Electrical/Battery issue.

[msmith1199]

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.

[MNRon]

Does AC mean one or two 15kbtu ACs (thanks rjstractor)? If two, most likely that sucked up most of the power the genny could provide and starved the battery recharge. I don’t know what converter you have, but if standard it probably can’t provide more that ~50A per hour to the batteries (or less); that would require 4hours of charging for two fully depleted 100AHr batteries.

[Krusty]

If you check the voltage at the converter and it's 14.5 volts and you only have 13.6 at the batteries, that is almost a 1 volt drop and may not be helping your situation. Might be a loose or corroded connection somewhere between batteries and converter. Check all your connections and check for voltage drop wherever you can

[msmith1199]

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.

[opnspaces]

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.

[msmith1199]

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.

[msmith1199]

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?

[nickthehunter]

How big a generator are you using?