@zdanylczenko why don’t you start your truck, let it idle, turn on your AC, disconnect the battery (don’t let those leads touch anything), and use your multimeter to see how many amps your alternator is sending to the system. Subtract that number from the rated maximum output of the alternator. If you still have 25 amps left over, then you can run your pump without hurting the battery or system
@florida_condo_cleani that’s awesome thank you
@Jake_Lambert I was going to do some further investigating but I wanted to see if anyone was successful with it already. Thank you for the suggestion, I’ll do that and see if it’s sufficient enough
You can usually get larger alternators for most vehicles. See if yours has that option.
I’m not going to delete that post of mine because IBS hates it when we delete stuff. But part of what I wrote was wrong, because your alternator’s maximum output doesn’t happen at idle; it happens at higher rpms.
A quick google search says that most alternators are putting out 20-50 amps at idle.
Your pump will be drawing around 20-25 amps. You can still measure what the rest of your system is drawing as I explained up there, and make your decision.
One house-wash will easily buy you a deep-cycle battery, a dry place for everything to live, and a charger.
Also I’m pretty sure @florida_condo_cleani isn’t running a Dodge Dakota. It’s not apples to apples.
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Sounds like @florida_condo_cleani has you covered. Might want to ask the specs on that vehicle just in case
This setup is on a f350 dual battery. And we have an idle up function. Truck runs at 1000rpm and I think it’s putting out between 80-100 amp at that rpm . But honestly most guys are lucky to working 30 minutes out of every hour. Basically 50 percent of the time being on the trigger . Batteries are measured in amp hours and I doubt a 12 volt pump could kill the battery in any vehicle that’s running even at idle . Considering it’s likely only operating 50 percent of the time
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@Jake_Lambert thank you for the update, I appreciate all the help. I will try that out. The only reason why I am looking to do this is because I rent and my landlord is not ok with me running an extension cord to the truck each day and I want to avoid having to disconnect the battery everyday to bring inside and change and have to reconnect in the morning. But I’ll see what my options are.
@florida_condo_cleani thanks for the specs of what you are running to make it more clear. I’ll test my truck and see what the output is. And that’s a good point that the trigger won’t be one 100% of the time.
@TexasPressureWashing I know it’s not apples to apples, that’s why I said I would have to do investigating on what my truck can do.
Just to put my 2 cents. I just paid someone to install a charger for the 12v that charges while we drive and automatically shuts off the vehicle battery so we run only from deep cycle battery when the vehicle is off. We also added an on/off switch and if the van battery ever dies we can jump start it from the deep cycle. I will be adding an meter to see the level of battery. We are doing a 25000-30000 sq. Ft. Roofs and we havent had any issues. It can be done, but my recomendation is to use a professional installer that knows what he is doing. I used a well known car audio/alarm installer that works on vehicle 12v day and day out.
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I will take some pictures tomorrow and post them here for future reference
@chinoltw that is awesome information, thank you and yes if you can post some photos that would e greatly appreciated
@chinoltw so your saying it charges both batteries while driving but while using the pump it only allows the one battery to be used, correct?
Lol I like you 
Yes… while we are driving it charges both batteries, when you shut off the vehicle and run the pump it will ONLY RUN THE PUMP BATTERY so your car bettery will not be used at all, so no worries about killing your vehicle battery and being stuck somewhere
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I ran a similar setup with a fender mount Ford solenoid, ran heavy gauge power wire from truck battery to one side of solenoid. On other side connect to deep cycle battery for 12v pump, and find a key on source of power from fuse box to close solenoid when key is on. That way when key is on you are charging both batteries and when key is off only deep cycle will feed 12v pump.
@chinoltw that might just be the answer for what I need, thank you for letting me know. So is it a separate charger or is the pump battery also hooked to the alternator?
One season, was only doing roofs at that time. Before I had a pressure washer and started down streaming lol. Now my pressure washer engine charges my battery when running and I have yet to have to put a charger on it
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@chinoltw this is as simple as 12v pumps need to be . I congratulate you on not using any 90 degree elbows. Do you run a reel or plug in hose as you need it?.
