Inexpensive Charger Controllers for 24v battery pack.

So before someone goes and recommends me a high quality MPPT I already own a few and understand the quality and benefits. I really enjoy my Victron and Genasun units, but I need something I am willing to loose if it gets stolen as its going to be deployed on mountain tops for temporary radio repeater use.

I know there a bunch of inexpensive options out there, but not sure what to consider. I am looking for something 12 or 24v compatible that has adjustable voltage parameters. I was going to use either a 4s or 7s pack and adjust the voltage of the max charge.

Any recommendations?

If you see my build, I use a eSmart3 MPPT controller. I bought a 60A version for around $150 I believe. Only had it running for 6 months though but I've seen others on Youtube with them running for longer without issues.

not2bme said:

If you see my build, I use a eSmart3 MPPT controller. I bought a 60A version for around $150 I believe. Only had it running for 6 months though but I've seen others on Youtube with them running for longer without issues.

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Its physically too big, plus it cost too much... needs to fit into something like an ammo can and be cheap enough to throw away as I am going to abandon this thingon top of mountains for months at a time.

Here is a $100 Genasun MPPT that fits into a 30 cal ammo can... its going to be something similar but with radio equipment inside of it and a lithiumbattery.

I guess it depends on what inexpensive is and how much amps you're looking at. You can take a look at a MPT-7210A. It's under $40 although I've heard about fan issues but can be modded with better fan.

I have one of those too, I guess I can use it. Its an ok charge controller makes a better general purpose DC-DC IMO which is what I have been using it for. I use it as a boost battery charger for going from 12v to 24v for maintaining the 24v pack in my truck.

Still, I guess it would work find considering its one of the very few boost controllers on the market and then I can use a single smaller panel, like a 20 watt.

There was a person a while ago that mentioned a really dirt cheap PWM controller he used which has user adjustable voltage limits. They ended up using a 3s or 4s pack and adjusted the voltage limit to not overcharge. I was thinking of doing something similar. The radios native voltage is 7.4v nominal, but the battery eliminator is basically as 12 to 24v buck converter.

Radio
https://powerwerx.com/wouxun-kg-uv8t-tri-band-amateur-handheld-radio

Battery Eliminator
https://powerwerx.com/wouxun-kguv9d-battery-eliminator

I havent measured it yet but the load / consumption is very small uses 5 watts for transmitting, and probably 50-100mA when on standby 95% of the time its just going to be on standby until I key up the repeater.

Some 24V Lead-acid chargers can be set to voltages better matching litium in 7S configuration, maybe they are cheaper. Since the load is so small, a DC-DC converter could be used for a 12V supply to the radio with minimum losses.

I have the mpt7210a and it's ok and works well but your battery voltage needs to be higher than your Solar Voltage so you would need < 20V solar Panels when your batteries are down at 21V.

jdeadman said:

I have the mpt7210a and it's ok and works well but your battery voltage needs to be higher than your Solar Voltage so you would need < 20V solar Panels when your batteries are down at 21V.

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I guess Icould do that, even though I didn't want to use that controller... ill test it out just for fun to see how it works. It really might be my best route at this point.

I don't really drain past 3vdc per cell, so 21v is about right.I have it connected to some lead batts just for panel testing... observed PV voltagestays below 21v...

I have 2 of these from Amazon. $45 They are MPPT charge controller that will step up the voltage. I use a 12 volt panel on it so it would work with 7s pack and its small in form factor.