Battery Chargers in Telemetry Systems

[CuriousElectron]

Greetings,

What are the advantages of using two solar battery chargers in solar powered system? One solar battery charger chargers the battery and the other is wired from the battery to the load. I'd think that if one charge controller is doing a good job of maintaining voltage on the battery and a power supply is used to feed the DC electronic load, that would be sufficient. Or, is the 2nd load charger taking the place of the power supply? Here we're talking about a 24VDC system, where the battery is at 24VDC and the telecommunications equipment is also rated at 24VDC.

Any thoughts would be appreciated!
EE

 

[FreddyNurk]

I must admit I've not heard of having separate chargers from solar to battery and battery to load. I can see a second regulator / power supply being used if the end equipment is incapable of withstanding the battery charging voltage (i.e. the batteries will float around 28V for a 24V system; maybe more with lithium systems these days) but otherwise I can't think of an application that would require it.

All the telco stuff I've seen is 48V positive grounded, and the charger, load and batteries are all connected together, rather than the load supplied by a second device supplied by the batteries. Multiple devices are often used in parallel for redundancy too.

EDMS Australia

 

[VEBill]

Many charge controllers employ PWM.

So as a general approach to limiting voltage to the load (if that was the intent), it makes no sense.

Edit to add:

Pulse Width Modulation (PWM) means that the charge controller (if it's actually PWM) would connect the full input voltage to the output load for a period, and then open the circuit for another period. The duty cycle of these two periods determines the output regulated voltage. This scheme works great if the load on the output is a battery that will have enough capacity to average out the voltage. This approach will not actually limit the peak voltage being supplied to a low current load.

The distinction between a PWM versus a 'Linear' (dropping) charge controller can be guessed by a comparison of the rated current as compares to how big the heatsink is on the series-pass element. If it's (for example) 7A and doesn't have a massive heatsink, then it's probably PWM. If it's rated for (for example) 1A, then maybe it's Linear.

Speculation alert. This thread doesn't provide any details.

 

[itsmoked]

In the configuration you describe I can't see any advantage. It would be better to apply ALL the panels to the battery charging and leave the system running off the batteries. What you describe seems like a recipe for more failures.



Keith Cress
kcress -

http://www.flaminsystems.com

 

[waross]

Possibly the design intent was to control the battery charging with the first device and to regulate the voltage to the loads with the second device.
It may have been an otherwise competent designer outside his normal comfort zone, erring on the side of caution.

Bill
--------------------
"Why not the best?"
Jimmy Carter