Dead Makita (konion) BL1430 packs

[wookey]

We've been using stock BL1430 packs with Makita BHR162 for caving expedition work. They are now in their 4th year of use (~1 month each year) and two of our 4 packs died completely. (<2V on the pack). This is rather mysterious and I really don't know what killed them. A bit of research on the cells in the packs brought me here as it seems our DrBass is a huge Makita pack/konion fan. Small world

So first - DrBass - I see you've just sold the last of your current batch - bum. I'll be very keen to buy a few packs if/when you get some more. Do please contact me (Unless anyone knows of a UK source for poorly packs?)

Some more details of our packs and usage to see if anyone can work out why we got less than 100 cycles out of two packs (of 4):
The packs are 4S2P 3Ah 14.4V. Expo runs for 5 weeks each year in approx August (in Austria) http://expo.survex.com/. The drills and batts are stored in a garage in the UK the rest of the year. Charge state is 'however they were left' during this storage. In Austria we have a base camp and top camp up the mountain. At base we have two makita-supplied mains chargers. The chargers use the smart battery monitoring which I note has a centre tap but does not do per-cell balancing. At top camp we have two digital RC chargers set to charge 14.4V li-ion at 4.1V/cell and 3A (those chargers are powered by a 300W solar system with charge controller and big SLA batt). Those RC chargers do not have balance taps, so are just charging all 4 pairs in series.

The caves are about 1C (34F) so the batts are normally discharged when quite cold. (The datasheet shows a 5% capacity reduction at 0C c.f. 20C). Normally two batts are taken on a trip. Maybe only one will be used. Both will the put on the charger when one gets back to the surface. The RC charger seems smart about just saying 'it's already full' after a short think (as do the makita chargers).

So, all 4 packs were working at the start of expo. These packs have internal protection, so how did they apparently get badly over-discharged down to just ~2.5V, such that the chargers refused to try and charge them? This was unsurprisingly fatal (at least after they had been sat like that for a couple of weeks, until we could get back to things like bench supplies). Are the internal boards on these batteries actually rather useless, and possibly defeated by low-temp discharge? But they have been OK for 3 previous years.

Suggestions as to what went wrong welcome. How many cycles do people normally get from these packs? Does anyone have details of the protection circuit? Can it be reset if the cells are replaced?

Recomendations for replacement cells? Apart from DrBass's returned packs I can't see any sources of new cells of this type, only the similar US 18650VT here: http://www.batt-energy-shop.de/product_info.php?info=p8_sony-us18650vt-li-manganese-battery-3-7v-1600mah.html

Is there in fact another cell optimised for this application (I haven't yet measured the Drill current consumption). I expecting it to be about 7A.

I hope this diversion from ebikes is of interest

 

[cassschr1]

Open them up and use the rc charger. When there open you can get to the + and minus directly without going through the board ( dont actually know if it makes a difference). To get open grind the stem of the security bit so its about 3/8 inch longer( being skinny) so it fits in the holes in the packs. reassembly is not a problem, nothing to break,etc....just today I charged some that were at 1v and they came back. It would be nice to have the balancing wires though, maybe essential if voltages are all over the place

 

[wookey]

Yes, we've opened them up - hoping that some cells could be saved, but in fact all 4 pairs were very low voltage. I've tried to charge the individual pairs with a bench supply, but they only took a few (~8) mA current for a while before taking no more (at 4.2V). The final voltages in one pack were 0.7V, 0.9V, 1.2V, 0.8V. So I concluded that they really are knackered.

Out of interest, if this cell chemistry gets discharged to <2V, how long have you got to charge them back up agian before they are permanently knackered? Is it minutes, hours, days, a week or two?

 

[Ypedal]

Seems to me like a few months below 3.0v and they are toast..

4 years may be the limit, not cycle life but calendar life..

I have been using these to power my Cycle Lumenator led light and i had a 6 cell pack go open circuit on me last night, she was toasty lol.. but no smoke no fire..

Did any moisture get into them ?

 

[cassschr1]

Thats pretty low, powerlab would pulse this till it comes up, it tries this for 3.5 min, then if not to 3.0v says BAD CELLS, so I try again and again. If there that bad they won't hold voltage after they are charged anyway, and cycle less ma than there good brothers. Get some packs fron Doc and take last pair off, put your packs back together and your done.

 

[ambroseliao]

Wookey,

Do you have any good cells in that pack? One thing you might try is to parallel a good 18650V battery with the bad one to help give it a "nudge" so that it can accept more of a charge. Connect the charger when the good and bad cells are paralleled and see what happens. If you need a good 18650V, I've got a couple I could send your way. The good doctorbass often has them, of course.

These cells are known to keep their balance pretty well. The 18650VT will not make any difference in your setup. It is, in fact, a lower capacity cell, however, it can put out more instantaneous current than the V version.

Ambrose

 

[wookey]

Ypedal: There was no evidence of moisture damage (corrosion, staining), but the packs are not waterproof and caving can be a little damp (actually in Austria it's normally quite dry, but pitches can be drippy and that's usually where you are drilling). We transport them (drill and batts) in a drybag and just get them out for use, so I don't think there has been water damage, but they probably have got a little humid from time to time.

Do we have threads on here for 'cell resurrection' procedures? I am not familiar with the recommended way of trying to charge over-discharged Li-ions.

Interesting idea that they simply don't last much longer than 4yrs (calendar). Our other 2 packs are still going (although somewhat reduced capacity I think - I need to do some tests to check, but charger was saying about 2.25Ah - I'm not sure how close to 3.0 they were when new). DrBasses returned makita pack stats might shed some light on how long before packs get sent back.

I wonder about making new packs with LiFePO4 cells instead as I think that may may be more long-term robust. We can take a weight/capacity penalty to some degree. (Our old nicad batts for Bosch 24V drills weighed about 5kG, so these lithium ones are _tiny_ in comparison

The easy option is to wait till DrBass gets some more, and we have till approx June next year to sort this out, so I'll wait for a while.

It would be interesting to read the data from the batt packs - has no-one got any info on the protocol used?

 

[wookey]

OK. I have some packs from Dr Bass to work on, and Makita have said they'll give us some new ones too as sponsorship (impresive to see back-up like that - they aren't just supplying sponsorship drills as a loss-leader!). So I can compare new packs and old packs and refurb packs.

No-one here got any details on the batt management chip? It'd be really good if we could read the 'how many cycles' info out of each pack, for example.

 

[pwbset]

No-one here got any details on the batt management chip? It'd be really good if we could read the 'how many cycles' info out of each pack, for example.

Apparently there is a Makita pack reader, but it's very expensive. I'd call Makita and work your way through the phone chain until you get someone that knows. I did that with Milwaukee years ago for their battery pack reader, but never plopped down the $100s they wanted for it. It told max temp, cycle life, individual cell voltages etc. etc. Let us know if you find the Makita pack reader and how much it is! Good luck!

 

[bionx 1954]

I have been using Bosch Fat Pack Bat836 from Ebay. These 36v 2A packs have 20 Konions inside. They were about 50.00 US a few years ago . Now they are around 100-120.00 on Ebay from US sellers. I have some packs 3 years old/ 1000 cycles still giving more than 80% of original capacity