Rolls Battery Engineering - Series & Parallel Battery Connection

[@electricengineer624]

Love your videos Daves God bless for these free valuable videos Thanks

[@Bacardibombillo]

Dude love the tip on 48v system. Removing a 2v batt... great tip

[@RollsBatteryEngineering]

Good to hear!

[@Do_the_Dishes]

I have a question about your parallel connections (like the setup around 17:00). I have a 3 string combo instead of 5 (24 volt system with 12 - 6 volt 220 A.H. batteries) but the question could apply to both. I see that you are not paralleling the inner connections of the batteries which may help with balancing (or so I’m told) and wanted to get your take on this practice. I would like to know the pros and cons of this. I just recently saw this done on youtube and it makes some sense. It is done with a smaller gauge wire and fused properly between the innermost connections. Hard to explain without drawing the circuit but I hope you catch my drift. Nonetheless, It would allow the slight voltage differences between each string to cross over and so called “balance”. I’m guessing that it would also amplify the attack on a weak battery but at least the whole string wouldn’t suffer. Thank you in advance.

[@RollsBatteryEngineering]

Hello.. yes running parallel connection within the strings is called cross tying. Back the the days some inverter manufacture recommended it. The main issue against this is if you ever have a very deep discharge, due to the impedance differences between the strings you could get a situation where one or more batteries become reverse polarized. While rare, and many bad things have to happen for this to occur it's still not a good idea for the second reason... it's just a waste of cable, and if there is ever an issue trouble shooting can be a nightmare. Ideally if you have a proper charge source (10 -20% of the c20 rate) you shouldn't need to do this... frankly most designers today will never do more than 1 to 2 parallel strings of batteries.

[@Do_the_Dishes]

Man that was a fast repose time! Thanks! Plus you help me with a question I was searching for and didn’t even ask. What should the charger be capable of? That being said, I have a Magna MS4024 4000W 24V inverter. If I read the specs right, the charger is capable of 105 ADC continuous @ 25 degrees C. So, each string is 220 ah. 220 x 10% = 22 amps & 220 X 20% = 44 amps. Then, (thinking and typing out load here, stay with me), 105 /3 = 35 amps. So then It’s not the best but ok and in the middle of the range. Please correct me if I missed figured. Thanks again.

[@RollsBatteryEngineering]

DoThe Dishes in total you have a 660 ah bank... so min charge rate would be 60 to 70 amps... if Flooded your max would be 132... if VRLA or GEL your max would be 180 to 200amps. Yes we try to respond quick, currently in Prague doing distributor training...

[@Do_the_Dishes]

Rolls Battery Engineering , they are flooded, and yes 660 for total bank. I see, the math works out to be the same now, I was looking too deep into it. So I guess I’m ok. I do realize now that parallel is not the best but this small project kept getting bigger and bigger and it lead me to this configuration. You guys have been very helpful and informative and truly thank you for taking the time answering my questions.

[@RollsBatteryEngineering]

DoThe Dishes No worries! Happy to help.. if you have a direct question you can email me at [e-mail]