greenbikecab

I recently purchased a 24v EV ebike. I use it mostly to pull my pedicab trailer. I ride anywhere from 30 to 100 miles a day. I bought 4 more 12 volt SLA batteries.... like the ones that come with the bike. But...with the trailer that only gets me 30 miles. I was thinking I would be able to go further if I could wire in two 12 volt deep cycle marine batteries. Would this work? Any opinions on how far I could go on them? Anyone know how I should wire them to the bike? Thanks for your help.

Abneycat

The batteries that come with your bike should be deep cycle. Marine batteries won't fare any better unless they've got a higher amp hour capacity.

If you want more range, you simply need to pack more total watt-hours, either by increasing your voltage (which isn't always a compatible notion with your hardware, or a good idea), by increasing the amp capacity of the batteries you're carrying, or by doing both.

cerewa

greenbike - if i understand you correctly, what you essentially want to do is set two new 12V batteries as a 24V battery, and then wire the new "24V" battery into your existing system so that it will add its own amphour capacity to the amphour capacity of your existing battery.

The way to do that is to create as many 2S (two in series which will be 2 times 12V= 24V) strings as you need, and then run all of the 24V strings in parallel (which will keep you at 24V but will increase the number of amp hours you have).

If you're not sure what series and parallel mean, look here:
https://www.allaboutcircuits.com/vol_1/chpt_5/1.html

Please ask more questions (be specific) if there are any parts of the process you don't understand.

If you know what the amp hour capacity of your existing batteries is and the range you get with them, then you can calculate how many miles you get per amp hour (with my bike setup, i'd estimate it would get 1.5 miles per amp hour@24V using lead acid batteries. lead acid batteries don't provide as much usable energy as other chemistries for a given amp hour capacity.)

graywolf

I assume you mean serious sized ones. They will run the the bike no problem. No reason you could not put them in the trailer (I would use a pluggable cable, so the on bike batteries could be used when you are not pulling the trailer. The cable should be a gauge or two heavier than the shorter ones on the bike.). However you do realize you are talking about 100 pounds or more of batteries? You will most likely want the AGM (Assorbed Glass Mat) type of batteries rather than the cheap ones.

As to how far you could go, simply divide the marine batteries amp/hour rating by the existing batteries amp/hour rating and then multiply your current milage by that number. For instance if your current batteries are 12 amp/hour and the new ones are 120 amp/hour you will get 10 times the distance.

So a pair of Lifeline AGM batteries will cost $600 or so, and will give you about 100 miles of range. They weigh about 140 pounds for the pair. Plain lead acid marine batteriess would be only about $200, but would not be spill proof, and will not stand up to deep cycling quite as well.

You will also need a higher rated charger to assure being able to recharge overnight.

I have been kind of playing with the idea of doing something like this with an adult trike.

pengyou

Is it possible to add batteries of another chemistry to the equation? They are more expensive but you have to realize, the more weight you add to your picture the fewer miles per amp hour you will get. I know that batteries with a different chemistry will need a different bms and charger but as far as the useage is concerned, volts is volts????

15rms

Why not go with a gasoline engine? You would not have to worry about all of the extra weight and you would have more power. Staton https://www.staton-inc.com/ carries about the best kits around. I personally am planning on doing some touring in the Rocky Mountains. The gasoline engine is about the only way I could find to have the range and power. Good Luck

cerewa

You can mix chemistries, but in my understanding, if you wire them up to work at the same time you need to use diodes to avoid the problem that one battery may try to charge another. The reasons this could be a problem are that the current could flow too fast for the batteries to tolerate, and a lot of energy could be wasted due to less-than-100% efficiency of charging/discharging batteries.