1998 Tioga RV 28 ft with Solar Panels on roof

lynnsorce

My husband and son in law just installed new 2 6 volt batteries in the coach and 2 more 6 volt in the under compartment it has a charge controller and breaker 3000 amp inverter a total of 5 batteries are going dead including the one under the hood they wont hold a charge the one in the truck should of been isolated from the system all 5 batteries are dead standing still turned off drains the batteries we need help new installation for us and we cant use our RV also battery in truck should of been isolated from the system but it draining too

BB.

Welcome to the forum Lynnsorce,,

I am sorry you are having all of these issues... They can be a pain to track down.

First, what are the house batteries (6 volt @ ~200 AH "golf cart" type)?

I highly recommend you get an AC+DC Current Clamp DMM (digital multimeter). They can measure current just by clamping on a single wire and measure the current via its magnetic field. Note there are AC only and AC+DC current clamp meters. AC only are fine meters, but for working with battery systems, you need the DC current Clamp function.

Here are a couple meters that are examples of what is out there:

https://www.amazon.com/UT210E-Handheld-Digital-Resistance-Capacitance/dp/B06XSMDMYV (inexpensive, good enough for our needs)

https://www.amazon.com/Auto-Ranging-Resistance-Klein-Tools-CL800/dp/B019CY4FB4 (mid-range meter, more features)

You can get a 12 volt battery charger, and at least get 12 volts on the battery buses, and start measuring current flow through the wiring. And see what circuits are drawing power when everything should be "Off".

Just to give you an idea, if you have 4x 6 volt @ 200 AH battery banks in series/parallel for 12 volts @ 400 AH battery bank.. A 1 amp load would "kill" the battery bank in:

• 400 AH / 1 amp draw = 400 Hours
• 400 hours / 24 hours per day = 16.7days
• And normally, would suggest that you draw around 1/4 to 1/2 of the bank capacity in normal use.

The truck battery (lots of different setups possible), but should be (at least) a 12 volt @ 80 AH battery (typical for light duty cars and trucks).

Get 12 volts on the battery bus (house or chassis batteries), and connect the DC Current Camp meter and see how much current you are drawing.

You want to trace the wiring to (for example) a 12 volt main panel for your RV, and you can turn off all of the circuit breakers and see if the current drops to zero amps or not. You can use the current clamp to find which circuits may still be loading your system and which are not.

Note--You may see small loads (like a smoke alarm, a radio that draws a bit of power for memory, etc.). You can also find a lamp in a cargo hold that is not turning off when the door is shut (my in-laws would leave the trunk on their car not fully latched, and the one small light would kill the battery in a few days).

You are probably looking for current in the 0.10 amps or larger that are draining the battery bank over time. Currents in the 0.01 amp or less would take years to drain the large battery bank.

Note that DC current meters do need to be "zeroed". Read the instructions and understand how to use it (DC meters do drift from zero over minutes or longer).

To learn how to use a DC  Current Clamp meter, I popped the hood on my car, and clipped it to the battery cable (negative or positive--Some positive cables have connectors and such on cars and are difficult to measure "all the battery" current because the clamp will not fit.... Anyway, measure current with the car off, turn on headlamps, start the car and see the "+/- sign flip from discharge to charging" etc.

That is the best way to start. You can try other methods (digital volt meter, or other ways)--But the Clamp meter is makes the job much easier.

-Bill

littleharbor2

Sounds like the inverter is being left on. That will definitely drain a set of batteries The inverter should only be turned on when it is needed then shut down when not needed.

BB.

Per Littleharbor2's comment... A 3,000 Watt AC inverter can take anywhere from (typically) 20-40 Watts (~2-3 amps) just being "turned on". That is a fair amount of power, and if left on 24x7, can easily/quickly discharge the house battery bank.

For a 4x "golf cart" type battery bank, a 300-600 Watt inverter (takes something like 6-10 Watts or so Tare losses), is usually a much better fit for smaller loads. A 3,000 Watt AC inverter can suck the battery bank down very quickly if you are actually trying to power 2,000-3,000 Watt loads (like power tools):

• 2,000 Watts * 1/0.85 AC inverter eff * 1/10.5 battery cutoff voltage = 224 Amps
• 400 AH (guess) 12 volt battery bank / 224 Amps = 1.8 Hours

And if you discharge to 50% typically (recommended for longer bank life), that is less than an hour to do that.

-Bill