Battery recharge on gen set.

Topic: Battery recharge on gen set. (Read 1053 times) previous topic - next topic

Battery recharge on gen set.

June 17, 2017, 03:57:15 pm

For you knowledgeable folks out there -

We have been doing a bunch of dry camping lately and am working hard to determine how our 12 volt system works.

Scenario - Been running on house batteries - 3 Lifeline 8a8ds - for 10 hours. It is hot here 90/95 deg. F. in the afternoon/early evening. From 6 PM to 8 PM we can run the generator to recharge the house batteries. 2 hours does not get us back to where we started, but that is another issue. Yesterday during gen run time we also had 2 A/Cs going.

Question - How do the A/Cs running effect the generator/inverter/charger system - typically? Prosine 2.5. Would the A/Cs running sap available power from the Prosine charger causing longer charging time to the house battery bank?

On a related issue, I can not find, in the Prosine Manual, how many Amps per hour the Prosine is supposed to charge. I realize that is contingent upon the battery state of charge is and what charging profile the charger happens to be in - ie: Bulk, Absorb or float. How can I verify what the charger is doing at any specific time during the recharge cycle(s). Our Magnum would show: Bulk, Absorb or Float but the Prosine apparently does not. Our Prosine does not have the upgraded control panel - just idiot lights.

We are in the Fruita Campground in Capitol Reef so our internet/cell access is only available when we drive the 8 miles to the nearest coffee shop so I probably won't see any responses, if any, for a couple of days.

Thanks in advance. Life is good.

Re: Battery recharge on gen set.

Reply #1 – June 17, 2017, 04:15:58 pm

Quote from: Carol & Scott – June 17, 2017, 03:57:15 pm

Scenario - Been running on house batteries - 3 Lifeline 8a8ds - for 10 hours. It is hot here 90/95 deg. F. in the afternoon/early evening. From 6 PM to 8 PM we can run the generator to recharge the house batteries. 2 hours does not get us back to where we started, but that is another issue. Yesterday during gen run time we also had 2 A/Cs going.

Question - How do the A/Cs running effect the generator/inverter/charger system - typically? Prosine 2.5. Would the A/Cs running sap available power from the Prosine charger causing longer charging time to the house battery bank?

My simple-minded answer (because that's the only kind I got):

You have (I assume) at least a 10Kw generator. It should have no problem running 2 air conditioners and simultaneously powering the battery charger. The A/C units running should not impact the battery charger performance.

Without knowing the specifics about your battery voltage and state of charge, both before and after your charging session, it will be hard for anyone to address your question. But in general, I would say "running on the house batteries for 10 hours" and then "charging them for 2 hours", is going to be a "losing ground" scenario. As you have probably guessed.

Solution: You will need to use less battery power, or run the generator longer, or plug in, or add solar. Take your choice.

Re: Battery recharge on gen set.

Reply #2 – June 17, 2017, 04:31:36 pm

Hey Chuck -

Thanks for the prompt response. You have confirmed my thoughts.

Late this year, I hope, we will replace the Prosine and add some solar to augment the gen set.

Re: Battery recharge on gen set.

Reply #3 – June 17, 2017, 04:35:42 pm

On the second part of your question, one simple solution would be to purchase a clamp on DC amp meter. Be sure it can read DC amps - many of them only work on AC circuits. Attach it to the cable running from your battery charger to the house batteries, and you can see exactly how many amps the charger is putting out at any given time. Once you know that, you could calculate how long it will take to replenish your batteries. Here is one example, but shop around for best price and features:

Amazon.com: Extech DC400 Mini 400A DC Clamp Meter: Industrial & Scientific

OR, you could install a simple "no-shunt" battery monitor to use until you get the new inverter. See this thread:

No Shunt Battery Monitor

As an Amazon Associate Foretravel Owners' Forum earns from qualifying purchases.

Re: Battery recharge on gen set.

Reply #4 – June 17, 2017, 05:17:01 pm

The two hour run time probably adds in bulk charge two hundred amp hours or so.

That gets you to 90 percent., will take 4 hours or so to get the last 75 amp hours at acceptance charging rate.

So you need to go between 50% SOC and the 90%. On your setup you have 750 amp hours to zero

So 50 to 90 is one half of 750 less ten percent=300 amp hours.

Lead acid's battery cycle life can be affected by the PSOC effect if done a lot. Plates sulphate.

Your lifelines are the only AGM's that can be equalized.

Plus their float voltage is 13.2 not 13.6 like the other AGMS or our gels.

If you have diminished capacity then careful equalization is needed and it might take multiple times to restore them.

If you wonder where I read this it was on the magnum me-50 control panels on line operating manual.

Not saying your AGM's need equalizing as careful notation of battery charging rates and/or a load test would be needed to show exactly what condition your are at.

The 50-90 percent was in the link 2000 operators manual for our old freedom 25.

Once the batteries get to the bulk charge set voltage the charger cuts the charge rate to maintain the set voltage. That's the last ten percent or so of acceptance charge to get to float

Re: Battery recharge on gen set.

Reply #5 – June 17, 2017, 05:36:59 pm

As said, A/C running has no effect on battery charging. The only (minor) effect would be if voltage were lower. Very much doubt it with your set up.

Most efficient use of generator run time (learned from months on a sailboat--no shore power). Discharge to 50%, recharge to 85%. Repeat all week. Once a week run until absorption phase reached (amps into batteries under 10 amps or so).

Running a generator each time to get above 85% is a waste of fuel. Not fully charging them once a week will shorten battery life.

Re: Battery recharge on gen set.

Reply #6 – June 17, 2017, 05:56:28 pm

Quote from: wolfe10 – June 17, 2017, 05:36:59 pm

Discharge to 50%, recharge to 85%.

What is considered 50% discharge, around 11.7 VDC?
Auto genset when selected is 12.2 VDC?

Re: Battery recharge on gen set.

Reply #7 – June 17, 2017, 06:09:15 pm

Quote from: Travelin' Man – June 17, 2017, 05:56:28 pm

What is considered 50% discharge, around 11.7 VDC?
Auto genset when selected is 12.2 VDC?

50% = 12.2 volts

Re: Battery recharge on gen set.

Reply #8 – June 17, 2017, 06:19:40 pm

Quote from: craneman – June 17, 2017, 06:09:15 pm

50% = 12.2 volts

Yes, 12.2 volts AS MEASURED WITH BATTERIES AT REST (no charging and no discharge for at least one hour).

If checked under load, voltage will read lower. We have all observed that battery voltage will RISE after a heavy load is turned off. There are also a number of battery monitor system that will count amp-hrs used. A good idea if you do a lot of dry camping, particularly if battery "care and feeding" is new to you.

Re: Battery recharge on gen set.

Reply #9 – June 17, 2017, 06:51:42 pm

Carol & Scott, Without all the good Magnum readouts, knowing the charge voltage & battery temperature will be an indication if the Prosine is in Charge or Float and if you are charging as fast as you can. As you said, only the battery itself determines the number of amps flowing. Increase the volts and the battery will accept more amps.

Re: Battery recharge on gen set.

Reply #10 – June 17, 2017, 07:40:38 pm

As others have said, the generator is best used to do a bulk charge of the battery bank and bring it up to 85-95% before it switches to absorption and then float. Once the bulk charge is completed you are at the mercy of the physics of battery charging at slower rates, and running a generator longer won't speed it up.

The situation you are describing is a time when a small or modest solar is a good addition after generator time is over. It doesn't have to be a big complicated setup, just something you can leave out in the sun for 6 or more hours to help move the batteries through the Absorption and/or Float stage.

Even a small 180 watt system (four 45 watt panels) can deliver up to 10 amps per hour. In good sun that's 60 additional amps between generator hours.

Chris

Re: Battery recharge on gen set.

Reply #11 – June 17, 2017, 08:37:17 pm

Our 270 watt puts out 14 amps optimally.

60-70 amp hours in a day does fill in the part from 85-90 to 100%

If we are down a lot of amp hours I know that over a few days it will bring everything back to 100%

The combiner helps as both battery systems where at float today when I turned the refer on for our Monday San Diego beach trip. 78 degrees.

Re: Battery recharge on gen set.

Reply #12 – June 18, 2017, 02:31:55 pm

TX guys.

Re: Battery recharge on gen set.

Reply #13 – June 19, 2017, 12:01:35 am

Update - Pulled out of Fruita CG today. 112 deg F and no A/C during most of the day. Gen times from 8 to 10 AM and 6 to 8 PM. Moved to Thompson Springs, just north of Moab today. Will stay here plugged in for 4 days then up to the Grand Junction area then on to Colorado Springs for a month. It's hot here too but we have 50 amp power.

Average temp in Capitol Reef is 85 this time of year, so we thought we might squeak by. 95/112 does not get it unless plugged in.

BTW - The Trimetric displays State of Charge, Battery Voltage and Amps in and out. Have tried to record the numbers during gen recharge times and dry camping times. Don't really know what it means yet but it clearly displays the loss of 2 to 4% of battery charge daily.

Solar will help during limited generator operation times, but staying out of HOT weather is a must.

Thanks for your input and suggestions.

Re: Battery recharge on gen set.

Reply #14 – June 19, 2017, 12:50:29 am

Sounds like you'll be much more comfortable. People say dry heat is better than humidity, but an oven is still an oven.

Extended dry camping in high temps is a challenge. A lot of people don't realize that the increase in ambient air temp inside the coach causes the fridge (both residential and LP) to cycle more to keep the proper temperature.

If you don't have any electrical items turned on, and you are seeing a 2% - 4% battery loss, this loss may be the parasitic draw from items such as LP solenoids, carbon monoxide detectors, inverter (even when in sleep mode when turned on), dash radios wired to the coach batteries, etc.

We found that successful extended dry camping requires knowing how many amps each of the coach's systems draw, knowing what parasitic draws exist, and then keeping track of 12 volt (and inverter) usage during the day. Good battery meters, and/or an amp clamp (digital volt meter with a clamp to measure amps) really help figure this out.

Figuring the coach's parasitic draws will teach you a lot about how the coach is wired. You need a time when you are not running anything, but are still not plugged in to shore power. Then you check your meter/amp clamp, start pulling fuses, checking the meter/amp clamp again, and write down what you find. You may be able to eliminate some of the draws by installing toggle switches on devices so they are only active when you want them to be.

Chris

Re: Battery recharge on gen set.

Reply #15 – June 19, 2017, 01:36:13 pm

Fruita Campground in Capitol Reef national park is really beautiful, but I didn't camp there in hot weather. The campground is located near the largest fruit orchard in the national park service so it's loaded with deer and birds. There's a different kind of tree producing fruit in the orchard at almost every time.

To fully charge your batteries quickly, crank up your coach and drive it on the highway an hour or so, then come back to your campsite. Leave something there on your campsite so someone won't move in while you're gone. The alternator will charge the batteries much faster than any other method. A bunch of people are gonna write in to say that you'll burn up your alternator this way but I do it all the time and so do other people on this forum. The alternator isn't very expensive and it's easily rebuilt or replaced if you do burn it up. New alternators are usually in stock at NAPA and you can change it yourself in the parking lot in a matter of minutes. Diesel gensets can cost $10,000 to replace or rebuild and some people on this forum have had to already.

There's a really nice hot weather campground I discovered up in the mountains in southern Utah. Maybe I should write about that now?

Re: Battery recharge on gen set.

Reply #16 – June 19, 2017, 04:57:02 pm

I have a 90 amp alternator driven by a 6hp (Powerfist) single cylinder (Horizontal shaft) engine and a fan belt.
I built it using a plate of steel purchased from The Epicenter in Eugene, Oregon who provides emergency preparedness kits and advice.
I have not started or tested it yet, but will soon.

Re: Battery recharge on gen set.

Reply #17 – June 19, 2017, 05:03:21 pm

Put solar on the roof and trickle charger run off the inverter and the engine batteries will never need charging.

Pierce

Re: Battery recharge on gen set.

Reply #18 – June 19, 2017, 06:18:58 pm

Quote from: Pierce & Gaylie Stewart – June 19, 2017, 05:03:21 pm

Put solar on the roof and trickle charger run off the inverter and the engine batteries will never need charging.

Pierce

Using solar to make 12 VDC, an inverter to "invert" that to 120 VAC then a trickle charger to convert that back to 12 VDC is a bit wasteful.

There are a number of good battery combiners that will connect the battery banks above a pre-set voltage and separate them below that. Solar to make 12 VDC. Battery combiner to charge house bank first, and then chassis bank when house bank up to pre-set voltage.

Agree, either will work, one is just more efficient.

Re: Battery recharge on gen set.

Reply #19 – June 19, 2017, 06:36:32 pm

Quote from: wolfe10 – June 19, 2017, 06:18:58 pm

Using solar to make 12 VDC, an inverter to "invert" that to 120 VAC then a trickle charger to convert that back to 12 VDC is a bit wasteful.
There are a number of good battery combiners that will connect the battery banks above a pre-set voltage and separate them below that. Solar to make 12 VDC. Battery combiner to charge house bank first, and then chassis bank when house bank up to pre-set voltage.
Agree, either will work, one is just more efficient.

Brett,
You are splitting hairs!

With the inverter on for the TV, etc, the tiny amount needed for the trickle charger is essentially nothing. In other words, I don't turn on the inverter to charge the engine batteries. I never leave the coach with the water pump or inverter on so the only draw is when the inverter is on for TV at night or the latte maker/microwave in the morning. This is way more that enough to overcome the very small parasitic draw on the engine batteries. With the amount of solar we have on the roof, it overkill for whatever we want to do. I believe in the KISS logic and this is about as simple as it can be. Battery combiners just add complexity to an already overly complex coach.

Using my trickle charger, it automatically starts charging the engine batteries as soon as I connect to shore power either at home or an RV park. I don't have to do a thing aside from plugging into power.

Pierce

Re: Battery recharge on gen set.

Reply #20 – June 19, 2017, 08:20:44 pm

Have to agree with Brett on this one. Have been using combiners since they first came out for the boating industry. Have never had a problem with them, and can turn the inverter off and still have a charge on both banks with solar, and not have to worry about any 110 sources. I have had several inverters that have stopped inverting. That being said, have never received a bill from the solar electric company.
Jim C.

Re: Battery recharge on gen set.

Reply #21 – June 19, 2017, 09:32:13 pm

I'm just learning here so this a question, not an opinion. I read this article and wonder how using a combiner as described in this thread avoids the "cycling" described in the article.

Preventing Cycling in Battery Combiners, Voltage Sensitive Relays, and...

Thanks

Randy

Re: Battery recharge on gen set.

Reply #22 – June 19, 2017, 09:41:53 pm

Scott
Here is your manual.
John M

http://www.xantrex.com/documents/Inverter-Chargers/PROsine-3/ProSine_25-30-Owner-Guide(445-0096-01-01_Rev-A).pdf

Re: Battery recharge on gen set.

Reply #23 – June 19, 2017, 09:48:16 pm

Quote from: floridarandy – June 19, 2017, 09:32:13 pm

I'm just learning here so this a question, not an opinion. I read this article and wonder how using a combiner as described in this thread avoids the "cycling" described in the article.

Preventing Cycling in Battery Combiners, Voltage Sensitive Relays, and...

Thanks

Randy

If you read the solution section, you will see the way to overcome the problem. Solar and inverter chargers are normally connected to house batteries. Also unlike fishing boats which may start and move short distances, shutdown and restart. Motorhomes will start and move a good distance. In this case the alternator is charging both batteries through the isolator and the combiner is just an add on. Have used combiners on coaches for many years and have never seen the cycling mentioned, and have never seen discharged start batteries.

Re: Battery recharge on gen set.

Reply #24 – June 19, 2017, 11:32:18 pm

John -
Thanks for the manual. I do have it but I could not find the Info I was looking for - or more probably did not understand the language that it used.

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