single lithium vs multiple parallel

[golfboy64]

Looking to upgrade to lithium. Have seen comments that say a single a 48v pack is better than mutiple parallel batteries having an equivalent amp-hr rating

What is the consideration? the idea of being able to add additional amp hrs at a latter time if needed is attractive, but I want the system to be a reliable as possible.

Just wondering .... Also if this has been hashed out previously can someone help me find the thread

[Capt. Lenny]

A single 48 volt lithium is a good choice if you know how many amp hours you actually need for the way you use your cart. There is nothing wrong with multiple 48 volt batteries in parallel. By buying individual 48 volt batteries like Epoch you can build a pack at different ah based on your needs if you’re on a budget. If 60ah is not enough just add another for 90ah, not enough just add another one for 120ah. The pack you don’t want to build is one with multiple 12 volt batteries. Amp hours equals range so if you drive a lot of miles in a day then you will need more ah. One nice thing about Epoch batteries is they have the same foot print as a 8 volt battery so there is no battery tray modification needed. If you know you’re going to need 105ah then get something like an EcoBattery.

[Volt_Ampere]

The big advantage to a single 48V pack is that you only have one BMS to handle the cells. If you have multiple 48V packs in parallel, they have independent BMS's that control only one pack. This is ok but there is more to fail and if one goes off line, then the others can be overloaded because all of the current will now go through the remaining packs. I am sure that others can chime in on other advantages. With packs in parallel, the assumption is that the current will split equally among them but in reality, the current won't evenly split unless the cells are matched in internal resistance. Single larger cells are better suited to handle the high current since all of it will go through every cell in series.
In most cases, a single pack say 105AH is still small enough to fit nicely in place of the old FLA batteries. There are a few frames out there where this isn't as easy. A single pack should be cheaper than an equivalent multiple pack setup since there is more packaging and cabling and multiple BMS's in a multiple pack setup.

[augiedoggy]

The advantages to multiple parallel packs is if one fails your not stranded (unless undersized to begin with), cheaper shipping for warranty or repair, you can add capacity as needed making it cheaper to implement and possibly much cheaper if you realize you dont need more, also they are lighter and easier to install with the footprint sometimes working better with the battery layout in the cart.

In truth they both have their advantages and disadvantages but either will work and they are both far superior to wiring 12v batteries in a series.

IMO building your own if possible is the best approach since you can design it to your application, then service and repair it without relying on others and you will typically save about 50% or more

[Volt_Ampere]

I sort of agree with those advantages but you won't necessarily know that one battery has failed until the whole thing drains much more quickly or trips the current limit. I strongly agree that you don't want to do batteries in series! I still favor one battery with robust cells that are capable of handling the current requirements with one BMS. Good companies have these in different shapes to fit most carts and the volume is far less than the batteries you are replacing. (not to mention the weight difference)

[augiedoggy]

Originally Posted by Volt_Ampere

I sort of agree with those advantages but you won't necessarily know that one battery has failed until the whole thing drains much more quickly or trips the current limit. I strongly agree that you don't want to do batteries in series! I still favor one battery with robust cells that are capable of handling the current requirements with one BMS. Good companies have these in different shapes to fit most carts and the volume is far less than the batteries you are replacing. (not to mention the weight difference)

True, but any battery I would consider would have some sort of SOC meter for each battery or bluetooth app to see whats going on. If one battery failed the cart would still work but it would be easy to trip the bms with an excessive load or aggressive driving in many cases which would also let the owner know something is amiss.

I am not saying one is superior to the other here only pointing out they each have strong points. I have 2 60ah packs currently in my cart for one 120ah 76v pack. both my packs have an illuminated soc gauge and each pack is capable of 200amps continuous output so I could run fine on one with limited range if the other malfunctioned.

[Volt_Ampere]

I bet most parallel setups don't have separate meters for each battery. IMO that is just another level of complexity that I wouldn't want. One battery is a very clean install with minimum of connection cables and fewer parts to fail.

[augiedoggy]

Originally Posted by Volt_Ampere

I bet most parallel setups don't have separate meters for each battery. IMO that is just another level of complexity that I wouldn't want. One battery is a very clean install with minimum of connection cables and fewer parts to fail.

Why wouldnt they?
If you bought a 50ah golf cart battery it would come with the gauge.. if you added a second for range I would expect the same. and most of the better designed packs have a bluetooth app as its been the norm for these things for most packs for years now. ironically its some of the most expensive options out there lagging behind in this capability.

My individual soc meters are located on top of my batteries since I have another meter for combined output on my dash. some like big battery and battery evo put the gauge readout directly on the batteries to easily check them.


It sounds like for you, parallel packs are not the best option. Just like having an onboard solar charging roof is not the best option for you as you often point out every time someone mentions having one because you store yours indoors and have no use for the extended range on the course. For me and my use it works so well I never have to plug my cart in.

We all have different opinions, uses and ways to implement our goals.. I dont believe theres always a one size fits all "Best" option for everything and every scenerio...

What if a person is really on a budget and wants to try lithium but doesnt have 3 grand lying around for a 105ah battery for their $1500 cart? Buying a 60ah or 2 30ah battreries and trying it out might be the best option for them. If they find they still need more current at times or more range they can make the additional smaller investment in a year or 2 to add a second battery. In that case its a better option for that person who otherwise might buy that 105ah battery and find they are never even discharging it more than 1/3 with their particular use...

Also on the flip side of all this we have all seen many folk here who buy a lesser known brand larger ah pack due to budget restraints and seen the headaches they go through when they fail... If I didnt want to bother learning how to buid or repair my pack I would go with a better supported brand pack and if the cost was prohibitive I would buy smaller packs such as the allied or battery evo or epoch packs over the 105ah amazon special because thats all I could afford or be willing to dump into my hobby cart at that time.

[Volt_Ampere]

I agree that different users have different requirements. Where I live here in Arizona, we have relatively flat golf courses and no real hills in the community - and we are not even allowed to have our carts outside overnight. There is nothing technically wrong with a parallel setup if the batteries are relatively well matched. We had a guy that was building "Solar" carts for a while and there are still several around. Solar is great if your cart will receive enough sunlight to get a reasonable charge. I could probably get a reasonable percentage charge with the 6 hours mine is outside during a golf round. I only charge after two or three rounds depending on how much other driving I do.

[TheCartBoy]

Originally Posted by Volt_Ampere

I bet most parallel setups don't have separate meters for each battery. IMO that is just another level of complexity that I wouldn't want. One battery is a very clean install with minimum of connection cables and fewer parts to fail.

On the epoch systems, when you add additional batteries the display gauge shows an averaged system level voltage, current draw. Using the app you can look at each individual battery's voltage, current, cells, temps.