LIFEPO4 setup and monitoring for our slide-on

Submitted: Friday, Oct 06, 2017 at 19:48
ThreadID: 135711 Views:988 Replies:6 FollowUps:4
Hi, we are just in the process of committing to buy one of these Lithium Power LIFEPO4 battery packs, does anyone have any direct experience with this business (based in Melbourne) or their product range that they would like to share or the EV Works BCU mentioned below? (feel free to send a PM also) Lithium Power 200AH pack

FYI, we have a small power requirement of about 50AH per day and we do not use/need a 240v inverter. We probably do not need 200AH LFP but it’s what fits in our tight space and does give us good capacity for the future and flexibility for long trips so we are happy to invest up front. We are not interested in a debate on LIFEPO4 batteries just if the approach we are looking at is reasonable from peoples actual LIFEPO4 experience and learnings.

The product makes use of the EV Power BCU (BCU-EVPPAK-4C) and I assume will be wired like this. Wiring Diagram (my battery will have 8 x CALB 100AH cells not 12 as shown in this diagram). The BCU manual is here: BCU user guide

As purchased the product comes configured with a high voltage cut-off (HVC) 3.65v and a low voltage cut-off of 2.5v (LVC), with a goal to achieve a SOC Usage Window 10% ~ 90%. Apparently, I could modify these if I wanted to by modifying the BCU directly but I think at this stage I will leave it as is. The HVC level seems ok to me but the LVC seems a bit lower than I would like (see below using BMV). Do these thresholds seem like a reasonable approach to go with?

We also need much better battery monitoring than we have in place currently in our slide-on camper. For monitoring we are thinking of going with the following products, Victron BMV700 with Bluetooth dongle (must have wireless information as the BMV monitor display will not be easily seen unless the slide-on is open, can get at if Bluetooth not working for some reason). I was thinking of getting the new Victron BMV712 Smart (BMV702 with Bluetooth built in) but I think I will also be buying the Victron BlueSolar MPPT 75/15 and I think I can use the same Bluetooth Dongle on both units (use on MPPT to setup and tweak as required but leave on the BMV700 99% of the time).

The other thing I think can be achieved with the BMV700 is to use it to trip the BCU latching relay at a slightly higher LVC threshold of say 2.9v thus discharging the battery pack a little less to hopefully make them last a bit longer (second line of defense). Do this approach with the Victron Energy gear seem like a reasonable approach to go with or are there other products that we should consider that would help us achieve a similar outcome that might be better/cheaper/smarter for whatever reason? (for example an Arduino product that could replace the Victron gear or most of it)

Are there other things that we should be considering for this setup that might stop us learning the hard way? (There is an isolator switch on the pack we are looking at)

When using the BMV700 to trip the BCU latching relay, will we be able to make use the same BCU relay or should we add a second latching relay to the BCU configuration just to keep things more separate?

What BMV alarm monitoring levels would be a good place to start off until we see what works?
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Reply By: noggins - Friday, Oct 06, 2017 at 23:00

Friday, Oct 06, 2017 at 23:00
Contact Terry at T1 Manum
http://t1lithium.net/
Specialises in Lithium installs and speaks from Practical experiences


zz
AnswerID: 614213

Follow Up By: Sam39 - Saturday, Oct 07, 2017 at 06:22

Saturday, Oct 07, 2017 at 06:22
Thanks, I spoke to the team at T1 about 6 months ago and went through a lot of the initial design and getting my head around the LFP batteries then. They helped me a lot, I did look seriously at getting them to do the install but ending up going in a different direction for a few different reasons.
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FollowupID: 884784

Reply By: Tim F3 - Saturday, Oct 07, 2017 at 11:09

Saturday, Oct 07, 2017 at 11:09
There is a very relavent discussion on the caravanners forum at the moment . A wealth of practical experience and technical skill to read.

I think it would assist you.
AnswerID: 614219

Follow Up By: Sam39 - Saturday, Oct 07, 2017 at 11:31

Saturday, Oct 07, 2017 at 11:31
Thanks, which particular thread as I have been following that forum also?
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FollowupID: 884786

Reply By: Tim F3 - Saturday, Oct 07, 2017 at 11:43

Saturday, Oct 07, 2017 at 11:43
Go to caravanners forum then rv electrics forum then it is the first item on top of the page it has about 43 comtributions.

All the best.
AnswerID: 614220

Reply By: Member - Racey - Saturday, Oct 07, 2017 at 15:14

Saturday, Oct 07, 2017 at 15:14
Hi, I don't know anything about EV. However, before committing to anything, I strongly suggest you have a chat with Phil at Solar4rv which are based in Knox (Melbourne) Solar4rv
I have a 400 a/h system from them and are very happy. What Phil doesn't know about solar and lithium batteries is not worth knowing. You won't be disappointed.
Cheers
Jon
AnswerID: 614224

Reply By: PhilD - Saturday, Oct 07, 2017 at 23:36

Saturday, Oct 07, 2017 at 23:36
I chose a few years ago to use 400 ahr Winston cells from EV Works and couldn't be happier. Each manufacturer uses different charging algorithms, so you need to take advice from whoever you are buying from. I don't know what is recommended for CALB cells. You could talk to EV Power in WA as they were distributing CALB and see what they say.
AnswerID: 614230

Reply By: Sam39 - Sunday, Oct 08, 2017 at 10:29

Sunday, Oct 08, 2017 at 10:29
Thanks all, I have been in contact with these suppliers on my LFP adventure so far!
AnswerID: 614236

Follow Up By: Member - silkwood - Sunday, Oct 08, 2017 at 12:44

Sunday, Oct 08, 2017 at 12:44
When you decide what you are doing, could you post your decision and reasons here? May be helpful to others in the future -like me! ;-).
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FollowupID: 884804

Follow Up By: Sam39 - Sunday, Oct 08, 2017 at 17:19

Sunday, Oct 08, 2017 at 17:19
We just paid the deposit and bought the Victron gear so I guess you could say we are now committed. Its been a long process (at least 6 months really brought on an AGM dying on us that we haven't replaced as yet and i didn't want to keep buying lead acid).

RE: Reasons are many but here is a summary:
- Weight is critical in slide-ons (so getting a few kg's back is a huge bonus)
- Hopefully they last many years and we manage them well, if they do then the upfront cost will be well worth it. In small installs like ours 150-200AH or above is really tough to justify the costs as we are not running an invertor etc. Larger installs I think it would be a lot easier.
- we needed a bigger change rather than just LFP batteries as we should have really had better monitoring and isolation when in storage, so its become a project rather than simply a battery swap out, so we have taken a longer term view
- I suspect "drop ins" will get better and larger capacity with bluetooth etc like the Enerdrive and maybe this would have worked for us but at the moment they are very limited, not good value in my opinion and closed units with warranties as long what we have purchased. At the moment I like the idea we can replace single components if we have specific issues (in a few years I will have a better view on this)
- We wanted a local supplier who will work with us and so far they have. I am hoping we can do the rest of the install ourselves so we minimise the install costs which seems to add up with most of other options we looked at and by having done the install and initial testing will then be able to do the ongoing maintenance and address most of the issues in the first instance
- If it all goes well then we are looking forward to having spare capacity for a change and using the solar panel less
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FollowupID: 884806

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