Unclear on doing AGM to Lithium battery replacement

[Scalf77]

Another option for replacing the Blue Sea ACR is using a Precision Circuits LI-BIM 225. This device replaces the ACR and will somewhat limit the charge going to your lithium battery. It limits the hit on your alternator by monitoring voltage and running less than 50% of the time 15 min on 20 min off. It also does not really charge the lithium battery much above 80% SOC. One could finish the charge with an existing solar charger. It does not limit current, you might need to match alternator current with max current charging (small lithium bank). Another plus is that it can be connected for emergency jump starts.

If you have a larger alternator system such as Ray's 220 amp or a Ford Transit with dual alternators 250 amps, I have seen this posted on vanlifeoutfitters.com. Here they use a Victron Smart BMS CL 12-100 as a current limiting device (bypassing the BMS functions) The current can be limited lower but at full tilt it would limited at 100 amps. This just passes current and has no charge profile. But, you then could add in Victron DC to DC for and additional 30 amps, and it could perform, your absorption functions. So when the battery SOC was close to being full, you could turn off the CL-12-100 and let the DC to Dc finish the charge.

I believe it is important to make sure you can disable any of these charging devices manually or (programmatically if you are inclined.) I would be another vote for not hanging the battery underneath under the van. Charging at higher temps (battery over 86) could reduce the cycle life of your battery.

Having said that, the same could have been said for your AGM battery in they same location. The nice thing is the cycle life of a lithium battery is generally so much higher it will still outperform. Prices continue to drop and will probably be even lower by the time you need to replace.

I do find that the charging efforts can be a little more involved with lithium, but it is worth it.

I also agree with the both the Victron DC to DC, or KISEA DMT1250 being pretty good chargers . The KISAE has active cooling (Read fan Noise).

[posplayr]

Originally Posted by 86Scotty

Stay away from the Renogy DC2DC chargers. I recommend Victron, Kisae or otherwise.

Any specific reasons from the known issues or others?

[JonBertsch]

Scalf77 thank you for the extra info and suggestions.


Overall I think I will look at swapping the Blue Sea for the Victron DC-DC. I have a 225Amp alternator so that needs to get factored into it.


Jon

[1der]

Since it is somewhat on the subject -

I have a brand new (the newest design) Sterling 70A DC to DC plus the optional remote panel that I just posted for sale.
https://www.sportsmobileforum.com/fo...tml#post326438

I decided for commonality to just add a third Victron 30, so the Sterling is available.

[kbeefy]

I'm sure you've already figured it out, but a lot of the nicer quiality LiPo batteries have built in heaters and provisions in the onboard BMS to control them.


I opted for a cheaper battery (200aH Ampretime) and built an insulated box with a thermostatically controlled heating pad, probably similar to @1der as a cheaper, but more complex solution.

[Scalf77]

Jon,
With your alternator size I would look at Ray's Sterling unit for sale. To be clear Sterling references their products based on the input current. In this case 70 amps. The Victron and KISAE DMT1250 are based on the output rating. So the KISAE DMT1250 can provide 50 amps on output. So it would be close to the Sterling unit as far as charge power. Although I like the KISAE unit, it is getting old, and they really haven't provided much in updates since they came out with it.

The Victron 12-30 would be a little small for a 200- aHr bank in my opinion, so if you went with Victron you might want to double up.

[JonBertsch]

Thank you everyone for your input. I am doing a little more reading around. The Sterling option may work better than the Victron. I need to get my head around the new info a little more before I make a final decision here.


Jon

[lchukar]

Originally Posted by 1der

Our Lith batteries are in an insulated box below the floor and incorporate thermostats to control heating pads to keep the batteries above 34F.

1dr , can you be more specific about just where the battery is located? How is “under the floor” different from the standard spot beneath the van behind the rear axle?

Thanks so much for your otherwise detailed explanation of this issue.

[lchukar]

So many Forum members with so much knowledge and experience! Is there a shop out there somewhere (west of the Great Plains) that can match y’all and do such AGM to lithium conversions for those of us who can’t do it themselves?

[1der]

Originally Posted by lchukar

1dr , can you be more specific about just where the battery is located? How is “under the floor” different from the standard spot beneath the van behind the rear axle?

Thanks so much for your otherwise detailed explanation of this issue.

Our rig is the EB version. There is a space directly behind the differential and forward of the frame cross member where the spare tire was. I have a basement box where the spare was. On EB models' SMB sometimes mounted a battery (or two) on a platform hanging from the frame rails in this area. Other EB's have a holding tank in this area directly behind the diff. The RB vans do not have that space since the spare tire is directly behind the diff due to the body being 20" shorter than the EB.

On our EB, I cut an access opening in the floor, fabbed a box that dropped in and is bolted to the body /floor. The batteries can be accessed from the interior as well as sealed off from the exterior.


Sideways but you can see battery box opening forward of the basement box opening.

From the top, 2 x SOK 206AH batteries

From underneath, diff is to the right in the pic.