[RE-wrenches] Charging a 108V battery bank

[bob at midnitesolar.com]

If you can't find a single compatible charger, what also works it to use 
2 (two) separate

MPPT charge controllers each with a separate PV array inputs and connect 
each CC's
battery to half of the battery bank.  This has worked fine for both OB 
and MNS controllers
in past years and should with others as well I would imagine.  Set each 
for slightly higher
voltage than 48V of course.

One thing you may not be able to do might be connecting the chassis 
grounds together
depending on how those grounds are tied to the battery negative and 
positive lines internally.

Sometimes the internal SPD MOVs can get in the way if their voltage 
isn't high enough to handle
the two PV voltages that are seen as in series from the MOV's 
standpoint.  But those MOVs are
usually sized voltage wise to handle much higher voltage than, say, 300V 
which would he the maximum
voltage both CC's would see for 150V max input controllers.

You also cannot use the same remote controllers if they are not isolated 
from battery minus except for
the controller that is on the bottom side of the battery bank.

I have seen this method used many times now for 120V battery banks and 
also for higher voltage
electric boats.   There is quite a bit of this kind of wiring out there 
as I remember.

There are some other standards for marine inverters like,  UL 458 marine 
supplement and ABYC ratings.

This includes neutral ground switching like in mobile apps too IIRC.

Of course, just adding the word "marine" has to increase the price not 
matter what the product is.
😁

boB



On 6/30/2021 12:50 PM, Dave Tedeyan wrote:
> Hi All,
>
> I am going to be working with someone who plans to completely 
> electrify a boat. The electric motor is meant to run on nine 12V 
> batteries, or 108V. The motor manufacturer recommends a charger that 
> can run on 120V or 240V. But has anyone seen a charger that can take 
> solar power and directly charge a battery bank of 108V? The 
> alternative that I see here is to have two separate battery banks, one 
> for the motor, and one for house loads. Then we would have the solar 
> charge a 48V battery bank, and then use an inverter to charge the 108V 
> battery bank. It seems inefficient, although that may be the only choice.
>
> A separate but related question: what is special about a marine 
> inverter? If there is a 5kw charger for the battery bank, we will need 
> a large inverter to handle this plus other AC loads, and I am not sure 
> if there are "marine" inverters this large. And so other than concerns 
> about getting wet, is there harm to putting a Radian, or a Sol-Ark on 
> a boat?
>
> Cheers,
> Dave
>
> -- 
> Logo <https://www.sungineersolar.com/> 	
> Dave Tedeyan, P.E.
> Owner | Sungineer Solar
> p: he | him | his
> a: 1653 Slaterville Rd. | Ithaca, NY 14850
> w: www.sungineersolar.com <http://www.sungineersolar.com/>
> c: (607) 288-2898
>
>
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