Does a low-cost BMS (e.g., Daly, etc.) limit the charging current? (i.e., does it eliminate the need for a DC-DC converter in a van?)

[carlos1w]

If I were to get, say, a 20 A charging BMS, does it actually limit the current to be < 40A? If that is the case, would it then not be necessary to have a DC-DC converter since the alternator current would be limited to 20 A?

 

[Bob B]

The BMS is not really going to limit the current .... at least with the BMS I am familiar with. It is just going to disconnect if there is over-current.

 

[John Frum]

If I were to get, say, a 20 A charging BMS, does it actually limit the current to be < 40A? If that is the case, would it then not be necessary to have a DC-DC converter since the alternator current would be limited to 20 A?

What is a charging BMS?

 

[carlos1w]

What is a charging BMS?

A bms during charging. Or to be more precise a BMS that has a 20 A charge limit. But see messages below, now I see that this limit will be ON-OFF only, so it will pulse on-off like crazy on the alternator (not good).

 

[Craig]

I know of none that limit the current but most are current limited so I would not use one as a B2B charger

 

[carlos1w]

The BMS is not really going to limit the current .... at least with the BMS I am familiar with. It is just going to disconnect if there is over-current.

Oh, I see, it is just an ON-OFF thing. OK, so I see the need for the current limitation by the DC-DC converter, indeed. Thanks!!

 

[carlos1w]

I know of none that limit the current but most are current limited so I would not use one as a B2B charger

Thanks!

 

[Zil]

The ampere rating is the maximum for the BMS, most can carry more, but the electronics don't like to be stressed and let the smoke out. The BMS is the last drop dead battery dis-connect when charge voltage is too high. Your charging system should regulate itself so the BMS doesn't get involved.