Looking for ideas


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Charly144

Member
Joined
Nov 22, 2017
Messages
287
Hi guys,

my setup is now up and running.

My 3 Victrons are outputting 105 Amp when charging, which killed 3 out of 5 40Amp China-BMS because they can handle 40Amp when discharging but only 20Amp when charging. 5 multiplied by 20 is 100Amp in total... too much!

I will now switch over to 5 x 60Amp Daly BMS which should be able to handle 150Amp when charging, which shouldn't be a problem withthe 105Amp coming from Victrons.

Next step is that I will add 16s 240Ah LiFePO4 in parallel. with 18650s.Managed byan AntBMS 300Amp discharge, but unfortunately only 50Amp charge.

I do worry that when Daly-BMS will switch off charging for any reason, full power is going into LiFePo4 pack with the AntBMS and this will die because of high current.

How would you handle this potential issue? Any ideas?

regards
Karl
 

daromer

Moderator
Joined
Oct 8, 2016
Messages
5,662
Get a proper bms. One that can handle the load instead of bunch of smaller Ones.

You asked for advice ;)
 

Charly144

Member
Joined
Nov 22, 2017
Messages
287
My point is, that I would like to monitor 5 strings separately in order to find out when one pack becomes weak. having 14s400p will not be so easy to manage in that perspective...

I think going forward with diy bms on the basis of an esp32 will be the right approach. batrium or other bms systems will be too expensive.

What I don't know is whether diy bms can manage 5 strings 14s80p plus 16s4p lifepo... maybe some one can give an answer on that...
Can diy bms handle 6 relays (one for every string)?


regards
karl
 

not2bme

Member
Joined
Oct 16, 2017
Messages
497
Charly144 said:
My point is, that I would like to monitor 5 strings separately in order to find out when one pack becomes weak. having 14s400p will not be so easy to manage in that perspective...

I think going forward with diy bms on the basis of an esp32 will be the right approach. batrium or other bms systems will be too expensive.

What I don't know is whether diy bms can manage 5 strings 14s80p plus 16s4p lifepo... maybe some one can give an answer on that...
Can diy bms handle 6 relays (one for every string)?


regards
karl

Why don't you look into the diybms4 instead? That will give you monitoring and relays to kick off an external shunt trip breaker.
https://secondlifestorage.com/showthread.php?tid=8540

On one giant pack. My packs are linked together in 6x 60p to turn into a giant 360p so I only need to run one bms. If they do go out of balance then yes I will have to take some time disconnecting the interconnects but I should be able to zero in the bad cell packs relatively quickly. All this interconnects can be removed on a live system without disconnecting.
 

Redpacket

Active member
Joined
Feb 28, 2018
Messages
1,392
Maybe connect the three Victron chargers one each to separate battery banks?
Or configure the BMS to use an external switch to cut all or some solar panel output when needed?
 
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