Charger for 10 AA batteries in series, from solar panel, driving 12V DC motor

Help & Support Robot Parts
1

Hi,

I’m building a project involving a 12V DC motor (linear actuator - actually two, but they never run simultaneously). I want to power it with a solar panel.

I already purchased a 36V solar panel and a voltage regulator, but the panel provides max. 0.55A, while the motor draws 1.2A. So I figure that I need a battery inbetween. The motor only works for very short periods, about 2 seconds every minute or so (it’s a solar tracking system), so it doesn’t need much capacity, but it must be able to deliver the 1.2A during these short periods. For the rest of the time, the battery can recharge.

For batteries, I am considering to use a battery holder with 12 AA batteries, for maximum convenience. 2700 mAh batteries should give me enough capacity. I read that the discharge rate of rechargable batteries is high (1C), so that should give me enough current.

My question is what kind of charger I need, and how to connect this. I read that there are charger boards that can do simultaneous charging and connecting a load, but for my 12V setup this seems hard to find? Also I read that charging batteries in series is a risk for overcharging individual batteries, but since I require the 12V, I have no choice.

Or should I try to find a proper 12V battery? I’ve looked around and nothing’s popping up that seems to be appropriate for this kind of project.

Thanks for giving some advise…

Best regards,
Vic

PS. when you read this, you’ll probably understand why this is in the ‘Beginners’ category :wink:

2

Hi,

I did some further searches and it looks like for my 12V system, the only battery/charger setups available are those designed for campers or similar applications, with lead acid batteries weighing 1kg or more.

I guess I’ll have to settle for one of those.

What’s the reason why there are no lipo or nimh solutions available?

Best regards,
Vic

3

@vicmortelmans Welcome to the RobotShop Community. Not really aware of any chargers intended to “balance charge” a 12x AA battery setup - normally AA batteries are recharged outside of the device in a dedicated AA charger. You can find dedicated 1S, 2S and 3S LiPo charging circuits (i.e. no need to connect to a dedicated charger).

Solar panel → Voltage regulator (1) → Battery charger (2) → Battery → Motor Controller → Load

(1) you need to provide the “charging voltage” to the LiPo, not a “random voltage”.
(2) battery charger needs to be appropriate for the battery pack being charged

As for the reason, again, most people are ready to remove the AA batteries to replace them or charge them externally, and it’s incredibly hard to “balance charge” AA batteries in both series and parallel.