Small Bestech BMSs!

ESK8 Electronics
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21

I have two chargers that both output 42.2v. Also my BMS (that doesn’t balance) charged to full.

@darkkevind You only need 1 BMS, and yes you treat each parallel group as 1 cell.

I think the brick chargers, especially the cheap 2a models are just not dependable

I think in the case of brick chargers, charging is entirely dependent on the BMS. The charger only thinks it’s full because the BMS is blocking any more current from flowing. I’m sure this is how all commercial boards are built as well. I’m guessing my BMS’s are just duds, or the overcharge release is somehow affecting charging behavior

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Maybe try contacting BesTech they seem to communicate well? Would be nice to have the answer to this

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No just one 8s BMS. The 4p is seen as a single larger cell and charges as one. each group in parallel gets the single balance lead to BMS - regardless if 1, 2, or 10p.

so for simple math - 25R in 4p is seen as 1 10,000mAh cell not 4 x 2500 mAh cells - per balance lead. As expected when you charge 2500mAh vs 10,000mAh - it’ll charge slower the larger the capacity.

HTH - GL!

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24

This is exactly what I’ve been looking for to use on my 10s Lipo board. I only wanted the charging option in a small footprint. Now how do I got about buying one? :unamused:

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That may be true for some BMS’s but it is a good idea to let the battery cool down after charging for 20-30 minutes before using it and vice versa don’t charge a hot battery pack immediately after using it.

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These look lif like a good small, inexpensive solution. But that shipping cost is pretty steep. Maybe someone can set up a group buy for these and we can all save on shipping.

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@sl33py Is what I have here correct when you have batteries in parallel and in series?

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It is correct if your not bypassing the bms during discharge and you have a bms capable of high discharge current.

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29

I bought a 60A BMS and I don’t have very many hills in my city so I imagine I will never reach that type of current.

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Those are tiny! My 12s 80amp bms is like 200mm long and 120mm wide! Well, not the actual bms but the sheet of metal it’s attached to, by the way is it safe to drill through that metal? It looks like just a normal sheet of aluminium, might actually be a heat sink, I don’t know

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60a will be plenty to handle discharge and you will have all the protection that the bms affords.

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@Jinra how do you order from Bestech? I’ve found a BMS I’d like but there’s no prices and I can’t see a way to order?

Cheers :thumbsup:

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you have to write them an email.

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Ah I thought that but then I thought, no wayyyyy they must have an online shop! lol

I guess not. Cheers :thumbsup:

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I just bought some LG INR18650-HG2 3000mAh - 20A Li-ion batteries to make up an 8s4p pack, can anyone recommend a good BMS please?

I have a question, why can’t I just use 4 x TP4056 boards and a 33.6v 10A charging brick?

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Any one tried this one? https://www.banggood.com/10S-36V-Li-ion-Lithium-Cell-20A-18650-Battery-Protection-BMS-MOS-Board-With-Balance-Function-p-1127995.html?rmmds=search or this one https://www.banggood.com/10S-36V-35A-Li-ion-Lithium-Battery-Protection-BMS-PCB-Board-With-BALANCE-p-1148775.html?rmmds=search It’s cheap with free delivery. Thanks Luke

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I bought the second one from banggood in advance of a more serious BMS like Besttech I am planning to use it on the charging side only due to it’s low Amp rating. It doesn’t having any charging wires

Anyone have experience of these ones?

http://www.ebay.co.uk/itm/162414146757?var=461438635593

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Can you use an 10s or 12s BMS on an 8s pack? You just don’t connect up the extra wires right? It’ll still charge and discharge each cell to the correct voltage won’t it?

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Also, another question, is the AMP rating you get with most BMS’ discharge capability for each cell/ ‘s’ or the whole output overall?

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@Jinra did you have to order two from them or do they allow only one? I recall they put their lowest limit on 2 products but not sure.

EDIT: I did notice they are adjustable aswell as there seem to be different variants of the BMS with different overcharge voltages. Maybe you got the wrong one or voltage is just set low?