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56v, 160 amp alternator with LiFePo batteries...BMS??

Springbok1817

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Feb 28, 2021
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I'm trying to setup a system in a Sprinter with 7.2 kWh LiFePo, 1,200W solar and a 56v, 160 amp alternator. The question is what type of BMS is needed? The alternator is from APS and they recommended Lithionics for the BMS, but they want like $8k for a BMS and a 7.2 kWh, 48v battery. Any other options out there? I don't want to cook the alternator.

Thanks
 

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  • 160 HPI Series High Output Alternators.pdf
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My first question is, is there a specific reason why we are building the system on 48v battery bank?

Usually for vehicle use, 12v or 24v is much cheaper, because you can use simple DC - DC lithium chargers to manage your aux battery bank, using an alternator as a charging source (as it decouples the 2 circuits), but I'm not aware of a 12v DC to 48v DC charger on the market that would be affordable.
 
My first question is, is there a specific reason why we are building the system on 48v battery bank?

Usually for vehicle use, 12v or 24v is much cheaper, because you can use simple DC - DC lithium chargers to manage your aux battery bank, using an alternator as a charging source (as it decouples the 2 circuits), but I'm not aware of a 12v DC to 48v DC charger on the market that would be affordable.
It's basically a time issue. It will take forever to charge a 7.2 kWh battery system with a 12v or even 24v charger in a 12v or 24v configuration. I will have solar, but on cloudy days I will need to charge the batteries in a reasonable amount of time. Second, I am utilizing a 48v heat pump for my heating and cooling. There is not such a thing that will charge a 48v battery with a 12v alternator.
 
Fair enough, makes sense.

So does your 160a alternator have an internal regulator, external regulator, and/or does it have a trigger wire style connection on it to allow the field current to be shut off with a wire signal (like to disable the charging output), and if you have a BMS with relay control on upper voltage limit, then you can signal to turn off the charging (alternator field current) on upper limit. You also would probably want to install a temp sensor circuit on the alternator for a failsafe field reduction or full shutdown of field current if it gets too hot.

Here is a good video I saw too awhile back from Victron about how not to blow up an alternator:

 
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BTW, just as a side note, I did remember having this DC-DC charger (12v to 48v) in my bookmarks somewhere:

Says it can handle 130a input and 25a output which may not be enough based on your time issue thing (1400w), but just thought I put it out there in case someone else reads it and finds it useful... Sounds like your alternator is capable of doing a whopping 160a at 56v which is 8960w...

You may also want to be mindful of your charge rate and be careful not to exceed the maximum c-rate your lithium bank can handle (with that alternator)...
 
BTW, just as a side note, I did remember having this DC-DC charger (12v to 48v) in my bookmarks somewhere:

Says it can handle 130a input and 25a output which may not be enough based on your time issue thing (1400w), but just thought I put it out there in case someone else reads it and finds it useful... Sounds like your alternator is capable of doing a whopping 160a at 56v which is 8960w...

You may also want to be mindful of your charge rate and be careful not to exceed the maximum c-rate your lithium bank can handle (with that alternator)...
Thanks for the info!
 
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