January 25, 20233 yr I have 3x 100Ah Lead Acid deep cycle batteries connected in parallel to a 2000W modified sine wave inverter (Outdoor Warehouse). I've been charging this bank with a 5A C-Tek smart charger, but I'm not keeping up with the loadshedding cycles. 1) Would a 2nd identical C-Tek increase the charge - I believe charging at 10A into 3x 100Ah should be under the safe limit 2) What would the ultimate wiring setup be (see my horrible sketch attached comparing two simple methods)
January 28, 20233 yr Download Victrons guide called "Wiring Unlimited". Its a good read. I think many people on this forum would benefit from it. In there they cover your question with diagrams.
January 30, 20233 yr Your Typical 100A Deep Cycle Battery has a Maximum Charge Rate of 25A. For each Battery you place in Parallel you add the Charge rate (This is Roughly accurate and there are a number of factors that could influence this). So Effectively you are charging 300Ah Battery with 5A Charger (about 30 Hours to Charge from 50% or 15Hours to charge from 25% - again roughly and depending on so many factors). You really want to charge at around 50-80% of the Maximum of the Battery, so in your case 30-40A Charger. These are just basic figures to help you understand, there are a number of Engineering Factors that still need to come into play, but if you look at it from this perspective: the amount of power you take out during load shedding is the same amount of power you must put back in while the power is on as long as it does not exceed the Battery or Charger Specifications (I like to use 50% of the Specified Maximum Values to be safe - Yes I know, I Over Engineer Everything, But is lasts...)
January 30, 20233 yr On 2023/01/25 at 4:46 PM, Sats Nkamoto said: 2) What would the ultimate wiring setup be (see my horrible sketch attached comparing two simple methods) the left hand side is the correct way of connecting the batteries/inverter/charger... On 2023/01/25 at 4:46 PM, Sats Nkamoto said: 1) Would a 2nd identical C-Tek increase the charge - I believe charging at 10A into 3x 100Ah should be under the safe limit yes, but as @DouglasBray wrote, higher charge currents would be better, to shorten the charging time, I'd say 30A in total for C/10, in other words, 10A current for each of the three 100Ah batteries...
January 30, 20233 yr Sats it does not make sense 1x C-Tek= R 1995 for 2 almost 4K you can buy a Victron BluePower Charger - IP65 - 12V 25A - Smart Charger for R3.5K and then you have Bluetooth monitoring on your phone as well
January 30, 20233 yr Author 18 minutes ago, TaliaB said: Sats it does not make sense 1x C-Tek= R 1995 for 2 almost 4K you can buy a Victron BluePower Charger - IP65 - 12V 25A - Smart Charger for R3.5K and then you have Bluetooth monitoring on your phone as well You're right, but I've had the one for a while ('sunk cost') and I figured "it almost works, let me just double up for now"
January 30, 20233 yr Author 2 hours ago, Kalahari Meerkat said: the left hand side is the correct way of connecting the batteries/inverter/charger... yes, but as @DouglasBray wrote, higher charge currents would be better, to shorten the charging time, I'd say 30A in total for C/10, in other words, 10A current for each of the three 100Ah batteries... With my 2x C-Teks (10A) I'm going from 12V to about 12.6V in the 6hrs between L/S. With a 2000W noisy inverter, I've only managed to run my son's high-powered gaming laptop and external screen and a 65" TV up to about 15mins ago. I clearly need more Amps! What are the options in the 30A range? @TaliaB already mentioned the Victron.
January 30, 20233 yr Author 11 minutes ago, Sats Nkamoto said: With my 2x C-Teks (10A) I'm going from 12V to about 12.6V in the 6hrs between L/S. With a 2000W noisy inverter, I've only managed to run my son's high-powered gaming laptop and external screen and a 65" TV up to about 15mins ago. I clearly need more Amps! What are the options in the 30A range? @TaliaB already mentioned the Victron. https://www.livestainable.co.za/product/victron-energy-blue-smart-ip22-12-203-230v-cee-7-7-battery-charger/ any experience with this product and supplier?
January 30, 20233 yr Great company good service. I got this one from them better choice for your application https://www.livestainable.co.za/product/victron-energy-blue-smart-ip65-12-251-230v-cee-7-16-retail-battery-charger/
January 30, 20233 yr Author 22 minutes ago, TaliaB said: Great company good service. I got this one from them better choice for your application https://www.livestainable.co.za/product/victron-energy-blue-smart-ip65-12-251-230v-cee-7-16-retail-battery-charger/ Thanks, @TaliaB but do I really need the IP65 "waterproofness" when I'm installing the system inside? Maybe I'm missing something, but the IP22 model is cheaper and has a higher charging capacity (30A vs 25A)
January 31, 20233 yr Author 1 minute ago, TaliaB said: 3 x batteries @ 20amps👌 This is the maximum (80%) according to @DouglasBray which amounts to 60A of current in total. Not sure if I'm up for 2x Victrons.... All this while I wait to have my 8kW Sunsynk + 14.3kWh SolarMD installed at the house I'm building. I need to get through the last 9 months of building.
January 31, 20233 yr 9 hours ago, Sats Nkamoto said: https://www.livestainable.co.za/product/victron-energy-blue-smart-ip22-12-203-230v-cee-7-7-battery-charger/ any experience with this product and supplier? This charger can do 3 batteries @20amps how many batteries are you planning of connecting in parallel?
January 31, 20233 yr 10 hours ago, Sats Nkamoto said: With my 2x C-Teks (10A) I'm going from 12V to about 12.6V in the 6hrs between L/S. With a 2000W noisy inverter, I've only managed to run my son's high-powered gaming laptop and external screen and a 65" TV up to about 15mins ago. I clearly need more Amps! What are the options in the 30A range? @TaliaB already mentioned the Victron. The problem with any lead acid or gel battery is they are C20 batteries. It doesn't matter if you increace the charge rate you will have the same discharge energy. The problem you have is the discharge current is most probably too high. Peukert's law,states when your battery is discharged faster than the c20 rate in your case (300ah@C20 = 15dc amps)you sacrifice capacity. Your essential load needs to be as low as possible.
January 31, 20233 yr 13 minutes ago, TaliaB said: the c20 rate in your case (300ah@C20 = 15dc amps) unless I'm wrong, please correct me, I understood C20 being 0C2 in other words .2 or 20% of rating, which would make the values 20A/battery for a total of 60A, which at 12V is around 700-odd W for reasonably happy batteries although I still recommend everyone to stay away from SLA/AGM/any type of lead acid battery, except, maybe, the large 500+Ah 2V cells that need regular topping up with distilled water etc.
January 31, 20233 yr It is the rate that will fully discharge a battery in 20 hours 300/ 20 hours = 15amps. Below link that explains Peukert's law. https://en.m.wikipedia.org/wiki/Peukert's_law
January 31, 20233 yr 23 minutes ago, TaliaB said: It is the rate that will fully discharge a battery in 20 hours 300/ 20 hours = 15amps. Below link that explains Peukert's law. ok, it seems the correct way of writing the 20 hour rate is C/20 or 0.05C, the few SLAs etc. I have been near specified a 20% max charge/discharge rate based on their Ah rating (170Ah), which would be C/5 or 0.2C, I guess... anyway, thanks, now I know a little bit more correctly about the sub C (less than 1C ratings)... however, editing this, to mention that @Sats Nkamoto did not specify the actual specs or make and model of his batteries, so the C/20 may not *really* be accurate... Edited January 31, 20233 yr by Kalahari Meerkat however
January 31, 20233 yr Just a thought... As you guys are talking about different Chargers etc... Why not consider a Cheap All in one Inverter that probably has Battery Monitoring and a Higher Rated Charger along with the option of a built in MPPT. Then you have a more valuable asset that can be re-tasked or re-sold when your building is done....
January 31, 20233 yr 10 hours ago, TaliaB said: If it is C10 then apply the rule Just so easy to divide C by 10 or 20 depending at which of the 2 rates the capacity was calculated/tested as in over 10hrs or 20. Edited January 31, 20233 yr by Scorp007
February 2, 20233 yr Author On 2023/01/31 at 6:50 AM, TaliaB said: 3 x batteries @ 20amps👌 The link I sent was actually the wrong one - it shows the 20A version. The one I intended to share was this one: https://www.livestainable.co.za/product/victron-energy-blue-smart-ip22-12-301-230v-cee-7-7-battery-charger/ which is the IP22 30A (with a single set of output terminals) model. I've placed my order and will update this thread with the result. Thanks for all the input, guys - much appreciated.
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.