DC changeover switch

[markthespark]

Can anyone advise which is the best DC changeover switch to use and what is the app cost of one. I want to have a spare set of batteries charging separate to my existing set which I can changeover to when the initial set runs out.

[Dylboy]

I don't know if DC but perhaps not easier to change over the charger ?

I don't know the setup so not sure but have a set of charge cables to pack A and then to pack B.

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[Isetech]

For an alarm system or inverter?

[Isetech]

Voltage : 12/24 or 48 VDC


Current rating : 7/18/ 55/105 or 160 amps ?

[markthespark]

It's for 1kva inverter

[markthespark]

1 set of batteries being charged by the inverter's battery charger. But if the batteries dont manage the 2.5 hour load shed then when the inverter alarms I can throw the change over switch to disconnect the one set and connect the other set already charged by a separate charger.

[Dylboy]

Thinking out loud...

Can you join it all and then parallel charge ? I.e have both chargers on. ?

I have done small research on parallel charging and seems ok.

That way enough charge capacity and then no need to change over ?

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[Isetech]

I assume you have 2 x 100 amp/hr batteries to make 24 VDC and have 2 spare batteries you want to charge separate using a different charger or chargers.

Once you pass stage 4 load shedding or 3 or more days without power, the charge capacity of the inverter is like the alarm systems, not designed for SA load shedding, by the third day the batteries are dying because the cutout is 10.5 VDC and because the charge current will take at least 10 hours to recharge the batteries.

You have already started damaging the batteries after the first day it dropped to 10.5 VDC, that is 100% DOD. A couple months of loads shedding and the batteries because lead doorstops.

Back to the switch enquiry, you can either use a DC switch like the one used in boats or fit Anderson plugs plugs to each battery set

https://www.tradeinn.com/waveinn/en/blue-sea-systems-e-series-selector-battery-switch/136183931/p?utm_source=google_products&utm_medium=merchant&id_producte=3770491&country=za&gclid=CjwKCAjwq5-WBhB7EiwAl-HEkvq0vSgTQWQDLG48W0YKW8zrgmCroJVcHrwIkNtHtIg8g2AP8Xo4ThoCxIcQAvD_BwE&gclsrc=aw.ds

[Derlyn]

Hi Markthespark
Why connect another set of batteries only when the inverter alarm sounds ?

Why not leave all the batteries connected permanently ? That will double your operating time and halve the discharge rate of the batteries, thus increasing their lifespan.

The more batteries connected the less they discharge on each cycle, the longer they will last.

[Dylboy]

His inverter may have a cut off charge capacity of only maybe a 100ah and then it switches off. One has a certain time of charge which is which for 100ah.

Our complex has one like that and can not add more ah as it would not charge it.

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[Isetech]

Hi Markthespark
Why connect another set of batteries only when the inverter alarm sounds ?

Why not leave all the batteries connected permanently ? That will double your operating time and halve the discharge rate of the batteries, thus increasing their lifespan.

The more batteries connected the less they discharge on each cycle, the longer they will last.

Without all the details, of the setup, its like pissing off the back of a truck, you need to know a few facts like is the wind going blow back in to the vehicle or will land on the road. Unless you have personally done it or know a few facts, your response might not be correct. Those who have done it will smile.


Without at least a model number , a voltage and a charge and discharge rate I just smile when I read 5 star rating for inverters purchased for stage 6 load shedding.

[Derlyn]

Interesting. It's like your car knowing how big your petrol tank is and it doesn't help fitting a bigger tank. Your car will stop going after x amount of litres has been used in one go.

How does the inverter know what A/H battery is being used ?

[Dylboy]

Interesting. It's like your car knowing how big your petrol tank is and it doesn't help fitting a bigger tank. Your car will stop going after x amount of litres has been used in one go.

How does the inverter know what A/H battery is being used ?

I agree but in the manual said that and then I asked this guy who builds batteries and knows a fair amount on inverters and he said it has a timer.

So I guess a 100ah take a max 16 hours so will stop charging.

I don't know the full daynamics but going what the Manuel said and that guy we ended up not putting more capacity

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[Isetech]

Interesting. It's like your car knowing how big your petrol tank is and it doesn't help fitting a bigger tank. Your car will stop going after x amount of litres has been used in one go.

How does the inverter know what A/H battery is being used ?

Its not the amp/hrs of the battery that is the concern, you can install many batteries to create a huge back of batteries to keep the power on for weeks, the question is how will you charge the batteries if you only have a 10 amp/hr charger and a 100 amp/hr FLA/SLA battery it will take 10 hours to charge the battery. If you have 5000 amp/hrs of batteries it going to a take awhile to charge the batteries.

This is the part that people are missing, if you for example you have stage one load shedding and it happens once a day, and you drain the battery lets say 100 % (you shouldnt but for this example its fine) , a 10 amp charger will charge the 100 amp/hr battery in 10 hours, no problem.

Now you add 4 batteries, stage 4 or 6 load shedding and it happens everyday, using a 10 amp charger now it becomes a problem. You batteries will not reach 100 % charge and so they will eventual turn into lead weights, not because you didnt have enough batteries, because you didn't have enough charge capacity to top up the batteries.

It is the same as the alarm and gate batteries, it all has to do with the 0.5 amp trickle charger. These systems are not designed for SA load shedding, they are designed for the odd power failure which might once or twice in their 3 year life cycle, throw level 4 load shedding for a couple days and we smiling all the way to bank as we order boxes of replacement batteries. its the cream on top of the the waffle, Quick in and out, pull of the 2 wires pop in a new battery and walla

All this battery talk is related to load shedding, this is why the C rating is important, as the load shedding schedule increases and become more frequent, the charge rate becomes critical. This is why FLA/SLA batteries are not suitable for high frequency load shedding. This is why the impact of these high levels of load shedding is not only destroying the infrastructure, but backup systems.

[Isetech]

I agree but in the manual said that and then I asked this guy who builds batteries and knows a fair amount on inverters and he said it has a timer.

So I guess a 100ah take a max 16 hours so will stop charging.

I don't know the full daynamics but going what the Manuel said and that guy we ended up not putting more capacity

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An empty battery will draw the full current and as it charges so the battery draws less current from the charger.

The hawkins charger auto pro series have an analog current meter on the units, or the victron smart charger with the app displays the battery charge stages, you can watch the current as reduce as the battery charges.