DIY cranking or booster battery pack

[myglaren]

I'm finding this rather bewildering.

I bought a new, over spec, Bosch battery a couple of years ago. Didn't need it, it was the starter that was duff.

Only ever been on the car although I do propose lifting it out and giving it a proper charge as the car does mainly very short trips, mostly in the dark now with everything running.

No problems with voltage (independent voltmeter).

Battery was ≯£55 (Independent garage, would have been three times that from Halfords).

The ancient and, under spec, battery is still here and charged occasionally, used for powering odds and sods as required. There was nothing wrong with it.

Hundreds of pounds for batteries, chargers and supercaps all seems rather strange. (My charger came from Tandy about 35 years ago ).

[white exec]

I’ve got an AGM battery fitted to mine, so even had to buy a charger that was AGM compatible. I suppose I would have to check up on something like that too to see if it’s compatible.

I have the humble little CTEK MSX 3.8* here, and the spec with it says it is suitable for charging Wet, Ca/Ca, MF, GEL and AGM batteries.
So unless you have something special there, even one of these standard small units would suffice.
* on Amazon at £57

[GiveMeABreak]

Just thinking about the solar jobbies for trickle charging during the day throughout winter - seems like a good idea - but not keen on having it on the OBD port because as I said, mine is in the centre console! I'll see what I can find.

[bobins]

Be careful of the solar chargers as - from what I've read - many of them are only capable of maintining the current state of charge of the battery and not actually increasing its state of charge.

[GiveMeABreak]

Righto, thanks Robin - I'll bar that in mind - if all else fails I'll borrow the solar panel from the fountain!

[MikeT]

I'm finding this rather bewildering.

I bought a new, over spec, Bosch battery a couple of years ago. Didn't need it,

You do make me laugh sometimes, Steve

[MikeT]

Got a couple more parts from China this week including jump leads with four parallel protection diodes. Cheap enough to sacrifice as a high-power fuse if need be though I'm still waiting on a power meter controller that has a 500Amp hall sensor (1000A version out of stock) to get a better idea of actual power needs for my cars or if I will need the higher-rated ammeter.

While I hailed first part of testing (remote unattended charging) a success I'm hoping the anticipated power meter will further offer a higher-rate charging option to speed up the process.
Then I'll look at a convenient method of it being self-charging off the alternator as well.

Part 2 on the other hand is the where the jump leads come in play to test cranking ability which should determine if I've got a big enough battery or will need more supplements.

Coincidentally, today I came across one of Julian's videos testing an off-the-shelf starter pack on his little 3-pot 1L Citroen. I won't comment on his testing method for obvious reasons but I think you'll agree the results are impressive for it's little 3S LiPo power source.

[EDC5]

I remember watching his video on jump starting the C1 at the time then I saw some huge engines being started with these tiny LiPo packs.

Following the project with interest....

[Hell Razor5543]

Currently if you call in at certain petrol stations (BP being one) they are doing, for £50, a battery pack less than half the size of a shoe box.

[MikeT]

I recently saw one on AliExpress for under £18 James but if they're fitted with LiPo's and don't have the proper protection circuitry (as most seem to be) they're just fire starters waiting to happen. There's good reason hobbyists keep them in fire-proof bags or ammo boxes and carriers have strict rules on transporting them.

[GiveMeABreak]

But if you're up for a giggle, here's the video:

https://videos.dailymail.co.uk/video/14 ... xhaust.mp4

[MikeT]

The slow-boat has birthed and produced more goodies, one of which I had high hopes for (VAC8010F-80V if anyone wants to look it up) but disappointed me right out of the box. The display screen is scratched and they've skimped on component population, first noticed by lack of temperature readout and different measuring input terminals than shown in the pics/instructions (of which I had to get off the web), ergo one less pre-made connector with lead they need to supply.

Admittedly, I lack relevant testing experience and equipment making me overly cautious not to release magic smoke from this kit but in testing so far, can't seem to get it to work as expected in "self-powered" mode, indicating the measuring device has to be powered by an external source for full functionality?
I also failed to get it to read ~0.5A draw through the hall sensor though it does give a seemingly accurate read on heavier loads - until the load's jumper wire failed making me initially think I'd cooked my power supply

If the power isolation instruction is crucial to either safety or accuracy of this device, I'm not sure it will be of any use in this project, which is a pity as it boasts some very useful features I'm still exploring. Is there a way to isolate two power feeds off the same source?

So the idea I could better gauge cranking power requirements with this device has somewhat evaporated (though I admit I still can't get my head round the voltage drop part of the equation anyway!). It's a pity as the LifePo>jump lead adapter should be arriving anytime soon.

[MikeT]

The VAC8010F-80V is going back for a refund and I'll see if I can get a fully working one elsewhere. The basic wireless measuring systems seemed to be working fine it but the rest was a mess.

Meanwhile, connectors arrived which I've now soldered onto the jump leads so I finally have a working booster pack ready for testing.

[MikeT]

The above mentioned item was intended to be the main over/under-charge protection & monitoring device. After all the waiting and work so far it's so tempting to just go ahead and try starting the engine with this battery but I must resist.

I also ordered a battery management system board as a second line of defence and because it has cell balancing which they say is conducive to long battery life. With yet more connectors to wire in, its first charge test only began last night though was interrupted when I needed my beauty sleep. Initial results show it does appear to be suitable and should allow me to further test it's over-charge protection on the car's electrical system.

[MikeT]

I've now (modestly) tested the BMS about as well as I can and the results are encouraging but in order to test it for real in the car I still need a way to keep the charge current low without having to revert back to a dedicated lithium charger. Suggestions welcome