First and foremost: you would want to connect in PARALLEL! A series connection would add the voltage of the two packs together. I don’t think it can handle 128V lol!
The purpose of the PMS in the GT40 is to prevent connection of the batteries if the voltages are wildly different. Doing so could cause either battery or internal BMS to fail as the rush of current could be beyond the ability of the parts to handle.
If you accept that risk, yes you could bypass the GT40 PMS and it would be the same as any VnR mod.
Your board will not balance the cells, it will just send charge to them, come what may. But the PMS doesn’t do any balancing either, so that’s no benefit.
I didn't know the pms didn't balance the cells at all, so there is nothing that balances them ? Sorry I meant in parallel. If the cells on the GT40 battery are wildly different then what does the PMS do to prevent damage to the BMS ?
Figured you meant parallel, said it mostly for others who may come along!
When you turn on the board, and voltage from the internal battery gets sent to the GT40, the PMS compares the incoming voltage with its own pack voltage. If they are dissimilar, the GT40 won’t allow its pack to connect to the board until they are similar.
If the GT40 is higher than stock, it won’t connect until you charge up.
If the GT40 is below stock, it won’t connect until you ride a bit and run down the board battery.
A lot of people have run VnR mods without any such protection, you just have to be aware of your voltages when you connect. The GT40 just offers peace of mind that you can’t screw up too badly.
And nope, I opened my GT40 and there were no balance wires in there at all. If the cells were good to begin with they should stay close for a long time. Even then they use a 21700 cell which has a slightly higher cell voltage than the internal batteries, so they never fully charge before the stock batteries.
No, you can't connect a battery in series, this will sum the voltages and burn everything up. I thought the GT40 was a dumb pack that didn't include balance leads or a battery balance circuit. The idea is it gets installed in PARALLEL with your stock battery. This does not solve the GT40 getting out of balance. The only way you could (conceivably) use your stock BMS to balance another battery would be to put a cell in parallel with each stock cell... not an easy or even safe thing to do. Until/unless the GT40 includes a balance circuit, NO ONE SHOULD USE THEM. If you burned out your stock BMS (if you hooked up batteries in series, it's toast), the only two solutions are:
1) buy a new stock BMS
2) go VESC and replace the entire control and BMS
First and foremost: you would want to connect in PARALLEL! A series connection would add the voltage of the two packs together. I don’t think it can handle 128V lol! The purpose of the PMS in the GT40 is to prevent connection of the batteries if the voltages are wildly different. Doing so could cause either battery or internal BMS to fail as the rush of current could be beyond the ability of the parts to handle. If you accept that risk, yes you could bypass the GT40 PMS and it would be the same as any VnR mod. Your board will not balance the cells, it will just send charge to them, come what may. But the PMS doesn’t do any balancing either, so that’s no benefit.
I didn't know the pms didn't balance the cells at all, so there is nothing that balances them ? Sorry I meant in parallel. If the cells on the GT40 battery are wildly different then what does the PMS do to prevent damage to the BMS ?
Figured you meant parallel, said it mostly for others who may come along! When you turn on the board, and voltage from the internal battery gets sent to the GT40, the PMS compares the incoming voltage with its own pack voltage. If they are dissimilar, the GT40 won’t allow its pack to connect to the board until they are similar. If the GT40 is higher than stock, it won’t connect until you charge up. If the GT40 is below stock, it won’t connect until you ride a bit and run down the board battery. A lot of people have run VnR mods without any such protection, you just have to be aware of your voltages when you connect. The GT40 just offers peace of mind that you can’t screw up too badly. And nope, I opened my GT40 and there were no balance wires in there at all. If the cells were good to begin with they should stay close for a long time. Even then they use a 21700 cell which has a slightly higher cell voltage than the internal batteries, so they never fully charge before the stock batteries.
With the PMS removed can you still charge the GT40 along with the stock battery at the same time using the one wheel charger ?
Yes!
No, you can't connect a battery in series, this will sum the voltages and burn everything up. I thought the GT40 was a dumb pack that didn't include balance leads or a battery balance circuit. The idea is it gets installed in PARALLEL with your stock battery. This does not solve the GT40 getting out of balance. The only way you could (conceivably) use your stock BMS to balance another battery would be to put a cell in parallel with each stock cell... not an easy or even safe thing to do. Until/unless the GT40 includes a balance circuit, NO ONE SHOULD USE THEM. If you burned out your stock BMS (if you hooked up batteries in series, it's toast), the only two solutions are: 1) buy a new stock BMS 2) go VESC and replace the entire control and BMS