# Renogy batteries

Solar Expert Posts: 92 ✭✭✭
edited February 2019 #1
Anyone familiar with Renogy batteries?  I'm looking at buying 4 of these, but just want to make sure that they are decent.

https://www.renogy.com/renogy-deep-cycle-agm-battery-12-volt-200ah/

This is for RV/mobile use, charging from solar, AC charger, and car alternator.  Constant low draw in the 5-10 amp range, with occasional high current demands like a microwave (160 Amps for 60 seconds sort of thing).

Just a suggestion, I personally like to use 6 volt (or other batteries with few cells) to make into a series string, then parallel them.

Especially with AGM batteries, the only way you can monitor the health of individual batteries is to measure the voltage across each battery. Then you can tell if you have a weak/problem battery with a simple voltmeter reading across each 6 volt battery.

With 12 volt batteries in parallel, the battery bus voltage is the result of the highest voltage of one of all the parallel cells. So, you are left having to disconnect each battery and letting it rest a few hours, to read the "true" battery voltage.

For example, if you get 8x 6 volt @ 200 AH -- Put two batteries in series (makes a 12 volt @ 200 AH "string"), then parallel 4x strings, you have your 12 volt @ 800 AH battery bank.

Another question... 4x 12 volt @ 200 AH = 12 volt @ 800 AH battery bank. That is a pretty good size battery bank. You are about at the dividing point where you may want to think about a 24 volt @ 400 AH battery bank. It allows you do use smaller AWG wiring (save on copper costs, 1/2-1/4 thickness wiring also is easier to terminate and route). Although, for RV use, many choose to stay with 12 VDC to run easy to obtain 12 VDC lighting and appliances.  Although, there are a fair amount of 24 VDC devices out there too (heavy truck, marine).

Another issue is paralleling a relatively large numbers of batteries... Wiring needs to be well thought out:

http://www.smartgauge.co.uk/batt_con.html

And, ideally, each battery string should have its own fuse/circuit breaker (in case there is a short circuit/somebody drops a wrench on the battery connections, etc.).

I, personally, like to limit a design to 3 parallel strings... And I prefer 2 parallel or 1 string if possible. So, looking at larger AH batteries (or even cells) is a possibility:

Here is an example of "2 volt" single cell batteries:

https://www.solar-electric.com/residential/batteries-battery-storage/deep-cycle-batteries.html?nav_battery_type=443&nav_battery_voltage=387

https://www.solar-electric.com/concorde-sunxtender-pvx-7680t.html (2 volt, 768 AH, 75 lb, \$370 each--Use 6x series for 12 volt @ 768 AH)

And back to the 800 AH battery bank... ideally, you want 5% to 13% rate of charge, with 10%+ being better for full time off grid usage (vs weekend/summer use).

10% of 800 AH is 80 Amp charging current nominal. If you are using solar panels for all of that charging:
• 800 Amp*Hour battery bank * 14.4 volts charging * 1/0.77 panel+controller derating * 0.10 rate of charge = 1,486 Watt array nominal
If you are planning on using for winter sports--Solar is generally difficult, especially the farther north you go.

Generally, for an off grid home, we suggest 2 days storage and 50% maximum discharge (for longer battery life). For RV use, 1 day storage and perhaps even deeper discharge is "better" (smaller, lighter, cheaper battery bank). Sizing your battery bank for maximum DC load:
• 160 Amps * 5 hour discharge rate = 800 AH for a Flooded Cell Lead Acid battery (max suggested for FLA)
• 160 Amps * 2 hour discharge rate = 420 AH for an AGM bank (perhaps even 1 Hour or faster discharge OK)
And use a genset during the day for normal/heavy loads. And just use a smaller battery bank at night for quiet time loads.

Use a 600 Watt microwave (~900 Watt 120 VAC load) to reduce your peak current draw is helpful too.

https://www.amazon.com/Counter-Rotary-Microwave-WCM660B-Westinghouse/dp/B00BGTO1WC

-Bill
Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
• Registered Users Posts: 4,478 ✭✭✭✭✭
At ~ 130lbs each, I wouldn't want to have to shift them around much in a confined space.  Might be ok if they can slide right into an externally accessed compartment though.
Off-grid.
Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
Night system ~1kw panels into 1xMNClassic150 700ah 12v bank morningstar 300w inverter
• Solar Expert Posts: 92 ✭✭✭
Yes to both.  The batteries will be fixed; one 200Ah bank on a trailer and 600Ah on the tow vehicle.  Accessible from the outside.  I get the wiring requirements, although I've never used the third one (AFAIK RVIA code limits you to 3 connections on a post so you'd need a tree-like distribution system.) The fourth one is a head scratcher; I'll have to look at it some more.

In the past I've always used 2 - 6V batteries in series, wired like the second diagram.  In the spaces I work in, it's not always possible to set up the batteries in an ideal location.  My current setup has one pair under the hood, and two pairs behind the rear axle.  Batteries in RVs are a wear item anyway and they're generally not well treated, so I just budget for replacement every few years.  Charging is from either a charger or the vehicle alternator, with solar for maintenance charging (I'll be lucky if i can put 800W of solar on all told).

I came across the Renogys as they seem to be cheaper than 2 - 6V AGMs and slightly more compact.
• Solar Expert Posts: 3,480 ✭✭✭✭

I know a 60 year old solar installer who struggles with carrying 110 pound solar batteries and that problem started a few years ago. Of the same age, I carried and installed ten 170 pound solar batteries fairly recently. Definitely got my attention.

I suspect that most people will know what their limitations may be and most have access to help when needed. I think the advantages of greater mass/weight outweigh the temporary "struggle" of installing them. Plus engine hoists are pretty easy to rent.

First Bank:16 180 watt Grape Solar with  FM80 controller and 3648 Inverter....Fullriver 8D AGM solar batteries. Second Bank/MacGyver Special: 10 165(?) watt BP Solar with Renogy MPPT 40A controller/ and Xantrex C-35 PWM controller/ and Morningstar PWM controller...Cotek 24V PSW inverter....forklift and diesel locomotive batteries
• Registered Users Posts: 45 ✭✭

I use these exact batteries, I have six in parallel. I haven’t yet completing the outside part (PV panels & combiners) but I am using a 12v 75a charger at night to simulate the daytime charge during the night. They are performing well in that configuration. The weight is a problem, but I have them on a shelving system that spreads that weight (800lbs) over a wider area. I am using mine in a hybrid setup, where I never run them lower than 75%, which will hopefully allow them to function for 12 years per the vendor. I did throw my back out putting them in place, and the delivery guy used to be friendlier, but as time goes on, he is getting over it.

• Solar Expert Posts: 1,560 ✭✭✭✭

They may "seem" to be working well, for now. The minor differences in charging and discharging current will slowly but surely appear, culminating in a rapid decrease in performance of the bank as a whole. Don't expect to be able to collect on the 12 year warranty with a parallel set of batteries. If you are going to hope to depend on any warranty coverage you need to have your batteries in a single series string and have detailed logs on maintenance .voltage setpoints , equalization, etc.

Do you own a DC clamp meter? if not you should invest in one. You will be able to see the charging and discharging differences on each individual battery. It may be difficult to get good numbers if your parallel wiring is linked from battery to battery. If you are using buss bars for each batteries connection you have more control over the current going into and out of each battery, as well as the ability to pull individual batteries from the bank without killing the whole bank.

2.1 Kw Suntech 175 mono, Classic 200, Trace SW 4024 ( 15 years old  but brand new out of sealed factory box Jan. 2015), Bogart Tri-metric, 700 ah @24 volt AGM battery bank. Plenty of Baja Sea of Cortez sunshine.

• Registered Users Posts: 45 ✭✭

I do have a clamp meter. I printed off your comments, and will incorporate them into my maintenance procedures. Interesting point, problems with shipping made it possible to get the six batteries for the price of four (minor shipping damage replacements.) After checking with the vendor, who confirmed they are still functional and safe, though scratched. My hope is that batteries will continue to evolve, and when the time comes to replace the bank, the price will be much lower, especially if you are right, and I have to replace them sooner than planned.

• Solar Expert Posts: 446 ✭✭✭✭

Don't plan on battery's being cheaper

Seems they are the only thing holding their price .

2225 wattts pv . Outback 2kw  fxr pure sine inverter . fm80 charge controller . Mate 3. victron battery monitor . 24 volts  in 2 volt Shoto lead carbon extreme batterys. off grid  holiday home