Planning on installing another battery so I get that extra milage

[SpanishFlyer]

Actually I have already purchased a battery (48V 30A) from Aliexpress and it will arrive whenever it does....
The real reason for asking for advice is on how to connect them so I use one and once it needs recharging I flick a switch and I connect the other; they will never work together.
In the market I see many 3 pole selectors and the way they are connected is to have a common negative, joining all three negatives (BAT1+BAT2+Controller) and the three positives connected into the selector where you have three options (0 or no connection, BAT1+ or BAT2+)... My doubt is if having the negative poles all joined together permanently, can affect the operation of this system.
By the way, both batteries are the same voltage (48), but the new one is 30A compared to the 17A the current one has....

 

[indianajo]

Most large batteries will deliver 50 amps. The sales number of sizes of batteries is AH, or amp hours.
I would do it that way. Common negative does not make a circuit. Paralleling two batteries with two different bms boards leads to uneven charging. bms board evens out the charge in multiple stacks of cells during the monthly or quarterly full charge. A two way plus off switch keeps the batteries from being in parallel.
Make sure the 2 way center off switch is rated for the current your controller will deliver. My best controller delivers 30 amps. 500 watt controllers are 10 amps at 48 volts. I've never seen a 30 amp rated 2 way center off switch. Only single pole ones.
Good luck on aliexp. I bought two piles of trash, one from amazon, one from ebay, before I bought a battery at twice the price from luna. He is out of the 48 v business, however. 3 & 5/6 years later, still running that battery without issues.

 

[SpanishFlyer]

Thanks a lot indianajo, I will surely look for the strongest three way switch.
By the way, I've been so busy these past weeks that I had no time to check my mail. I have now finished installing my three 5000W inverters with 36 panels and three Pylontech 3000 batteries and for the first time ever I'm producing more current than what I need (I have however set the system in such a way that I don't allow production to flow to the power supplier; the inverters reduce the power produced when needed). Forgive me for the non e-bike comment, but I just had to mention it.
Will expand details the extra 48V 30A battery connection when all parts come and will add some pictures.
Best regards,
Spanish Flyer

 

[indianajo]

Spain is a nice sunny country. I live in a place it rains 220 days a year. I don't think solar panels would pay off here.
I did buy a solar battery charger panel last year for car batteries, 16 v nominal, 18v open circuit. Kept my tractor & crane batteries (lead acid) alive last winter instead of sulphating dead as they usually do. Out at my summer property. Extension cords to the crane & tractor are subject to theft. 200' to crane 700' to the tractor shed. $1000 to rent a digger a week to bury an electric line. Electricity is subject to theft if I leave it on. Some slicky steals $200 of electricity/month in January and February if I don't unwire the main breaker box before I leave. Thieves knocked the walls out of the community center 1000' from my summer property and stole all the copper wire. Fortunately my summer trailer is wired with Aluminum. Summer property is way out there. Nice to see squirrels, raccoons, groundhogs, chipmunks, deer, songbirds all warm days.

 

[SpanishFlyer]

Hi again indianajo, amazed of what happened to you; I thought those things didn't happen in the US...
Spain is small compared to your country, but over here we have all sorts of climates and I live in the north, where the Atlantic Ocean brings more water than what we can cope with : (
So you get an idea, our weather is similar to the one you have in Seattle...
Anyway getting back to the battery installation on my e-bike, it's ready but haven't been able to try it out because of.... yes you guessed it, RAIN!! It has been pouring for the last 10 days.
Anyway the battery is a LiitoKala 48V 30A that I have fitted to a rear bag. Have added a switch box so I can select 1, 0 or 2, being 1 the original battery (a 48V 17A) 0 means all batteries disconnected and 2 makes the new battery do all the work. Have also added several fuses for protection. A month ago I replaced the rear wheel for a 20" and added a few more watts to the hub motor (was 750 originally and now it is a 1500W and that was the main reason to add another battery), I have mentioned this before, but just in case someone hasn't read it. And the 20" wheel is so I could firmly put both my feet on the ground; I'm 5.7 feet tall, but have an incapacitated left foot after a bike accident in 2009, and have an external prosthesis that makes me very clumbsy walking so just imagine riding a bike...
Have added a few photos so you can get an idea of what I have done.....for the time being.
Best regards,
Spanish Flyer

 

[indianajo]

Nice to be able to build a ride exactly for your needs. Sorry about your injury.
It's our rainy season now. I still ride the bike but I put the battery in storage under a heat pad. It freezes here frequently until May. Did a motor+controller replacement since I burnt the old one out July 14 due to rain damage. I got to ride it one time after ironing the bugs out, and not to my summer property. Just to the in-town grocery. I'm disappointed. New motor is feeble. I can buy no replacement Mac-12t in the USA, but I can have a pallet of 8 from aiibaba for $1600. The first one was $800, that is quite a mark up. My first motor with plastic gears wore out in 4500 miles. I'll probably use two or three motors before I stop riding. The pallet of motors may be worth the price. If not counterfeit.
I'm short, 5'8", with extra short legs (28" pants inseam). I have to get new pants hemmed shorter. I found the drop frame bike left on the web. It is suitable for people down to 4'8". I had it shipped in from California, there was nothing like that here. I'm too stiff at age 71 to lift my leg over the seat & book rack.