrogen into the room (it still has to be
vented for safety - like a vent that opens at 5 bar).
Yes, that's the battery. I had to open it up after I posted because the USB
switch got stuck. Took complete disassembly to get to it - squirt of contact
leaner and all's good.
If connecting your own charger, I'd use a smart charger
with charge current in the ballpark. Say, a 2A charger max.
Don't use an old dumb charger (transformer plus selenium
rectifier), because the current flow is rather uncontrolled.
Since you won't be running it all the way down, it will
never take 34 hours to charge with the included adapter.
Maybe 6 hours to top up, after a usage. The unit should
really have undervoltage cutoff, to protect the battery.
Since it has overcurrent protection, the protection
device can be used for more than one function (like, a
relay or contactor for heavy current).
Note that there is a switch to switch on the battery leads!
The switch contacts are not rated at 150A, but some other
contactor inside might be worked by the switch or something.
This might present some issues for forcing charge in
through the croc clips.
A battery that small is going to be limited on CCA.
You won't be able to start a vehicle with that unit alone.
The battery in the vehicle also has to help.
I think it has pretensions of jump starting - but I've never needed it. I'll
be using it as low rent leisure battery, just for things like phone charging,
tyres, lights.
The larger Walter jump starter, has 240A max output. This
unit, no spec is offered for the max output (overcurrent protect).
Neither is there any mention of undervoltage cutoff. The
USB SMPS for the phone charger, that should have an
undervoltage cutoff, to avoid damaging the battery
by draining to zero.
But since Walter offers no downloadable manual, we're forced
to guess by looking at tiny pictures of the product. I don't
buy products without a user manual, for this very reason,
poor marketing materials online.
It did come with a manual. And there is one on that page I linked to. Amongst
other things, it says 'charge monthly'. I think I've charged it 5 times in 5
years, and then only to top up. It's been barely used.
So, thanks, overall I think you're saying it should work.
FYI, the jump leads connect direct to the battery, nothing inline. Two smaller
wires feed direct to the other gubbins from the battery. I suppose my concern
is that the charger might push something unpleasant along those smaller wires.
But quite what, if anything, is way beyond my pay grade . . .
You might not want to have both chargers connected at the
same time. That's the only case I can think of that might
be an issue. If the external charger went to over 15V, there
might be an issue this way.
15V 500mA --------- charger ----------- battery ------ === external charger
PCB
Should be OK like this, with 15V input open-circuit.
The charger PCB has to be able to "withstand" the potential
offered by the battery. And that should (to be safe) be
designed to cover up to 18V, when the charger PCB is open
circuit on the left side. It's when the charger PCB has a power
source connected on the left, there might be a failure
case to worry about, moving current from right to left. The
wall adapter might not like that particularly.
X--------- charger ----------- battery ------ === external charger
PCB
If you were to use the product to start a car, the car alternator will
be pushing current from right to left, just like the external charger
will be. So they have to handle the case of the alternator putting say,
14.4V on the right.
Paul