Trojan battery charging advice please

[Mike90250]

When I run my genset, I charge till the amps the batteries are drawing, start to drop off.
My generator can manage 35A @ 60VDC (plus my AC loads), when the DC amps drop to 20, I shut down the generator.

[hammick]

Is the charging done by commercial AC power or generator as most hybrid systems do?

My place is completely off grid. It has no possibility of grid power in my lifetime.

My charging will be through the Conext MPPT-60-150 charge controller and supplemented by generator if needed.

[Sunking]

My charging will be through the Conext MPPT-60-150 charge controller and supplemented by generator if needed.

It will be needed frequently and likely the only way you ever get a full charge. amd absolutely required for Maintenance and EQ charge. If not, you are in for frequent battery replacement. EQ charge can be as long as 24 hours.

[hammick]

It will be needed frequently and likely the only way you ever get a full charge. amd absolutely required for Maintenance and EQ charge. If not, you are in for frequent battery replacement. EQ charge can be as long as 24 hours.

Sunking I hope you are wrong. I'm hoping to not go below 80% SOC and be fully charged by early afternoon. I'll report back next summer. I know I'll need the generator if I'm there in the Winter, Spring or Fall.

Thanks for all the info.

[Sunking]

Sunking I hope you are wrong. I'm hoping to not go below 80% SOC and be fully charged by early afternoon. I'll report back next summer. I know I'll need the generator if I'm there in the Winter, Spring or Fall.

Thanks for all the info.

Sumeer should be no problem, it is the shorter daylight months that get you.

[hammick]

Summer is my only real concern. I won't be up there much in Fall and Spring and not at all in the dead of winter.

[Sunking]

Are you bringing those batteries home?

Or are you leaving them for me and my friends to find? Those bright shiny reflectors of Solar Panels will lead us right to them. If we do not find them sitting idle for 8 months going through a charge cycle every day and you run a high risk of drying them out. If that happens game over.

[hammick]

No I plan to equalize them the day before I leave (with generator if needed) and top off with distilled water if needed. My closest neighbor is retired law enforcement and is there full time. There is only one road in and the neighbors six miles down with power keep a good eye on any strange vehicles. Very possible that in Jan and Feb the road is impassible at time due to drifting snow.

A neighbor that lives six miles away has offered to check the fluid levels.

I am hopeful that having the Trojan RE batteries, Water Miser caps and the batteries just being on float all winter will let me get by for four months without adding fluid.

I will remove the string handles to hinder any random thief from stealing them. Pretty sure they will focus on the other toys that are separately insured. Obviously if somebody really wants them they will get them.

My closest neighbor has gone four years now with no security issues. He has regular L16 430ah Trojans. He is running a lot more loads than I have planned. In addition to the well pump that I will run he is running forced air heat, washer and propane dryer, fridge a lot bigger than I will have and a much bigger living quarters.

[TommyDre]

This seemed like a good thread to post this question. I have 4 Trojan L16RE-B batteries on the way. I'm putting the batteries in the basement of my barn to help run my freezer. I plan on connecting the batteries for 24 volt use and have an inverter run my freezer. I have two pigs in that freezer and with this warm winter weather I'm interested in giving my generator a break from everyday use. The basement is ambient temperature to whatever the outside temp is. According to my kill a watt meter the freezer draws approx 1.03 amps/ 0.1 Kwh per hour. Does it seem feasible to any of you that I could run the freezer for two days off the batteries and then charge the batteries on the third day with my generator while also running the freezer? Without destroying my batteries? And any suggestions on a charger that can charge at 24 volts? I don't have grid power and won't for some time. The small Renogy 12 volt, 400 watt, solar array that I have isn't up to the task of charging these batteries. At 1.9 hours of insolation in the winter I I think there is enough time to charge those batteries off of solar no matter the size.

[sensij]

This seemed like a good thread to post this question. I have 4 Trojan L16RE-B batteries on the way. I'm putting the batteries in the basement of my barn to help run my freezer. I plan on connecting the batteries for 24 volt use and have an inverter run my freezer. I have two pigs in that freezer and with this warm winter weather I'm interested in giving my generator a break from everyday use. The basement is ambient temperature to whatever the outside temp is. According to my kill a watt meter the freezer draws approx 1.03 amps/ 0.1 Kwh per hour. Does it seem feasible to any of you that I could run the freezer for two days off the batteries and then charge the batteries on the third day with my generator while also running the freezer? Without destroying my batteries? And any suggestions on a charger that can charge at 24 volts? I don't have grid power and won't for some time. The small Renogy 12 volt, 400 watt, solar array that I have isn't up to the task of charging these batteries. At 1.9 hours of insolation in the winter I I think there is enough time to charge those batteries off of solar no matter the size.

That is 1.03 A at 120 V? If your inverter is 90% efficient, that is 137 W of power. If you don't discharge your batteries below 50%, they could supply maybe 4 * 370 Ah * 6 V * 0.5 DoD = 4440 Wh daily, or about 32 hours of run time... maybe not enough to get through two full days, depending on how often the freezer cycles. If you let the Kill-a-Watt run for a full 24 hours, what is the total?

[TommyDre]

It was 1.03A at 120 volts. I ran my generator for 10 hours and it remained at about 1.03 A from what I could tell. The kill a watt didn't give a cumulative value for the A used. But it did give the cumulative for the kWh hour and that broke down to 0.1 kWh per hour. I've been cycling the freezer, on about 5 hours off 6. Based run time on the interior temperature of the freezer from 0 to 20 degrees F. This is the first time I've ever used the generator for something like this. I generally use a propane refrigerator for my needs, but I couldn't put the pigs in that. So for the next several weeks I have to run the freezer until I distribute the cuts to my family. And the warm winter weather has caught Central Virginia by surprise. 60's to 70's is not typical winter weather. I will run the generator for 24 hours next week. The forecast is calling for about 20 degree cooler temps. My caretaker's while I am away will run the generator based on freezer temps like I have been doing in the meanwhile. I would like to use the batteries in a 24 volt configuration.
I was thinking of buying a Samlex 24 volt inverter either in the 1000 or 2000 watt range. I'm using my Honda eu2000i generator to run the freezer right now.

[Sunking]

You do not need solar panels.

AC Charger > Batteries > Inverter.

Basically you are building a Dual Conversion UPS which means you use a Rectifier (battery charger) to charge the batteries and run the Inverter. Under normal conditions the batteries sit there and do nothing just like solar during the day. The charger is supplying all the power to the Inverter. If power fails, the batteries are already online and take over with no interruption. When commercial power is restored, the batteries are recharged and wait until needed again.

The beauty is in the design. You size the battery to run the load. for a reasonable amount of time like 24 hours. Commercial UPS only use 30 minute to 1 hour just long enough to get the generator to take over. But we can borrow from the commercial idea and tweak it. Put in a battery that can last 1 hour, 10 hours, 24 hours, or a week.

So let's say 24 hours, and in 24 hours your fridge uses 1.2 Kwh. You can run either 12 or 24 volt battery with 1.2 Kwh. For the battery you want to discharge it to 50%. So the battery capacity needs to be 2.4 Kwh. So at 12 volts needs to be 2400 watt hours / 12 vols = 200 Amp Hours or a pair of 6 volt golf cart batteries. For 24 volts 100 AH or 2 12 volt golf cart batteries.

The charger needs to be sized to run the load and charge the battery at the same time. So you want to charge at C/8 or 8 hour rate. So at 12 volts needs to be a 25 amp charger or 15 amp charger for a 24 volt battery. For th einverter you want a True Sine Wave model rated twice the size of the load. So if you fridge uses 150 watts, you want a 300 watt Inverter and up to 500 watts.

For an extended outage longer than 24 hours, plug the charger into a generator to recharge the battery and turn th egenerator of for 24 hours. Repeat as necessary.

If it a lot less expensive and more reliable than solar. It will also double to tripple the battey life because the battery is not cycled every day. So in th elong term is way less expensive because you do not have to replace a $400 battery every year or two.

[TommyDre]

OK Sunking, Thanks for that response. I had been thinking I would have the freezer plugged into the generator, the charger plugged into the generator, and I would unplug the freezer and plug it into the inverter to run the freezer. completely wrong. Plug the freezer into the inverter and leave it plugged in. I'm basically going to have planned interrupted power supplies by turning off my generator for a certain timeframe to let my freezer run off the batteries, and then run the generator to charge my batteries back up. And so on. An altered UPS I guess.

I want to be able to go two days without charging the batteries. Since my freezer draws 0.1kWh per hour, that equals 2.4 kWh per day. discharging my batteries to 50% means my battery capacity needs to be 4.8 KWh for one day. Multiple that by two days and I need 9.6 kWh. At 12 volts that means an 800 amp hour battery. At 24 volts that means a 400 amp hour battery.

I had planned on getting 4 Trojan L16RE-B batteries configured for 24 volts. But the 20-hr rate for those batteries is 370 amps. Not enough for two days. They cost $394 per battery and I would need more than 4, perhaps 6 for a 36 volt system. that's an odd number that basically costs $1600.

So instead I need to buy 2 of the Trojan IND17-6V which has a 20-hr rate of 925 amp hours. They cost $1287 per battery. Plus tax. With those two batteries configured to 12 volts I have only one string of batteries that exceed my 2 day requirement with a little wiggle room. Do you numbers add up by your reckoning? I'll need that wiggle room as my nephew helps me watch my hobby farm and I can tell him that we run the generator on a Monday, Wednesday, Friday schedule, which will be easy for him to remember. I have a Samlex 12 volt, 2000 pure sine wave inverter that was given to me as an xmas present. I had planned on returning it and getting a 24 volt inverter. do you think that is too much inverter. I've ready your sticky on inverters n the 12 volt range and the amps flowing through them. I was leery about 12 volt all together, but it seems to be the best way to go. I still need to get an appropriate charger.

[Sunking]

I want to be able to go two days without charging the batteries. Since my freezer draws 0.1kWh per hour, that equals 2.4 kWh per day.

STOP.

I seriously doubt it uses 2.4 Kwh per day unless this is a 1950's model freezer. Yes it tmay use 100 watts running, but it does not run all day. You did this wrong with your Kwh meter. To get accurate it needs to run a week. Example start today at say 6:00 pm. Let it run one week util 6:00pm. Say it reads 7 Kwh/7 days is 1 Kwh per day. Otherwise you are going to eff yourself out of a lot of money. .My educated guess which is pretty good is it use less than 1 Kwh per day. Only way you are going to know is a long term test.

[TommyDre]

I'll grant you this, it would be best to run the freezer for a week to get a good baseline. I know I'm reading the kill a watt correctly. I punched the model number of this freezer into google. It seems there is a rebate being offered by the manufacture after the Dept of Energy(for what that is worth) tested several different units off the store self and determined that they are using a helluva lot more electricity than the model is advertised to use. Over 50% more than the stated energy usage.

The freezer was free. I got it from my brother, by way of his daughter using it for a couple of years and not needing it anymore. Sometimes free can be costly. But not today. I'll run the week long test, I'll bring it a friends garage as I'm not running that generator for a week straight. and probably see about getting a different freezer. I have a lot more pigs that are going to be going through my freezer soon. Thanks for your patience and help with the questions.