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8x4 MAZ/MA3 535A from Lunchkins 2 weeks 2 days ago #61822

Test drive was very disappointing; After little more than two minutes the battery voltage dropped to the extent that the front wheels were stuck pointing in different directions & no progress was possible forwards or backwards - and the transmitter (telemetry) was bleeping & showing the battery voltage (?) as one or no bars (out of 5).

I have 3 of these (Lucas LSLA12-6, sealed lead acid, 12Ah) batteries, this one showed 5.9v, the one from my Combine showed 6.1v, and the spare, 6.4v. The first two have both had light, testing use & have never been charged, the spare has never been used or charged. I would expect them to be 7v fresh off the charger, and somewhere between 6.3 and 6.6v after sitting for a while, so the spare should be good, the other two need charging - but I can't help feeling that the one I've been using should have lasted way way longer before needing it.

I couldn't find any charging specs on the battery, most batteries should be able to take 1C, but these are "sealed" (or at least have a one way valve) so I don't want to push them as far as outgassing ... Almost all information on charging on the internet is theorectical and focuses on voltage. This is no use when I want to know what amperage limit to use on my Imax B6 (0.1A to 5.0A). I did find that a maxium of 0.25C is recommended for selead batteries & 0.3C for AGM (which these may or not be): would be 3 to 3 to 3.6A,. which seems like a lot for a battery a battery which is generally intended for constant charging & only for use in lights, bath lifts & alarms when the power fails.

I guessed at 1A, and from what it's taken so far, and assuming a charging efficiciency around 1.4, charge (from flat) would be about 17 hours, which seems reasonable ... but very long.


I'm off to try the spare battery :)

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8x4 MAZ/MA3 535A from Lunchkins 2 weeks 2 days ago #61823

2nd attempt was a lot better :)





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8x4 MAZ/MA3 535A from Lunchkins 2 weeks 2 days ago #61824

9.4kg is one badword of a baby... but it's definitely pretty.

Simply awesome.
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8x4 MAZ/MA3 535A from Lunchkins 2 weeks 2 days ago #61827


Lights :)





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8x4 MAZ/MA3 535A from Lunchkins 2 weeks 1 day ago #61835

Oohhh awesome 8x8 Jonny. And lighted it is crazy.
Love it.

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8x4 MAZ/MA3 535A from Lunchkins 2 weeks 1 day ago #61838

Brilliant JR
If you can't fix it with a hammer, you've got an electrical problem mate :)

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8x4 MAZ/MA3 535A from Lunchkins 2 weeks 1 day ago #61844

I should have read the manual :whistle: ... the B6 booklet says to charge at 0.1C, so 1.2A in this case.

It also says that the peak can be difficult to detect, so after putting around 8000mAH in (which took som time, as I didn't want to leave it unattended) and the charger saying the voltage was 7.35V, I called it a day :)


ETA - 2nd ("spare") battery took a total of 3h 51m over two sessions for a total of 4598mAH; it hit the capacity limit on the charger I'd entered some time ago, but the voltage was showing as 7.35V so I thought that was enough.

3rd battery (out of my combine harvester) charged for 4h 53m & 5872mAH without stopping, again the charger was reading 7.35v so I wasn'y inclined to let it go any further.
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Last edit: by Jonny Retro.

8x4 MAZ/MA3 535A from Lunchkins 2 weeks 20 hours ago #61851

0,1C ??!! That is a very low charge. :huh:

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8x4 MAZ/MA3 535A from Lunchkins 2 weeks 19 hours ago #61853

It's the output of my borrowed power supply so I could run the Grasshopper once a day in the '80s.

Correction- that was 100mA. I'm so out of the game.

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Last edit: by Edou.

8x4 MAZ/MA3 535A from Lunchkins 1 week 5 days ago #61864

This project is still awesome, heavy or not :silly:
The following user(s) Liked this: 1972 LeMansGT Jim

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