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Old 06-12-2020, 05:47 PM   #1
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Batteries getting tired?

Config: 2-12v wet. 1kw inverter. 600w Coffee maker.

Batteries read 12.1v at rest. Plug in coffee maker and it alarms for source too low. It should at least be able to get started, correct? I know this worked once, toaster too. Batteries getting tired?
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Old 06-12-2020, 05:57 PM   #2
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How old are they?
It sure sounds as if they're not improving with age!
Are you going to try AGM style batteries next?
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Old 06-12-2020, 07:46 PM   #3
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Originally Posted by The_Breeze View Post
Config: 2-12v wet. 1kw inverter. 600w Coffee maker.

Batteries read 12.1v at rest. Plug in coffee maker and it alarms for source too low. It should at least be able to get started, correct? I know this worked once, toaster too. Batteries getting tired?

Possibly, or should I say likely. However, you could have a bad connection between batteries and inverter. Or a bad inverter?

Before replacing batteries, do a simple test to rule out other problems. Put a voltmeter across your battery terminals, and then have someone turn on the coffee maker. If batteries are bad, voltage should drop right at terminals.

Youíll have to check both batteries one at a time because cable connections at batteries can be bad/weak, preventing a battery from doing its part.
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Old 06-12-2020, 09:48 PM   #4
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How long since the last charge by gen, shore or engine and what was drawing power dive then.

Not enough info so all are WAGs.
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Old 06-12-2020, 11:14 PM   #5
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Thanks for the feedback Guys. I should have mentioned I'm boon docking but no reason for your eyes to pop out of your heads I'm a very conservative boon docker. Ok, relatively...

Bob: Sort of why I asked about tired - original OEM from 2016. So yes, may not be improving with age. What stumps me is it worked once and handled a 750w toaster right afterward, but that was just once. I'm considering AGMs for mere ease of maintenance, otherwise I see no distinct advantage over wet. I'm still trying to understand something Chance wrote a while ago about 2-12v 'strings'. It sounded like it wouldn't be a fit in a RV (I have room for 4-12s)

Chance: Fortunately or unfortunately, I fly solo so I'd have to recruit some help. I pulled the batteries last night, clean all connections, applied a liberal - but neat - amount of dielectric grease hoping poor connections were the problem. The bats will charge my laptop and cell phone simultaneously until the cows come home. On a similar note, a while back, we were discussing battery configurations and you stated that 2 strings of 12 were required if I wanted to wire 4 batteries in parallel. Is there something I can read to help me understand why that's a preferred configuration and if it's a good fit for a RV application? Thanks.

EA37TS: I ran the gen for 90m the night before. Taxed them a little using my laptop and cell phone (see response to Chance), and ran the heater when I woke this morning to take the chill out of the air (off all night). Other than what's stated, it's just the fridge and any other parasitic draws. Chassis battery doesn't charge on shore or gen so it's disconnected for this stay.

Hope that helps you help me. I'm beginning to believe they're just not up to snuff anymore. The 12.1 threw me a little so I wanted to ask and after I attempted the brew. Indicator panel showed 'good'. I expected to find 11 or less.

I full time. If I remove the batteries, the fridge goes out. By the time I get done monkeying around with taking them to get tested, separately, I'll just knuckle under and replace them.

Thanks again.
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Old 06-13-2020, 12:29 AM   #6
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A 12 volt battery reading 12.0 volts is only about 25% charged. May not be enough amps left to run your coffee maker
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Old 06-13-2020, 01:19 AM   #7
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Depending on the age of the batteries it may be time to look at replacements.

As to battery configurations Harris Battery had a document on their site a few years ago. If you are an FMCA member late last year thee FMCA Family Magazine had a multi part article on RV electric systems and they went into detail about batteries and battery configurations.

4 12VDC batteries can be connected in parallel in one string. 4 6VDC batteries must be connected in series-parallel (2 strings of series connected in parallel).

Here is the link to the document from Harris. The document is to large to post on the forum. Page 13 has diagrams for the various battery configurations.

https://www.harrisbattery.com/sites/...ide_web2_1.pdf
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Old 06-13-2020, 02:02 AM   #8
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Originally Posted by EA37TS View Post
Cut...
Here is the link to the document from Harris. The document is to large to post on the forum. Page 13 has diagrams for the various battery configurations.

https://www.harrisbattery.com/sites/...ide_web2_1.pdf
Thank you EA and yes, I believe they're on the verge of expired. I saved the link for a better connection. Stay well.
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Old 06-13-2020, 02:56 PM   #9
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I pulled the batteries last night, clean all connections, applied a liberal - but neat - amount of dielectric grease hoping poor connections were the problem.
I hope you do not apply the grease until the connections are complete. Dielectric grease is non conductive and is used to seal out moisture (corrosion).
Just checking.
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Old 06-13-2020, 03:17 PM   #10
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If the batteries are still out, that then to auto parts store and have them losd tested.
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Old 06-13-2020, 07:04 PM   #11
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Originally Posted by The_Breeze View Post

.....cut.....

Chance: Fortunately or unfortunately, I fly solo so I'd have to recruit some help. I pulled the batteries last night, clean all connections, applied a liberal - but neat - amount of dielectric grease hoping poor connections were the problem. The bats will charge my laptop and cell phone simultaneously until the cows come home. On a similar note, a while back, we were discussing battery configurations and you stated that 2 strings of 12 were required if I wanted to wire 4 batteries in parallel. Is there something I can read to help me understand why that's a preferred configuration and if it's a good fit for a RV application? Thanks.

.....cut.....

There are many articles on this topic, the following being just one.

https://batteryuniversity.com/learn/...configurations

If upgrading to 4 batteries, Iíd go with 2S/2P (Series/Parallel) configuration based on 6-Volt batteries. If you research it, most RVs that come from manufacturer with 4 lead batteries use 6-Volt batteries in 2Series/2Parallel configuration. I would personally avoid 4 X 12-Volt lead batteries all in parallel. Newer lithium batteries are a new exception because of battery management systems.


Regarding your 600-Watt coffee maker, thatís not really much juice for two good batteries. The inverter should pull in range of +/- 60 Amps at 12V, which is only 30 Amps per battery. If inverter trips out immediately on coffee maker start, thereís definitely a problem.

Do you know at what voltage the inverter trips? Some are around 11-Volts.

If you want to test batteries again under normal coffee maker load, but are by yourself, have you thought of temporarily moving coffee maker near batteries so you can check voltage when you turn it on? Youíd only need an extension cord.

When troubleshooting I usually check the easy stuff first, particularly if itís likely to be the problem. Bad batteries are a common problem and easy to check, so where I would start.
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Old 06-13-2020, 10:31 PM   #12
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Originally Posted by OldWEB View Post
I hope you do not apply the grease until the connections are complete. Dielectric grease is non conductive and is used to seal out moisture (corrosion).
Just checking.
Not too worried. I was an aircraft mechanic in the AF and was taught to do it that way. You may be right for loosely coupled connections but I always make sure connections are tight. It's been working for over 40 yrs so I gotta stick with it, ya know? It also does a great job at deterring corrosion. Thanks for trying to help though. Safe travels.
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Old 06-13-2020, 10:36 PM   #13
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Originally Posted by Chance View Post
There are many articles on this topic, the following being just one.

https://batteryuniversity.com/learn/...configurations

If upgrading to 4 batteries, I’d go with 2S/2P (Series/Parallel) configuration based on 6-Volt batteries. If you research it, most RVs that come from manufacturer with 4 lead batteries use 6-Volt batteries in 2Series/2Parallel configuration. I would personally avoid 4 X 12-Volt lead batteries all in parallel. Newer lithium batteries are a new exception because of battery management systems.


Regarding your 600-Watt coffee maker, that’s not really much juice for two good batteries. The inverter should pull in range of +/- 60 Amps at 12V, which is only 30 Amps per battery. If inverter trips out immediately on coffee maker start, there’s definitely a problem.

Do you know at what voltage the inverter trips? Some are around 11-Volts.

If you want to test batteries again under normal coffee maker load, but are by yourself, have you thought of temporarily moving coffee maker near batteries so you can check voltage when you turn it on? You’d only need an extension cord.

When troubleshooting I usually check the easy stuff first, particularly if it’s likely to be the problem. Bad batteries are a common problem and easy to check, so where I would start.
Thank you Chance, for the words and the link. I think you and Bob are right about the batteries. I found the sticker: 3/16. It's time to swap them out. Just FYI, this will be 4-12s either wet or AGM. Haven't decided yet.

Just for kicks, I checked them and they were 12.23v. I plugged up my phone (.5A) and my laptop (1.5A) with a 41% charge and fired up the inverter. Batts dropped to 12.15 on a 2A draw. They need replacin'

I may run my config past you once I'm done with my homework (reading), if you wouldn't mind commenting on it. Thanks again. Take care

One last note: the battery indicator light drops from good to low as soon as the coffee maker fires up.
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Old 06-13-2020, 11:10 PM   #14
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After reading both articles, I think I'm going to with something like the attached. Neither article addresses cycle life for the different configs, though Battery University did address that in 'Tapping A Series'.
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Old 06-17-2020, 08:31 PM   #15
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At 12.1 volts your batteries are too low to be useful.
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Old 06-17-2020, 08:40 PM   #16
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my inverter had this condition, and it was found that two cells in one of the four batteries were 'low', their specific gravity was not even registering - now, I originally 'refreshed' this battery by draining it, refilling with distilled water, charging overnight... again, and still again, then filling with battery acid. It solved the problem, the battery then worked fine, and with all four the inverter stayed solid when powering outlets and appliances for month, and months afterwards.

About a year later I replaced all the 5 year old batteries with Duracell GC2's from Batteries+Bulbs as they were also on sale there and at Sams Club for $99 each. What I liked about B+B is that they put them on a flat 'roller cart' and allowed me to wheel them out to my Motorhome, parked on the far other side of the large parking lot, and replace/install them there, at my leisure, and bring back the 'trade ins'...
I did replace two battery cables to provide a better 'connector' than the original, but otherwise everything was the same. These batteries have been installed for a year now, have a great time frame when on the inverter, and still look brand new, with no growths at the cable ends/terminals like the last ones.
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Old 06-18-2020, 12:50 AM   #17
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Thanks to everyone for your help, input and feedback. I bit the bullet last night and bought 4 wets to experiment with.

They're 109AH G27 DC and this is an experiment - how much can I get away with and still do what I need to? So far, the results are good. Question: how long will it last? Lithium is the last add to a solar build and I'm saving the most expensive component for last. I have a portable 1kw inverter I'm playing with and will hand that off to daughter when I'm done.

I took Chances advice and reference and ran 2 strings of 12. I joined the 2 strings at the breaker post on the battery box wall. I had to completely serialize the ground because I wasn't in a position to ground the other, though I think it'll help isolate the banks a little more. Could be wrong on that. It all ties together at the end of the day - somewhere.

I installed the batteries last night and they came in bundled at 12.25. I ran my inverter to use my laptop and charge my cell phone for about 2hrs @ ~4A draw and they dropped to 12.19 when I was done. I ran the gen for about an hour and was too tired to measure but it made coffee the next morning w/o a hiccup (600W) and I was a happy camper. So far so good. I think they measured 12.19 after that. I have to start keeping better notes.

I made a 2 hr run today and measured them after a 5m rest. They registered 12.97. I've been using them for 1.5hrs @ ~4.2A(avg) draw and they currently come in at 12.76. I don't know if that's good or bad but we'll see.

Again, thanks to everyone for their help. The forum is a good place to be. Safe travels.
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