Charging the house batteries

[dwh]

According to the installation manual, the new 180a model is available starting March 2015.

https://cdn.shopify.com/s/files/1/0...6c-bf8d-7b95407ab43b.pdf?11538045812489177130

 

[SkiFreak]

I really think the best way to get where you want is an externally regulated alternator with a "smart" regulator that you can program. Not to sound like a broken record or anything.

I absolutely agree that this is a very good option, but it's definitely not a cheap one. This is what I had initially wanted to do.
My problem is that I don't know anyone that can supply, or is willing to supply, the necessary bits to modify my Fuso OEM alternator from an internally regulated unit into a P-Type, externally regulated one. As I mentioned earlier, I thought I found a company that would help with this, but now they won't.
If I am forced to buy a new alternator and something like the Balmar regulator then I would be up for about $2K, which is a bit more than I would prefer to spend to be able to charge my LFP batteries safely from the alternator.

As I said... I am open to suggestions, as I have not committed to anything specific as yet.

 

[dwh]

The alternator output voltage is up to 14.6v. I only want to charge the LFP batteries at 14.0v, so I want a voltage reducer.

Looking at the manual, to get it to output 14.0v, you'd have to select GEL. Also, apparently NOT actually programmable - preprogrammed selectable charge profiles.

 

[SkiFreak]

According to the installation manual, the new 180a model is available starting March 2015.

Not of real interest for me if I stay with the OEM alternator (my preference at this time), as it only outputs about 100 amps.
The 120 amp model however... if that does what it says it will, it could be a suitable option for me.

You also mentioned that it was "also programmable".
All I saw was that it had 9 preset charging profiles. Did I miss something?

 

[SkiFreak]

I guess we posted at the same time...
And yes, I figured that AGM1 (14.1v) was the best suited profile for my needs, as it has a lower float voltage, effectively turning the charging off when the batteries are full.

 

[pugslyyy]

I absolutely agree that this is a very good option, but it's definitely not a cheap one. This is what I had initially wanted to do.
My problem is that I don't know anyone that can supply, or is willing to supply, the necessary bits to modify my Fuso OEM alternator from an internally regulated unit into a P-Type, externally regulated one. As I mentioned earlier, I thought I found a company that would help with this, but now they won't.
If I am forced to buy a new alternator and something like the Balmar regulator then I would be up for about $2K, which is a bit more than I would prefer to spend to be able to charge my LFP batteries safely from the alternator.

As I said... I am open to suggestions, as I have not committed to anything specific as yet.

Hmm, how are you ending up at $2k?

$150 for the alternator (rebuild with lifetime guarantee)
$125 for the regulator (ebay MC-612)
$250 for fabrication, belt, etc

If you buy a new regulator direct, add $200, but still have a hard time getting to even $1000. In my experience the Balmar regulator is worth it but the alternator isn't.

 

[SkiFreak]

Firstly... I was looking at the MC-614, not the MC-612, as it is user programmable. Here the MC-614 is over $500, then add to that the battery and alternator temp sensors and it's over $600.
If I were changing the OEM alternator for a P-Type one I would get a high output alternator. The 220 amp bolt-in one I was looking at runs at about $1400, which adds up to $2K.

I know I can get the regulator from the US for a cheaper price, but warranty is always an issue if doing that.

If I could get all of the bits to modify the OEM alternator I would still consider that as a viable option.

 

[LeishaShannon]

If you are keeping start batteries on the truck why not have a relay to connect/disconnect the house batteries at a particular voltage/SoC ?

 

[SkiFreak]

The relay part is easy, as I could use one of my 500A latching relays. However... unlike you, I do not have the skills to build a circuit that would detect the on and off voltages.
Sure, I could probably use a small BMS and utilize its alarm feature, but that is not a perfect solution as the alarm gives a constant voltage, not a pulse, which is what is needed for the latching relay. Not using a latching relay would mean that the circuit would always be drawing current from the relay.
Well, that's my assessment; maybe I am wrong.

 

[pugslyyy]

Firstly... I was looking at the MC-614, not the MC-612, as it is user programmable. Here the MC-614 is over $500, then add to that the battery and alternator temp sensors and it's over $600.
If I were changing the OEM alternator for a P-Type one I would get a high output alternator. The 220 amp bolt-in one I was looking at runs at about $1400, which adds up to $2K.

I know I can get the regulator from the US for a cheaper price, but warranty is always an issue if doing that.

If I could get all of the bits to modify the OEM alternator I would still consider that as a viable option.

Ah gotcha. The big ticket item for you is the alternator. After having my very expensive Balmar fry, I ended up choosing to go with the highest output widely available externally regulated alternator I could find. So far the 120 Amp has been adequate for my needs.

 

[DiploStrat]

Probably referring to an older unit.

Absolutely right, I was referring to current production units as sold in the US. These are some interesting new products. The big problem Sterling (and everybody else) have had with their B2B units is that you throw away a lot of amps to get a few volts. Volts and amps that you can probably save simply by using properly sized wire in the first place.

Interesting historical comment, Charles Sterling Sr. was one of the first to recognize the need for higher charging voltage, thus his products were a generation ahead of the rest of the world when first introduced. Later, when alternator voltages rose to where they should be, it became harder and harder to justify a product which essentially duplicated what your vehicle charging system would do anyway. I would still be using a Sterling A2B if it didn't shut down at 15.5v. I am kind of glad that it did, however, as it showed me that I didn't really need to spend the money, give up the space, or pay for the complex wiring.

The nice features of most Sterling products are:

-- Remote voltage sensing, which can reduce voltage drop.
-- Remote (i.e. directly at the battery) temperature sensing which allows the unit to adjust the charging voltage up or down as required.
-- Ability to set a different charging profile from the vehicle system. This may take on a whole new value if, as may be the case, lithium batteries need significantly less voltage than lead acid.

One drawback is that many are diode based, so they created a lot of heat and they do not allow solar or shore power to be shared with starter batteries. (There are, however, ways around this.)

Sterling have a bit of a reputation for vapor ware, so you need to be sure that the product that you want is actually available. (See, for example, their Wildside, a combination B2B and MPPT solar controller which looked very interesting.)

Back to the original poster, if you REALLY want a secondary regulator, consider this CTEK system:

-- CTEK D250S Dual: A combination B2B and MPPT solar controller - http://smartercharger.com/battery-chargers/#CTEK D250S DUAL
-- CTEK SmartPass: An intelligent relay, especially designed to work with the D250S - http://smartercharger.com/products/dcdc/ctek-smartpass/

Grossly, during bulk charge, the SmartPass closes its relay, directly coupling the starter and camper batteries. When the charge rate drops to 20A, the relay opens and the D250S continues through the absorb stage.

 

[DiploStrat]

The relay part is easy, as I could use one of my 500A latching relays. However... unlike you, I do not have the skills to build a circuit that would detect the on and off voltages.
Sure, I could probably use a small BMS and utilize its alarm feature, but that is not a perfect solution as the alarm gives a constant voltage, not a pulse, which is what is needed for the latching relay. Not using a latching relay would mean that the circuit would always be drawing current from the relay.
Well, that's my assessment; maybe I am wrong.

Bit of a brute force cure, but I use a Magnum Smart Battery Combiner (http://magnumenergy.com/smart-battery-combiner-me-sbc/) to control a 200A relay. You can adjust the high voltage disconnect from 14 to 15v. You can also adjust the connect and disconnect voltages over a wide range. You could use this to force a disconnect, but I fear that might simply mean that you never got a charge to your lithiums; you may be forced to go with a new regulation regime.

I went with the Magnum SBC unit because I was terrified of feeding too much voltage to my AGM batteries. Later I learned that my vehicle alternator would not, in fact, ever exceed the specified voltage, so I added a force combine switch to use in extreme cold. Hence my enthusiasm for the Blue Sea ACR line.

 

[Buckstopper]

Ok - you guys have me thinking. My house batteries are a pair of flooded lead 6V golf cart batteries that were original to the camper so they are 7 or 8 years old. They have served me well but maintenance is a minor pain as they have to be removed to add water. I also have 94 100 amp hour Sky Energy Lithium Phosphate in my electric car that are getting a bit long in the tooth for the EV but could work well for a larger single pack in the truck.

Obviously I wouldn't need or want the entire pack in the truck - it could power a small town and would need to be grid tied to charge entirely. I am also not happy with the BMS that I have for the EV so I would need to replace that. Using a single pack to serve both starting and house functions would simplify charging. I have a the space presently occupied by the starting battery plus the the area between there and the cab so could easily locate a 800 to 1000 Ahr pack there. Thats still more than needed but would give some reserve for starting and account for cold weather sag. Lithium cells are happiest when the middle of the pack capacitiy is used so having some excess capacity is good. This also allows for the aging of the pack. I need to give pack size some thought.

Issues to sort out would be charging from the truck alternator to get the preferred charge curve for Li but Skifreak is probably on the right track with that - a programmable regulator with or without a larger alternator. My camper has solar but a lot of our travels is in the cloudy and tree covered PNW so it doesn't add a lot of amps year round (works great in the summer except for treed campsites). Third source of amps would be plug-in shore power. I would need a system to coordinate 2 or 3 out of 3 charging sources at a given time but that should be solved with a solar charge controller.

More thinking to do...

 

[Mock Tender]

Is this new or just new to me?

http://www.nationalluna.com/battery_systems.htm

 

[DiploStrat]

Is this new or just new to me?

http://www.nationalluna.com/battery_systems.htm

Not new. Company based in Jo'Burg; have a distributor in the US. You can read more here: http://www.expeditionportal.com/for...onal-Luna-Split-Charge-System-Charging-Issues

I like the product made by Blue Sea better as it has higher capacity and is water protected. https://www.bluesea.com/products/7620/ML-ACR_Automatic_Charging_Relay_-_12V_DC_500A