14s 52v 200ah Battery

[Ebike toter]

Hi all.. I'm building a custom 4x4 van overlander & a 10ft scamp trailer which will be my mobile office.. I need 52v 200ah to do my offgrid computer 3d design office.. I want 21170 cells with 60 amp bms... shrink wrap battery is fine...
Any ideas as to a reliable source with a reasonable delivery time?? I can fit multiple batteries (4×50ah) but I'd prefer to keep it to two batteries... as always $$ will be
Charging will be by:
- dc to dc charger from van alternator when running
- 390w solar with 58v charger
- shore power 58.8 charger

 

[harrisonpatm]

Looks like a cool build, looking forward to seeing more of it!

For something slow and big, may I ask my you're preferencing 21700 cells? If I were you, I'd go with LiFePO4 prismatics, 16s, source your own BMS, keep everything else almost the same.
How about 180ah?

https://batteryhookup.com/products/calb-ca180-3-2v-180ah-lifepo4-prismatic-cell-90-100

16x of those = $1088, plus an $80 JKBMS since you said you only need a 60a BMS.

Just my two cents

 

[Ebike toter]

Looks like a cool build, looking forward to seeing more of it!

For something slow and big, may I ask my you're preferencing 21700 cells? If I were you, I'd go with LiFePO4 prismatics, 16s, source your own BMS, keep everything else almost the same.
How about 180ah?

https://batteryhookup.com/products/calb-ca180-3-2v-180ah-lifepo4-prismatic-cell-90-100

16x of those = $1088, plus an $80 JKBMS since you said you only need a 60a BMS.

Just my two cents§

Thanks for your reply.. I have also looked at lifepo batteries.. but they take up a lot of space & are lots heavier.. plus I already have two luna 52v 24ah triangles for my bike..

 

[Ebike toter]

I have also looked at lifepo batteries.. but they take up a lot of space & are lots heavier.. plus I already have two luna 52v 24ah triangles for my bike.. real estate in the 10ft scamp is tight

 

[BlueSwordM]

I'm not sure you should use 21700 cells.

You should instead use big format cells (33140/32140/46800/46950) NMCA cells to make building and BMS stuff much simpler

Plenty of Chinese manufacturers make these now and you can actually order them on places like Alibaba and directly from a manufacturer if your order quantities are high enough.

 

[Ebike toter]

I'm not sure you should use 21700 cells.

You should instead use big format cells (33140/32140/46800/46950) NMCA cells to make building and BMS stuff much simpler

Plenty of Chinese manufacturers make these now and you can actually order them on places like Alibaba and directly from a manufacturer if your order quantities are high enough.

Thanks.. sound advice..

 

[Ebike toter]

BlueSwordM.. so do you know anyone who is building batteries using the 46950 cells?? I like the specs & I energy density.. as you mentioned the cells are available in china... are the 3d printed bases and buss bars available here?? I'm looking for something I can get within 4 weeks as I still need to design & get all the sh~~ installed & tested .. any suggestions?.

 

[A-DamW]

I'm looking for something I can get within 4 weeks as I still need to design & get all the sh~~ installed & tested .. any suggestions?.

Buy 14 of these and be done.
https://batteryhookup.com/products/new-1s70p-3-6v-210ah-756wh-eve-inr18650-33v-99-kwh

~10kWh,
$840 before shipping.
~$165 shipping to Idaho.
They have a shipping estimator at the bottom of the page, enter the qty and your address.

 

[Ebike toter]

A-DamW.. I'm loving this forum.. so 70p cell 3.6v batteries... if I were to use these I'd wanna slap 14 together.. what bms would properly balance so many cells??

 

[BlueSwordM]

BlueSwordM.. so do you know anyone who is building batteries using the 46950 cells?? I like the specs & I energy density.. as you mentioned the cells are available in china... are the 3d printed bases and buss bars available here?? I'm looking for something I can get within 4 weeks as I still need to design & get all the sh~~ installed & tested .. any suggestions?.

Sadly, no. I'd have to look but I believe there isn't any prebuilt hardware yet for these large format cylindrical cells.

Anyway, I much prefer @A-DamW's idea as it allows you to quickly build packs from cells that are all perfectly matched and already welded.

As for a proper BMS, such large packs likely require active balancing, so an active balancer of your choice should be purchased.

 

[Ebike toter]

Ok my gurus.. I'm ready to pull the trigger on this killer deal but I need guidance on a proper bms to control 14 of these modules.. as these batteries will be housed in the same scamp trailer as my 20k of computer stuff...
Any ideas??

 

[BlueSwordM]

What's the absolute maximum power you'll ever draw in your system?

 

[Ebike toter]

I'm thinking office trailer 1500w at 120ac... around 900w for computer thingys & misc 600w (including low temp battery heating pads for the winters here).. the Van & trailer will be umbilical corded together with voltage passing both ways..

 

[A-DamW]

what bms would properly balance so many cells??

If you operate that bank @
0.1C discharge rates, (2000 watts)
charge to 4.05 volts or lower per cell, (~56.7 volts)
discharge to 3.3 volts or higher per cell (~46.2 volts)
do an initial balance by paralleling all 14 modules for a day or two when you get them,

You could run without a BMS indefinitely.

 

[A-DamW]

Now, that is not to say you shouldn't have overall pack voltage monitoring, and a rigorous charge and discharge cut off on your solar charge controller/inverter, but I've been running lithium ion batteries for 10 years without bms's with some occasional manual monitoring.
The key is to keep them out of their "redline", and inside their safe area of operation i.e, not discharging at a higher rate than the cells can tolerate, not charging them to too high voltage, not discharging them to too low voltage etc. etc.

 

[A-DamW]

Here are a couple bms's that can work for you:
https://batteryhookup.com/products/12v-lifepo4-smart-bms-w-low-temp-cutoff?variant=36287975588002

https://batteryhookup.com/products/7s-21s-24v-75v-300a-lithium-ion-bms?variant=43085312884898

 

[rafalg]

The key is to keep them out of their "redline", and inside their safe area of operation i.e, not discharging at a higher rate than the cells can tolerate, not charging them to too high voltage, not discharging them to too low voltage etc. etc.

So basically you become the BMS (Battery Master?)
BTW many cheap BMSes can be found on Aliexpress, i think something usable can be bought for around $30-$50
These 70P packs look really great for the build, but for such large capacity i'd look for a BMS with bluetooth and an app for monitoring (dont have any recommendation here, but there is a large choice of DALY smart BMSes)

 

[Ebike toter]

Sorry gents... forgot to post this reply last nite.. ordered the 14 batteries..
"I'm thinking office trailer 1500w at 120ac... around 900w for computer thingys & misc 600w (including low temp bat heating pads for the winters here).. the Van & trailer will be umbilical corded together with voltage passing both ways.."