House Batteries draining quickly

musicflog · 07-21-2022, 01:59 AM

I have 2 new (6 months) interstate house batteries. Boondocking we usually get about 4 days out of them before they're drained. This last trip to a mild climate (beach was about 65-70 degrees) they drained in a day. I checked the water levels and that was fine in all cells. I could charge them up with the generator (all lights glowing on the control panel), but again they drained quickly. I did this a couple of times. Driving home, the chassis battery indeed charged the house batteries to full. But once again the power drains quickly. The only power that was on was the radio display--the radio wasn't on, just the front display of the time. And that display was always on previously when we would get 4 days out the charge. I checked all the lights in the under cabinets. No heater on. The fridge was on propane. I even turned off the water pump switch so make sure that wasn't the culprit. Any ideas on what it is or how I can test for it? As always, your responses are very much appreciated.

Chateau_Nomad · 07-21-2022, 02:15 AM

I would recommend you stop by an auto parts store and have them do a free load test on the batteries... or go where you purchased them. Just because they are "new" doesn't mean they're healthy. Secondly, get a cheap battery hydrometer to check the batteries electrolyte level. Those two "tests" will confirm if the batteries are okay.

Also be aware that you should NEVER drain lead-acid batteries below approximately 50% state of charge. Doing so repeatedly will drastically reduce their ability to maintain a charge.

Next, look for parasitic drains on the batteries... stuff that's "on", but shouldn't be.

It may just be that you're using more DC power than you realize. Which means more frequent generator use to recharge. In which case be certain that your batteries are in fact "deep cycle" type. Then there's the whole upgrade path to other types of batteries...

Judge · 07-21-2022, 09:46 AM

The above is sound advice.

If you are not monitoring the voltage properly and just waiting for them to "drain" down instead of starting the charging process at a 50% SOC, you could have seriously impacted their performance in just 6 months if you have been boondocking a lot.

musicflog · 07-21-2022, 01:37 PM

Thanks Chateau Nomad--I always like becoming more knowledgeable.

Chateau_Nomad · 07-21-2022, 01:44 PM

Quote:

Originally Posted by musicflog

Thanks Chateau Nomad--I always like becoming more knowledgeable.

Some have claimed I stayed in a Holiday Inn last night... but I just sleep in my motorhome like everyone else...

The Gritz Carlton · 07-21-2022, 01:56 PM

If you boondock a lot, invest in a Honda 2000-2200 type inverter generator. We use several of them when boondocking for days at racetracks, etc. It will run microwave, hair dryer, coffee maker and other small 120V appliances and keeps you from having to start generator for short intervals. I run it for a couple hours each evening and it keeps batteries topped off. My fridge is residential and runs off house inverter so it eats battery juice like candy. I can usually go nearly 2 days on house batteries before it reaches the critical state so you probably have weak or bad batteries. Maybe not both of them but one bad one will take a good one down with it. The Honda is an excellent back up just to have along for the ride.

musicflog · 07-21-2022, 02:09 PM

I already have a decent inverter and never thought of using that. Love the advice I get here.

musicflog · 07-21-2022, 02:14 PM

Am I assuming correctly that I would plug the "external" generator into the RV via the SP connection?

The Gritz Carlton · 07-21-2022, 02:23 PM

Quote:

Originally Posted by musicflog

Am I assuming correctly that I would plug the "external" generator into the RV via the SP connection?

Yes, I use the 50 to 30 pigtail and then 30 to 120V adapter. One of my Hondas also has an RV 30A plug as well as part of the parallel kit.

The Gritz Carlton · 07-21-2022, 02:26 PM

This is an excellent and cheap tool to add to a storage bay. It's the only way to really test the state of a battery...they must be fully charged before testing and it's best to disconnect the cables from the post to get a true reading. There's no second guessing with this tester.

https://www.amazon.com/OTC-3181-Heav...80762288&psc=1

Scubawise · 07-21-2022, 02:58 PM

Quote:

Originally Posted by musicflog

I have 2 new (6 months) interstate house batteries. Boondocking we usually get about 4 days out of them before they're drained. This last trip to a mild climate (beach was about 65-70 degrees) they drained in a day. I checked the water levels and that was fine in all cells. I could charge them up with the generator (all lights glowing on the control panel), but again they drained quickly. I did this a couple of times. Driving home, the chassis battery indeed charged the house batteries to full. But once again the power drains quickly. The only power that was on was the radio display--the radio wasn't on, just the front display of the time. And that display was always on previously when we would get 4 days out the charge. I checked all the lights in the under cabinets. No heater on. The fridge was on propane. I even turned off the water pump switch so make sure that wasn't the culprit. Any ideas on what it is or how I can test for it? As always, your responses are very much appreciated.

Interstate will check and replace if bad

musicflog · 07-27-2022, 04:56 PM

I finally got back from an out of town (non RV) trip and was able to test the house batteries. They are both in bad shape, won't charge and certainly can't handle a load. So I will replace them ASAP. BUT, I want to be sure how to proceed in the future. For example, should I always leave the STORE/USE toggle switch in STORE if I'm not using the MH for a while? Also, can I rely on the MH's control panel to judge the SOC percentage?

**16ACE27** · 07-27-2022, 05:40 PM

Quote:

Originally Posted by musicflog

I finally got back from an out of town (non RV) trip and was able to test the house batteries. They are both in bad shape, won't charge and certainly can't handle a load. So I will replace them ASAP. BUT, I want to be sure how to proceed in the future. For example, should I always leave the STORE/USE toggle switch in STORE if I'm not using the MH for a while? Also, can I rely on the MH's control panel to judge the SOC percentage?

Leave the USE/STORE switch in USE unless:
MH is stored without being connected to SP.

No, the MH control panel can NOT be relied upon to give an accurate state of charge. If you boondock a lot (sounds like you do) spend $80and get a true battery SOC meter:

https://www.amazon.com/gp/product/B07RP5B5P7

You will see it once you have it installed it actually takes at least 4 to 6 hours of generator run time to fully charge your batteries.

musicflog · 07-27-2022, 06:09 PM

Is there any harm to the system if the SP is plugged in for a week (for example)? Can the batteries be "over charged"?

Scubawise · 07-27-2022, 06:14 PM

Quote:

Originally Posted by musicflog

I finally got back from an out of town (non RV) trip and was able to test the house batteries. They are both in bad shape, won't charge and certainly can't handle a load. So I will replace them ASAP. BUT, I want to be sure how to proceed in the future. For example, should I always leave the STORE/USE toggle switch in STORE if I'm not using the MH for a while? Also, can I rely on the MH's control panel to judge the SOC percentage?

For us we leave it in use and let the 1 solar panel keep everything well.

Before solar leave plugged into 110 and use on

Scubawise · 07-27-2022, 06:15 PM

Quote:

Originally Posted by musicflog

Is there any harm to the system if the SP is plugged in for a week (for example)? Can the batteries be "over charged"?

Before solar. Always left plugged in with use on

**16ACE27** · 07-27-2022, 06:43 PM

Quote:

Originally Posted by musicflog

Is there any harm to the system if the SP is plugged in for a week (for example)? Can the batteries be "over charged"?

Not if your converter/charger is working correctly. If will go into float/maintain mode once the batteries are charged.

Judge · 07-27-2022, 06:47 PM

If you are going with new batteries, spend a little more and got with maintenance-free AGM batteries. Then you can leave the coach plugged in on shore power to maintain the batteries without worrying about adding water and corrosion from acid.

The Gritz Carlton · 07-27-2022, 06:57 PM

Quote:

Originally Posted by musicflog

I finally got back from an out of town (non RV) trip and was able to test the house batteries. They are both in bad shape, won't charge and certainly can't handle a load. So I will replace them ASAP. BUT, I want to be sure how to proceed in the future. For example, should I always leave the STORE/USE toggle switch in STORE if I'm not using the MH for a while? Also, can I rely on the MH's control panel to judge the SOC percentage?

If you're not plugged in to SP and storing the coach, disconnect the batteries at the battery. If you have a SP option, leave it plugged in. I've done this since new. If you go with flooded batteries, check them once a month at least...if you go the AGM route, no need to check them. Seems everything dies or goes to deep sleep when you store it for extended periods and not on shore power. A single 15A 120V plug will do as long as you don't run A/C's.

holtcg · 07-27-2022, 10:10 PM

Quote:

Originally Posted by The Gritz Carlton

Yes, I use the 50 to 30 pigtail and then 30 to 120V adapter. One of my Hondas also has an RV 30A plug as well as part of the parallel kit.

Quick note for anyone getting a generator for SP hookup. Some auto switches have protection built in and might not be happy with the lack of a ground on your power source. If your generator's "RV outlet" is not bonded, you can buy or make a bonding plug for cheap. You can use any of the "regular" 3 prong 5-15r outlets. And the bonding plug I made is just a replacement plug with a wire to bond the ground and neutral.

You may also like: