[RE-wrenches] Charging a 108V battery bank
bob at midnitesolar.com
bob at midnitesolar.com
Thu Jul 1 16:54:31 EDT 2021
Normally you definitely do not want to tap a high voltage battery for
use at say, 12 or in this case, maybe 48V when the top end is
108V nominal.
But with a separate charger for the house inverter, (48V ?), and the
60V side, it would work a lot better than just using
a single 108V charger and tapping down at 48V. As long as there is
enough charging power for both battery sides the
two halves should stay balanced.
boB
On 7/1/2021 9:00 AM, Dave Tedeyan wrote:
> Dave,
> This is for a boat that will stay mostly on the finger lakes and in
> the Erie Canal system in upstate NY. Definitely not an ocean boat. But
> the plan is to convert it to a full time residence, potentially in the
> winter as well.
> Cheers,
> Dave
>
> On Thu, Jul 1, 2021 at 11:52 AM Dave Angelini Offgrid Solar
> <offgridsolar at sti.net <mailto:offgridsolar at sti.net>> wrote:
>
> Less is more offgrid. On a boat, if it is oceangoing, it is a life
> or death kind of world. A fire at sea probably will happen at
> night in bad seas. Not sure if this is your clients scenario for
> their use. An all electric boat sounds a bit scary. How will they
> get ashore? I use to give the owner a schematic that showed the
> location on the boat of electrical devices, wiring, and disco's.
>
> Hopefully this is for a lake sailor. Although one of the round the
> world guys I know tells me that he was never as scared as he was
> on a lake one day...Good Luck!
>
>
>
> *Dave Angelini Offgrid Solar "we go where powerlines don't"
> http://members.sti.net/offgridsolar/
> <http://members.sti.net/offgridsolar/> e-mail offgridsolar at sti.net
> <mailto:offgridsolar at sti.net> text 209 813 0060*
>
> On Thu, 1 Jul 2021 11:21:51 -0400, Dave Tedeyan
> <dave at sungineersolar.com <mailto:dave at sungineersolar.com>> wrote:
>
>> Bob,
>> This is a very interesting idea to have two separate battery
>> banks in series. I find it odd though that this particular
>> motor's datasheet calls for 9 12V batteries. I suppose that I
>> could have one charge controller set for 48V and the other set
>> for 60V. Although this will also pose the problem of trying to
>> run the house loads - if I have two 48V inverters that still
>> leaves one battery that will get loaded less than all the others.
>> And it seems that everyone else is pointing to the fact that it
>> seems important to keep the neutral and ground internally
>> separated in the inverter in a boat, so I'll stick to marine
>> inverters for this one.
>> Cheers,
>> Dave
>>
>> On Wed, Jun 30, 2021 at 5:30 PM bob at midnitesolar.com
>> <mailto:bob at midnitesolar.com> <bob at midnitesolar.com
>> <mailto:bob at midnitesolar.com>> wrote:
>>
>>
>> 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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>>
>> --
>> 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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> --
> 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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