The post explores an innovative automatic dual battery charger with isolator circuit for alternators and engines, which allows monitoring of the charge levels of two individual batteries, and switching them across the loads appropriately. The idea was requested by Mr. Daz.
Very promising circuits you've always shared, actually I always visit your blog coz im also electronics hobbyist from Philippines .. i have read many of your posted electronics design especially on battery charging circuits 🙂 its very simple and yet reliable and efficient circuits, building those circuits using your designs works great and thank you so much swagatam! but until, i was thinking an solid-state automatic dual battery charger isolator for deep cycle agm 100ah batteries, i am using some of your design charging circuits and delay and relay techniques, but unfortunately, always got me an error... what should I do sir?. can you guide me with my issues? thanks so much.
here is the step of how the circuit may do...
1. before starting, the two agm batteries 1&2 will combine in parallel connections to be used for starting the engine in order to provide smoother and more power to the start.2.Then, once the engine is started, the battery 1 will automatically disconnect via a relay for automatic fast charging until float mode is reached.3.while the battery 2 is connected, a voltage low level cut-off circuit will be monitoring its condition until its voltage reaches 11.5v,4. When the low volt reaches 11.5v, the circuit will automatically trigger the relay connecting the fully charged battery 1 parallel with battery2.5. after battery 1 is connected in parallel, a delay relay cut-off will disconnect of battery 2 and engage it for automatic fast charging and to float mode.
6.a continuation cycle of relays, monitor, charging. that's it.
I hope you understand of what i mean.
hoping to hear from your sir. i hope you can help me with this circuits to make.
Thank you so much and more power to you sir!
The Circuit Design
Instead of addressing the two batteries as battery#1 and battery#2, I thought it was better identifying them as "charged battery", and "partially charged battery".
The proposed design of an automatic dual battery charger with isolator circuit for alternators may be understood with the following given points:
Initially due to absence of power, the two relays are held at their respective N/C positions which allow the two batteries to get connected in parallel with the load.
Let's assume battery#1 as the charged battery, now when the engine is switched ON, both batteries provide their combined power to the alternator via the relevant N/C contacts.
As soon as the alternator starts, it powers the opamp circuit so that the opamps 1 and 2 which are configured as voltage comparators are able to sense the connected battery voltages at their relevant inputs.