Alarm Battery Charging

[atunguyd]

I am just beyond the level of being competent to wire up a plug so please bear with the lower grade questions. Are you saying that the input from the bench supply is interpreted by the alarm system board as the state of charge of the battery and it therefore dials back it's own supply accordingly? if not that are you saying that the two combined are still within the acceptable parameters of the battery?

Yes the two combined will not impact the total 14AH battery. If you wanted to to tally disable the alarms capability to Chand the battery you could put a power diode between the alarm panel and the the bench supply /battery combination. This will ensure that the panel is unable to drive current to the battery and supply combo but I think it is unnecessary

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[DaavG]

A bench power supply can be set to limit both voltage and current. So I set it to 13.8v with a maximum current of 1.4A.

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It will also not impact the alarm system as it only sees a 13.8v attached to it (ie fully charged batteries). This is seeing me through load shedding and charging quickly enough between sessions

Re-reading this thread - can you shed light on this statement? Does a normal intelligent charger overcharge the batteries or damage the alarm system when its charging above 13.8v? Can the lab power supply be upped to charge at a higher rate but limit the volts to 13.8v?

If I am running an 18Ah battery I would guess a charging rate of 3.5A (using your ratio of 7Ah / 1.4A = 5 - is this a rule to observe?)?

I'm clueless on this stuff.

[DaavG]

I came across this item which may solve the problem of slow charging - http://kesa.co.za/product/2-amp-charger-pcb/

[Vaal]

I had the problem twice where the alarm drains the Lithium battery lower than the bms cut off voltage, that caused the battery to completely die and then it doesn't want to charge anymore. The only way to "wakeup" the battery is to bullshit the bms a bit by paralleling it with a charged battery and then charge the parallel setup for a while till it is above the bms shutdown voltage. Then you can disconnect the spare battery and the Lithium will charge as normal.
The whole trick is you must bullshit the bms, you have to do this with a inteligent or dumb charger. Then the bms will control the charging process from there on.