Charge Controller Float Voltage Problem

The only thing that makes any sense is your diagram showing the wiring. What charger alarm? On the solar charge controller or the charger for the power tool battery?

Your diagram shows a solar charge controller feeding a couple of 6 volt batteries which are hooked to a small power inverter. Which device is setting an alarm?

> (batteries in parallel) two, 6V Flooded T-105 batteries

6V is under voltage for most inverters.

Better stop and re-look at what you have laid out, because what you are saying is wrong and would not likely ever work

If those 40v batteries are being charged from the inverter I would expect a low voltage alarm from the charger if the battery is being drained too fast, not a high voltage alarm from the charger.

Have you tried to just use the battery system and the inverter to charge those 40v batteries?

It sounds like your charge controller is not working correctly

I'll try it without the solar panels and see what happens. Its not the controller as I keep replacing them (I have 3) because they're so cheap.

Maybe you need a less cheap controller ? Are you overvoltage them on cold mornings ?

I’m curious what the rating of the battery charger is for the 40 volt batteries.

If this 1000 watt dewalt inverter is hooked to a cigarette lighter, it only gets 240 watts off one of the reviews on the Dewalt site. Perhaps hooked to batteries alone will get 1000 watts, but hooking it to a solar charge controller may make the electronics think that its only connected to a cigarette lighter.

I have a 400 watt charger that delivers different wattages depending on whether its directly connected to the battery or the cigarette lighter, but because the two different sets of connectors get hooked to the same screws, I don’t know how the inverter knows if its connected to a cigarette lighter or battery. This inverter also trips an audible alarm when I try to push too much wattage through it when it hooked to the cigarette lighter. I think this alarm is set because there's not enough voltage and amps coming through for the device supported so there must be some sort of limit that comes through the cigarette lighter.

Yes, I suspect the inverter holding back watts, but that’s crazy isn’t it? Maintenance power for two 40V batteries takes between 28W and 60W as viewed on the inverter display. It seems to fluctuate at the charger kicks in. The charger itself displays 14.4 Volts. I’m going to partially drain a couple of batteries tomorrow and try charging them then, but today is way too hot! 91⸰ to go outside.

I forgot to tell you it is connected to 2 -100 Watt solar panels, not a car lighter. Although when I do plug my 100W guitar amplifier into the inverter connected to the battery thing it works very well as long as I keep the truck turned on.

I would think that you are using the 120v chargers that come with the 40v batteries. I have a similar charger for my Black and Decker 40v weed wacker.

Correct me if I am wrong but I believe those 40v chargers are plugged into the inverter. The inverter gets its power from the battery and the battery gets its power from a Charge controller which gets its power from the 200 watts of panel.

Maybe those 40v chargers are doing something to the inverter causing it to fluctuate.

You are correct in the description. Most astute.
I've had similar problems trying to power six 18V Ryobi chargers plugged into a power strip, plugged into the inverter. If I plug them all in at once and flip the switch on the power strip--the inverter alarm sounds. If I switch it on, then plug in each 18V charger individually, that will work for a while, but will sound the alarm later on. My only goal with this solar rig is to charge 18V & 40V tool batteries. Hurricanes cause us serious power outages and I can run everything we need, except the refrigerator, on these batteries.
FYI, today one 40V battery, partially discharged, showed a surge of about 102W (down to about 14W when charged) on the inverter. I never have problems charging a single battery.

I wonder if more than one charger on the inverter is causing either voltage dips/spikes or harmonics which leads to an alarm. Switch mode power supplies (which is what those chargers are) will cause all kinds of dirty power that an inverter isn't engineered to handle. Just a thought.

I have similar 18V and 40V chargers that I can experiment with to see if they cause my inverter to alarm.

I think you finally hit on my problem. There's sensitive circuitry inside my battery chargers and coupled with the sensitive circuitry in the sine wave inverter--beep-beep-beep! I never have a problem with one battery charging so that's what I'll have to do, charge one at a time.