Removable batteries: Considerations required.

[BuddyRayment]

Hi,

Im putting together a small "toy" system for charging Lithium batteries and require some advice on the effect of removing batteries as they are fully charged from the system and replacing them with depleted batteries. The batteries are used in a toy electric car I made for my nephew and thought it would be fun if he could swap them out once depleted rather than wait for them to charge. And of course to make it easier I thought it would be more fun if they were charged by solar!

- What effect will this have on an MPPT controller?
- With multiple batteries in the bank should they be connected to the controller separately and charged one at a time using a PLC to switch between batteries once fully charged?? Or this not necessary?
- Without a load connected to the controller does it matter if all batteries are fully charged for a period, do I need an automatic cut-off from the panels?

Any thoughts would be much appreciated

Regards from NZ and a DIY Christmas

[Sunking]

Most likely damage the CC.

[Naptown]

Most likely damage the CC.

Care to elaborate?

[Sunking]

Care to elaborate?

It could be done at night or with the panels covered up, but you would really be taking your chances disconnecting the batteries during daylight with the panels connected.

The way i would do it is just like most CC operators manual instruct you to do. Disconnect the panel s first, then the batteries. To reconnect; first connect the batteries, then reconnect the panels.

[BuddyRayment]

Thanks for taking the time to respond guys.

So even with multiple batteries connected (parallel) to the Controller removing one battery would likely cause some damage?

Would switching between individual batteries (batteries not connected together) not just make the Controller readjust its calculations for the new battery and continue charging as per normal?

New to all this so really appreciate the feedback!

[Sunking]

As long as one battery remains you are OK. Sorry did not catch that part.

[BuddyRayment]

Thanks Sunking

So I'm assuming the batteries couldn't be wired in parallel as removing and inserting individual batteries would affect how they were charged (constant, topping or float phase) by the controller as opposed to it viewing them as effectively one big battery?

But if I was to use a Programmable Logic Controller to effectively switch between individual batteries once fully charged, as long as there was a constant load on the charger there shouldnt be any problems - it will just detect the requirements of the new battery connected and charge away??!

What happens when all batteries are fully charged and there is no additional load on the Controller, can it just sit like that (obviously wasting potential energy) ??