Question about electrical issue.I have two 100 watt LiPo batteries. Been dry camping for 7 days now. The first 3 were on the road so batteries were charged by alternator for the first three and the generator only for the last 4. Everything has been going fine until last night. I turned the generator off at 10pm and it had run at least 5 hours during the day, maybe more. But at 1am my batteries died. I knew they died because my CPAP tried to suffocate me! :). I have a residential fridge and my Satelite receiver was on, but other than those and CPAP there wasn’t much other electrical draw. So the only thing I can conclude is for some reason the batteries didn’t fully charge. They are charging today and I can get power out of the inverter so I know the charger is working.I’m not much of an electrical guy but I check the voltage at the converter with the generator running and it’s at 14.5 volts. The voltage at the batteries both with the generator running and without is 13.6 volts. I think those numbers mean it’s should be working fine.The only thing I did different yesterday over any of the other days is whenever I had the generator running I had the A/C on. Is it possible all the power was taken by the A/C and wasn’t going to the converter to charge the batteries? That’s the only thing I did different yesterday over the others.

How big a generator are you using?

Onan 4000 watts. I just got an email back from the manufacturer of the converter who suggested maybe I’m not running it long enough. I would have thought 5 hours would be plenty of time, but maybe they take longer to charge?

Not to mention I had just had it running from 8pm to 10pm before shutting it off for the night and the battery was too dead to power the inverter by 1am. That seems odd. The batteries did have enough power left to start the generator again, but you could tell they were weak.

If the generator was running during the AC use then it's not very likely the cause of the batteries going dead.Did you by chance plug your shore power cord into the inverter? That will setup a loop of using battery power to try to charge the batteries which is a losing endeavor.

opnspaces wrote:If the generator was running during the AC use then it's not very likely the cause of the batteries going dead.Did you by chance plug your shore power cord into the inverter? That will setup a loop of using battery power to try to charge the batteries which is a losing endeavor.No.

Electrical/Battery issue. | Good Sam Community

msmith1199
Explorer II
Jul 24, 2023
Yes, I meant AMP. Told you I’m no electrician! And it’s only one A/C. I’m guessing I wasn’t at full charge, but I don’t understand exactly why. Like I said, I’m on day 7 and every other day there was power in the batteries to last all night. And when starting the generator the next morning you can tell the batteries were still strong. Just wondering why on night 7 it didn’t work. The tech department at the converter maker said it’s possible I was simply using 5% a day more power than I was charging and by the 7th day that resulted in a 35% loss so that’s why it gave out on the 7th day. I’ll run the generator longer today and see what happens tonight.
CA_Traveler
Explorer III
Jul 24, 2023
OP Your posts suggest that over the 7 days you used 160AH (80%) of your batteries that was not replenished due to inadequate charging. It's likely setup for flooded batteries and not for the LiPo batteries.

Your A/C is not the cause. If your A/C plus charger tried to draw more AC amps that the CB rating then the CB would have tripped on the gen.
pianotuna
Nomad III
Jul 24, 2023
The OP is seeing 14.5 volts when the generator is running.

I wonder why the batteries are not fully charging when presented with that?
ScottG
Nomad
Jul 25, 2023
From your orig post "The voltage at the batteries both with the generator running and without is 13.6 volts. I think those numbers mean it’s should be working fine."
13.6 is not going to charge Lithium batteries. Something is very wrong between the converter/charger and your batteries. You should be seeing well over 14V.
msmith1199
Explorer II
Jul 25, 2023
CA Traveler wrote:
OP Your posts suggest that over the 7 days you used 160AH (80%) of your batteries that was not replenished due to inadequate charging. It's likely setup for flooded batteries and not for the LiPo batteries.

Your A/C is not the cause. If your A/C plus charger tried to draw more AC amps that the CB rating then the CB would have tripped on the gen.

It’s set for LiPo
msmith1199
Explorer II
Jul 25, 2023
ScottG wrote:
From your orig post "The voltage at the batteries both with the generator running and without is 13.6 volts. I think those numbers mean it’s should be working fine."
13.6 is not going to charge Lithium batteries. Something is very wrong between the converter/charger and your batteries. You should be seeing well over 14V.

The converter is putting out the 14.5. The 13.6 is at the battery. According to sources I looked up, 13.6 indicates a fully charge LiPo battery. So I don’t know if it’s supposed to show 14.5 at the battery when charging or if it’s correct in showing 13.6 even when charging.
wa8yxm
Explorer III
Jul 25, 2023
What is the make and model (And ampreage) of your converter

You have 300 amp hours of batteries. Let's say you use 80% (240 amp ours)

Well converters can be as low as around 20-25 amps or as high as 100.
To replace 240 amp ours will take at least 250 amp hours.. 25 amps that's 10 hours in theory.. but wait there's more.

As the battery charges the converter "Backs down" a bit so it might take 12 or more.. and if it's not a LI-charger (Still an LA charger (Lead acid) it may well never it 100% because it simply has not the push to do it.
3.4 volts resting. 3.65 charging times 4 cells = 13.6 volts resting and 14.6 charging.... Many converters are 13.6 Float(that's good) and some that's all they do and 14.2-14.5 Boost/Absorption (Not enough) to fully charge LiFePO4.
(Voltage source google)
msmith1199
Explorer II
Jul 25, 2023
Okay, batteries lasted all night and showed fully charged still this morning. I ran the generator longer yesterday and reduced power consumption so I don’t know which one really fixed the problem. But the problem is solved. I’ll just keep that pattern going.
wolfe10
Explorer
Jul 25, 2023
msmith1199 wrote:
The converter is putting out the 14.5. The 13.6 is at the battery.... So I don’t know if it’s supposed to show 14.5 at the battery when charging or if it’s correct in showing 13.6 even when charging.

The only reason for a higher voltage reading at the converter than at the battery bank is RESISTANCE between the two. Could be a connection at one end or the other, could be a fuse (if there is one) between them, could be too small a gauge wire.

And, the lower the charge rate, the less voltage drop you should see.
theoldwizard1
Explorer II
Jul 25, 2023
msmith1199 wrote:

I have two 100 watt LiPo batteries.

I assume you mean 100 Amp-hour (Ah) batteries. I also assume you have LiFePO4 batteries)
msmith1199 wrote:

Been dry camping for 7 days now. The first 3 were on the road so batteries were charged by (vehicle) alternator for the first three and the generator only for the last 4.

The power source is not the issue. What are you using for charging ?

Hooking directly to your tow vehicle 12VDC is NOT the best way to charge yoiur batteries. You will never get 100% fully charge that way. You really should be using a DC-DC charger with output settings for LiFePO4

Second, a "standard" converter is NOT the best way to charge your Li batteries either. You will never get 100% fully charge that way. Get a converter that is designed to charge Li batteries.

Better yet, remove the converter and your current inverter. Replace them with a combination charger/inverter/automatic transfer switch. Wire your 12VDC circuit directly (via a fuse) to the battery bank

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