Electrical diagnosis

[garwhal]

Good evening. I need some help diagnosing an electrical problem.

Issue: battery rapidly drains when pump is connected.

Components.

12 v 100amph battery, Y split SAE connection with 15 amp fuse
USA adventure water pump (http://www.usaadventuregear.com/product/olympic-12v-dc-power-blaster/)
ARB 85 qt fridge

This is a very simple setup and this has been happening for the last two days. When my ARB is plugged into the sAE connection, my battery will easily hold the power for 3-4 days. But when I connect my pump, the system will work perfectly. Then suddenly approximately some x time later, the battery will drop to 4-5 volts. I will quickly detach the pump, wait for an hour or so and the battery will be back to 12.5 volts. Then I can use the pump and repeat.

USA adventure has been awesome to work with but before i invoke more of their customer service time, I am attempting to track down any issue first to help them out. For the life of me I can’t seem to pin point the error or even how to test. The pump is less than 90 days old.

Does anyone have any sage wisdom for an electrical noob?


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[john61ct]

What model battery? How old, what sort of usage?

How are you charging it overnight?

How do you determine your battery is at 100% Full?

Measure the amps drawn by the pump. Also the fridge.

An AH counter better than an ammeter only.

Likely need a better battery and a bank of them.

May need to run your alt charging while using the pump.

 

[john61ct]

And doesn't the SAE connector get hot?

What gauge is the wiring?

 

[Hilldweller]

An old or worn battery (one that wasn't cared for and recharged properly) can show nominal voltage and only have 60% or less of its rated amp hour capacity.
Amps add up. Batteries need to be recharged fully as quickly as possible after discharging.
12.5 volts is not a happy battery.

Sounds like you need a new battery and method of keeping it topped off. You've buggered the beast.

 

[garwhal]

I really appreciate the posted comments.

1. I think the battery may be the issue. It has been on a trickle charger for the last 4 months and gave signs of everything okay.

2. Perhaps the gauge wiring is not enough to hold the amps of the pump and arb fridge at the same time.




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[john61ct]

Even if you fix the wiring, the bank needs to be larger to support those loads.

We can help you more specifically if you can get answers to the Qs above.

If you don't know how, ask more specific Qs and we can help.

 

[Hilldweller]

I had two 122 AH house batteries feeding some lights and an ARB 40 L fridge. 100 W solar to feed them ---- and that was just about enough with our tree cover.

When a battery says 100 AH, that doesn't mean you've got a well with 100 amps to use. Wish it worked like that...
That's a big fridge you've got. Look for a couple of big batteries to feed it ----- and a way to feed your batteries (solar or gennie).

 

[Martyn]

Best to rule out each item one at a time.

1) get the battery load tested. Any of the auto parts stores can run a load test for you. Make sure the battery is fully charged before load testing.

2) find out how many amps the pump is pulling and compare it to the spec.

These are your two main suspects, after that it’s down to wiring, connectors, etc.

 

[garwhal]

Thanks guys for the assistance. The arb has been running on this scenario for several years without issue. My problems have only arisen when I introduced the pump. I will get more detailed information and post some pictures and perhaps that will help the issues.


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[Hilldweller]

Batteries have a finite lifespan no matter how well you care for them....

I just tore apart and rebuilt 3 UPSs and have to scrap one due to neglect. People think they can do their job forever without replacing the batteries. What a mess.

 

[joe51]

I really appreciate the posted comments.

2. Perhaps the gauge wiring is not enough to hold the amps of the pump and arb fridge at the same time.

Use a volt meter and measure the voltage drop in the wiring. Connect one side of the meter to the battery + and the other side to the input at the pump and/or fridge with them running and see how much voltage you're losing in the wiring. You're only starting with 12.5 volts to begin with so any loss of more than about 2/10 volt is pretty significant. Also any voltage loss in the wiring is lost as heat and any significant loss means that you're heating up the wiring and could start a fire. You can test for voltage loss in the ground or the return side the same way. Connect directly on the battery post (not the clamp) and as close to the device input as you can. You may be surprised at how much voltage (and power) is lost through some connections.

 

[jeep-N-montero]

Try posting here too https://www.expeditionportal.com/forum/forums/power-systems-12v-solar-gen.48/

 

[Hilldweller]

That pump linked to, Interesting.
Too bad its vendor is stupid and not print its motor ’specs.
5.3gpm @ 60psi, that thing is a beast. Likely draws around 20 amps.

I found a similar one on Northern Tool's site @ 15 amps. That's still a lot.
The fridge is probably only 5 or 6 when it's cycling.

 

[john61ct]

My post #2 is a starting point for being methodical, making decisions based on evidence you collect.

Post and followup Qs you have to that and you'll get help, be an expert in no time.

Otherwise guesswork will yield suboptimal results perhaps waste money.

 

[Hilldweller]

My post #2 is a starting point for being methodical, making decisions based on evidence you collect.

Post and followup Qs you have to that and you'll get help, be an expert in no time.

Otherwise guesswork will yield suboptimal results perhaps waste money.

This is ExPo.
Wasting money is what we do.