My dad has an old Austen 7 classic car which still use a 6V battery that died again (naturally). Those 6V batteries cost around R3000 and he is looking for alternatives.
I first looks for 2 cell BMS but I could not find anything with decent current rating (in fact there are very little boards able to handle 2 cells.
Next option was to use a 12V battery and look for a boost and buck converter, but that also does not seem like a viable option.
Does anyone have a brilliant plan I could use?
If we had lots of time we could convert all the electrical to 12V, but that takes time and a lot of work.
My 2 cents:
Option 1: If we had lots of time we could convert all the electrical to 12V, but that takes time and a lot of work.
Option 2: Trojan T105 cell, 2nd hand, like i.e. here: https://www.trynosbatteries.co.za/
… if it can fit in the vehicle?
Answer: Which option is cheaper?
Check out this SLA battery: Cartronic Sealed Lead Acid Battery 6 Volt 12 Amp WP12-6 – Carter Direct South Africa
I bought a couple of these years ago and I’ve still got them!
If one isn’t big enough to crank the Austen then get a couple and connect them in parallel…
I would first try a motorbike shop. Many use 6V batteries, and they should not be that expensive.
In a push, a 2S3P A123 pack should be fine. Add a passive balancer. No real need for a BMS, as these cells are robust against over charge/discharge (although it does shorten their life).
From my googeling seems like 15A is probably the upper range of the Austin 7 Dynamo with not much heading towards the battery. No idea what the cranking amps are like but the lead equivalent batteries look to be around 300-360CCA and capacity 50-70Ah.
So if not doing long journeys, motorcycle batteries could be options (as pointed out by @justinschoeman) - even get them in lithium but 7Ah will likely cost more than the lead acid in any case.
Otherwise, if feeling like experimenting this with two 50Ah or 100Ah LiFePO4 cells might work and come in a bit cheaper than the R3K lead battery? looks like about R160 + R800 shipping (at least is fedex)
See lithiumbatteriessa’s 2nd life 100Ah cells are R800 a piece. (spec sheet says 300A for 30sec @ 25 ℃ - when new)
Might even be able to get the form factor close to the lead acids.
Your gonna struggled to get one for R3000 now and the availability is terrible. My dad has been waiting months for his.
The motorbike battery option sounds like a good option. The Austin has a light engine and does not take much to turn.
The 2S 40A Lipo bms could be a nice long term option as well.
@Village_Idiot you are spot on with the estimate. The old battery has 300CCA and 70Ah