Energy Matters Forums

[davef]

australsolarier,

I did miss the comment about internal regulator. I recall old threads about these 13V5 lead-acid equivalent packs only having internal BMS.

Cheers,
Dave

[dRdoS7]

Hi,

Recommended Solarking charge settings:

https://www.solarking.net.au/images/oth ... 0above.pdf

I have noticed that when they are recharged (via the caravan's chargers), that the BMV712 shows slighly less than 100% each time. I am assuming that's due to me using a slightly lower than recommended setting. It's only -3Ah, so not worth worrying about. I have also pulled out more than 200Ah once or twice (when testing - all chargers off). Both could be meter reading errors too (+/- 0.4 according to the specs).

I'll also add that I ran a 2200W kettle for 3 mins, drawing 199A at the start, which tapered off a little. I had expected the BMS to shut it down after 30secs.


dRdoS7

only having internal BMS

Some would call that "evolution".

[Quokka2]

I note that this thread has been dormant for a while but thought I'd ask here if anyone has knowledge or experience in using lithium batteries in series. I look like having to re-power my 48v cart (see alternative-vehicles/topic6773.html) but most lithium batteries seem to have caveats about using them in parallel or more than a couple in series; something to do with the BMS that they all seem to come with these days. I suspect the current draw may also be an issue, but have no idea how high that gets (maybe not as high as it has got carting around 160kg of lead acid batteries!).

I can't be the first person to have come up against this problem; hopefully someone out there has found a solution.

[Privatteer]

If you build it with 16 individual cells you should not have an problem. It is done a lot for different equipment most house systems are that way.
Current draw should be less of an issue most I've seen are speced far higher than lead acid.

[Quokka2]

Hadn't really thought of that; I suppose the beauty of the "drop in" lead acid substitutes is that they would be compatible with the existing charging system and fit snugly in the vehicle's battery compartment. The people who sell batteries for these vehicles seem to sell mainly 12V batteries (lead acid or LiFePO4) which must all be used in series, so I'm trying to understand the conflicting advice out there.

[australsolarier]

quokka,
nothing must be used in series.

some of them "drop in" 12V lithium batteries can be used in series up to 24V a very few up to 48V (more expensive though) and most can be used in parallel. probably all.
they cannot be used to start the motor though as the BMS limits the current and cuts out.
have a look on ebay and check the specs.
i had ordered an optimum brand and it had less than half of the advertised capacity and the terminals were reversed. (successfully returned)
i bought two solarking and they had the advertised capacity.
you never know what kind of quality battery cells are inside those boxes, they might well be second hand.

[Quokka2]

Hi australsolarier and thanks for your thoughts. I have to use any sort of battery in series if I need 48V; most of them just seem to come in 12V packages!
As you found out, the specs offered on eBay come with a pinch of salt; I'd ruled out Optimum based on your previous post and had the Solarking on my list. Lowenergydevelopments' current eBay listing for them says that they "Are suitable for arrangement into 12/24/36/48V battery banks" and yet lists the maximum series voltage further down as 30.4V. I contacted another eBay supplier with the same issue last week and the only reply I got was "Some of our customers have".
For the moment I am still trying to salvage my old Trojan lead acid batteries, but suspect I might have to need Plan B. If I'm going to have to shell out nearly three grand for four 100AH lithium batteries, I need to be sure it's a quality product and it's going to work.

[australsolarier]

have you contacted ev-works?
rd sells finished plug and play systems.
not cheap though, but this is an investment that you want to last 20 years or longer.

[Quokka2]

have you contacted ev-works?
rd sells finished plug and play systems.
...this is an investment that you want to last 20 years or longer

This is quite helpful as none of my Google searches had turned up Ev-works and I hadn't heard of them. Shame about the Google reviews though!
Who/what is rd? As for this being a 20 year investment, it isn't; I'll be well out of here by then in a cottage by the sea, or in a bag of garden compost.

[australsolarier]

sorry, spelling mistake, Rod, not rd