Second battery (52v + 48v)?

[joshuabjorg]

Hey gang,

Have an Ariel Rider D-Class that I'd like to add a second battery to. To make matters slightly messier, I'd really prefer adding on a 52v battery to get a little more juice at the top end. So... Couple lines of questioning:

1) should I go in parallel? And if so, anybody have a handy wiring configuration or should I really cough up the cash for a battery blender (which seems criminally overpriced)? Like the elegance of parallel, but also not super into anything exploding.

2) if I go with a switch instead, any suggestions for a waterproof switch that can handle 30a at 48v? And any concerns with voltage cutoff settings if I'm regularly switching between 48v and 52v?

Thanks

 

[E-HP]

1) should I go in parallel? And if so, anybody have a handy wiring configuration or should I really cough up the cash for a battery blender (which seems criminally overpriced)? Like the elegance of parallel, but also not super into anything exploding.

Yes, this will cause a fire or explosion.

 

[joshuabjorg]

Sure, if I just straight wired them in parallel, that would obviously be (explosively) bad. But I could add one of these: https://www.sparkcycleworks.com/index.php/product/battery-blender/

... and it would just run down the 52v till it got level with 48 and then run down the other two..in principle should be able to do the same thing wiring up some diodes (as you'd want to do with two 48v in parallel too), but would prefer to hear from someone who's done it before...

 

[E-HP]

Sure, if I just straight wired them in parallel, that would obviously be (explosively) bad. But I could add one of these: https://www.sparkcycleworks.com/index.php/product/battery-blender/

... and it would just run down the 52v till it got level with 48 and then run down the other two..in principle should be able to do the same thing wiring up some diodes (as you'd want to do with two 48v in parallel too), but would prefer to hear from someone who's done it before...

:thumb:

 

[calab]

Just unplug one battery and plug the other battery in, I do that every single day when I am riding my ebike.
But that is a great device, but very expensive and I would not gamble on it.

 

[mybike]

Sounds good and tooooo expensive.

Like Calab said unplug and plug in the other battery in 10/10. But I wonder what will happen if the device fails ummm..

 

[joshuabjorg]

Alright, alright gang. But... Recommendations on (ideally waterproof) switches that can handle 52vdc at 30a? I'd really like to not have to literally plug/unplug every time. Also, big rotary switches look cool...

 

[JackFlorey]

Alright, alright gang. But... Recommendations on (ideally waterproof) switches that can handle 52vdc at 30a? I'd really like to not have to literally plug/unplug every time. Also, big rotary switches look cool...

I have used these with some success. Just don't switch under load.

https://www.digikey.com/en/products/detail/nkk-switches/S822-CUL/4512508

 

[E-HP]

Alright, alright gang. But... Recommendations on (ideally waterproof) switches that can handle 52vdc at 30a? I'd really like to not have to literally plug/unplug every time. Also, big rotary switches look cool...

Well unless you have switches on your batteries, the product on your link would still require you to disconnect the 52V battery manually anyway. To me, it's a formula for killing the 52V battery, since you have to constantly monitor your voltages in order to know when to disconnect the 52V pack.

"When using two different voltages, the Blender will “burn” charge from the higher voltage battery first, then engage the 2nd battery when within the lower voltage battery’s charge. As a result, it is important to turn off the higher voltage battery when it gets to a low level!"

 

[joshuabjorg]

Not if you're rocking a decent BMS on your battery, which should have a low voltage cutoff.

 

[E-HP]

Not if you're rocking a decent BMS on your battery, which should have a low voltage cutoff.

If that's what you'll rely on, then I think all you need is an $8 diode on the 48V battery, then parallel the packs.

 

[mybike]

Joshuabjorg anything electronic can fail even its reliable period, you just don’t know when.

Youtube Vid:
https://www.youtube.com/watch?v=JCaDz_2YcGQ

The Vid: Who is right who is wrong here? Simply if he had just unplugged and plugged the other battery
when he needed this could have been avoided.

 

[joshuabjorg]

Solid point my bike (and a chilling vid). Manually unplugging it is ...

 

[khorse]

that "battery blender" looks like a diode in a $150 plastic box.

 

[calab]

What is the big deal in stopping, taking 2 seconds to switch connectors?

 

[joshuabjorg]

Totally agree with khorse, which is why I'd never buy that thing was asking about folks experience with DIY approaches.

Calab, not a big deal, but I'm not a huge fan of having exposed connectors easily accessible, especially given that I ride in a lotta heavy rain. Just means I'll have to setup a watertight enclosure for connector swapping (most of the connections are under the seat and am not super into pulling that off every time I gotta swap batteries... :wink: ).

 

[Talon]

that "battery blender" looks like a diode in a $150 plastic box.

From my research ...... The "battery blender" is designed to add a 2nd battery and provide both longer range + less "battery sag" that we all hate together Why not?

 

[khorse]

that "battery blender" looks like a diode in a $150 plastic box.

From my research ...... The "battery blender" is designed to add a 2nd battery and provide both longer range + less "battery sag" that we all hate together Why not?

It's magical technology is that whenever the two battery voltages don't match, the bike takes power only from the higher voltage one. When the voltages match, it draws equally. And then it also prevents reverse current from entering the lower volt battery.

My friend, that is literally the behavior of two diodes. It's nothing else.

 

[felas]

I am adding my second battery just using this switch, 15A 220V, DPDT. Put in a plastic box and sealed with silicon to make it waterproof. So far no problem even riding in heavy rain

 

[99t4]

Good to know that it works. Like that is a make-break-make switch. Of course, it's still important to never switch when under load.

 

[Talon]

that "battery blender" looks like a diode in a $150 plastic box.

From my research ...... The "battery blender" is designed to add a 2nd battery and provide both longer range + less "battery sag" that we all hate together Why not?

It's magical technology is that whenever the two battery voltages don't match, the bike takes power only from the higher voltage one. When the voltages match, it draws equally. And then it also prevents reverse current from entering the lower volt battery.

My friend, that is literally the behavior of two diodes. It's nothing else.

I am very interested in these "Diodes" Where do you suggest that I get these "diodes" to accomplish this feat without a switch that is mentioned above ???

 

[E-HP]

I am very interested in these "Diodes" Where do you suggest that I get these "diodes" to accomplish this feat without a switch that is mentioned above ???

Amazon. Just search on the current range that you need. Best to use two, so maybe $15-$20 total.

 

[khorse]

What kind of person writes the word diode in doctor evil quotes? it makes you sound skeptical that they're real, which is a bizarre attitude because it's one of the oldest and most rudimentary electric components ever invented.

 

[bogdandumitrescu]

I am adding my second battery just using this switch, 15A 220V, DPDT. Put in a plastic box and sealed with silicon to make it waterproof. So far no problem even riding in heavy rainView attachment 312788View attachment 312789

I got a DPDT switch (20A / 125V) ... i connected 2 48V batteries on it ... i can check the connections with the multimeter ... but when i flip the switch ( when i apply the voltage from the battery) ... even though the multimeter tells me there is a connection ... the electricity does not flow thru ... any thoughts ??

 

[glennb]

What kind of person writes the word diode in doctor evil quotes? it makes you sound skeptical that they're real, which is a bizarre attitude because it's one of the oldest and most rudimentary electric components ever invented.

I get what you’re saying, but I think the quotation marks are warranted if it’s unclear whether the implementation is of an “ideal diode”.