arduino relay and charging batteries ?

hi,

I have 5 batteries and 5 relays that is connected between the power supply (for charging the batteries) and the five batteries. And there are 5 relays that is connected between the five batteries and the load.

the approach is this:

one battery is charging and the other four is connected to the load. this means, there will be one ON relay in the first stage of relays are off . in the second stage of relays, there are 4 relays that are ON (connected the load) and one relay is off.

so the sequence is there will be 4 batteries supplying the load while one is charging. and by controlling the two stage of relays, I can choose which four that are supply the load and which is charging.

note that the supply can be controlled and it is not important at this point.

does anyone think this strategy is possible !when controlling these relays by the arduino?

You, that would be possible for the Arduino to do.

BUT, just connecting batteries in series which are at different charge states (and they are by design here!) is NOT a smart idea!

A simple solution would be to add a (Schottky) diode between each battery and the load so only the fully charged battery is used. Downside, this introduces a little loss and I have no idea what kind of current's we're talking about. Also, the fact the fullest battery is preferred will mean the battery that was last charged is used. Which may give you uneven load/use of the batteries in time. Although you can reduce that by for example just use 2 (or even one) batteries connected to the load.

septillion:
You, that would be possible for the Arduino to do.

BUT, just connecting batteries in series which are at different charge states (and they are by design here!) is NOT a smart idea!

A simple solution would be to add a (Schottky) diode between each battery and the load so only the fully charged battery is used. Downside, this introduces a little loss and I have no idea what kind of current's we're talking about. Also, the fact the fullest battery is preferred will mean the battery that was last charged is used. Which may give you uneven load/use of the batteries in time. Although you can reduce that by for example just use 2 (or even one) batteries connected to the load.

Thank you for your reply, i want to implement my idea just for exploring. but

1- how can i 5V for each individual relay?

2- your idea is better, but if i want to use a schottky diode, there would be a problem. Because I don't to charge a battery that at some point will supply to the load when it is full. I just want a control over which battery is charging and which is supplying

For 1) I don't understand what you're asking... What is powering the Arduino controlling this all? Can't that also power the relays?

For 2) the diodes is only in series with the load, not with the charger. So I don't see a problem....

septillion:
For 1) I don't understand what you're asking... What is powering the Arduino controlling this all? Can't that also power the relays?

For 2) the diodes is only in series with the load, not with the charger. So I don't see a problem....

I agree, but note that the charger is connected to one battery while the other 4 supply the load. then when the one battery I am charging gets full, I replace it with one of the batteries that supplying the load and take one out to charge. it goes in a sequence

for ur idea, there will be a time where i charge a battery that will supply to the load at the same time.

Abu_kald:
for ur idea, there will be a time where i charge a battery that will supply to the load at the same time.

No there wouldn’t!

I only suggested a diode between the battery and the load, not to remove the relay :wink:

Because without it all load batteries will just be in series. Which will lead to high currents when you switch in a freshly charged battery to a pack that’s not at 100% charge.