24v to 12V for ligths

[expresso]

BM i have a question - a friend has Led lights on here chair - 12V - she has a 24V to 12V converter attached - then going in the Rnet cable so the chair powers it - she has a 200ah pack -

sounds correct - but is it correct - i just want to be sure its not draining the pack - it is using the pack but is it correct and not making the pack out of balance this way ?

would it still be draining when chair is off - lights off ? i believe it has a remote so can keep lights off with chair on also

i just want to be sure the pack is not being affected in a neg way- its not connected to the Pack itself -

what do you think ?

[Burgerman]

The inverter 24 to 12V thingy will always be taking a small current from the pack. How small? You would have to measure it. It may be say a few mA in which case you can "ignore" it. Or not. The powerchair itself also takes power all of the time, even when off. In the same way.

If you leave any chair for more than a couple of weeks then it must be repeatedly topped up by charging. Or the battery disconnected. Either by disconnecting a batt terminal, or by switching off a breaker, or by fitting a Anderson "loop" in a plug where you can disconnect it.

[expresso]

ok its 200ah pack - its not connected directly to the pack - - the lights and converter is connected to the Rnet wiring somehow -

so it always can work if turned on or off -

So no matter what - chair is off - lights are off - its always draining something - even if minor - i dont know how to check how much its draining

you suggest recharging every 2 weeks ? if not used ?

if thats the case - should she use a different preset for just topping up - or the same one at 20A charge rate - or same one and lower the charge rate for the top ups ? she wont like that if i ask her to top up every two weeks - but i want to make sure the pack is taken care of at least - give her the details if it has to be done to keep it balanced better - or will take hours to balance at some point - which already happened - over the winter - if left a while sitting

i get the feeling shes not too happy with all the little things to keep watch of - i know its minor - but she wont do it - just charge and use -

i guess lithium isnt for everyone -

[steves1977uk]

Why is she using an inverter through the R-net wiring? You can set the voltages for the lights in the programming software, 12v or 24v I believe.

Steve

[Burgerman]

Who knows what or why she is doing.

Does she even know the ISM can do lights. And remember that in the US some cant.

[expresso]

Ok lets back up a moment


i put the pack in her chair - then she got Led motocycle ligths she wanted to add - they were 12 V - i didnt want her to add any or touch the pack - i advised to get a 24V to 12V convertor so it wont affect battery volts - should be good

i didnt see how its connected but its thru the Rnet cable somehow in the rear - when you have recline they put the sort of like a power strip of Rnet plugs - when i get a chance i like to see how its connected - wont be for a few weeks - i take a picture

the lights come with a remote so they can be turned on or off -

so thats where we are at -

i dont know how to connect to ISM to control lights etc, - that would be more involved taking it apart to get to the ISM -

So as it stands now -

i wanted to know if that would affect the pack in any Neg. way ? i want to make sure its not and if its just about a drain on the battery - but its fine - then either she can charge every few weeks when not in daily use - or deal with a very long time to get them balanced when she does charge

i just want to give her the Facts and options so she can decide for herself how she wants to deal with - so far - shes not too happy with the lithium - its as plug and play as can be - but still need some basic effort to make the best of it -

i cant force anyone to things the way i would -

As it stands

is it OK - or is this light setup affecting the pack in a Neg. way ?

[steves1977uk]

She has 3 choices...

1. Go back to Lead bricks and suffer the limited range they offer.
2. Go with a BMS style setup and hope for the best.
3. Look after her chair and take care and time learning the benefits of a Lithium setup. If she can't be bothered doing a little maintenance every two weeks to a month to look after it, then it's the two options above unfortunately.

Steve

[expresso]

yes i know that -

BUT the question i have - is


IF she leaves it this way - is it correct - or is it affecting the pack in a Neg. way - ?


yes its going to have a small drain on the battery all the time as the chair is also - but other than having to TOP it up every few weeks when not in use - its Fine otherwise ?

[Burgerman]

Yes.

[expresso]

Yes.

Ok thats what i needed to know - i can pass the info - so she can decide how she wants to charge and when

now if topping it off every two weeks when not in daily use of course

what charge rate should be used - she has one preset at 20A

would that be fine ?

[Burgerman]

Yes.

It might be fine for months. Lithium doesent like to be full anyway. I was talking about lead. But if you dnt know the current draw you just need to check that the pack doesent get left unattended for long enough to discharge to below safe limits. That may be a month or a year.

[expresso]

Yes.

It might be fine for months. Lithium doesent like to be full anyway. I was talking about lead. But if you dnt know the current draw you just need to check that the pack doesent get left unattended for long enough to discharge to below safe limits. That may be a month or a year.

its 200ah - and the current draw cant be that much to drain it low enough for damage - in a month -

so i would suggest to charge each month if left unused that should be fine - it may take time to balance - but no damage is done -

yes this is lithium

[Burgerman]

If it takes just 20mA idle, and the control system on your chair takes the same when off then 208 days will cost you 200Ah. So 100 days will eat half the full charged pack. It may take a little less. Or unlikely, a little more. Now thats damaging for a lead battery. And harmless for a lithium battery as long as you know its doing it. So you dont leave it so long the battery gets over discharged.

[expresso]

i see - good to know - so even if you dont know how much it drains - doing it once a month would be safe enough not to worry

next time i will see if which did she use and can check the specs on it

just to know - being LED - i dont think it would be high

[Burgerman]

Being LED has nothing to do with it. When off!

There is an inverter on a board. It turns 24V to 12V all the time. Usually. So that the current to run the 12V lights is available. The OFF current maybe approx 6 to 25mA at a guess. When lights are not on. And a few Amps when on.

[expresso]

oh yes thats right - i didnt think of the converter

so i need to know how much the converter uses when off ?


https://www.ebay.com/itm/383335639119?_ ... %3A2334524

i think its this one or similar for sure

[Burgerman]

It doesent say. I have one 48 to 12v on the BM3. It took 12mA. At lower voltage it may take more. I dont know without measuring.

[expresso]

It doesent say. I have one 48 to 12v on the BM3. It took 12mA. At lower voltage it may take more. I dont know without measuring.

Ok - how would you measure ?

even so - take a quess - give or take how much more can it draw over your 12mA ?

[Burgerman]

I would use a small clamp meter that can measure very low currents down to a single mA. Over a wire that feeds the inverter.

You can also use a mumtimeter set to mA and feed the power to the inverter through the meter.

I cant guess, but it wont be more than 20/ 25mA I think. Maybe as little as 5 or 6! All depends what the designer did!

[expresso]

ok i may have to get a small clamp meter - thats the easiest to use - just around a wire and find out what its using ?

which clamp meter would you suggest - not too expensive because i may never use it - or very little usage - or i may find alot of uses after wards - who knows - this is just me being curious - its not even mines but since i got her started with the lithium - i dont think she would continue with it when this is over with

[Burgerman]

We went through all this a year back!

UNI-T UT210E or any that can do 1mA dc resolution. You must learn to press the ZERO button before taking a measurement. Or it will not be accurate. They are affected by metals, magnetic fields etc.

Check amazon and ebay.
https://www.youtube.com/watch?v=ZLsk4s1oYs0

[expresso]

yes i never needed it - i actually ordered it and it never arrived ebay

i got refund and just forgot about it - i dont have a use for it really

i look again and see

thanks

[ex-Gooserider]

The type of battery DOES NOT MATTER!!! - the electronics will do the same whether it is lead bricks or LiFePO4 (or a Nuclear power plant set to the right voltage....)

IF there is a switch on the INPUT side of the DC-DC, then turning it off will remove the DC-DC from the circuit and there will be no power draw. If the switch is on the OUTPUT side of the DC-DC (which is what it sounds like) then the DC-DC will ALWAYS be drawing power, though not much when the load (lights / controller) is off. Since it has a remote, it has to be drawing some just to power the circuitry that detects the signals from the remote.

ex-Gooserider