New 6v house batteries & main battery losing charge

[PinkLeopard]

Replaced 2-6 volt house batteries because they weren't holding a charge. Immediately afterwards voltage dropped rapidly to about 12.8. Checked water - it's ok. Charged with generator and shore power to 13.6 but they're not holding a charge.

[wwest]

JQgolf wrote:
I have a related question on batteries. I also have two 6v house and a 12v chassis on my 2011 Itasca F53. Can I charge my 6v with a battery charger plugged in to generator w/o unhooking batteries from the coach?

NO...


Have never seen clear answer on this? We normally have hookups on most of our trips but on upcoming trip, we may have some one night stops w/o hookups plus a 7 day stop at Jasper NP w/o hookups.

No battery can be fully charged, correctly charged, while remaining under a significant load level. That's why most modern day inverter-chargers isolate the battery from the load when the inverter section is powered.

[wwest]

deleted

[MrWizard]

According to this website
http://www.tripplite.com/sku/RV750ULHW/

It is a combo inverter & charger and has a selectable charge rate, either 11 amps or 45 amps, selectable using DIP switches

Find the manual, and check the switch setting for the charge rate
Other switches control over voltage protection, where shore power is disconnected and inverter turns on, this will only be for circuits that are using the inverter circuit, most likely the entertainment circuits and some 120v residential lighting

[JQgolf]

I have a related question on batteries. I also have two 6v house and a 12v chassis on my 2011 Itasca F53. Can I charge my 6v with a battery charger plugged in to generator w/o unhooking batteries from the coach? Have never seen clear answer on this? We normally have hookups on most of our trips but on upcoming trip, we may have some one night stops w/o hookups plus a 7 day stop at Jasper NP w/o hookups.

[myrtle_beach_rv]

MrWizard wrote:
With your RV it should have a good 3 stage smart charger

Why not give us the converter/inverter info, model# etc..

Thank you for the battery info royb. Mr.wizard my inverter is a
Tripplite RV750ULHW

[Golden_HVAC]

RoyB wrote:
Consider this handy STATE OF CHARGE chart...


Also consider this report from Progressive Dynamics on how long it takes to charge a deep cycle battery.

"Progressive Dynamics ran this test on the amount of time it took a PD9155 (55-amp) converter/charger set to three different output voltages to recharge a 125 AH (Amp Hour) battery after it was fully discharged to 10.5-volts.

14.4-VOLTS (Boost Mode) – Returned the battery to 90% of full charge in approximately 3-hours. The battery reached full charge in approximately 11 hours.

13.6-VOLTS (Normal Mode) – Required 40-hours to return the battery to 90% of full charge and 78-hours to reach full charge.

13.2-VOLTS (Storage Mode) – Required 60-hours to return the battery to 90% of full charge and 100-hours to reach full charge."

This is battery charging science - not many ways to get around it...

When camping off the power grid you want to watch your battery voltage and when it gets down to around 12.0VDC (approximately 50% SOC) then you want to do a smart mode charge starting out with 14.4VDC for two hours and dropping back to 13.6VDC for another hour (three hours total) to get your battery back up to its 90% SOC. Then the battery will perform almost like it would if it had a 100%SOC. You can do around 12-14 cycles of the 50% to 90% SOC rates but will have to perform a full 100%SOC after that to keep from doing damage to your batteries.

When charging with the higher DC Voltage the battery will draw the proper amount of DC current to complete its charge cycle. Then it rest back to 12.6VDC showing you it is at a 100% SOC. Your battery will usually rest at full charge of 12.6-12.7VDC after being charged at 14.4VDC and 13.6VDC for three hours...

Something like this at any rate haha..
Roy Ken

This is a very good chart to indicate what voltage the battery will be at while discharging.

Yes charging at 14.4 volts is acceptable (if you are on a generator and want to minimize generator run time and will not mind the battery getting warm and losing water)

Sometimes I would do a "Equalize charge" - that is charge the battery fully with shore power, then let my 10- 15 amp solar charger fully charge the battery, a bit of overcharge at up to 15 volts. While this can heat up a battery and cause a lot of water loss, I would only do this about every 2-3 months and just after filling the battery with water, and then check it again afterwords. This will break up any sulfur deposits on the battery plates and leave it clean. But doing this more often than 4 times a year can lead to less battery life. Charging a AGM battery above 14.0 volts can shorten it's life a LOT because you can not add water to them.

Fred.

[Golden_HVAC]

PinkLeopard wrote:
Replaced 2-6 volt house batteries because they weren't holding a charge. Immediately afterwards voltage dropped rapidly to about 12.8. Checked water - it's ok. Charged with generator and shore power to 13.6 but they're not holding a charge.

Seems normal to me.

12.8 is the highest voltage that flooded lead acid battery will sit at when it is full of power.

You might be expecting something else, but the rest of us are not.

13.6 volts is the normal charge battery (power flowing slowly into the battery). Say up to 5% of the battery capacity per hour - thus 220 amp hour golf cart battery might charge up to 11 amps per hour when the battery is between 90 and 99% full, while at 13.6 volts charging.

13.2 is a normal "Float" charge, say if the charger is well designed, and the battery will not overcharge, and will not be discharging, or charging rapidly. It might be charging very slowly, like less than 5 amp hours per hour.

12.8 volts is the normal "Full" battery resting voltage, say when it is between 90 and 100% full. 12.7 or 12.6 would indicate 80 - 85% full.

11.5 would be the lowest I would allow my battery to go without recharging, and normally I would not let them get that low. Kinda like running your car until it is well below the E on the gas gauge. Better to refill at 1/4 full. Much better to refill at 50% discharged, the battery life will last much longer if you recharge the battery before it is less than 50% full.

The RV will use about 35 amp hours per day if the CO and propane detectors are left on all the time and the RV is not plugged in. If you only have a 15 watt solar panel, then that will not keep up with normal usage, even if all the lights are left off and the furnace is not run.

One of my 120 watt solar panels can make about 35 amp hours daily, and keep the battery full.

Fred.

[CT_WANDERER]

Don't you have a converter? That should charge your battery.

[MrWizard]

With your RV it should have a good 3 stage smart charger

Why not give us the converter/inverter info, model# etc..

[myrtle_beach_rv]

myrtle beach rver wrote:
New question which will charge coach batteries quicker/better absent an ac charger the generator 7 kw or the alternator?

What if I don't have ac charger with me just generator or engine alternator

[lanerd]

Let me ask you a question. Once your batteries have been on the charger overnight and then you remove the charger.....exactly what are you expecting the voltage to be on the batteries?

Charging voltage is different from the battery voltage. You can't expect the batteries (once charged) to stay at the charging voltage rate. They will automatically drop down to their "full charge state" which is 12.6 to 12.8 volts.

I think you are making much to do about nothing.

Ron

[jorbill2or]

From what you describe there is nothing wrong with your batteries ..while Under use voltage does drop. If your reading it while using it
I think the Trojan batteries were fine 😞 they should last years esp if you test them and they can hold 12.6. + volts

[time2roll]

^^^^ The generator powering the ac charger is usually fastest.

[myrtle_beach_rv]

New question which will charge coach batteries quicker/better absent an ac charger the generator 7 kw or the alternator?